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April 1

Artificial nectar

constructing a bird feeder is one thing, now I need a recipe for nectar to supply it.Eg. Tui —Preceding unsigned comment added by Mike Penhey (talk • contribs) 03:26, 1 April 2009 (UTC)

Your local pet shop will sell all kinds of bird food. If you want to make it yourself, it would probably help to know what species of bird you are hoping to attract (at least, where you are). --Tango (talk) 03:58, 1 April 2009 (UTC)

He did say "e.g. tui" which would suggest: 1) He's hoping to attract tui (amongst other birds). 2) He's somewhere in New Zealand (at least I hope so since if the OP is in say Australia and hoping to attract tui I don't think we can help) Nil Einne (talk) 05:51, 1 April 2009 (UTC)

Nectar is usually mostly sugar water, so you could just dissolve as much white sugar in water as possible. Some birds are attracted to bright colors, so you might want to add some food dye, too, perhaps red. You might want to add some actual fruit juice to supply some vitamins, too, although that might make it more likely to spoil. StuRat (talk) 13:28, 2 April 2009 (UTC)

No, no, NO!!! There was a big hoo-ha here in Texas (where humming birds are relatively common - and people often put out feeders to attract them). People who are feeding them sugar water and (worse) artificially colored sugar water - were found to be killing off these poor birds in vast numbers because the birds are not getting all of the proteins, minerals and vitamins they needed - and at least one brand of artificial nectar contained a food coloring that's OK for humans - but toxic to humming birds. Most humming birds eat nothing but nectar - and if you provide them with a free supply - that's all they'll eat. So this is a very serious concern. There has even been talk of passing a law banning the sale of of hummingbird feeders and artificial nectar that does not contain everything that real nectar has. SteveBaker (talk) 14:16, 2 April 2009 (UTC)

I hate to disagree with my hero, but I think that Steve is wrong. Here is what one good source says: "The sugar water we use to fill hummingbird feeders is only a supplement to the birds' natural diet. It's not necessary to buy a commercial "nectar" mix that includes additional vitamins, protein, or other substances, because the birds get all they need from the flower nectar and insects they consume. All they want from us is the quick energy they get from ordinary white cane sugar. It's just fuel for chasing bugs, and causes no known health problems in hummingbirds, whose metabolism is significantly different from humans'." (hummingbirds.net)--Eriastrum (talk) 17:51, 2 April 2009 (UTC)

The Cornell Laboratory of Ornithology concurs that a sugar solution is not harmful. -- Coneslayer (talk) 20:00, 2 April 2009 (UTC)

And note that I did suggest adding some actual fruit juice to provide at least some of the missing nutrients. StuRat (talk) 17:37, 3 April 2009 (UTC)

Also, I'd expect that hummingbirds, like other birds and animals, will detect that they are deficient in some nutrient and become hungry for foods which have provided that nutrient in the past (say nectar from real flowers). This type of reaction is extremely important to the survival of the species, so I'd expect just about every species to exhibit it. Do we have an article on this ? StuRat (talk) 17:41, 3 April 2009 (UTC)

Ahem, Stu that doesn't even work for humans. We'll happily consume high calorie foods and run out of vitamins and minerals. Vitamin deficiency can make vegetarians who don't take supplements seriously ill after a couple of decades. If you want an animal model, cats will gorge themselves on cat food and may run out of taurine if their food doesn't contain that. (OR Even outdoor cats don't supplement their diet with sufficient amounts to offset that deficiency.) Survival of the species only has to keep enough individuals in reasonable shape to reproduce until they have done so. Over many generations natural selection will favor individuals most adapted to a certain diet, but it will just as easily wipe out populations when certain foods are unavailable. There are some mechanisms that evolved over time, like many species having a craving for salt. That can however lead to individuals being killed off by consuming too much salt if it becomes available in abundance. 76.97.245.5 (talk) 06:51, 4 April 2009 (UTC)

The mechanism I described certainly doesn't work perfectly, but does work to some extent. I find myself craving protein when I'm protein-starved. I imagine that vegetarians do, as well, but are unfortunately able to suppress that craving. StuRat (talk) 17:30, 5 April 2009 (UTC)

cell division

why division takes place in living cells only. —Preceding unsigned comment added by Muzhu (talk • contribs) 08:29, 1 April 2009 (UTC)

Hmm, as opposed to dead cells? Dead cells (and dead people) in general aren't very active. Please rephrase your question if you meant something else. ;) -- Aeluwas (talk) 08:41, 1 April 2009 (UTC)

(ec) Cell division requires co-ordinated expenditure of chemical energy to drive specific reactions to create specific proteins and nucleic acid chains. This metabolism cannot occur in dead cells. Axl ¤ [Talk] 08:43, 1 April 2009 (UTC)

Actually I was analyzing the Biology papers of 0-levels, i found this question and it asked for an appropriate answer, so I intended to know more appropriately that why only living cells tend to divide? —Preceding unsigned comment added by Muzhu (talk • contribs) 09:06, 1 April 2009 (UTC)

Isn't the reason that the very definition of "death" in a cell is its inability to divide? SteveBaker (talk) 17:55, 1 April 2009 (UTC)

I don't think that's the definition of death in a cell -- otherwise red corpuscles and neurons would be dead. Looie496 (talk) 18:00, 1 April 2009 (UTC)

And so would senescent cells. Algebraist 18:02, 1 April 2009 (UTC)

Damn! I forgot about that. OK - let me put it another way. A cell that can still divide is not considered to be dead PRECISELY BECAUSE it can still divide and hence must still be alive. Hence dead cells cannot by definition divide - and no further explanation of why that is can be made. SteveBaker (talk) 14:08, 2 April 2009 (UTC)

(for Looie or others) Just curious: by what definition are red corpuscles alive? --Scray (talk) 01:59, 2 April 2009 (UTC)

If we use the Conventional definition here, I'd argue that a RBC satisfies (1) homeostasis, (2) organization, and (3) metabolism pretty well - for 120 days or so. They really don't (6) respond to stimuli in a coordinated way, and the other three requirements clearly aren't met. I'd say RBCs are dead, they just don't know it yet. --Scray (talk) 02:07, 2 April 2009 (UTC)

That definition begins "Life is a characteristic of organisms...". Using that definition, anything that is not an organism cannot be alive. Axl ¤ [Talk] 08:32, 2 April 2009 (UTC)

Awesome! Now would you care to define "organism" without using the word "life" anywhere? SteveBaker (talk) 14:08, 2 April 2009 (UTC)

A collection of organelles which together can conduct homeostasis, metabolize, grow, adapt, respond to stimuli and reproduce? Cyclonenim :  Chat  18:06, 2 April 2009 (UTC)

Hehe! Our article begins: "an organism is any living thing...". The second sentence is (perhaps) more helpful: "organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole". Using this definition, we could argue that a von Neumann probe is an organism. ;-) Axl ¤ [Talk] 18:19, 2 April 2009 (UTC)

You appear to have missed the ability to organise and metabolize which are listed later on in the article, which von Neumann probes cannot do ;) Cyclonenim :  Chat  18:31, 2 April 2009 (UTC)

I respectfully disagree. The (theoretical) von Neumann probe does indeed organize both its own structure and that of its children. It needs to "metabolize" the raw materials that it encounters using chemical reactions to maintain itself and build children. Axl ¤ [Talk] 18:40, 2 April 2009 (UTC)

I respectfully embarrassed myself, then ;) Cyclonenim :  Chat  19:25, 2 April 2009 (UTC)

What came first, the chicken or the egg?

67.184.14.87 (talk) 08:45, 1 April 2009 (UTC)

I guess you could say the egg since the chicken evolved from a prehistoric bird species (actually according to our article two, Red Junglefowl and Grey Junglefowl) which laid eggs but we are unlikely to call chickens. Nil Einne (talk) 08:57, 1 April 2009 (UTC)

As I expected, this question has been discussed lots of times before (with basically the same answer), check the archives. We also have an article chicken or the egg. It gets more complicated if you ask: which came first the chicken or the chicken-egg or which came first, the bird or the egg? But since you didn't we don;t have to worry about that. Nil Einne (talk) 09:01, 1 April 2009 (UTC)

You'd have to make that "bird or bird egg", as many egg-laying creatures lived before birds, such as insects and reptiles. Still, under every possible interpretation of the Q, the answer is still that the egg came first, as the egg is genetically identical to that which hatches from it, but not to that which laid it. StuRat (talk) 13:17, 2 April 2009 (UTC)

You might like to know that for reasons I don't understand but am happy to follow, when you're offering people a question of dilemma, it's usually rendered "Which...?". Can anyone explain why? --Dweller (talk) 09:11, 1 April 2009 (UTC)

Because this is the current meaning of the interrogative adjective 'which', which used to be used as a fairly general interrogative, analogous to 'what', but is now restricted to (OED which 3) 'In limited sense, expressing a request for selection from a definite number: What one (or ones) of a (stated or implied) set of persons, things, or alternatives.' I don't know how these changes came about, but the OED, as ever, has many illustrative quotations. Algebraist 11:35, 1 April 2009 (UTC)

The mother of the egg that became the first chicken was not herself a chicken. So the answer is 'egg'. —Preceding unsigned comment added by 79.75.39.108 (talk) 00:37, 2 April 2009 (UTC)

The Easter Bunny, silly people. --jpgordon^∇∆∇∆ 00:41, 2 April 2009 (UTC)

Squirrel monkey behaviour

Can someone tell me if squirrel monkeys like doughnuts and use them for rituals? Simply south (talk) 11:23, 1 April 2009 (UTC)

Rituals??? (Incidentally, it's generally a bad idea to trust random comments you hear on radio) Nil Einne (talk) 13:09, 1 April 2009 (UTC)

I would not give them donuts. They are not good for people, I doubt they are good for monkeys. And you don't want to start a monkey cult. 65.121.141.34 (talk) 13:42, 1 April 2009 (UTC)

Well we know squirrels like nuts, so all we have to do is find a monkey playing with dough and and there are lots of recipes available for monkey bread, so just do some algebra and we're all set. DMacks (talk) 14:54, 1 April 2009 (UTC) DMacks (talk) 15:47, 1 April 2009 (UTC)

Yes, it is true, the use them for very complicated rituals concerned with choosing a partner. It is fascinating to see and there have been many questions asked about what they used before doughnuts were invented. The really, I mean really, odd thing is that they only carry out this ritual on one day in the year, Hmm? I wonder which date that is??!! —Preceding unsigned comment added by 86.4.190.210 (talk) 18:26, 1 April 2009 (UTC)

I believe that the scientific consensus is that the monkeys actually invented the doughnut 50,000 years ago, and that people adapted the monkey dating tool to a morning energy booster for police officers. 65.121.141.34 (talk) 18:52, 1 April 2009 (UTC)

Solar Eclipse

This is a question asked to me by my little sister and somehow i just couldnt give her a satisfactory answer... the question is... its said that a solar eclipse occours when the moon comes between the sun and the earth. But that happens so many times a year, so why don't we have that many solar eclipses each year??? —Preceding unsigned comment added by Rrkrish (talk • contribs) 13:15, 1 April 2009 (UTC)

Because that doesn't happen many times a year. For our article solar eclipse: 'The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the ecliptic). Because of this, at the time of a new moon, the Moon will usually pass above or below the Sun. A solar eclipse can occur only when the new moon occurs close to one of the points (known as nodes) where the Moon's orbit crosses the ecliptic.' Algebraist 13:22, 1 April 2009 (UTC)

The moon may come "Between" the earth and the sun once a month in a rough sense, but in order to have an eclipse they have to be exactly lined up in a straight line. That doesn't happen often, it's usually off a little one way or the other.

This might not be obvious on a flat drawing of the solar system, but if you consider the situation in 3d, it's pretty clear. (ie: if you draw the solar system on paper, you need to understand that not all the heavenly bodies are exactly on the paper, they might be a little above or below it.) APL (talk) 13:37, 1 April 2009 (UTC)

Also check out this illustration showing the relative size and distance of the Earth and Moon to scale. APL (talk) 13:46, 1 April 2009 (UTC)

The other point is that although total eclipses are fairly rare (because the earth/moon/sun system have to be lined up to a spectacularly precise degree) - partial eclipses of various kinds are about three times more common. There are typically around two eclipses per year - although in 2011, there will be four of them! The moon orbits the earth about 13 times per year - so the odds of it causing an eclipse is about one in every six times it passes roughly between earth and sun - which I think we can tell your little sister is actually "pretty common". However, you don't see them all that often because you have to be standing in the shadow of the moon to see them. Since the moon is rather tiny compared to the earth, its shadow is pretty small too - so the odds of you happening to be in the right place to see a partial eclipse is also surprisingly small. If you look at List of solar eclipses in the 21st century - you'll see that the next eclipse (in July) is only going to be total in Central and Northeastern India, Bhutan, Bangladesh, Myanmar, China and the Ryukyu Islands - if you don't live there - you won't see it (although it's also going to be a partial eclipse in Asia, the Philippines, Indonesia, Melanesia and Hawaii). SteveBaker (talk) 17:43, 1 April 2009 (UTC)

evolution or creation

why are we always taught that all the species that we see on the earth today have in some way or the other evolved from the ones that were there before them??? why aren't there any theories being taught today in schools and colleges that also stress on creation of life and different species by God, rather than by plain evolution?? —Preceding unsigned comment added by Rrkrish (talk • contribs) 13:19, 1 April 2009 (UTC)

Assuming that's true, it's probably because there isn't any evidence supporting the creation theories. See Creation and evolution in public education for more. Zain Ebrahim (talk) 13:27, 1 April 2009 (UTC)

Because it is not possible to prove creationism with science as an omnipotent being could reinvent the laws of science in any way to get stuff done, and science is built upon there being a set of rules that are assumed (and so far observed) to be immutable. 65.121.141.34 (talk) 13:41, 1 April 2009 (UTC)

There are lots of theories out there about all sorts of different things. Only the ones that have strong evidence on their side get to be taught in the schools. Theories about the origin of species are no exception. Dauto (talk) 15:05, 1 April 2009 (UTC)

In practice it is a bit more complicated than having strong evidence (see, for example, string theory—evidence is NOT the reason people think it is a good idea and why it gets taught at university levels). I think usually it is safer to just say that what gets taught in schools as "science" is that which the scientific community as a whole considers to be "science". Why they think this or that theory is more scientific than, say, another, can vary from theory to theory, field to field. --140.247.241.244 (talk) 16:47, 1 April 2009 (UTC)

Put more practically (no epistemological assumptions needed), public schools have for a long term determined that "science" needs to be taught in "science" classes. The idea of differently, uniquely created types of species by God is not considered by the courts or the scientists to be "science". There are some who disagree, but they have not been terribly successful in convincing people of that on the whole. "Evolution" is currently the explanation for speciation that is considered to be the most in line with "science". In "religion" classes they do read Genesis though they don't necessarily claim that it is actually "what happened" more so than they would for, say, the Koran, which they'd probably also read. --140.247.241.244 (talk) 16:44, 1 April 2009 (UTC)

You actually can be taught in public school that God created the different species, if you're willing to move to some of the most backward places on Earth. --Sean 16:58, 1 April 2009 (UTC)

Actually - you aren't allowed to teach "God did it" in public schools in Texas - that's still contrary to the US constitution. All you're actually allowed to teach is that evolution isn't necessarily a proven theory...which is still ridiculous...but the US constitution still applies, even in the Texas public school system. SteveBaker (talk) 17:09, 1 April 2009 (UTC)

Of course that is subject to interpretation. The constitution only says "Congress shall make no law respecting an establishment of religion", which according to a an originalist really says nothing about this matter. Sorry, this is getting a little tangential.-RunningOnBrains 17:20, 1 April 2009 (UTC)

Why pick only on evolution? We could be trying to teach students the formula for the period of swing of a pendulum as a function of it's length - and we'd have to keep stopping and saying "Unless God just decided to make up the evidence to make it seem that this is how a pendulum swings in order to test our faith". But then, that's just the christian god and the christian creation myth - in the interests of open-mindedness and skepticism - wouldn't we also have to teach the theories of all of the List of religions and spiritual traditions (check out that list...it's VERY long!). If we opened up the teaching of evolution to include creationism - wouldn't we also have to teach that the universe was farted out of the butt of a camel (or whatever it is that other people believe)?

The problem is that to teach science - you have to teach "The Scientific Method". That method says that all of science is the result of application of the Hypothesis/Experiment/Theory approach. The problem with creationism and intelligent design is that they quite utterly fail to use that approach. Hence they cannot be taught as "Science" because they really aren't at all scientific. But in the end - we teach evolution because it's true. We don't teach the other things because they are clearly a pile of steaming crap that doesn't stand up to the slightest scientific investigation! Frankly - if I were interested in pushing a religious POV - the very last thing I'd want would be to have scientists telling our children about it! They are going to have to teach that the creationism myth has no evidence leading toward it - that no experiments have been done to back it up - that there are a million pieces of rather impressive evidence that it's NOT true - that, far from answering the question of how all of this happened - it just creates another question ("How did God originate?"). Personally - I'd think you'd probably do better to avoid that happening and stick to teaching your poor kids all of this crap in the privacy of your own home/church/mosque!

Another problem: There are a literal infinite number of unprovable things that we could teach (See Russels teapot. If we tried to teach even 0.000001% of them - we'd have no time left to teach students what they actually need to know to become working scientists - to earn money - to make breakthroughs and generally be scientists. If a kid tries to get a job as a working scientist and it comes out in the interview that they don't consider evolution to be true - then they really aren't going to get jobs. That's not a matter of discrimination - it's a matter of survival in a modern science-laden world. There is simply no need to teach this other stuff in order to get the job done. If the religious fanatics out there need to push this stuff - then let them do so - but please - not while we're trying to teach teach kids science. SteveBaker (talk) 17:09, 1 April 2009 (UTC)

Sean, what evidence do you have that creation is commonly/usually taught as science in Iranian schools? While religious education is a compulsary part of education in many Islamic countries, including Iran and I presume the creation idea is taught there, my understanding, supported by our Islamic creationism and Creation–evolution controversy#Islamic countries is that the evolution-creation controversy has largely passed over the Islamic world until recently. The controversy appears to have started to take hold, particularly in Turkey. Our article mentions evolution is taught in Egypt, but banned in Sudan and Saudi Arabia (it doesn't however say that creationism is taught as science in either schools). Iran is not mentioned. Iran is not mentioned. However from [1] and [2] while not entirely clear, it appears to me that evolution is accepted and may in some instances be taught, provided it doesn't get to the point where it's considered in opposition to the Islamic teachings. It's definitely not clear that creationism is taught as science in Iranian schools. (Actually my gut feeling is that potentially nothing is taught). Nil Einne (talk) 10:23, 2 April 2009 (UTC)

Iran was not mentioned twice ? :-) StuRat (talk) 12:32, 2 April 2009 (UTC)

Sorry I striked that Nil Einne (talk) 17:33, 14 December 2009 (UTC)

Steve, you seem to be passionate about your arguments, but the fact that creationism is not scientifically provable does not translate it into being a complete pile of crap. It just means that it can not be proven scientifically. Science does not have all the answers, no matter how much some may wish it did. The key difference is that some think that science CAN get all the answers eventually, and others think that humans are rather arrogant to think that they can eventually understand and explain every phenomenon in the universe, past present and future. 65.121.141.34 (talk) 18:26, 1 April 2009 (UTC)

No - that doesn't really hold water.

Either...

You have to look at:

• All of those neatly arranged fossils - dated and arranged in timewise order, they show a clear progression of gradual change.
• The DNA evidence for common ancestry - all living things share large chunks of DNA in common - and where they differ, that follows the evolutionary chain that the fossils provide (eg Human DNA is more like Chimp DNA than Dog DNA - but all mammal DNA has more in common than all fish DNA).
• The demonstrable evolution of things in modern nature such as antibiotic-resistant bacteria in hospitals or warfarin tolerant rats in big cities - butterflies on remote islands, Darwins finches...you name it.
• The ability to demonstrate evolution in simulation and in laboratory experiment - if you set up a computer program that has creatures with simulated DNA, simulated mutation, simulated survival-of-the-fittest - then your synthetic creatures evolve just like real ones. If you take a bucket of bacteria and sequence their genes - then stress them with some toxin over many generations - then after a week or two, do a gene test on the survivors - then you can find the gene that mutated...the bacteria evolved - right there in front of your eyes.

and then, you must seriously ask: Does your theory have an explanation for ALL of these well-established easily demonstrable facts? (Evolution does - creationism certainly does not) - if it does not - then it's disproved because it doesn't explain the facts. Disproved is a lot stronger than "Not proved". If creationism were true then we would have human fossils of the same age as dinosaur fossils - and we don't...not even close. The efforts creationists take to weasel their way around these problems are flat out laughable in their lack of scientific rigor.

...OR...

You have to resort to the purely religious approach of saying "God put all of these bizarre things like fossils and DNA and warfarin-tolerance into the world in order to make weak-willed people believe in evolution as a test of their faith"...or something like that. In so doing - you are heading down a dark and dangerous path. Every time anyone raises any objection whatever to your theory you are now forced to say "God made it that way to test you - logic doesn't apply here". You can do that - and science certainly can't prove it's not true - but in so doing, you've shed any hope of a logical outcome to the debate - and you head down a road where you can't reason about the universe anymore. You can't build a bridge without having no clue whether it'll fall down or not - because you can't trust your math and materials science anymore...maybe God just put those there to test our faith too? What you have is religion, belief, faith and all that goes along with it...and you can't teach that in US public schools - because it is (quite rightly) illegal. In most school systems around the 'civilised' world, that kind of thing is moved out of science classrooms and into 'religious instruction' classes because parents of non-christian children have a right to NOT have their children indoctrinated by a bunch of raving loonies (as we atheists see you guys...let's be quite clear about that!). In the worst school systems in the world, religion gets taught to the exclusion of science - and I'd like for you to pause and look at the quality of life in those places - and ask yourself whether that's really where you'd like to go.

If you go with the former approach then the failure of creationism and the success of evolution to explain those things - AND have the predictive power that all good scientific theories should have - means that it is (objectively) a far less viable theory than evolution - and it should therefore be shelved and largely ignored...just as we have given up on the steady-state theory of the universe in favor of the Big bang because the former cannot explain the nature of the cosmic microwave background - and just as the big-bang theory may one day have to be shelved when we figure out what 'Dark energy' actually is.

If you go with the latter approach - then you have created for yourself an "unfalsifiable" theory - which means that science MUST ignore it because unfalsifiable theories are as firmly disallowed as dividing by zero in mathematics (and, interestingly, for similar reasons!).

So this is not simply a matter of "not yet having all of the answers" - it's a matter of having two competing theories - one of which fits the facts elegantly and perfectly - and the other of which either contradicts the facts and is therefore false - or is unfalsifiable and therefore not worthy of further consideration. Either way - evolution wins...just as the big bang wins over steady state and the periodic table of elements beat out the earth/air/fire/water theory of matter. When a theory is useless - we put it back on the shelf, stop teaching it to our kids and we move on. And that's PRECISELY what's happened here with creationism - it had a good run of several thousand years - but now it's as obsolete as flat earth theory, heliocentricism, astrology, etc. Of course there are always (and should always be) people who continue to defend the old theory for a while - we need a measure of skepticism. But there comes a point (and we're certainly WELL beyond that with evolutionary theory) where the evidence is so totally overwhelming that it's time to put creationism away along with lysenkoism and the theory that mice are created from bits of cheese and old clothing. Without some kind of evidence of ANY kind - it's simply crazy to keep beating that dead horse.

If you maintain that creationism "can not be proven scientifically" - then you are in the 'non-falsifiable' camp - and science simply doesn't teach non-falsifiable things. SteveBaker (talk) 20:39, 1 April 2009 (UTC)

Thank you Steve, you completely made my point. You can not disprove that which is not scientific, so that is why it is not taught in a science class. As an aside though, creationists don't usually go with God creating fossils and leaving them around fo people to find. Most of them believe that the geological record is not as constant as the majority of scientists believe and that the great flood found in the Bible buried them.65.121.141.34 (talk) 20:54, 1 April 2009 (UTC)

Actually, Steve did an excellent job disproving creationism as it contradicts all the available evidence, unless you want to subscribe to the idea of dishonest god(s) who plant fake fossils, etc. to trick mankind. I guess you can't disprove those god(s). But I'm not aware of any religion that actually subscribes to such a view so I guess one would have to invent one. A Quest For Knowledge (talk) 12:14, 2 April 2009 (UTC)

Yes. My point exactly. You either use logic to argue that creationism is possible - and find that science beats your crappy theory into a small mangled splat on the sidewalk of life...or you loudly assert that God can make fossils if he wants to - and that's that. I have met fundamentalist christians who first start down the "logical argument" path with me - and then when I actually have them cornered and convinced that they've run out of arguments, they ALWAYS fall back on the "Well, God just made it that way" argument. Typically this comes about roughly when you explain precisely WHY the dinosaurs couldn't have died out in the same flood that killed the Neanderthals and floated Noah's clearly impossible boat. Isaac Asimov said that violence is the last refuge of the incompetent. I think he was wrong about that - it's religion. When your brain is too tiny to accept all of the evidence with an open mind - and reason your way through it - it's just easier to sit back and say "God did it" in response to every difficult question. SteveBaker (talk) 14:02, 2 April 2009 (UTC)

Yeah - and that's just typical. They make that statement and then walk away without listening to the scientist's response. Firstly, if these prehistoric creatures all died at the same time and been buried in some amazing flood - then they wouldn't be found in rock strata organised by age. We find all of the early fish in one layer - all of the creatures that just climbed out of the water and onto the land in another layer on top of that - dinosaurs of various kinds in more layers on top of that - larger mammals on top of that. You can find all sorts of mineral deposits that let you see how the layers of compressed silt are separated by things like lava flows. You can see that those lava flows had then been eroded by thousands of years of wind and water - then more fossils in layers on top of that. This doesn't in any way fit with one single mass-extinction event. With more recent species we can do radio-carbon and other radioactivity datings. There are literally DOZENS of ways to disprove that crazy theory. However, the nut-job creationists don't want to hear any of that. As I said - if they submit themselves to the processes of scientific tests, logic and explanation - their theory evaporates - it's a joke. Only if they resort to "Because God did it" - can they escape that conclusion - and at that point, this is religion - and it doesn't belong in science classes. SteveBaker (talk) 00:38, 2 April 2009 (UTC)

There are versions of Creationism which purport to be as "scientific" as the real "science". They purport to have lots of evidence. Institutionally trained scientists almost always disagree with their evidence and disagree with their assertion that they practice the scientific method. Creationists can point quite validly to a large body of literature about scientific practice which has shown for some decades now that 1. scientists are not a "scientific" as they claim to be in such debates, 2. the line between "science" and "non-science" is often in the eye of the beholder, and 3. there really is no consistent "scientific method" that holds true for all fields of what is considered to be "science". Nobody is arguing about teaching everything (there aren't the resources)—the question is, with limited resources, what to teach? The Creationists believe there are good reasons to teach Creationism that go beyond simple careerism (in part because if the educational system changed dramatically the careerist approach would not be relevant—if everyone learned Creationism then it wouldn't be a way to sort it out). Now I'm no Creationist in the slightest but I don't think the debate is helped by appeals to a single Science with its singular Method and its unfailing adherence to Evidence and all of these concepts that are trotted out despite being quite problematic both in practice and in theory. It ends up being an argument against a straw man and a false dilemma when formulated in such terms. I think it's a lot easier to take an almost Wikipedia approach to it: in schools, we generally agree that in "science" classes "science" should be taught. The line between science and non-science should not be mediated by civilian school boards who don't have the necessary training or broad view in order to decide what the long-term consequences of such a decision would be. The most appropriate place for that sort of discussion to take place is probably with the established scientists who have brought us all those good things that we like about science enough to teach it anyway (which we can claim is about a love of knowledge, but in this society the number one reason we want institutionalized science training is because 1. science affects our world in massive ways, and 2. one of the main outgrowths of science is technology). So if you want to teach Creation "science" in schools, you've got the convince the scientists first that it is real science! --140.247.241.244 (talk) 17:21, 1 April 2009 (UTC)

From the scientist point of view the Evolution vs Creation is a very boring debate. The creation side has nothing going for it. No evidence at all. None. Zip. Nill. Zero. That makes the decision wheather to teach creation or not a very trivial matter indeed. Dauto (talk) 01:44, 2 April 2009 (UTC)

Let's consider what happens if Biblical Creationism were to be taught as science. In addition to being taught as an alternative to Evolution, there also would need to be Biblical alternatives to teach plate tectonics and geology, as the current scientific approach requires the Earth to be far older than the Bible would indicate. Similarly, the rate of nuclear decay would need some alternative explanation in chemistry class, to prevent carbon dating, etc., and the speed of light would need to be altered in astronomy class to allow light to reach us from stars very far away in a universe that's not old enough to permit that. Moving on to social studies, we would need to move the first humans from Africa to "Eden", wherever that is, and make all languages form at once (tower of Babel), rather than when they actually did form. And, if only God can create different languages, and does so to confuse mankind, we need an explanation for why languages change over time, or else we need to deny that they do, and insist that Shakespeare was using the exact same words that we use now. If great floods and other natural disasters are also used by God to punish people, we need a class that teaches exactly what sin each natural disaster was created to punish, and how we can therefore prevents disasters by repenting rather than building levies, clearing flammable underbrush, etc. StuRat (talk) 12:58, 2 April 2009 (UTC)

The folks who are writing the new Texas public school science books are here - taking notes - and would like to personally thank StuRat for this comprehensive guide to how they should be updating the 2010 editions. Awesome - excellent - thank you!

There is no doubt that once you start to doubt the findings of mainstream science - it's hard to stop with evolution. As I explained before - you get to a point where no scientific explanation whatever can be considered entirely valid - and at that point, you can't do engineering anymore. If you want to build a bridge - you can't trust materials science - so your calculations on the stresses involved are essentially worthless. But that's OK because when the bridge collapses, you can just say it was "The will of God" - and there was just nothing anyone could do. I always find it amusing that property insurance covers "Acts of God"...I always wonder whether they should take into account my blameless and relatively sin-free life when setting the premiums!

For me, personally, God (and gods in general) are precisely as believable as Santa Claus, the Easter Bunny and the Tooth Fairy. Seriously basing how I teach science on the premise that somewhere there are flying reindeer and a sleigh that can deliver toys to all of the children of the world in one night - is PRECISELY as ludicrous as teaching creationism. There is truly no distinction in the scale of lunacy involved. I'm pretty sure that almost all religious people would be very upset if teachers in public schools started teaching their children that Santa Claus was real and that they WILL be getting free stuff delivered down the chimney on Xmas eve - and that the Tooth Fairy literally does come in the middle of the night and swap out that tooth for a nickel. They should consider my (identical) position when (as an Atheist) I demand that they do not inflict their pile of steaming bullshit on my child. SteveBaker (talk) 13:48, 2 April 2009 (UTC)

I can comprehend your viewpoint without the need for profanity. I request that you strike it from the record and refrain from such comments in the future. There may be children present. 65.121.141.34 (talk) 18:57, 3 April 2009 (UTC)

Two problems with that:

1. As a matter of policy Wikipedia does not censor for the benefit of children or otherwise - and I think children (even quite religious ones) are completely aware of what 'steaming bullshit' is - it comes out of bulls - and it steams. And just in case they don't, I should explain that it's "moo-cow poop" kiddies!
2. The entire concept of "profane language" is meaningless to an atheist. The definition of 'profane' (according to Wiktionary) is:

1. Unclean; ritually impure; unholy, desecrating a holy place or thing.
2. Not sacred or holy, unconsecrated; relating to non-religious matters, secular.
3. Treating sacred things with contempt, disrespect, irreverence, or undue familiarity; blasphemous, impious. Hence, specifically; Irreverent in language; taking the name of God in vain; given to swearing; blasphemous; as, a profane person, word, oath, or tongue.

I'm fully in favor of verbally desecrating things that are complete nonsense. I'm more than happy to be 'non-sacred' and 'un-holy' and I most certainly do intend to continue to treat "sacred things" with contempt, disrespect...etc. I do not intend to give religion of any kind any respect whatever - it's nonsense and I intend to continue saying that because to do otherwise would be dishonest - and I value honesty. Hence profane language is a goal - not something to apologize for. SteveBaker (talk) 21:05, 3 April 2009 (UTC)

Some might claim that the scientific explanation of the origin of the universe is equally ludicrous considering there is no explanation given for where the energy to create the big bang originated, especially considering that some scientific principals Conservation of energy, Conservation of mass state that neither energy nor mass can be created or destroyed. If there is an explanation for the spontaneous generation of energy and mass from nothing using current scientific laws, I would be most interested in reading it. 65.121.141.34 (talk) 16:16, 2 April 2009 (UTC)

If that bothers you - then you don't understand the theory. The big bang created spacetime as well as all of the matter. There is no "before" because time itself starts at the big bang. That's not just a 'theological matter' as you'd say if I asked where God came from - it's actually what the math and the physics say must have happened given the evidence that is everywhere around us. And it's an elegant solution because it answers the entire set of questions that you're asking. May I recommend reading "A brief history of time" - by no less than Stephen Hawkins himself. It's a short and easy read and it covers this exact point rather well in language that the layman can understand. SteveBaker (talk) 20:26, 2 April 2009 (UTC)

But certainly the idea is correct, that neither science nor religion can completely explain everything. We get down to "did God always exist or was he somehow created ?" or "what are strings made of ?". You could always push the question back a bit farther, by creating an earlier race of gods or explaining what strings are made of, but there's always another "then what caused that ?" question to be added. StuRat (talk) 17:30, 3 April 2009 (UTC)

The fact that there are no current scientific explanations for some things does not invalidate the scientific explanations that do currently exist. The one disadvantage that Science has in arguments with Religion is Science's willingness to say "I don't know" in response to the question "Why?"

Of course, that is ultimately to Science's advantage, as it then toddles off to find the answer. - Eron^Talk 16:45, 2 April 2009 (UTC)

It's not even that - certainly, when presented with something we don't know, we say "Hold on while I find out" (which might take an hour or perhaps a century or two). But more importantly, when we do find that one of our theories is proven wrong, the overwhelming response is "OH! COOL!". We love nothing more than to have our world overturned by something freakishly unlikely that has somehow gotten strong evidence for it. This doesn't happen when creationism challenges evolution because it doesn't overturn anything - it just turns out to be wrong. But when (for example) the rate of change of speed of the Voyager probe as it leaves our solar system is not what we expect - we don't try to hush it up because it messes with out theories - we leap out there and excitedly start looking for seemingly bizarre explanations and things that might point to new forces or a new understanding of gravitation. The most exciting moments for most scientists are when experiments don't come out the way we expect - because that's when we learn something new. SteveBaker (talk) 21:16, 2 April 2009 (UTC)

Hot water for drinking

Why don't we like warm water for drinking, whereas it is very pleasurable to use warm water while taking shower and warm food to eat? Is there some role of evolution? - DSachan (talk) 14:26, 1 April 2009 (UTC)

Because we associate warm-water with standing-water. I would expect it is quite cultural rather than evolutionary. We associate ice-cold water with freshness/quality (as in drinking water quality) - we associate tepid water with standing/stale water, and we associate hot-water with hot-drinks, though plenty of people drink hot-water as a drink (at least where i'm from). 194.221.133.226 (talk) 14:56, 1 April 2009 (UTC)

I know a lot of people who drink hot water, in preference, say, to tea or coffee. (And I don't associate warm water with standing water.)--Shantavira|^{feed me} 15:52, 1 April 2009 (UTC)

Mind your "we"; it's totally cultural. In Great Britain, if you ask for "a glass of water", you will most likely get a glass of room-temperature water. You have to ask for ice specifically, and if they have any you'll get it, but it's considered a slightly special request. —Scheinwerfermann ^T·_C16:03, 1 April 2009 (UTC)

Where, here in the US, you typically get water with ice in it - whether you want it or not - and it may be a major struggle to NOT have ice in your Coke when you go to some fast-food place. SteveBaker (talk) 16:45, 1 April 2009 (UTC)

Most of the taste of pure water comes from dissolved oxygen, and warm water has a lot less than cold water. Looie496 (talk) 18:04, 1 April 2009 (UTC)

I'm not sure about Schein's comment - generally if you ask for a glass of water in the UK the host will run the tap until the water is cold (i.e the water in the the house's pipes has been purged and the water is fresh from the main) - while not ice cold it's certainly colder than room temperature. Exxolon (talk) 19:34, 1 April 2009 (UTC)

Are we talking about hot water say 45C which is disgusting, or warm water, say 25C which is fine? Also, I have noticed that if you boil water and then cool it, it still tastes funny. —Preceding unsigned comment added by 65.121.141.34 (talk) 19:11, 1 April 2009 (UTC)

That follows naturally from Looie496's comment - when you boil water, you drive out the dissolved oxygen - so afterwards it tastes 'flat'. SteveBaker (talk) 19:53, 1 April 2009 (UTC)

The concept is likely much more than cultural; clearly people all over the world from various times and places prefer hot or cold water to tepid water. Consider this 2000 year old text; "I wish you were either one or the other! So, because you are lukewarm—neither hot nor cold—I am about to spit you out of my mouth." The original Greek uses the word for "Vomit" in the place of "spit out"... Clearly tepid water as disgusting was a well known concept; otherwise this analogy would have not been so easy... --Jayron32.talk.contribs 21:56, 1 April 2009 (UTC)

Although many Christians would like to believe the bible is universally applicable, I'm not convinced that its use here indicates anything other then it being applicable to the culture of those who wrote it. Also in terms of the cooled hot water, it is common practice and often recommended to boil your tap water before drinking. So I used to drink cooled or cold tap water all the time and to be honest I've never noticed anything odd about the taste. Nil Einne (talk) 09:55, 2 April 2009 (UTC)

I've been told that vigourously shaking water after boiling it will re-oxygenate the water and eliminate the "flat" taste. - Eron^Talk 16:46, 2 April 2009 (UTC)

Maybe cold water (with ice) is less favored in Britain because it has a colder climate? All but the northernmost parts of the US are pretty hot in summer. 128.194.103.37 (talk) 13:27, 5 April 2009 (UTC)

schrodinger's time independent equation

in the relation of time-independent schrodinger's equation

            ∆^2Ψ + 2m/(ħ^2)[E-V]Ψ  = 0                                              -(1)

there appears a "E" in (E-V),which is kinetic energy of the particle. but if we take the kinetic energy of any particle executing some non-uniform motion,how can be the kinetic energy independent of time? since kinetic energy of any particle can be expressed as

                       E=1/2(mv^2);

where,

           m = mass of particle
           v = velocity of particle

if a particle executes non uniform motion its velocity and hence kinetic energy will depend upon time and the the whole equation seems to be dependent on time.

for a particle, its total energy E(total) can be expressed as sum of its kinetic energy as well as potential energy,which is independent of time.

               Et = E + V

where,Et = total energy of the particle

     v= potential energy of the particle

so, E = Et-V -(A)

Making this substitution in the schrodinger's equation, we get

                         ∆^2Ψ + 2m/(ħ^2)[Et-2V]Ψ  = 0

this equation is totally independent of time, making schrodinger's expression independent of time —Preceding unsigned comment added by Sachin nishchal (talk • contribs) 17:15, 1 April 2009 (UTC)

1. If you have seperated the time-dependent Schroedinger equation then the E which appears in the time-independent equation cannot depend on time. So, I'd say this rules out from the start a lot of what you go on to say.
2. E in the time-dependent equation is the total energy. Not the 'kinetic part' as I think you suggest.
3. Due to the subtleties of what can be known simultaneously (a la Heisenberg), it's not true that you can seperate the energy into a kinetic part and a potential part for most systems. (In light of this, how would that affect your definition of E in terms of v?)

I realise I wasn't comprehensive but there are some comments to get you started at least. 86.140.160.93 (talk) 19:56, 1 April 2009 (UTC)

Yes, indeed the 'E' that shows up at Schroedinger's time independent equation is the total energy. Dauto (talk) 02:49, 2 April 2009 (UTC)

Genetics Question

A brown-eyed man whose mother is colorblind and whose father had blue eyes is engaged to marry a woman whose colorblind mother had blue eyes and whose normal visioned father had blue eyes. What is the Genotype of the young man? Of his fiancee? If they marry and have children, what are the chances of having a brown-eyed, normal visioned child? A blue-eyed, colorblind child? A brown-eyed normal visioned daughter? A blue-eyed, colorblind son? —Preceding unsigned comment added by 198.85.212.10 (talk) 17:17, 1 April 2009 (UTC)

I added a section header for you. APL (talk) 17:29, 1 April 2009 (UTC)

Looks like a homework problem, and we don't do those. Looie496 (talk) 18:09, 1 April 2009 (UTC)

Isn't colour-blindness a male trait, so this is an unusual situation to find yourself, likewise eye colour isn't based on a single gene... But nevermind, read the through the question and draw a family tree, although I think you probably need more infomation. —Preceding unsigned comment added by MedicRoo (talk • contribs) 18:32, 1 April 2009 (UTC)

Colorblindness is mostly male because the most common form is X-linked recessive. Looie496 (talk) 18:41, 1 April 2009 (UTC)

(ec) No, color-blindness is (most commonly) a recessive trait on the X chromosome, meaning it is apparent more often in males (since they don't have a second X chromosome to "override" the trait). This question has "homework" written all over it—specifying the mothers are colorblind is a convenient way to fully-indicate their genes ("normal-vision" could mean they have 0 or 1 colorblind gene). To solve it, consider each "trait" (colorblindness, eye color) independently, find the genes of the parents, their children, then prospective offspring. Your book will most likely have example problems similar to this one. If you get stuck, explain where you're at and what you're having problems with and we might be able to help, but we won't do your homework for you. – 74  18:54, 1 April 2009 (UTC)

Briefly, your teacher apparently wants you to assume that eye color is determined by a single gene (not true, but I guess close enough for government work) at which "brown" is dominant and "blue" is recessive, and also wants you to assume that the kind of color-blindness he's talking about is X-linked recessive.

With these assumptions:

A brown eyed person with a blue eyed parent must have inherited a blue allele from that parent, and a brown from the other.

A person with a color-blind mother must have inherited her color-blindness gene, because she must have it on both X chromosomes or she wouldn't be color-blind; a man only has one such gene, so all her sons will necessarily be colorblind. A woman with a color-blind mother inherits a color-blindness gene from her, but also inherits a gene from her father, and in this case, he's not color-blind. So the financee is heterozygous for color-blindness.

A person with blue eyes necessarily is homozygous for "blue" eyes (the information about the fiancee's parent's eye color is unneeded; you know her genotype because you know her phenotype, because only one genotype produced that phenotype. You'd need to know the parent's eye colors if her eyes were brown, because more than one genotype produces that phenotype.)

So, using BLUE/BROWN and CB (for colorblind) and N (for not-color-blind), and - for no gene at all:

groom = BLUE/BROWN; CB/-

bride = BLUE/BLUE; CB/N

	BLUE	BROWN
BLUE	BLUE/BLUE = blue	BLUE/BROWN = brown
BLUE	BLUE/BLUE = blue	BLUE/BROWN = brown

If you make a Punnet square, you will see that you would expect half the couple's children to be blue-eyed, and half to be brown-eyed.

The colorblindness question is probably most easily explained if you consider where a person's X chromosome comes from. Men have one X chromosome, and it comes from their mother. So all sons of this couple will be color-blind. Women have two X chromosomes. One of them is from their father, and the other is a mixture of their mother's X chromosomes. Since one gene is enough for normal color vision, and she is certain to get one of these from her father, all daughters of the couple will have normal color vision.

To work out the chances, you have to realize there are only two independent traits of the three: eye color is independent, color vision is dependent on sex. All daughters will have normal color vision; all sons will be color blind.

So, the chances of any particular child being:

a brown-eyed, normal-visioned child: 50% chance of brown eyes, 50% chance of being female => 25%

a blue-eyed, colorblind child: 50% chance of blue eyes, 50% chance of being male => 25%

a brown-eyed, normal visioned daughter: 50% chance of brown eyes, 50% chance of being female => 25%

a blue-eyed, colorblind son: 50% chance of blue eyes, 50% chance of being male => 25%

The chance of:

a brown-eyed, normal-visioned son: 50% chance of brown eyes, 0% chance of being male with normal vision => 0%

a blue-eyed, colorblind daughter: 50% chance of blue eyes, 0% chance of being female with colorblindness => 0%

- Nunh-huh 11:30, 2 April 2009 (UTC)

I thought we weren't supposed to answer homework questions here... 74 already gave enough information to get the right answer. That being said, I would agree with the genotypes given by Nunh-huh above, and the eye color calculations are correct, but the color-blindedness conclusions are wrong. It was correctly stated that the man in this relationship is heterozygous for blue/brown eye color and hemizygous for the colorblind mutation on the X chromosome (i.e. he's affected, but the questioner wanted you to deduce that from the fact that his mother is colorblind). It was also correctly stated that the female in this relationship is heterozygous for the colorblind mutation because her father was colorblind and she is therefore an obligate carrier.

Here is where the problems start: "Men have one X chromosome, and it comes from their mother. So all sons of this couple will be color-blind" - only if the mother is affected. In the couple we're talking about here, the mother is a carrier and hence has a 50/50 chance of passing the colorblind mutation to each child. Therefore, all male offspring (who inherit their father's Y chromosome) have a 50% chance to inherit the colorblind mutation from their carrier mother and thus be affected and a 50% chance to inherit the normal copy of the gene and thus be unaffected.

"Women have two X chromosomes. One of them is from their father, and the other is a mixture of their mother's X chromosomes. Since one gene is enough for normal color vision, and she is certain to get one of these from her father, all daughters of the couple will have normal color vision" - only if the father has normal vision. In this example, he's colorblind and therefore all of his female offspring MUST inherit the colorblind mutation on his X chromosome. However, since the mother is ALSO a carrier, they have a 50% chance to inherit the colorblind mutation carried by their mother, making them homozygous for the colorblind mutation and thus affected, and a 50% chance to have inherited the normal copy of the gene from their mother and thus be unaffected but carriers of the mutation.

"To work out the chances, you have to realize there are only two independent traits of the three: eye color is independent, color vision is dependent on sex" - well, sort-of... eye color in this example is an autosomal trait and colorblindedness is X-linked. Color vision depends on the number of X chromosomes you have and whether or not you have any normal copies of the color vision gene. It is possible for a female with Turner syndrome (i.e. only one X chromosome) to be colorblind if she inherits a mutation of the colorblind gene from her mother, and it is possible for a male with Klinefelter syndrome (i.e. XXY) to have normal vision if he carries one mutated copy and one normal copy of the gene. Granted, these are extreme examples but they illustrate the point. "All daughters will have normal color vision; all sons will be color blind" Not exactly. The question posed by the OP's presumed homework question is also another extreme example meant to illustrate a point. In this case, the sex of the offspring doesn't matter in terms of the % chance of having an affected child (50%) because both parents have a copy of the colorblind mutation.

I'm sure the OP can multiply the probabilities together to get the correct answers to the last parts of the question. Hopefully working through the problem will help the him/her understand the concepts rather than just spitting back answers provided by strangers on the internet... --- Medical geneticist (talk) —Preceding undated comment added 22:41, 2 April 2009 (UTC).

An extraordinary delusion

Does there exist a delusion in which the sufferer believes himself or herself to be the same person as another specific individual(say, a celebrity), and living a double life? Like the Fregoli delusion except that the delusional person identifies himself as one of the "imposters". 69.224.37.48 (talk) 18:04, 1 April 2009 (UTC)

Do you mean something like Syndrome of subjective doubles? 152.16.16.75 (talk) 02:00, 5 April 2009 (UTC)

Nicotine concentrations of cigars?

Hi all. I am trying to find a page.. somewhere that gives the nicotine concentrations of different cigar brands, but I am not having any luck.. most of my searches lead me to nicotine concentrations of cigarettes, or FAQ's about cigar smoking.

Much help appreciated ! 98.242.86.119 (talk) 18:13, 1 April 2009 (UTC)

(Subscription required to access the article) This study "examined characteristics relating to nicotine delivery of 17 cigar brands..." 152.16.16.75 (talk) 23:36, 5 April 2009 (UTC)

Chemistry and lock?

16:41, 8 April 2009 (UTC)bsm (=bimellahalrahmanalrahim) We must draw a plan for hacking door`s look that relate to chemistry any way, at least a little relation. we saw very ways but there are physically, completely. if there is any way or starting point?80.191.15.10 (talk) 16:41, 8 April 2009 (UTC)

Chlorine gas

Will chlorine gas react with water vapor to create HCl? 65.121.141.34 (talk) 19:28, 1 April 2009 (UTC)

I'm not sure if this applies to gaseous water, but yes in general: [3] Cyclonenim :  Chat  19:53, 1 April 2009 (UTC)

Adding impedances

I'm not sure if this question is in the right category, but there isn't a "tech" category.

I am wanting to build a speaker cabinet for my guitar amp head. The head has an output impedance of 16ohms - but the speakers I am looking at have an 8ohm input impedance. I know I could add an 8ohm resistor in series with the speaker, but I don't want to lose any of the power.

How do I connect two 8ohm speakers together so that they become one input with a 16ohm impedance?

I think that if I wire both "hot" wires from the speakers to the "hot" of the input, this would be them connected in parallel - which I think (only think) will half the overall impedance.

Also, what is the equation to work out what frequency a value of a capacitor will allow an AC signal through? This isn't worded very well, but I am trying to figure out how I could divert the higher frequency signals to a tweeter, mid range to a mid speaker and low frequency to a bass speaker. I know this may screw up the impedance calculations - and if so, I may not bother with it - but could you let me know it anyway.

Any help is appreciated! —Preceding unsigned comment added by 81.153.145.76 (talk) 20:02, 1 April 2009 (UTC)

Resistances and impedances add in series—"cold" on the first speaker connected to the "hot" on the second, with the remaining wires connected to the respective source lines. On the second part, you want a high-pass filter, band-pass filter, and low-pass filter. You could construct them yourself, but they generally aren't all that expensive. – 74  21:58, 1 April 2009 (UTC)

Audio crossover should give some help on the second point —Preceding unsigned comment added by 79.75.13.2 (talk) 22:21, 1 April 2009 (UTC)

Thanks for the tip on connecting the cold on speaker 1 to the hot on speaker 2. I just remembered some stuff I forgot to ask - What could I do to up the impedance with only one 8ohm speaker? Can I use a ferrite toroid(inductor) instead of a resistor? And how do I measure the impedance? Can I use the resistance setting on my multimeter? —Preceding unsigned comment added by 81.153.145.76 (talk) 16:00, 2 April 2009 (UTC)

It would be easier to get a different amplifier, or modify the one you have. With the current technology speakers cost more than amps. If you promise to only go to half power you should be able to run your 8 ohm speaker from your amp with out anything blowing in the amp. An ohm meter will not measure the impedance of your speaker, as it is actually working at audio frequencies. When the speaker is driven to move by the power applied, it gives a back EMF, so that not all the power goes to heating the resistance, but instead goes into moving the cone back and forwards. You will need to measure using an AC source. In practice your meter probably cannot do that, so you may just have to use the meter in AC measurement mode, connect it to an amp and play something with a constant volume (say an electronic organ note), then measure the AC current and the AC voltage. Graeme Bartlett (talk) 20:34, 2 April 2009 (UTC)

I believe you want to use a 2:1 transformer, not an inductor or resistor. 75.62.6.87 (talk) 22:38, 5 April 2009 (UTC)

Ancestry

http://en.wikipedia.org/enwiki/w/index.php?title=Wikipedia:Reference_desk/Science&action=edit&section=46 What is the approx. percentages that there might be Eqyptian or Mongolian or African ancestors in my family tree if both my parents are the everyday US causasian people? They are not sure but one parent says they have Irish great parents and the other parent says English Canadian great grandparents. I think it's facinating when someone says that they have an exotic ancestor. --Reticuli88 (talk) 20:17, 1 April 2009 (UTC)

Depends from where you start, Human are meant to have originated in Africa about 200,000 years ago, so everyone had 'African' ancestry. From there people have travelled around a bit and as 0.5% of the worlds population are descended from Genghis Khan[4] it is entirely possible if you had any Asian ancestry it is possible you would have a Mongolian blood. In that way everyone has exotic ancestry, probably best to do a bit of research into your family tree. Irish ancestry tends to be a heady mix of Viking, Anglosaxon and Norman, but a lot of migration has occured over the years so that itself doesn't mean that much... MedicRoo (talk) 20:34, 1 April 2009 (UTC)

Irish ancestry would surely suggest predominantly Celtic descent before those other possibilities you mention. --ColinFine (talk) 23:54, 1 April 2009 (UTC)

You might find the Passing (racial identity) article interesting. Grantus4504 (talk) 09:38, 4 April 2009 (UTC)

Strength of human hair

What is the tensile strength of human hair and can it be made higher by using certain hair products? Also, what does the phrase 'stronger feeling hair' mean? Ive seen this on a TV advert. —Preceding unsigned comment added by 79.75.13.2 (talk) 22:14, 1 April 2009 (UTC)

TV cosmetics adverts are amongst the worst examples of poor science you'll see out there in the real world. So "stronger feeling hair" is probably ad-speak for "not stronger at all". But they are more than happy to use excessive precision - to make statements like "57% more shine!" - without saying 57% of what? 57 percent more than filthy, dirty hair is not impressive. 57 percent better than your leading competitor might be. But "shininess" is a vague property. The amount of light reflected isn't the only thing - plastics can reflect a lot of light - but they don't look as shiney as metals because they reflect it over a wide range of angles...so are they talking 57% more 'reflectivity' or a 57% sharper lambert coefficient. As for the strength numbers...first be aware that according to our Hair article, human hair varies in diameter 17 to 181µm. Since strength is likely to be proportional to cross-sectional area - you'll probably find that there is at least a factor of 100 between the weakest human hair and the strongest. Several sources I found suggest that a single human hair can support a weight of about 100 grams. [5] talks about strengthening hair and suggests that it's possible - but also that it's still a research topic. I strongly doubt that existing haircare products have any significant impact on the strength...but it is at least possible. SteveBaker (talk) 23:37, 1 April 2009 (UTC)

Just for comparison, and probably not from a very reliable source, but I read that human hair is "stronger" (in what way?) than aluminum. ~AH1^(TCU) 00:47, 2 April 2009 (UTC)

Of course, there are many kinds of strength. There's compressive strength, tensile strength, shear strength, elasticity, hardness, plasticity, toughness. etc. etc. --Jayron32.talk.contribs 00:55, 2 April 2009 (UTC)

Those ads may not mean tensile strength at all, but rather resistance to being pulled out of the follicle or forming split ends. A scientist wouldn't call this "strength", but they aren't scientists, are they ? The reason I doubt that they mean tensile strength is that this is rarely a problem, in my experience. How many people have hair that breaks in half ? StuRat (talk) 12:09, 2 April 2009 (UTC)

Ah - yes, that makes more sense. A more straightforward: "Our product helps to stop your hair from falling out." would get them into a lot of legal trouble - and wouldn't help sell the product to people with a full head of hair. But as I said - science and clear language is not the strong point of people selling stuff for cosmetic purposes. SteveBaker (talk) 13:26, 2 April 2009 (UTC)

Hair follicle actually has more info on the structure of hair than the hair article does. Hair is made up of 3 layers. The outer cuticle layers are 6 to 10 layers of dead cells arranged in a scaly overlapping pattern like roof shingles. In healthy hair these ce3lls lie flat together. IF you treat hair with an alkaline substance the scales will lift and your hair will become less shiny and will break easier. (People who dye their hair and those with certain health defects or nutritional deficiencies have hair that breaks easily.) Acidic substances make the scales lie flat. The next layer is the inner cortex. It's made up of bundles of lots of keratin fibers. They are interconnected with sulfur bridges and embedded in a keratin matrix that determines the tensile strength and flexibility of the hair. The innermost part, the medulla contains waste materials and fat substances. Healthy follicles will also produce sebum to coat the outer hair. That will protect the hair. You can replace this layer with waxes or silicone substances after it got washed off. Hope this helps. 76.97.245.5 (talk) 04:38, 3 April 2009 (UTC)

I once saw three girls on the subway having a hair contest. Each pulled out one of her own hairs. The brunette's hair broke that of the redhead, and the redhead's hair broke that of the blonde, when the girl held a piece of her hair tightly between fingers and pushed it against the other girl's hair until one hair broke. So "stronger" hair might mean "brunette" hair. (I seem to recall also an old possible unrelated engineering term relating colors of some type of hair and closeness of adjustment. This terminology implied that blond hairs were smaller in diameter than red hairs). Edison (talk) 04:58, 3 April 2009 (UTC)

There is certainly a very large range of hair diameters (our article suggests a 10:1 ratio between the thickest and thinnest). The article I referenced up above says that Asiatic hair tends to be a LOT stronger than European hair. 12:46, 3 April 2009 (UTC)

I've noticed that there seems to be more of a gender difference in Oriental hair. That is, men's hair tends to be much thicker, stiffer, and stronger than women's. I don't believe that this pattern holds, to the same extent, for European hair. StuRat (talk) 17:19, 3 April 2009 (UTC)

Does studying actually improve IQ scores?

Taking a degree makes you more knowledgeable, but does it also raise your score in IQ tests? 89.242.107.39 (talk) 23:18, 1 April 2009 (UTC)

In theory - no. In practice - probably, yes. If nothing else, there is good evidence that doing lots of IQ tests can improve your score significantly. SteveBaker (talk) 00:45, 2 April 2009 (UTC)

Since most IQ tests are written, having good written language comprehension (in the language used on the test) would be important, and you can improve that with study. StuRat (talk) 12:02, 2 April 2009 (UTC)

Are there any research papers available about this? I was waiting for someone to mention of London taxi drivers whose brains develop to allow them to memorise all the streets. Although with Satnav, sadly that tradition may be in danger. 89.243.219.134 (talk) 17:47, 2 April 2009 (UTC)

That would be "The Knowledge". London cab drivers are required to memorize the entire map of London in exquisite detail in order to get their licenses. Some of the things they need to know - such as traffic patterns at various times of day - are not covered by GPS navigation systems - so it's likely that this tradition will stand for a while yet. It's also a way for the established cab drivers to limit the amount of competition they have to face. SteveBaker (talk) 20:17, 2 April 2009 (UTC)

One problem is the reliability of IQ tests. I've seen a lot of self-proclaimed "IQ tests" filled with questions about sports and movie trivia. --79.116.90.132 (talk) 17:32, 3 April 2009 (UTC)

In such cases, it's still a valid IQ test, just one that's used to judge the IQs of the test-makers, rather than the test-takers. :-) StuRat (talk) 17:13, 5 April 2009 (UTC)

April 2

Hominidae?

In layman's terms, how can one easily distinguish Hominidae (humans, bonobos, chimps, gorillas and orangutans) as different from other primates (or other mammals in general)? Do they have certain easy characteristics that set them apart from other primates? Maybe their weight?--Sonjaaa (talk) 00:20, 2 April 2009 (UTC)

According to the article, distinguishing characteristics include the absence of a tail, and sexual dimorphism (males larger than females in this case). ~AH1^(TCU) 00:44, 2 April 2009 (UTC)

And, of course, they are more intelligent. For example, there's the test of leaving a series of boxes on the floor and a banana hanging from the ceiling, where the more intelligent primates can figure out how to stack the boxes to get to the food, while less intelligent primates can't. StuRat (talk) 11:54, 2 April 2009 (UTC)

Oh - THAT'S how you do it? I always wondered. SteveBaker (talk) 13:22, 2 April 2009 (UTC)

How about developing IQ tests for bonobos, chimps, and gorillas to see which is the more intelligent species? That would also show much variation there is in intelligence among individuals of the same species. Maybe IQ tests could be developed for other animals too. The thought that would go into developing animal IQ tests might show how to improve the validity of human IQ tests too. The same test could not be used for all animals because their intelligence varies so much. Separate tests would have to be developed for use with closely related species only. The basic thinking patterns of various species would also require different tests - for instance, separate IQ tests would be needed for cats and dogs. Obviously, animal IQ tests could not be written tests, but would be administered on a food reward basis. - GlowWorm. —Preceding unsigned comment added by 98.17.35.74 (talk) 13:56, 2 April 2009 (UTC)

There are skeptics that IQ is a good test for intelligence for humans. I think it would be even less effective for animals. 65.121.141.34 (talk) 15:35, 2 April 2009 (UTC)

With human IQ tests there is the well-known problem of a person's former experience aiding him in doing the test. If he reads well, he will do better on an IQ test. If he has taken a lot of such tests, he knows how to go about it. He may even have seen similar questions before, such as rope-and-pulley problems. He may also be familiar with the way the questions are asked. (In poll taking, the way a question is asked can influence the answer.) In contrast, wild animals of the same species that have been taken very recently from the same environment, will mostly have about the same former learning experiences – not in IQ tests but in life experiences. There will be more variations in life experience with farm animals, pets, and possibly in wild animals that have lived near humans. – GlowWorm. —Preceding unsigned comment added by 98.17.35.74 (talk) 15:53, 2 April 2009 (UTC)

One type of IQ test that works on a variety of animals is the mirror test:

1) The least intelligent animals act as they would when they encounter another animal of their same species and gender. In the case of male crabs, for example, they will attempt to fight with their mirror image.

2) More intelligent animals, like cats and dogs, might react as above briefly, but, after looking behind the mirror and sniffing it, realize it's just some type of illusion and move on.

3) The most intelligent animals (such as those mentioned in this Q) eventually realize that they are seeing their own image, and are fascinated by it. For example, they may use it to try to look at parts of their body they can't normally see. StuRat (talk) 17:12, 3 April 2009 (UTC)

That's very interesting. Do you know how some of the smarter birds, such as ravens or crows, react? -GTBacchus^(talk) 17:18, 3 April 2009 (UTC)

Actually, Google answered my question very quickly. Magpies get it. -GTBacchus^(talk) 17:21, 3 April 2009 (UTC)

Birds seem to have an extreme variation in intelligence, between chickens at the stupid end and parrots (and apparently magpies) at the smart end. StuRat (talk) 15:07, 8 April 2009 (UTC)

They look like people, unlike other animals such as dogs, cats, horses, snakes, rats, birds, etc. Edison (talk) 04:52, 3 April 2009 (UTC)

5 in one fruit tree

I've seen these five-in-one grafted fruit trees in catalogs, but what I'd like to know is, are there any drawbacks to grafting five different types of plant (sometimes of different, but related species) to the same tree? Different species have different needs, so I would think that having five different types of tissue in one tree would compromise the integrity of the whole tree in some way. It's a really neat idea (the tree I'm looking at possibly buying has five different species of fruit from the genus prunus on it), but it could be just a gimmick to sell trees that aren't that good. Please help me decide whether I should buy a combination tree or simply buy one that has only one species and cultivar. Thanks, Wikipedians! 63.245.144.68 (talk) 00:58, 2 April 2009 (UTC)

I think your example shows that this only works if the plants are all similar, which would mean they have similar nutritional requirements. Grafting has been used commercially, which seems to indicate that it has some benefit. I imagine the grafted tree is more expensive, and you could have the problem of a "graft failure", which can't happen in a normal tree, in addition to the regular things that can go wrong with a tree. So, I'd say that you should get the grafted tree if you really want all those varieties, and stick with a normal tree otherwise. StuRat (talk) 11:48, 2 April 2009 (UTC)

For some plants grafting is the only way to be sure about the quality of the fruits you will eventually get out of the tree. I believe Prunes, Apricots, Peaches and Nectarines are so closely related that it is unlikely that the multiple grafting should be a problem. Dauto (talk) 14:00, 2 April 2009 (UTC)

shouldn't that be plums? Prunes are dried plums.--TammyMoet (talk) 17:56, 2 April 2009 (UTC)

Maybe he forgot to water the tree... - Eron^Talk 18:02, 2 April 2009 (UTC)

Yes, I meant plums. I got misdirected by the word prunus for the genus. Dauto (talk) 05:14, 3 April 2009 (UTC)

We actually had a prune tree once. It had something wrong with the skin on the plums, so it wasn't waterproof. This caused them to shrivel into prunes while still on the branch. We should have thought to market the tree (perhaps in Florida ?), maybe we'd be rich by now. StuRat (talk) 16:52, 3 April 2009 (UTC)

Dauto is right that only closely related types of fruit can be successfully grafted. Grafting different types varieties of fruit on the same tree is really only done as a novelty, not for serious fruit production. What happens is that one type tends to take over the entire plant, since it is very difficult to have exactly equal vigor for each variety. So, buy one if you want to create a conversation piece and amaze your neighbors, but buy separate trees if you want the fruit for eating.--Eriastrum (talk) 17:24, 2 April 2009 (UTC)

"Dauto is right that only closely related types of fruit can be successfully grafted." Actually, I said that. StuRat (talk) 16:44, 3 April 2009 (UTC)

Sorry, Stu, I didn't read your post carefully. Won't happen again.--Eriastrum (talk) 20:57, 4 April 2009 (UTC)

No prob. Sometimes I say things I wish I could blame on someone else. :-) StuRat (talk) 16:52, 5 April 2009 (UTC)

When I was a child we had one of these. The first summer it produced five kinds of apples. Then after a hard freeze during the winter, the grafts died and it only produced one kind of apple. Edison (talk) 04:50, 3 April 2009 (UTC)

HAMMER DRILL VS IMPACT DRILL

WHAT IS THE DIFFERENCE? —Preceding unsigned comment added by 64.88.177.194 (talk) 01:11, 2 April 2009 (UTC)

Please do not type in all caps. It makes it appear that you are screaming, and is pretty rude. Now, to answer your question... Nothing. They are the same item. If you look for an article on impact drill you will see it redirects to our article on hammer drill. There may be some marketing differences, for example one manufacturer may use one term and a different one may use the other, but functionally they are the same tool. --Jayron32.talk.contribs 01:20, 2 April 2009 (UTC)

Maybe you mean Impact driver or Impact wrench? In which case a hammer drill uses a hammering action to help break-up the masonry when drilling, where as the other tools I mention use impact to generate large amounts of torque for loosening tight bolts etc.90.220.130.74 (talk) 21:02, 2 April 2009 (UTC)

Life Without Plastics Video

I once saw a humorous brief video detailing "life without plastics" (or oil or petroleum products, etc.) with a 1950s housewife. She is standing in the kitchen and things begin to fall apart. I can't seem to find this anywhere online; where can I find it? —Preceding unsigned comment added by Dlempa (talk • contribs) 03:06, 2 April 2009 (UTC)

Wasn't that on an episode of The Simpsons ? There has been an even more ridiculous one on TV in the USA during the last year or so about "Chemicals" disappearing - which is bizarre since essentially every material object is made of chemicals...but that had a modern theme, not 1950's. SteveBaker (talk) 13:16, 2 April 2009 (UTC)

I believe you're talking about this segment from Kentucky Fried Movie. --Sean 13:48, 2 April 2009 (UTC)

...which was probably inspired by A Case of Spring Fever (presented here as the MST3K version for your convenience and pleasure), or some other educational short film in the same vein. -- Captain Disdain (talk) 20:15, 2 April 2009 (UTC)

Oh god I laughed so hard at that MST3K episode. Springy! --BiT (talk) 20:37, 2 April 2009 (UTC)

The Kentucky Fried movie was the one I was looking for - it was zinc oxide, not plastics. Thanks! dlempa (talk) 20:14, 5 April 2009 (UTC)

Meanings

What is the meaning of A in this picture? In the summary, the abbreviation"ca." means what?96.53.149.117 (talk) 04:33, 2 April 2009 (UTC)

"A" almost certainly means Angstrom units. "Ca." means "circa", or "about". Looie496 (talk) 04:36, 2 April 2009 (UTC)

It very well mean "canada" or located in canada. THIS will be edited out soon so please read quickly.67.193.179.241 (talk) 14:17, 4 April 2009 (UTC)

It can't very well mean that, as we've been given context in which it means "circa". 86.166.149.141 (talk) 00:34, 5 April 2009 (UTC)

Diamond Cutting

What is the reason that Diamonds are used in machine tools, especially when machining non-ferrous alloys, compared to other alloys?96.53.149.117 (talk) 04:45, 2 April 2009 (UTC)

I suspect the author of that line was thinking of non-ferrous alloys that are harder than steel. It seems sensible that one would use diamond on hard materials. You don't use it on materials that can be machined more easily, because it is more expensive than alternative materials.--Srleffler (talk) 05:26, 2 April 2009 (UTC)

from article diamond... "Diamond is not suitable for machining ferrous alloys at high speeds as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools when compared to alternatives.--Digrpat (talk) 13:06, 2 April 2009 (UTC)

"

When a Star Evolves into a Black Hole...

I was reading List_of_common_misconceptions the other day, and it said:

"Black holes, unlike the common image, do not act as cosmic vacuum cleaners any more than do other stars. When a star evolves into a black hole, the gravitational attraction at a given distance from the body is no greater than it was for the star. That is to say, were the Sun to be replaced by a black hole of the same mass, the Earth would continue in the same orbit. Due to a black hole's formation being explosive in nature, the object would lose a certain amount of its energy in the process, which—according to the mass–energy equivalence—means that a black-hole would be of lower mass than the parent object, and actually have a weaker gravitational pull."

Note that paragraph was removed by an editor earlier today for being poorly sourced so if you look at it now, it's not in there but I still want to ask a question about it.

Assuming that this is correct, if a black hole's gravitational pull is the same as the star that preceded it, how did light escape the star in the first place? Is it because as the star collapsed, its size shrank and the black hole has a higher density? A Quest For Knowledge (talk) 17:54, 2 April 2009 (UTC)

No, as the Schwartzschild radius of such a BH is about 15km, the star's light was sent well outside that. Of course, the gravity decreases alot when going from 15km radius to 100.000km or what a typical star has radius. When you read the scenarios of a BH emitting light, it's always from inside its event horizon. --Ayacop (talk) 18:14, 2 April 2009 (UTC)

Er... I'm not quite sure what to make of the above answer. Generally, your initial understanding is correct. At the surface of the Sun (more relevantly, a point one solar radius from the center of the Sun, 6e5 km away), escape velocity is 6e5 m/s, far less than the speed of light (3e8 m/s). As such, light escapes. If you swapped the Sun for a solar-mass black hole, then escape velocity from a point one (original) solar radius away remains the same, and a light source there is still detectable.

Next consideration: a solar-mass black hole has an event-horizon radius of 15km (I'm going off the above response, and have no idea whether or not it's correct, but it's useful for these purposes). Light can't escape from points at or within 15 km of the center of mass. Here's the key distinction from when it was a star: the Sun's mass is not contained within a 15 km radius sphere, so the Sun's gravity at that point is far less. Volume increases with the cube of radius: if we assumed the Sun to be of uniform density (it's not, but not the point), then we would expect about one trillionth of one percent of the Sun's mass to be within the event horizon of a solar-mass black hole. The mass of the Sun above that radius is evenly distributed, and as such, can be ignored for gravitational purposes. One trillionth of one percent of the mass needed for the black hole obviously doesn't stop light from escaping from a point 15 km from the center of the Sun.

Escape velocity boils down to a function of mass and distance. When you compare "the Sun" and "a solar mass black hole", you've kept mass the same but varied the distance (and thus changed your answer). When you compare "the center of the sun" and "a solar mass black hole", you've kept distance constant but varied the mass (and thus changed the answer).

So, your original concept of density is basically correct. However, this should not be confused with the idea that black holes (in reference to the volume contained by the event horizon) need to have "high" density. Normal matter (of a given density) increases mass by the cube of radius. Black holes increase mass proportionally to radius. If you take a ball of clay of radius r and mass x, then a ball of clay with radius 2r has mass 8x. If you swap "ball of clay" with "black hole", then mass 8x black hole has radius 8r. Put into more practical terms, envision a sphere around the solar system, out to 100 AU (three times the orbital radius of Neptune). Fill that sphere with sea-level pressure air. The solar system is now a black hole.

Now, as for the original answer: black holes "emitting" light do so from their accretion disks, which always lie outside of the event horizon. Nothing is emanated from within. Even Hawking Radiation only works when particles form outside the horizon. — Lomn 19:08, 2 April 2009 (UTC)

Ayacop, I don't understand what you mean by "BH emitting light, it's always from inside its event horizon". Black holes don't emit light. Are you referring to Hawking radiation? A Quest For Knowledge (talk) 20:20, 2 April 2009 (UTC)

if its within the event horizon, how would we know if it emitted light or not? 65.121.141.34 (talk) 20:23, 2 April 2009 (UTC)

Now let's look at ways the perception of black holes as "cosmic vacuum cleaners" may be correct:

1) While it's true that a black hole has no more gravitational attraction at great distances than a star of equal mass, that neglects the fact that most black holes have a greater mass than most stars. In fact, most stars have insufficient mass to ever form a black hole. There are also supermassive black holes at the center of spiral galaxies which are millions or billions of times more massive than any star.

2) Stars tend to give off more mass than black holes, via conversion to energy which is emitted as light, etc., solar wind, and sometimes violent explosions like novae and supernovae. Black holes can lose mass due to Hawking radiation, but this is only significant portion of the mass for small black holes. Thus, most black holes can be thought of as one-way doors, unlike normal stars. StuRat (talk) 16:28, 3 April 2009 (UTC)

source of dietary cholesteryl esters?

As I was studying the enzyme bile acid-activated lipase, it says it degrades cholesteryl esters in the small intestine. But where do these come from? Do they always come from eating animals? Are there plants that contain amounts of cholesteryl esters? --Ayacop (talk) 18:20, 2 April 2009 (UTC)

Just to be safe you are talking about Bile salt dependent lipase right? Although not specifically "cholesteryl esters" you may want to look at dietary sources of cholesterol. I am not familiar with cholesterol biochemistry, so I don't know what form the majority of cholesterol is in when it is absorbed in the small intestine. It might be that cholesteryl esters are a storage or transport form of cholesterol. Plants do synthesize some cholesterol (some sources say otherwise but they're wrong) but it is very little compared to animal cells. You may also want to take a look at phytosterols. As dietary contributions go (assuming an omnivorous diet), cholesterol from plants is negligible compared to other sources (like the butter you cook your vegetables with for instance). Sifaka ^talk 19:08, 2 April 2009 (UTC)

Genius

Looking for any valid statistics on people who are labeled a genius of some sort (mathematical) and the possibility of having a personality/mental disorder/dysfunction. Also, any statistics, say a mathematical genius, to have children who are supra-intelligent. --Reticuli88 (talk) 18:41, 2 April 2009 (UTC)

I don't know whether you'll find much in the way of statistics. There are an awful lot of smart people (including MANY mathematicians) with Asperger's syndrome shading into borderline Autism - but because it's a spectrum condition, there is no hard definition of who has it and who doesn't. It's a matter of degree. Of course there are mathematicians who have pretty serious mental conditions - John Nash is the one that always leaps to mind because his story is told in the movie A Beautiful Mind. His paranoid schizophrenia is serious matter - but that didn't stop him from earning a Nobel prize. SteveBaker (talk) 20:11, 2 April 2009 (UTC)

As an extra comment, that film is my favourite of all time. Excellent story, thoroughly recommended. Cyclonenim :  Chat  20:49, 2 April 2009 (UTC)

Yep - all the better because it is 100% true. I like that Prof Nash still points to people he hasn't met before and asks people he knows whether they are real or not. He does it without a shred of embarrassment - and when he finds that some of the people he meets are not actually real - he happily ignores them and carries on with life! I think it takes the temperament of a good mathematician to be able to do that. Most of us would be too freaked out to cope. SteveBaker (talk) 21:02, 2 April 2009 (UTC)

Well, 100% true except the bit that shows him taking his medication voluntarily. According to the real-life Nash, he rarely ever took it unless forced to, and recovered with his own will as you described above. Now that's persistence. Cyclonenim :  Chat  23:46, 2 April 2009 (UTC)

I was under the impression that he didn't actually have visual hallucinations, just auditory. As brilliant as that film is, it is heavily dramatised. --Tango (talk) 05:12, 3 April 2009 (UTC)

People who have worked with him have told the story that he will (on occasion) point to some stranger in the room and ask everyone else: "Is this person real?" - and on much rarer occasions, he'll point to an empty piece of space and ask the same question. Assuming those reports are true - then this can hardly only be an auditory hallucination. SteveBaker (talk) 12:40, 3 April 2009 (UTC)

The our article needs correcting. --Tango (talk) 00:35, 4 April 2009 (UTC)

There is also Kurt Gödel, who starved to death for fear of being poisoned. G. H. Hardy who hated looking at his own reflection. Alas, I don't have any statistics, however. --TeaDrinker (talk) 21:40, 2 April 2009 (UTC)

It all depends on what you call intelligence. If you consider social abilities a form of intelligence, not many aspies would fall under the category intelligent. So as many people only understand math when you explain things to them clearly, step by step, aspies only understand social dynamics when you explain everything (even knowledge that other people take for granted). Since Asperger's syndrome has rather being defined recently, I don't believe you'll find many serious diagnosis of highly skilled mathematicians with it. --Mr.K. (talk) 11:26, 3 April 2009 (UTC)

It is often said that aspies don't know how to have social relationships. Actually, I think it's that they don't want to have social relationships. They get no pleasure from it. They regard social relationships as a chore and a nuisance – something they have to force themselves to do. —Preceding unsigned comment added by 98.21.105.25 (talk) 11:45, 3 April 2009 (UTC)

It's both. As an Aspie, I strongly dislike having to meet and get to know people who I don't already know well. When I do have to do it, I'm not good at it. (Although training can cover the latter to some degree - and I'm getting pretty good at faking it). Furthermore, it's not just a matter of some diffuse inability - many aspies (myself included) are completely blind to things like body-language, facial expressions and some linguistic subtleties like sarcasm. I really, deeply, hate going to parties for example. A party is an event designed solely in order that people meet and interact for no especially well-stated reason - we frequently use alcohol at these events to make that interaction more intense - and that amount of forced interaction is something I strongly prefer to avoid! My only reaction at such events is to try to find a way not to have to be involved - this is sometimes mistaken for 'shyness' - but that's not it. However, I think it's a BIG stretch to say that social abilities are "a form of intelligence". Ants and Bees have really great social relationships - but we don't generally call them "intelligent". There is a movement to get all sorts of human behaviors labelled as "forms of intelligence" - I've heard of teachers talk about "body posture intelligence" as an attribute of good dancers who are otherwise as dumb as a bagful of anvils - but that's entirely so that the teachers don't have to go around labelling people as "unintelligent" just because they can't do IQ tests or crack open a book to learn something. However, that's not the usual definition! Anyway - the OP specifically wants to know about 'mathematical geniuses' - and social skills most certainly have nothing whatever to do with that! SteveBaker (talk) 12:40, 3 April 2009 (UTC)

The amount of social interactions by humans and the complexity of these are not comparable with the social life of any other creature. Human social interactions require that you integrate all these things cited above - body-language, facial expressions and some linguistic subtleties - and much more. They are far away from a binary communication style. I don't see any problem labeling all human abilities as a form of intelligence, since all of them require processing of information of some kind. Evenly I don't see any problem admitting that animals process certain kinds of information. Some of them - like smell information - even better than us. Others - like language - only at a very primitive level, if we can speak of language in animals at all. According to the intelligence article, there are many definitions of intelligence. I would go with the intelligence = processing of information. Other definitions are probably so broad and badly defined that you could call any one 'intelligent' or you would like to guess who is intelligent or measure it with some dubious IQ test. The definition above would imply multiple types of intelligence - as many as types of information probably. Many, many people could be terrible processing one kind of information type and excel at other kinds. So, it would not be a surprise finding an aspie good at mathematics, a field that strives to define everything as precise as possible and everything has a clear purpose. There is more information aboutmultiple intelligences in the corresponding article.--Mr.K. (talk) 15:51, 3 April 2009 (UTC)

Are aspies who are good at math, also good at fuzzy math? (In fuzzy math things are not precisely defined.) —Preceding unsigned comment added by 98.17.36.180 (talk) 20:44, 3 April 2009 (UTC)

I assume any aspies who work in fuzzy maths are good at it. Fuzzy mathematics (which is, as far as I know, just as precise as the rest of mathematics) is a tiny field; I've never encountered anyone who worked on it. Algebraist 20:52, 3 April 2009 (UTC)

Are aspies good at stistics, in which things are not precisely defined?

The person who springs to mind in this field is Simon Baron-Cohen, if you look him up on Google Scholar you will get heaps of academic papers on autism. This study on the link between Autism and Engineering might be of interest to you. There is also this article on the BBC site. SpinningSpark 01:17, 4 April 2009 (UTC)

As a family therapist, some of the most challenging yet rewarding clients are those on the Asperger's continuum. An Aspie's difficulty with (or disinterest in) social skills can easily carry over into this forum where replies are at times given in a very rude and condesending manner (especially when an OP asks about Creationism vs. Evolution). So, social skills can be more than just face-to-face interactions.

As for IQ, this is only a measure of how well one is able to complete IQ tests. It was not that long ago where IQ tests had a cultural bias which often led to non-white, non-western persons not doing as well as the white westerners the IQ was designed by.

As for multiple intellegences, I would suggest that there needs to be a balance. We can't just give some arbitrary characteristic an "intellegence" name (I.E. "posture intellegence") just to make people feel better! So, while some people may be more inclined to mathematics ("math intellegent") while others are more artistic ("visual/spacial intellegence")or even people oriented ("emotional intellegence" or "social skill" intellegence - I am much better at the former than the latter)I would suggest that it is better to focus on our strengths. Thus, I became a therapist because I really am a klutz at math, mechanical things and the like. —Preceding unsigned comment added by 74.12.66.165 (talk) 21:01, 4 April 2009 (UTC)

Creativity and mental illness

It appears that a disproportionate number of creative artists considered "great" in their fields have suffered from bipolar disorder - especially poets, and among poets, especially Lord Byron. There's a good book about this by creative, bipolar psychiatrist Kay Redfield Jamison, called Touched with Fire. It's an excellent read. -GTBacchus^(talk) 16:35, 5 April 2009 (UTC)

Abiogenesis vs Evolution

I need a WP:RS that a) explains the difference between abiogenesis and evolution b) states that this is a common or popular misconception or misunderstanding. I've found plenty of blogs and forums about this, but these aren't usually considered WP:RS. The best I've been able to come up with is here [6] and here [7] but I'm hoping for something better. I'll keep looking but I thought that maybe somebody here already knows a good cite off the top of their head. If not, it's no big deal. I'll keep looking. A Quest For Knowledge (talk) 23:28, 2 April 2009 (UTC)

I would bet you could find that in one of Richard Dawkins' books - I don't have an exact ref for you though. SteveBaker (talk) 00:26, 3 April 2009 (UTC)

Ironically, I choose this item because I mistakenly thought that finding a WP:RS doing a Google search with "abiogenesis" as one of the search terms would be trivial. How wrong I was! Unfortunately, we have an editor who's apparently on a crusade to make sure that every single item in this article is correctly sourced. Not that he/she doesn't have a valid point, but they're doing a blanket removal of all unsourced items even if the information appears to be correct (just not sourced). A Quest For Knowledge (talk) 01:10, 3 April 2009 (UTC)

Yeah - in these "List of..." articles - especially those with "fun facts" like this one - there is a tremendous tendancy for junk to accumulate in the article. This SPECIFIC form of article really does have to have 100% reference coverage and a rigorous purging of unsourced junk is needed. That's only reasonably possible if all of the important stuff is referenced to within an inch of it's life. In most 'normal' articles, it is sufficient to reference only the 'likely to be doubted' facts. SteveBaker (talk) 01:38, 3 April 2009 (UTC)

I think you have to clarify the question a bit better -- this is sort of like asking for a reliable source for the difference between radio stations and submarines -- they're just different things, that's all. Looie496 (talk) 02:34, 3 April 2009 (UTC)

Sorry, I'm trying to find a WP:RS for this:

"Biological evolution does not address the origin of life; for that, see abiogenesis. The two are commonly and mistakenly conflated. Evolution describes the changes in gene frequencies that occur in populations of living organisms over time, and thus, presupposes that life already exists. Evolution likewise says nothing about cosmology, the Big Bang, or the origins of the universe, galaxy, solar system, or Earth, although the term 'evolution' in the sense of a slow unfolding is used to describe such processes, e.g. Stellar Evolution, Cosmic Evolution." A Quest For Knowledge (talk) 02:50, 3 April 2009 (UTC)

I think you just need a dictionary to verify all of that except the fact that they are commonly conflated. I'm not sure where you would find a source for that, though (finding examples is easy, but you need something more than just a list of examples otherwise you are doing original research). --Tango (talk) 05:06, 3 April 2009 (UTC)

@Tango: That's true - but you have to look at this in the context of the article that's being written here. It's a list of common misunderstandings. So whilst it's trivially easy to use the dictionary definitions of the two words to prove that Abiogenesis and Evolution are not the same thing - it's not so simple to prove that they are commonly confused or conflated. SteveBaker (talk) 12:22, 3 April 2009 (UTC)

Hmm I think it should be pretty easy to find. I mean the whole evolution vs creation myths "debate" must be sort of showing that some mix up? I would assume it must have been addressed somewhere (Just think of the possibility for someone who would want to mock the religious person/group not knowing). I am guessing one group religious that seem to have understood the difference in the catholic church, I have at least read I think that they're accepting evolution (but not accepting abiogenesis of course I guess) "post-creation" or something. chandler · 12:36, 3 April 2009 (UTC)

Discussing evolution/abiogenesis there is;

• Iris Fry, The emergence of life on Earth: a historical and scientific overview, p57, Rutgers University Press, 2000 ISBN 0813527406.
• John Augustine Zahm, Evolution and dogma, pp41-42, Ayer Publishing, 1978 ISBN 0405108745.

The above and on confusion of terms (especially historical),

• James Edgar Strick, Sparks of Life: Darwinism and the Victorian Debates Over Spontaneous Generation, pp11-13, Harvard University Press, 2002 ISBN 0674009991.

Direct dictionary definition of abiogenesis,

• Elizabeth Tootill, The Facts on File dictionary of biology, p247, University of Michigan, 1981 ISBN 0871965100.

Clear statement of confusion of the two from the other side of the debate;

• Daniel Jappah, Evolution: A Grand Monument to Human Stupidity, p21, Lulu.com, 2007 ISBN 1430324902.

Not sure about the second part of that paragraph, "evolution has nothing to do with cosmology and the Big Bang". This is like asking a for a ref that differential geometry has nothing to do with bananas. While true it is unlikely that either books on differential geometry or bananas will make this statement. Not many books covering both subjects. Seriously, I cannot really work out what that statement is supposed to be doing for the article - it is enough to differentiate evolution and abiogenesis, a contrived analogy is not really needed. SpinningSpark 15:54, 3 April 2009 (UTC)

As I was looking for cites last night, I was jokingly thinking to myself that Google should come up with a reliable sources search engine. Then I discovered that Google does let you create your own custom search engine [8]. So, I started creating a Reliable Sources Search Engine. I realize the futility of creating anything that is even remotely comprehensive, but as I was sifting through a bazillion Google hits (many of which were blogs and forum posts), I think that something that narrows down the hits might be useful (to me, anyway). My custom search engine is here [9]. So far, I have about 20 sites that are generally considered to be reliable per WP:RS standards. I left some obvious ones off such as www.abcnews.com since ABC News allows readers to add comments to a news article and I'm not sure yet how to get the search engine to distinguish between article content and user comments. I've left the search engine open so if anyone wants to contribute to this search engine, feel free. A Quest For Knowledge (talk) 15:51, 3 April 2009 (UTC)

April 3

Limiting Reagent

Hello. If limiting reagent R is to be completely consumed by reacting with reactant X, is adding 10% in excess of the minimum amount of reactant X needed common industry practice? Are there any safety limitations in some reactions that may prevent the use of this procedure? Thanks in advance. --Mayfare (talk) 00:20, 3 April 2009 (UTC)

It's a common rule-of-thumb for something to try when developing a process, but I don't know if it's "common industry practice" for what actually goes into a full-scale production run. Gotta consider how expensive and/or difficuult it is to buy, separate, and dispose of that unreacted material, and the effect of that excess reagent could have on the reaction and products. DMacks (talk) 01:18, 3 April 2009 (UTC)

It also depends on your industry. (Let me preface this by stating that I'm not a chemical engineer). But I just got a very fancy new wall poster of a Modern Refinery (Crude Distillation), as designed by Mustang Engineering ("you hung a poster of WHAT on your wall?") which is a supposedly super-realistic depiction of a top-of-the-line refinery as it would be designed today. (So, chemical-engineer or not, after reading this detailed document, I'm now ... qualified to comment). The poster goes through the process control units in a fairly detailed way, and for the most part it seems more likely that they allow each chemical stage to reach partial completion, say 80% or thereabouts, before taking the refined product on to the next stage (by buoyancy separation, vacuum distillation, etc.). This leaves a sort of "unrefined sludge" in the each of the reactor stages. This unreacted reagent isn't "waste product," because those chemicals continue to cook or settle or dissolve or mix, and eventually reach reaction completion; but they go out with the next batch of product at a later time. Surely the process engineers understand the limiting reagents, (most likely, it seems, these are the catalyst concentrations), but have made a decision NOT to overstock limiting reagent. This could be for many reasons - in crude refining, economic pressures dictate volume throughput, so "reaction completion" is better measured in terms of absolute quantity of output product, rather than percentage-of-total-reagents-converted (that's more of an "efficiency" metric than a "completion" metric). Also, not all catalysts are "good" in large doses - metals can leach into the product; catalysts can perform side-reactions with impurities, etc etc. Nimur (talk) 13:20, 3 April 2009 (UTC)

Only slightly on topic because you mentioned posters and this is the science reference desk; I recommend these two biochemical pathway posters. Sifaka ^talk 20:31, 3 April 2009 (UTC)

I believe it works out that it costs a lot to get the last little bit to react, so often isn't worth the expense, especially if the unreacted portion can be reacted in a later batch, as noted above. Also, having extra "X" left over isn't necessarily any better than having extra "R" left over. StuRat (talk) 16:07, 3 April 2009 (UTC)

Nimur, that poster was not the Playboy pullout I was hoping for and it took forever to download, but still quite interesting. Why are the "sour water stripper" and "sulfur recovery unit" not connected to anything else? It upsets my sensibilities as an electrical engineer to have components that are not in circuit. SpinningSpark 01:34, 4 April 2009 (UTC)

Most likely because they are batch processes, rather than continuous like the rest of the plant. (A lot of people are talking about batches, but it is more efficient to deal with continuous processes. Outside pharmaceuticals, most processes are continuous) What is not shown on that diagram are the recycle streams. You would usually expect to get partial completion and recycle some of your product stream; that is, send it back into the process to mix with your reactant stream. This gives more time for the reaction to take place. Once you've separated your product from the unreacted reactants, you would probably send them back into the product stream as well. Overall, you're looking to lose very little of the excess reactant. 86.151.238.242 (talk) 00:26, 5 April 2009 (UTC)

What's the deal with black holes and escape velocity?

People talk about how light can't escape a black hole because its escape velocity is higher than the speed of light. If you used newtonian mechanics, that would mean that something within the event horizon moving the speed of light would not be able to escape orbit, but it would still be able to go arbitrarily far out. This isn't a remotely accurate description of a black hole. Something within event horizon can't even move towards the event horizon, let alone escape. Is the thing about escape velocity just a lie-to-children? Is escape velocity even the speed of light at the event horizon? — DanielLC 04:02, 3 April 2009 (UTC)

That the Newtonian calculation gets the correct result for the radius of the event horizon is little more than a coincidence. You have to use relativity to do anything meaningful with black holes. I'm not sure the concept of an escape velocity really makes sense at the event horizon of a black hole. I think the escape velocity arbitrarily close to the event horizon (but outside it) is arbitrarily close to the speed of light, though. --Tango (talk) 05:02, 3 April 2009 (UTC)

Yes, Tango is right. The scape velocity steadily approaches the speed of light as you get closer and closer to the horizon. The OP is right that a naive interpretation of that within newtonian mechanics leads to the false impression that light can reach out of the horizon but fails to make its way all the way to infinity and is forced back in. The correct description requires relativity. To put it as simply as possible, an observer falling into the blackhole could observe a photon moving outwards at the speed of light, but from the point of view of an observer at infinity that same photon would stand still right at the horizon never inching its way out of the blackhole. Dauto (talk) 05:31, 3 April 2009 (UTC)

Indeed. The problem is that time has stopped advancing at the event horizon (at least as far as outside observers are concerned)...this is an entirely relativistic phenomenon - and I suppose you could say that it's just a mathematical coincidence that this happens at the same distance that the classical escape velocity became equal to the speed of light. Of course, since we're talking about relativity - we have to be careful to say 'for whom' this effect is happening. For an outside observer, time has stopped on the event horizon - but from the perspective of something trying to escape the black hole (at less than light-speed), they can still travel past the event horizon - although they'll eventually get dragged back in again. The tricky part is that for them, time in the rest of the universe is progressing infinitely quickly - which will have all manner of nasty consequences in terms of the energy of objects (or even light) travelling into the black hole - which will now tend to have infinite frequency (and, I suppose, infinite energy)! SteveBaker (talk) 12:19, 3 April 2009 (UTC)

Question - "... from the perspective of something trying to escape the black hole (at less than light-speed), they can still travel past the event horizon - although they'll eventually get dragged back in again" - are you sure about that ? I thought that within the event horizon all timelike curves reduce their distance from the singularity at all times, so an object within the event horizon cannot even get closer to the event horizon, let alone get past it (in other words, I think I agree with what DanielLC said above). Gandalf61 (talk) 14:45, 3 April 2009 (UTC)

Answer - NO, SteveBaker got only half of the story right. The gravitational redshift which he talks about happens even to objects falling into the hole. They seem to slowdown to a stop as they approach the horizon from the point of view of an observer at infinity. But from the point of view of an observer falling into the hole the same object reaches the sigularity at the center of the hole after a finite amount of proper time. On the other hand, an outward moving light ray sits still on the horizon from the point of view of every observer. See Black hole#Event horizon. With respect to the infinite blueshift that SteveBaker talked about, You would have to sit on the horizon in order to see that. In other words, you would have to be a photon. Any observer falling in the hole would see a finite amount of red/blue shift. But photons always 'see' an infinite amount of blueshift from the direction towards which they are moving (and an infinite amount of redshift in the oposite direction), so that's notthing specific to the fact that the observer is on the horizon. In fact, such observer would not feel anything special as s/he crosses the horizon. Dauto (talk) 15:36, 3 April 2009 (UTC)

I'm unhappy with this talk of "observers at infinity". In special relativity the word "observer" is often treated as synonymous with "inertial reference frame", but that definition doesn't carry over into general relativity. In general relativistic usage, an "observer at infinity" can only observe things at infinity; he can't directly observe an object falling into a black hole, though he can observe light emitted by that object (if it eventually escapes to infinity). You can't say "from the point of view of an observer at infinity [the] photon would stand still right at the horizon", because that photon never gets anywhere near the observer.

I agree with Tango's response, except for the last sentence. The real trouble with defining escape velocity is that you need to choose a coordinate system to do it. If you choose Schwarzschild coordinates then the radial escape velocity (dr/dt) actually goes to zero at the event horizon—it has to, because the speed of light goes to zero and the escape velocity is bounded above by that (since light outside the horizon can always escape). If you use proper Schwarzschild radial velocity (dr/dτ, where r is the Schwarzschild r and τ is proper time) then the escape velocity is actually given by the Newtonian formula at all radii. (In fact, the equation of motion in terms of r and τ is d²r/dτ² = -GM/r², the same as the Newtonian equation.) The funny thing about this, though, is that the proper speed of light is infinity, not c—so the proper Schwarzschild escape velocity approaches c at the horizon, but that's not the speed of light! I don't know what to conclude from this except what Tango said—you shouldn't trust the Newtonian analogy any farther than you can throw it straight up. -- BenRG (talk) 20:03, 3 April 2009 (UTC)

I'm sorry I made you feel unhappy. I agree with you that my usage of an 'observer at infinity' was a little lazy, but I wouldn't be so draconian to the point of saying that observers at infinity cannot talk about their interpretation of what happens at the horizon just because they cannot directly observe the horizon. May be observer is a poorly chosen word. I'm not entirely sure about what you mean by "If you choose Schwarzschild coordinates then the radial escape velocity (dr/dt) actually goes to zero at the event horizon—it has to, because the speed of light goes to zero", but, at least to me, it sounds suspiciously like saying that a outward going photon stands still at the horizon, which is exactly what I said. But from whose point of view does the speed of light go to zero? Certaily not from the point of view of an observer falling into the blackhole. It is for that reason that I (lazily) chose to describe this point of view as the point of view of an observer at infinity. Dauto (talk) 05:53, 4 April 2009 (UTC)

If an object inside a black hole could get outside the event horizon temporarily then it could fire rockets during that time and escape permanently, which clearly isn't the case since that would contradict the definition of an event horizon. --Tango (talk) 00:25, 4 April 2009 (UTC)

Generation length and human evolution

How does the length of a generation affect the rate of human evolution, given how the mutation rate increases with the parents' ages? NeonMerlin 05:35, 3 April 2009 (UTC)

I think the average age people (in particular, women) have had children has been pretty constant throughout human existence until recently, so I don't think there has been enough variation to affect evolution. I'm not sure what would have happened if, hypothetically, the average age of having children had been different. There is more involved that just the rate of mutations, though - the rate of change in the habitat is also highly relevant, and that is beyond human control (or, at least, was until recently). --Tango (talk) 06:10, 3 April 2009 (UTC)

Indeed - it would be hard to know the answer to this because significantly longer generation times have only happened in the last dozen or two generations and this has corresponded with many other changes for humanity. In modern times, our ability to evolve is constantly being counteracted by our ability to adapt our environment to our needs. For example: in previous generations, if a group migrated into a sunnier part of the world, they would gradually evolve darker skin - nowadays, we slap on sunscreen. Hence the evolutionary pressure that would tend to kill off lighter skinned people in sunny climates has been greatly attenuated. Similarly, better diets and vitamin supplements allow darker skinned people to live in less sunny areas without becoming vitamin-D deficient - hence they are less likely to evolve lighter skins. Modern medicine and social support structures may bias our natural ability to evolve away inherited diseases. For example, in previous centuries, a genetic condition which might cause infertility could be evolved away in a single generation since infertile people would be unable to pass their flawed genes onto the next generation. With modern infertility treatments, those flawed genes may be passed on to the next generation who will also require infertility treatment. Hence, a gene that would normally vanish (or at least be kept strongly in check) may flourish.

This is not to say that evolution in humans has stopped - that's highly improbable - but the criteria for being successful in reproducing and raising our children has changed - and the causes that lead to reproductive success or failure are changing. Modern human evolution also has a lot more to do with memetics than genetics - when parents pass on their knowledge, stories, biasses, culture and other memes, our ideas evolve and change over generations. Take as an example, the present cultural 'war' between the Western and Arab worlds. This is largely a result of memes causing two distinct 'memetic species' - groups of people with different memes who (largely) no longer interchange their memes and are becoming memetically diverse. Just as two genetically diverse groups will eventually become so different that they can no longer interbeed - and must therefore be classified as different species - two groups who do not exchange ideas will become memetically diverse and become unable to talk to each other. That's evolution in action!

SteveBaker (talk) 12:09, 3 April 2009 (UTC)

I've got a question about this: With modern infertility treatments, those flawed genes may be passed on to the next generation who will also require infertility treatment. Hence, a gene that would normally vanish (or at least be kept strongly in check) may flourish. I've heard similar claims in the past, and they don't make sense to me. Surely the extra hurdle of infertility treatment will discourage some women from having children. People with the gene will be less likely to pass on their genes that those without. Thus the gene is still selected against. It may not disappear in one generation but it will be pushed out eventually. Right? On the other hand my understanding of genetics comes from NPR and a really old third edition copy of The Origin of Species - I've never had any formal training. Plasticup ^T/C 14:09, 3 April 2009 (UTC)

I believe your analysis is essentially correct. The only way infertility might become more common is if the natural genetic drift would produce more infertile people with each generation than people who failed to get successful fertility treatments would remove. StuRat (talk) 15:21, 3 April 2009 (UTC)

While we don't know definitely how the longer generation times would affect human evolution, it's interesting to note that in some other animal species, it has been shown to lengthen the average life span. Of course if you think about it, this is hardly surprising Nil Einne (talk) 20:41, 3 April 2009 (UTC)

We seem to have drifted from the original Q. The answer would be that evolution should indeed speed up as a result of higher mutation rates from longer generations of humans, if all other factors are kept constant. There are, as noted previously, factors slowing evolution down, as well, or at least changing which characteristics are selected as "successful" (for example, changing from being able to raise kids to now having as many kids as possible and taking no responsibility for them whatsoever). StuRat (talk) 15:28, 3 April 2009 (UTC)

Wouldn't the higher mutation rate be counterbalanced somewhat by the fact that it takes longer to produce each new generation? I mean, where do you get more evolution: in 20 generations of 40 year-old parents, or in 40 generations of 20 year-old parents? -GTBacchus^(talk) 22:15, 3 April 2009 (UTC)

To some extent, yes. However, I don't think a 40 year old mother has just twice the mutation rate of a 20 year old, in her ova, but more like 10 times as high a rate. For example, take a look at this graph showing how dramatically Down's Syndrome increases with the age of the mother: [10]. StuRat (talk) 16:39, 5 April 2009 (UTC)

While natural selection is hard to quantify, it is possible to talk about variability and the rate at which it accumulates through mutation. There are two things to worry about: the time between successive generations and the mutation rate of germline cell DNA (not somatic cell DNA). An appropriate metric to express the mutation rate is the average number of mutations per zygote divided by the generation time. (By per zygote I mean the number of mutations accumulated during the time between when the parent was a zygote to when that parent produces its first daughter (or son) zygote) If, on average, women are having children later in their life (see generation) then the generation time has been lengthened. The question is how much does that extra time increase the amount of mutation? I couldn't find information about age vs. mutation rate and mutation accumulation rates during each portion of the cell cycle.
Imagine a case where most of the mutation takes place during DNA replication and very little takes place during other stages. Considering that the germline cell production of mothers has mostly finished shortly after birth, if the mutation rate is low while the oocyte is "waiting around" then the total number of mutations will be similar whether it is fertilized after 16 years or 26 years. Since the oocyte's DNA makes up half of the zygote's, this means that the "number mutations per zygote / generation length" ratio will be lower when the average generation length is longer. If the rate of mutation in gametes is non-constant and increases as the parents get older (i.e. it's accelerating) then you could get the opposite case where the number of mutations is more than enough to compensate for the extra generational time. Sifaka ^talk 21:55, 3 April 2009 (UTC)

Both sexes have the potential to undergo spontanous mutation during gametogenesis, but as correctly pointed out by Sifaka, oogenesis is basically complete at the time of birth, and no new eggs are generated in adulthood. The type of mutation that occurs in advanced maternal age has nothing to do with DNA mutations (as implied by StuRat) but rather nondisjunction during meiosis -- where the chromosomes fail to segregate normally -- thus leading to a higher risk for conditions such as Down syndrome. It's actually men who are more susceptible to the generation of new mutations with age, since they continually make new sperm and thus their gametes undergo many more replicative cycles over their lifespan. --- Medical geneticist (talk) 17:57, 7 April 2009 (UTC)

Quantummechanical operater

why quantum mechanics deals only with linear operater? why not with other operater ?Supriyochowdhury (talk) 11:25, 3 April 2009 (UTC)

You can apply any operator you like to any wave function you like. However, most physical processes in elementary quantum mechanics can be described as linear operators (e.g. A⁺ and A^- for quantum state increment and decrement). If you want to model a process that is actually physically observed, you need your mathematical model to match the physical phenomena. "By dumb luck" most of the important (elementary) phenomena are well-modeled with linear operations. Nimur (talk) 12:41, 3 April 2009 (UTC)

(Actually dumb luck has nothing to do with it. Physicists constructed the entire conceptual modeling framework of quantum theory, and made it quite different from the classical mechanical description of particles and energy, specifically so that the mathematical operations could be simplified while still matching the observed physical reality. In fact, they created such a conceptual model twice, and both times came up with "equivalent" mathematical operations. Nimur (talk) 13:04, 3 April 2009 (UTC) )

This is not really accurate. All operators in quantum mechanics are exactly linear, regardless of the physical system and the precision of the model. But those operators operate on the wave function, which is defined over the phase space of the system, which has one dimension for every degree of freedom. Quantum theories are nonlinear in the more ordinary three-dimensional sense. Here's an analogy in classical physics. Say you have a system of two billiard balls, a cue ball and an eight ball. In initial state A the cue ball is about to strike the eight ball and knock it into a pocket, which is final state A'. In initial state B the cue ball strikes the eight ball but it misses the pocket—final state B'. The evolution of the system in both cases is nonlinear (if it were linear the cue ball would have to pass through the eight ball instead of striking it). However, if you think of the "time evolution operator" that takes A to A' and B to B' in the phase space, that operator is linear in the following sense: if you start with pA + qB, representing a probability p of being in state A and a probability q of being in state B, then the operator has to take that to pA' + qB'. If it did anything else, it would be saying that there's some sort of interaction between possible worlds, which would be a lot weirder than interaction between billiard balls.

Quantum mechanics does have a kind of "interaction between possible worlds", but it's limited by the fact that the time evolution operator is still linear. People have devised nonlinear variations of Schrödinger's equation with the goal of solving the measurement problem, but it's hard to make a workable theory that's nonlinear in phase space. -- BenRG (talk) 13:21, 3 April 2009 (UTC)

This paper, Relativistic models of nonlinear quantum mechanics, seems to outline the issue, and cites several other papers which have attempted nonlinear generalizations. Nimur (talk) 13:34, 3 April 2009 (UTC)

Quantum Mechanics

In analytic solution of H-atom Scrodinger equation a coordinate transform from cartesian to sherical polar coordinate because although Cartesian coordinate (x,y& z)are not suitable for this problem .I read many books but don't able to know in details about this problem.Please tell me what kind of problem I face if I don't change the coordinate from Cartesian to sherical polar coordinate.Supriyochowdhury (talk) 11:43, 3 April 2009 (UTC)

Have you tried to solve the Schrodinger equation in x,y,z coordinates? You can perfectly well set up the boundary conditions if you so desire. Your algebraic representation of the problem will become unwieldy, and you will end up carrying dozens of sines and cosines around the equations. Take a look at spherical symmetry, and think about why it is easier to write a description for a circular wave field using circular-style coordinates. Nimur (talk) 12:43, 3 April 2009 (UTC)

Also see this "applications" section of the Spherical coordinate system article. "Two important partial differential equations, Laplace's equation and the Helmholtz equation, allow a separation of variables in spherical coordinates. The angular portions of the solutions to such equations take the form of spherical harmonics." In Quantum Mechanics, you will find similar easy solutions because the spherical coordinates match the physical problem description better than a cartesian grid. Nimur (talk) 12:54, 3 April 2009 (UTC)

superconductivity

Does superconductivity happen in all materials when sufficiently cooled or only in some materials ? —Preceding unsigned comment added by Rkr1991 (talk • contribs) 13:50, 3 April 2009 (UTC)

Our article entitled superconductivity starts as follows: Superconductivity is a phenomenon occurring in certain materials. Plasticup ^T/C 14:12, 3 April 2009 (UTC)

Many materials are not even conductors, let alone superconductors, at low temperature. SpinningSpark 14:53, 3 April 2009 (UTC)

I suggest the following modified Q: "Do all conductors become superconductors at a low enough temperature ? How about semiconductors ?". StuRat (talk) 15:10, 3 April 2009 (UTC)

A more interesting question. The answer, however, remains "no". As the third paragraph of superconductivity notes, many metals (such as gold, an excellent conductor) and insufficiently doped semiconductors do not display superconductivity. — Lomn 15:42, 3 April 2009 (UTC)

The next obvious question, then, is how we know that they don't become superconductors. That is, could it be that they do at a low enough temp, but we have been unable to test them that close to absolute zero ? Or, is there some theoretical reason why they can never exhibit superconductivity ? StuRat (talk) 16:38, 3 April 2009 (UTC)

In the case of semi-conductors, they cease to conduct because all the electrons have returned to the valence band and none have sufficient energy to cross the energy band gap into the conduction band. Conduction can no more take place in a completely full band than it can in a completely empty band, in fact there is a principle that maximum conductivity occurs in a half filled band. SpinningSpark 18:09, 3 April 2009 (UTC)

My understanding from physics lectures (which I may not correctly remember being as the distance in time is now measured in centuries) is that pure crystalline silicon (and presumably also germanium and carbon) are actually perfect insulators as absolute zero is approached. SpinningSpark 16:04, 3 April 2009 (UTC)

Carbon has many different crystalline forms. Some Carbon nanotubes are metalic. Dauto (talk) 19:08, 3 April 2009 (UTC)

Fairly certain we did not have those in the 1960s. I was, of course, referring to the crystal form of carbon analogous to silicon crystals, ie diamond. SpinningSpark 00:30, 4 April 2009 (UTC)

Capsaicin and squirrels

Hi. I've got a question about my backyard bird-feeder. It's full of sunflower seeds and peanut halves, and the squirrels in the neighborhood like to get into it, and eat up way too much of the bird food. There are many technologies that have been developed to keep squirrels from doing this sort of thing, and that one that appeals to me most involves the chemical capsaicin, which as you know, is what makes peppers hot.

Evidently, birds have no sensitivity to capsaicin, but mammals do. Thus, it makes sense to treat the bird food with capsaicin, and then the squirrels won't like it.

So... I bought 15 habanero peppers - very hot. I diced them into little bitty pieces, tried to crush and break the seeds, and boiled it all in water for 10 minutes or so, then I put the water in a spray bottle, and sprayed the seeds. It didn't work.

The water is kind of hot, but not 15-habaneros hot. I can spray it on a potato chip and eat it without trauma. Then I read that capsaicin is "hydrophobic", so water was probably a bad choice of substrate. A guy in a bar who claims to be a doctor, or at least a pharmacist, told me that vinegar would absorb the capsaicin quite well. However, I don't know if vinegar might make the seeds unpalatable to birds.

So... I seek an appropriate substrate for a hot pepper spray. It has to absorb the capsaicin, it should carry the hotness to the seeds and nuts, and it shouldn't make the bird food unpalatable or unhealthy for the birds. Any ideas? -GTBacchus^(talk) 16:53, 3 April 2009 (UTC)

Why not use hot sauce, like Dave's Insanity or something similar, that has done the work for you? Livewireo (talk) 17:38, 3 April 2009 (UTC)

I think I would end up spending a lot of money if I treat all the birdseed with a commercial hot sauce. I did smear a pack of "fire sauce" from Taco Bell on the outside of the feeder one time (it's a cage-type feeder, where seeds fit through the mesh). That didn't seem to do much. -GTBacchus^(talk) 17:49, 3 April 2009 (UTC)

Oil, such as sunflower oil, should be better (and birds like fat). You're probably better using a food processor or blender to dice the peppers into tiny bits rather than cooking it, and I'd probably leave the micro-diced peppers in the oil for a few days so it fully infuses into the oil. Having it in the oil should also mean that if Mr Squirrel does eat some and decides to spit it out, the spicy oil will still stick to his mouth, giving him a lasting reminder of where not to eat. 87.115.166.150 (talk) 17:40, 3 April 2009 (UTC)

If you're thinking "but what if the birds eat one of the pepper fragments" - that's the idea (indeed, that the fragments are so small that any mouthful will contain some). Peppers have evolved to be eaten by birds (for the purposes of moving their seeds around), and the reason the birds aren't affected by the capsaicin and mammals are is that the peppers have evolved this to that end. To the bird the habanero probably just tastes like a tomato. 87.115.166.150 (talk) 17:45, 3 April 2009 (UTC)

Yeah, I'm not worried about the birds getting burned. I chose capsaicin because I know birds have no sensitivity to it.

I like the oil suggestion - of course sunflower or safflower oil would be acceptable on sunflower and safflower seeds! I might want to use something other than my spray bottle, because those oils are quite a bit more viscous than water. Maybe I would treat the seed in a big jar by pouring oil in and rolling it about... -GTBacchus^(talk) 17:49, 3 April 2009 (UTC)

At the expense of sounding a bit Delia, I'd either dip or drizzle. Better yet use a fat that's solid at room temperature but that can easily be melted. A lot of bird food is made with lard, so melt some lard, chuck in the peppers and seeds, mix, put into a container, and put into the fridge. Once it's set, put a hole through it for a string. My local petstore sells little cages that such blocks can go into. Gosh, with this curried seeds in lard diet, it'll be a wonder if your birds don't end up looking like little feathered Bernard Mannings. 87.115.166.150 (talk) 17:58, 3 April 2009 (UTC)

You could experiment a bit, vinegar, oil whatever, the birds won't really mind. 65.121.141.34 (talk) 18:19, 3 April 2009 (UTC)

The RSPB says chili powder, curry powder, and various kinds of hot sauce. These birds eat better than I do. Dog Day Today (talk) 18:23, 3 April 2009 (UTC)

I don't like the oil idea because it would get on the inside of the feeder making it hard to clean and the oil could become rancid after a while. Sifaka ^talk 23:50, 3 April 2009 (UTC)

Why not just dice the peppers and chuck 'em right in with the seeds? The squirrel may eat a few seeds, but the first time he eats a pepper he'll be out of there. Lord knows I wouldn't hang around. Plasticup ^T/C 18:40, 3 April 2009 (UTC)

The squirrels could probably avoid the diced pepper bits if they're large enough. Also, the squirrels are probably patient enough to pick through the seeds until they get ones that are not peppered up. You need to make sure each seed packs a wallop. To do this, I would just blend the peppers in the blender and mix the resulting noxious slurry in with the seeds directly using a mixing bowl and a spatula. If getting a good even coat is difficult, try adding a little water to reduce the viscosity of the pepper slurry. Adding oil will make the inside of the feeder gross, especially if it becomes rancid. You may also wish to dry the seeds out before you put them in the feeder to avoid possible rotting and dirtying the inside of the feeder with pepper juice. Also make sure your peppers are really unpalatably hot. Really hot peppers make my eyes burn just by cutting them. Try a miniprep using your mix with some edible sunflower seeds. Sifaka ^talk 23:50, 3 April 2009 (UTC)

I have a follow up question. If peppers evolved to be pleasant to birds but not to mammals, how come I - a mammal - enjoy peppers? Dauto (talk) 19:05, 3 April 2009 (UTC)

Masochism? 65.121.141.34 (talk) 19:10, 3 April 2009 (UTC)

Eating peppers triggers release of endorphins. That's not the full story, but it's part of it. The other part is that you can learn to associate intrinsically unpleasant things with pleasant things that they go together with -- so for example, even though bitterness is intrinsically unpleasant, the bitterness of a gin-and-tonic is part of its appeal. Looie496 (talk) 20:19, 3 April 2009 (UTC)

Mammals have TRPV1 channels, birds do not. So its not the case that "peppers evolved to be pleasant to birds", its simply that birds do not have the genes required to detect the noxious "heat" of capsaicin and therefore they don't avoid them as mammals might. Why do you enjoy peppers? because thermosensation is complex, and the range between pleasant warmth and noxious heat depends on a large range of factors, including experience and genetics. Moreover, at some concentrations capsaicin be be an analgesic. I can guarantee, while you may enjoy some peppers, that there will be a point on the Scoville scale that eating a paper is no longer pleasant and instead becomes noxious to you. That will not happen to birds. Rockpocket 00:09, 4 April 2009 (UTC)

I think it is likely that "peppers evolved to be pleasant to birds", but would state it more completely in this context as, peppers were selected by evolution to be relatively more pleasant to birds than to mammals. The capsaicin works for the latter part - unpleasant to mammals in large quantities - so the plants that made more capsaicin might have had an advantage because mammals, which might completely digest the seeds or otherwise not distribute them as well as birds, don't eat them in large quantities. --Scray (talk) 13:10, 4 April 2009 (UTC)

A product called Squirrel Away does the capsaicin isolation for you. Does it work? Somewhat. -hydnjo (talk) 21:59, 3 April 2009 (UTC)

I read somewhere that the powder bothers birds, not because it's hot, but because it's powder. If I could see that product in a store, I'd at least read the label, and see if it relates more information than that link. My local bird store doesn't sell it, though. -GTBacchus^(talk) 22:08, 3 April 2009 (UTC)

As a data point, my birds eat powdered food, in the form of the dregs from their feed, without complaint. --Sean 22:16, 4 April 2009 (UTC)

GTBacchus: The birds and squirrels aren't exposed to powder but to seed. The seed has indeed been exposed to the powder but it sticks to the seed and so seems a natural part of the seed, not a powdery cloud. -hydnjo (talk) 23:44, 4 April 2009 (UTC)

It seems to me that you will need a dehydrator, in order to remove the excess moisture from the peppers, to prevent them from rotting in the bird house. I agree with the suggestion of using a blender to chop them into little bits. After this, dehydrate, then mix them with the seeds. You could also try mixing them with the seeds first, then dehydrate the mix. If you don't want to use a dehydrator, an oven can also be used. StuRat (talk) 16:31, 5 April 2009 (UTC)

(Removed off-topic post by User:Dweller). SteveBaker (talk) 01:47, 8 April 2009 (UTC)

neuron state during mania

According to this web page, an increase in "brain derived neurotrophic factor" (BDNF) improves neuron health and leads to recovery from clinical depression. But what about mania? What is the state of neurons during, say, hypomania? Could it be that it is the opposite from that of depression, i.e., the neurons swell and establish many more synapses with other neurons? --Halcatalyst (talk) 18:31, 3 April 2009 (UTC)

First, the idea that BDNF is the "final common pathway" for depression is very much a minority view. Second, as a general rule of thumb, treatments that improve unipolar depression tend to make mania worse. In any case it's unlikely that any relevant effects have much to do with overall neuron health. Looie496 (talk) 18:38, 3 April 2009 (UTC)

Yes, I know that "treatments that improve unipolar depression tend to make mania worse" (athough the point I appreciated at the referenced web site is that exercise also causes an increase in BDNF, which obviously has no side effects other than, perhaps, better physical health). The question is, what effects does mania produce in neurons? Could it be that excessive BDNF is produced? Or do other molecules play a role? I'm interested in what might be going on at the cellular level during mania. --Halcatalyst (talk) 19:10, 3 April 2009 (UTC)

I beg to differ: exercise has a bunch of side effects, we just don't usually describe them that way. Anyhow, the cellular change that seems to be drawing the greatest interest at the moment in regard to mania is an overexpression of a substance called glycogen synthase kinase 3beta (GSK3B). There's also strong evidence implicating a circadian gene called CLOCK in at least some cases. But basically it's still a wide-open question. Looie496 (talk) 20:14, 3 April 2009 (UTC)

Interesting: I see that GSK3B is involved in "energy metabolism, neuronal cell development" and that CLOCK "encodes proteins regulating circadian rhythm." Makes sense: one of the first signs of mania is that sleep gets out of kilter (a problem with depression too) and of course being excessively energized or deenergized is also a defining component of the disorder(s). Thanks for your response. I'm always interested in knowing more, though I'm pushing the limits of my understanding. :) --Halcatalyst (talk) 01:05, 4 April 2009 (UTC)

Mike Phelps

I recall reading somewhere that Michael Phelps (8x gold medals in 2008 Olympics) eats 12,000 kcal a day of food. I presume its because of his workout routine. My question is, do athletes (M.P. in particular) have a higher average body temperature compared to less physically fit individuals? 65.121.141.34 (talk) 19:03, 3 April 2009 (UTC)

Mostly not. He eats that 12,000 kcal because he's doing aerobic exercise for 5 or more hours a day. During that exercise he's obviously hotter (and such a huge duration will push the average up) although of course the thermoregulation his body employs will keep even the highest temperature down pretty well, so his body temperature won't be that much hotter than normal. When he's not exercising his body temperature should be normal, again because of thermal homeostasis. Now he does burn more calories when resting than normal people, because he has a higher muscle mass, and muscle needs calories to keep alive (so the well-muscled have a higher metabolic rate than the low-muscled). 87.115.166.150 (talk) 23:46, 3 April 2009 (UTC)

Unless he's in hot water, Phelps's particular sport is going to keep his body temperature down pretty effectively though.John Z (talk) 22:11, 4 April 2009 (UTC)

I assume you meant "hot water" physically. DMacks (talk) 09:12, 5 April 2009 (UTC)

There is a fairly efficient homeostasis mechanism to control normal human body temperature. Despite this, during exercise, the core body temperature can rise to over 40°C. Fitter people are able to generate higher power output than the unfit. Fit people generate more heat and need to dissipate this more quickly. This is partially achieved by increased blood flow to the skin. Also, fit people can tolerate a higher core temperature during exercise than the unfit. [Short answer: yes.] Axl ¤ [Talk] 11:36, 6 April 2009 (UTC)

pleural tap

does this problem occur in men as well as women? —Preceding unsigned comment added by 71.185.151.107 (talk) 21:42, 3 April 2009 (UTC)

I'm not sure what problem you are referring to, as a pleural tap (or thoracentesis) is a medical procedure to treat fluid or air in the pleural space. If you are asking whether accumulation of air and/or fluid can occur in both men and women, the answer is yes. If you're asking whether thoracentesis can be performed on men, then the answer is yes again. Otherwise, you will have to clarify your question. Cyclonenim :  Chat  22:22, 3 April 2009 (UTC)

Post edit conflict: Aaargh! Your answer made my mine completely redundant, so I am going to wikilink a bunch of words in yours to make up for it. Darn you for being faster with the save page button. Sifaka ^talk 22:30, 3 April 2009 (UTC)

Sorry :) Cyclonenim :  Chat  22:39, 3 April 2009 (UTC)

Eating feces

Assuming that the individual who defecates does not have any kind of infection, does eating feces actually pose a health risk? Does it make any difference if person consuming it is different to the person producing it? Does it matter if they are different species (as long as the feces doesn't contain any foodstuff poisonous to the consuming species). Thanks. JackMacBlack (talk) 22:24, 3 April 2009 (UTC)

Yes, eating feces does pose a health risk because the gut flora, while normally benign, can cause serious disease when they escape from their normal confines. On example is bacterial sepsis following intestinal perforation. Before you ask, complete lack of any gut bacteria may cause other problems. Sifaka ^talk 22:37, 3 April 2009 (UTC)

We've also got an article, coprophagia, which partly addresses your question. -GTBacchus^(talk) 22:38, 3 April 2009 (UTC)

We have a whole article on diseases that can arise from this: fecal-oral route, though that article can use some work. --Bowlhover (talk) 22:08, 4 April 2009 (UTC)

April 4

1+1

1+1=2 —Preceding unsigned comment added by 72.138.176.179 (talk) 01:41, 4 April 2009 (UTC)

See 1+1=2. -- kainaw™ 01:55, 4 April 2009 (UTC)

Better yet, see Principia Mathematica. --Anonymous, 11:01 UTC, April 4, 2009.

1+1=10, Dave. HAL 9000 (talk) 03:21, 5 April 2009 (UTC)

Actually HAL would probably think that 1+1=1 SpinningSpark 09:46, 5 April 2009 (UTC)

1+1=0 mod (2) (talk) 09:30, 5 April 2009 (UTC)

There are 10 types of people in this world. Those that understand binary and those that don't. A Quest For Knowledge (talk) 14:32, 5 April 2009 (UTC)

2 + 2 = 5 for extremely large values of 2. A Quest For Knowledge (talk) 14:32, 5 April 2009 (UTC)

They can with rounding. 2.4 + 2.4 = 4.8. Round those and you get 2 + 2 = 5. StuRat (talk) 16:13, 5 April 2009 (UTC)

Yes, and isn't 2.4 an extremely large value of 2? --Anon, 19:50 UTC, April 5, 2009.

What is the question? ~AH1^(TCU) 18:04, 5 April 2009 (UTC)

No, What is playing second base. DMacks (talk) 08:56, 6 April 2009 (UTC)

Put 1+1 between the two segments of = and you will obtain a window!--pma (talk) 20:11, 5 April 2009 (UTC)

Do you mean like this ${\underline {\overline {1+1}}}$ ? SpinningSpark 23:41, 5 April 2009 (UTC)

And in biology 1+1 can be anywhere from 3 to several million (guestimated) after a while  ;-) 76.97.245.5 (talk) 16:36, 6 April 2009 (UTC)

Adapating to running

As of late i've taken up running (we all want to be healthier, dont we?).

I have seen running programs around the web like this one:


Week one: Walk for 6 minutes, then jog at an easy pace for 1 minute. Repeat 3 times. Aim for three sessions with that same sequence for week one.

Week two: Walk for 5 minutes, then jog for 2 minutes. Repeat 3 times. Aim to do three sessions in week two.

Week three: Walk for 3 minutes, then jog for 4 minutes. Repeat 4 times. Aim for four sessions in week three.

.....

Week seven: Walk for 1 minute, then jog for 11 minutes. Repeat 3 times. Do four sessions this week.

Week eight: Congratulations on making it to week eight! For your first run this week, try walking for 5 minutes to begin and end the workout, and run for 20 minutes in between. By the end of the week, try to run for 30 minutes without stopping. Aim to run for 30 minutes four times a week, and you'll notice that your stamina and fitness will continue to improve. Soon you'll be ready to run your first 5K!'''

They all follow that general run/walk pattern.

What adaptions or changes would you suppose would take place that would allow you to be able to run for 20 minutes at the end of week 8 where you could barely jog for a minute at week 1.

(just a little side question, would there be populations of people that would be better runners [eg, have larger lungs than everyone else, long legs ect] for one reason or another.. (running from daily godzilla attacks ) )

(well i thought this stuff was interesting anyway..)

Kingpomba (talk) 09:44, 4 April 2009 (UTC)

Not sure this program is designed for people who have trouble with week 1. It's intended to step up gradually to give your muscles time to adapt and not to overtax your metabolism. Ideally you would avoid doing things you can "barely manage" and start or progress more gradually if you have trouble. See Muscle#Exercise, Aerobic exercise and Microtrauma 76.97.245.5 (talk) 21:22, 4 April 2009 (UTC)

The semantics of the program and the whole thing wernt important (im not following this program or any one..just doing what my body tells me) i was just interested what makes you better at the end (eg larger lungs than before ect) —Preceding unsigned comment added by 58.167.5.29 (talk) 23:15, 4 April 2009 (UTC)

(1) If you are above age ~30, or have any medical issues whatsoever, consult your doctor before embarking on a fitness program designed for fast progress, such as the one you've outlined.

(2) The general idea of an untrained individual's adapting to running by alternately walking and running is widely accepted.

(3) You wrote: "we all want to be healthier, don't we?". Being healthier is about changing your lifestyle. It is not about reaching some numerical goal within a given number of weeks. Really! There's no hurry. Be patient.

(4) Be sure to get good running shoes adapted to your feet.

(5) The limiting factor is likely to be injuries. Never, ever run if it's painful. I believe that stretching after running is a good way of preventing injuries, although this has been a subject of considerable debate. (I'm speaking as an ex couch-potato now 40+ km/week runner, who started running at a mature age, and who has had just about every injury in the book). --NorwegianBlue ^talk 21:14, 5 April 2009 (UTC)

1) General adaptations: certain lower-body muscles will grow, your lungs will become more efficient at processing oxygen to fuel your muscles, your heart will become better at pumping blood to fuel your muscles. If you're doing this purely to build cardio, then be sure to get enough calories. In retrospect, when I began my running program, I took in far too few calories which ultimately caused me to decrease my muscle mass significantly.

2) It is controversial, but if I were to bet, I would claim that there are both populations and people who live in certain geographic areas that are more suited for running for long distances. At the population level, the controversial claim goes that East Africans have certain biological features that make them ideally suited (again, at the population level) for long distance running. This is accentuated by social and geographic factors. At the geographic level, any person who is born and lives a significant portion of their life in a region that has a high altitude will have lungs that are better at processing oxygen. If I remember correctly, any person who trains at higher altitudes will also become better at processing oxygen, but this benefit diminishes quickly compared to a person who was born and spent a significant amount of time there. If you want to read someone who advocates biological differences between populations (and their descendants) in relation to sport performance, then Taboo : Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It by Jon Entine and Earl Smith is worth reading.

3) As someone who began a similar program last year, I think your expected progress is unrealistic. I began running for say 30s then walk for a minute, repeat for 30 minutes. Next came run for 1min, walk for 1min; run for 1:30, walk for 1min; ... I began running at the end of July and by October I was running for the entire 30 minutes I allotted for cardio. Admittedly, I wasn't pushing myself to exhaustion every workout, so it is certainly possible to progress quicker than my pace, but the progress you posted seems unlikely. But nevertheless, good luck.--droptone (talk) 12:02, 6 April 2009 (UTC)

What's this bug?

I was playing with my new camera, and I came across a bug that I photographed. I wouldn't mind adding it to an article, but I'm not sure what kind of bug it is? Any ideas? [11] — Deon555^talk_{I'm BACK!} 12:49, 4 April 2009 (UTC)

edit: I thought it might have been a Dung beetle but it looks a little long and a little thin for that...? — Deon555^talk_{I'm BACK!} 12:51, 4 April 2009 (UTC)

I'm thinking it's either some sort of ground beetle or a scarab of the family scarabaeidae.130.127.99.54 (talk) 19:02, 4 April 2009 (UTC)

How would this one be for a match de:Datei:Stierkäfer (Typhoeus typhoeus) weiblich.jpg ?

76.97.245.5 (talk) 21:14, 4 April 2009 (UTC)

Looks a bit like a mealworm beetle to me. Mikenorton (talk) 11:10, 5 April 2009 (UTC)

ok, the family is probably dermestidae but most are, as yet "undescribed". You may very well have just discovered a "new" species. If that is the case, than please feel free to name it after me.67.193.179.241 (talk) 16:17, 5 April 2009 (UTC)Rana sylvatica

Incidentally, before adding that pic to an article you should crop it, so we just see the beetle and a small area around it. StuRat (talk) 16:06, 5 April 2009 (UTC)

origin of multi cellular species

if we just had simple single-celled organisms when life first 'originated' on earth, then how did the more complex multicellular organisms evolve form the single celled ones who couldn't reproduce sexually and produced exactly the same type of offspring when they did reproduce asexually?? —Preceding unsigned comment added by 117.197.122.138 (talk) 12:55, 4 April 2009 (UTC)

See Evolution of multicellularity. PrimeHunter (talk) 13:05, 4 April 2009 (UTC)

Coral, which reproduce both sexually and asexually, are an interesting "in-between" species. They are normally considered a single-celled organism, but they do form colonies, some with a fairly complex shape. If you continue this trend, with added specialization by individuals, you eventually get to multi-cellular life. StuRat (talk) 16:04, 5 April 2009 (UTC)

It's not really that hard to imagine - after all, even we humans have a brief unicellular phase of our lives! But one really good thing to read is the life cycle of 'slime molds'. These are truly amazing. They spend parts of their lives as amoeba-like creatures that function like animals - independently moving and hunting bacteria - they reproduce sexually during that time. But then, they can group together to form colonies - (sometimes up to a meter across) which can flow like a gelatinous blob - moving and seeking food as a unit - other times behaving like small slug-like creatures up to a half centimeter long - effectively becoming large animals. Then under other pressures, they make plant-like stalks with fruiting bodies on the top - requiring the cells to become specialised as root, stem and fruit - meaning that you really can't consider them as individual cells anymore. These does more than blur the line between unicellular and multicellular - it also blurs the line between plant and animal, microscopic and macroscopic. Truly weird stuff. But this kind of primitive organism shows how cooperating unicellular creatures can benefit from acting in a multicellular way when stressed in particular ways - and that (in all likelyhood) is how modern multicellular animals and plants came about. SteveBaker (talk) 17:05, 5 April 2009 (UTC)

physics

why does electric dipole always start with a negative sign124.125.39.197 (talk) 17:26, 4 April 2009 (UTC)

See electric dipole moment, it is just a matter of convention. The negative sign arises because the vector is pointing in the opposite direction to the electric field vector (at a point on a line between two charges). SpinningSpark 18:20, 4 April 2009 (UTC)

April 5

Evolution of Wings

Here's a new idea about the evolutionary development of wings:

http://www.telegraph.co.uk/scienceandtechnology/science/dinosaurs/5105218/Dinosaurs-may-have-evolved-wings-to-attract-mates.html

GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 08:41, 5 April 2009 (UTC)

And? Zain Ebrahim (talk) 11:02, 5 April 2009 (UTC)

There is also the modern-day lizard that runs upright on its two hind legs. As it does that, it holds its front legs sideways, spreading out a large flap of skin between each front leg and its body. I think it does that only when frightened, and the tactic may serve to scare the creature that frightens it. I don't remember the name of the lizard or where it's from, but most people have seen videos of its comical appearance when running like that. Can anyone give a lead to a site giving information about this lizard, including its taxonomic name? – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 14:21, 5 April 2009 (UTC)

Further information on biological wings is given in the Wikipedia articles Flying Fish and Flying and Gliding Animals. These articles provide arguments against creationists who refer to wings to support their views. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 14:54, 5 April 2009 (UTC)

Are you referring to the frill-necked lizard or one of the dracos? -- kainaw™ 15:02, 5 April 2009 (UTC)

The one I was thinking of runs along the ground but I don't think it glides through the air. Thanks for the reference to the frill-necked lizard and the Draco gliding lizards; I was not aware of those. – GlowWorm —Preceding unsigned comment added by 98.17.33.139 (talk) 15:21, 5 April 2009 (UTC)

On second thoughts, it is probably the frill-necked lizard that I am thinking of. It does not fly or glide. The photo of it in Wikipedia was taken from slghtly above it, rather than straight on while running, which is the way a rather well-known video shows it. I think the difference between flying and gliding of any creature is that gliding does not involve rising in the air except on thermals or other updrafts. Also, flying uses muscle-power input to rise. (Although gliding of living creatures may involve muscle-power input to maintain stability and to change direction.) But there is a very fine distinction between flying and gliding. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 15:56, 5 April 2009 (UTC)

Yes, it's the frill-necked lizard (Chlamydosaurus kingi) I am thinking of. It does not fly, but its skin flaps could develop into wings. Some videos of this lizard are shown at http://www.youtube.com/watch?v=xWDgQH-2pCo. A couple of the videos show it running. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 16:12, 5 April 2009 (UTC)

Atherosclerosis

Atherosclerosis can be caused by smoking, but a person with Atherosclerosis might not necessarily be a smoker. Am I right? Thanks. —Preceding unsigned comment added by 116.71.32.237 (talk) 09:31, 5 April 2009 (UTC)

Yes, read our article. 121.72.192.28 (talk) 10:47, 5 April 2009 (UTC)

Puberty and growth

On average, at what age does puberty stop and at what age does growth and physical developemnt peak. Are there significant physical changes between the ages of 16 and 18, 18 and 21? Clover345 (talk) 12:18, 5 April 2009 (UTC)

Did you read our articles on Human development and Puberty? --Jayron32.talk.contribs 12:37, 5 April 2009 (UTC)

Yes but they don't really answer my question. Thank you for your efforts however. Clover345 (talk) 13:36, 5 April 2009 (UTC)

Girls typically finish growing before boys do (which is how boys usually end up bigger). Girls often reach full adult height before 16, while boys may continue into the 16-18 year old range, and sometimes into the 18-21 year range. Growth often follows the pattern of "growing up" first, then "filling out". So, both boys and girls may reach full adult height, but be skinny, then later become more muscular (mainly in the case of boys) and more curvy (mainly in the case of girls, with additional fat deposits on breasts, butt, and hips). Because of the age delay, girls are likely to have reached their full adult height by 16, but may continue to fill out in the 16-18 year old range (it would be somewhat unusual if this continued into the 18-21 year old range). Boys may reach full adult height in the 16-18 year old range and continue to fill out in the 18-21 year old range. Note that ethnic group, diet, exercise, and other factors also have an effect here, as may exposure to hormones in food and medications. StuRat (talk) 15:40, 5 April 2009 (UTC)

Don't girls also usually start puberty earlier? Nil Einne (talk) 14:15, 6 April 2009 (UTC)

Yes. StuRat (talk) 17:17, 6 April 2009 (UTC)

Foods endemic to the Americas...

I got into an interesting discussion tonight over dinner with a fellow here in China about which foods are endemic to which areas.

With respect to the Americas I know of corn, peanuts, tomatoes, "wild" rice, sunflowers, and peppers. I'm sure there are more, however, and am having trouble finding a scholarly listing.

Can anyone help me out? —Preceding unsigned comment added by 61.189.63.137 (talk) 12:42, 5 April 2009 (UTC)

You missed potatoes...there's more obscure things, too, like fiddleheads, eulachon and eulachon grease, camas....I suggest you go looking for "ethnobotany" materials, though many indigenous foods like eulachon and camas are not widespread and were not exported like so many others were; particular animal species, too, I don't think is waht you mean, nor specialty dishes like poutine or Nanaimo bars; i.e. you're looking for plants/vegetables yes? If indigenous foodtsuffs like those and particular wild game and fish species are taken into account, the list is conceivably quite large....as for indigenous cuisines, whether aboriginal or creole or French-Canadian, like poutine, that's even bigger, likewise "generic North American cuisine" like the hamburger....see figgy duff...oh, gee, there's an article needs writing, I'm not qualified to do so however....Skookum1 (talk) 12:57, 5 April 2009 (UTC)

Yeah, I was intending to keep it solely to plants...61.189.63.137 (talk) 12:59, 5 April 2009 (UTC)

Cassava is another major one. Cacao is essential for all human life ;-). And corn should probably be specified as maize, as in most non AmE-variants it stands for generic cereals ("corn, such as wheat and maize..."). If you also allow for meat, there is Turkey (bird).--Stephan Schulz (talk) 14:07, 5 April 2009 (UTC)

This site has a pretty extensive list. Looie496 (talk) 15:57, 5 April 2009 (UTC)

Wikipedia's list is at Indigenous peoples of the Americas#Agriculture. Beans, squash, pumpkins, vanilla, chicle, strawberries, pineapple, tobacco... Rmhermen (talk) 23:19, 5 April 2009 (UTC)

In addition To things listed above there are things that weren't farmed, but gathered. Some of these are also found/used in other parts of the world. > Acorns, Beech nuts, Pine nuts, red Huckleberry, Elderberry as well as several leaf vegetables like Goosefoot, Clover, water lettuce (Sources vary on whether this is native or was introduced later) and roots like Arrowroot and Nymphaea (our article only mentions the Egyptians, but Native Americans made flour from them, too) . Plus Quinoa and Sweet potato in South America. This is very likely still an incomplete list and varied quite a bit by actual location. 76.97.245.5 (talk) 05:46, 6 April 2009 (UTC)

Are these droppings?

Hi. Today I have been cleaning out my shed and I have come across what seem to be some kind of droppings on a couple of boxes and also on the floor. The link below show the droppings and also some damage to some childrens floor tiles (not sure if they have been chewed). I just wondered if anybody could please verify whether these are droppings, and from what animal. Also, if anybody could verify that those tiles have been chewed, and possibly identify what has chewed them.

http://www.flickr.com/photos/37087515@N04/sets/72157616380686806/

Thanks in advance. Lonely Banana (talk) 14:15, 5 April 2009 (UTC)

Those look like rodent droppings -- could be rat, mouse, or some other rodent depending on size and situation. Rat droppings are typically about an inch long, mouse droppings much smaller. Looie496 (talk) 15:52, 5 April 2009 (UTC)

Thanks. I think that they are too small for rat droppings, so are likely mouse. I am going to throw out all of the boxes and sanitise the shed floor with bleach and hot water. I amy also set some traps. Are there any other precautions I should take? Thanks again. Lonely Banana (talk) 19:35, 5 April 2009 (UTC)

You can mouse proof the shed by filling in all the cracks, especially around and under the door. so that they cannot come back in once you have trapped them. Graeme Bartlett (talk) 21:26, 5 April 2009 (UTC)

In my (limited, UK) experience, this could be either or both.

The chew damage resembles that which I once incurred on the foam-rubber padding of some folding garden chairs I was keeping in an astronomical observatory I then helped to run. This was almost certainly the work of yellow-necked mice (similar to field mice: we later caught one), probably collecting bedding material. Rats more often chew to test potential foodstuff (or to gain access, or merely to trim their ever-growing teeth, neither applicable here), but being more intelligent would probably not have persisted so long with these (presumably non-edible) bricks.

The droppings could be either large mice or young rats. I once found similar droppings in my house (next to modestly nibbled, pictorially wrapped plastic-sealed chocolate I'd left out on display) which I initially attributed to mice. Subsequently (after failing with traps, more food being assaulted, and the droppings becoming larger) it turned out to be rats, which I eventually eliminated by persistently supplying them with proprietary-brand poisoned grain. (I had to endure a moderate pong for a few weeks, while presumably a rat corpse or two in the foundations decayed away.)

Mouse-proofing a shed would be possible but difficult - they climb, and can get through amazingly small gaps. Rat-sized gaps are easier to fill: I used expansion foam, which can be bought in aerosol cans, injected into a pre-emplaced matrix of steel wool, as recommended to me by a professional pest control operative who serviced my workplace. Realistically, however, rats can gnaw a new entrance through wood any time they feel like it (brick and concrete merely slow them down).

Either way, try to remove anything that rodents might consider food or bedding material (cardboard, paper, cloth, etc) from both in and near the shed (don't put foodstuffs in your compost heap if you have one), and try to organize the shed contents so that you can periodically inspect all floor and wall areas for newly-created holes.

Since rodents are evidently in the area, think about similar measures for your house, and try to keep rodent-attractive foods inside well-sealed cupboards or stout sealed containers, preferably metal. 87.81.230.195 (talk) 09:37, 6 April 2009 (UTC)

wathurrrrrrrrrrrrrrrrrrrrrrrrrrrrr

Since ice is less dense than water, and a liquid put under enough pressure becomes a solid, what happens to water when it's under enough pressure to turn to ice? Water expands when it freezes, but it can't do that here...

To be overly general, water compresses to minimal volume at 4 degrees Celsius. If you want a lot of technical science stuff, just ask. -- kainaw™ 15:03, 5 April 2009 (UTC)

In general if you lower the temperature of a liquid to below its freezing point but it can't become a solid, it is called supercooling. --98.217.14.211 (talk) 15:07, 5 April 2009 (UTC)

That's not what I'm asking though... lemme try again. The solid form of water takes up a greater volume than the liquid form, right? And when a liquid is under great enough pressure it becomes a solid, right? So what happens when water is under great enough pressure to solidify? It can't do it the same way it normally does, right? There's not enough room.

I think if you read Triple point#Triple point of water, it will answer your question. If not, try Water (molecule). Looie496 (talk) 15:50, 5 April 2009 (UTC)

Look at the phase diagram (in some article mentioned by other replies): If you are at standard atmospheric pressure, and a bit below the melting point (273.15 K) then ice will actually melt if the pressure is increased by a few atmospheres. Only at much higher pressures will it solidify again. There is a certain pressure at which the melting point is lowest, see here. -Icek (talk) 16:18, 5 April 2009 (UTC)

The short answer is that the statement "water expands when it freezes" only describes its behavior under normal pressures. (Likewise, the statement "liquid water is incompressible" is only an approximation.) Under high pressure water does not turn into normal ice, but forms other kinds of ice with different crystal structures that do not involve expansion.

These other kinds of ice are identified by Roman numerals, ice II, ice III, and so on up, about 10 or 15 kinds altogether. They are considered distinct phases of water just as ordinary ice and liquid water are distinct phases, and a complete phase diagram of water will show them all. (And now someone will not be able to resist mentioning ice-nine, a phase of water that exists only in fiction, so I'll do it first. Follow the link to read about that.)

--Anonymous, 19:59 UTC, April 5, 2009.

Regurgitation in animals.

I was reading about Orca where it says some captive specimens had learnt to regurgitate fish to attract sea gulls which they could then eat. I was wondering how animals get around all the side effects that characterise Bulimia (hypokalaemia, hyponatraemia, oesophageal damage etc) when they induce vomitting, question can be expanded to birds land mammals that feed their young in this way. MedicRoo (talk) 17:48, 5 April 2009 (UTC)

Our Gastric acid article unfortunately doesn't include non-human info. Some animals cough up Hairballs and owls are well known for their pellets. On the other hand animals can engage in behavior that is ultimately detrimental. Sea otters have learned to crack oysters on a rock they put on their belly. However it was found that that will eventually damage their ribcage. 76.97.245.5 (talk) 16:19, 6 April 2009 (UTC)

Our articles on vomiting and regurgitation point out there are mechanistic and physiological differences between the two, and that regurgitation and vomiting are not interchangeable terms. Although the regurg article says that some people (including bulimics) are able to train themselves to voluntarily regurgitate, I would expect that the majority of people with eating disorders who purge on a regular basis are in fact inducing vomiting rather than regurgitating, and that is the reason for the frequency of electrolyte abnormalities, oesophageal trauma and dental damage. Mattopaedia ^{Have a yarn} 02:39, 8 April 2009 (UTC)

Blue water

Time for a question of my own. My family recently had the bathroom redone, and now we have a white tub in the place of our previous blue-colored porcelain one. Since then, I have seen something I've never seen before: our water has a decidedly blue tint to it. We have a well and live near the top of a hill away from any farms, so I doubt its any sort of additive or contamination. My question is this: what sort of mineral/chemical in ground water (or possibly our pipes?) could cause a blue tint in water?-RunningOnBrains 19:23, 5 April 2009 (UTC)

Well, water is slightly blue. I'd suspect that you've just managed to set up nice conditions to see it. See color of water. 81.158.123.157 (talk) 19:49, 5 April 2009 (UTC)

I suppose that could be part of it, but the areas of the tub where water hits most often (underneath the faucet and near the drain) have a blue stain on them, so that led me to believe it was something in the water (probably should have mentioned this initially).-RunningOnBrains 19:57, 5 April 2009 (UTC)

You'd need a lot more water than a bath holds to see the blueness of the water. 90.195.179.144 (talk) 21:01, 5 April 2009 (UTC)

The blue stain can be due to copper. Slightly acid water can dissolve copper in the pipes. Particularly if the water was sitting in the pipes unused for a few weeks, it could have built up somewhat. You can probably remove the stain with ammonia if you can't scrub it off. In my area the water company adds slaked lime to the water to control the pH. —Preceding unsigned comment added by 152.91.9.190 (talk) 21:20, 5 April 2009 (UTC)

Wouldn't that actually be copper sulfate? I would have thought that copper from pipes would most likely be an oxide, and therefore a bit greenish. I've seen some rivers and underground lakes at Jenolan caves (in the Blue Mountains, Australia)that were distinctly blue, and I remember being told it was from CuSO4 in the vicinity of the river's spring. Mattopaedia ^{Have a yarn} 02:43, 8 April 2009 (UTC)

Light bulb energy

Do light bulbs use up more energy during activiation (er...when you switch them on) than they do during normal running? My mother insists I leave lights on all around the house because "it takes more energy to turn them back on".

Also, this bit's more for curiosity - what does this apply to? I know blast furnaces need to be left on all the time because it takes a lot of energy to re-start them. What abut cars? Computers? My Wii? 90.195.179.144 (talk) 19:38, 5 April 2009 (UTC)

Mythbusters actually tackled the bit about the lights. It does take more energy to activate lights than to keep them on BUT this is only about a second or so of light operation's worth. So it wastes much more energy to leave lights on then to turn them off (episode summary here). As for your other questions, that's for someone smarter than me :-D -RunningOnBrains 19:53, 5 April 2009 (UTC)

Thanks. Err...Don't suppose you'd know how that would translate to these new energy-saving light bulbs that my mother bought, would you? :p 90.195.179.144 (talk) 20:00, 5 April 2009 (UTC)

As far as I know, all energy-saving bulbs are either fluorescent or LED lightbulbs adapted for a normal bulb's outlet.-RunningOnBrains 20:04, 5 April 2009 (UTC)

The common fluorescent lights that first come on dimly, then brightly a second later use more electricity during the dim phase. Incandescent lights use more electricity for a brief fraction of a second while coming to full brightness. As stated, the amount of electricity is insignificant. However, the wear and tear on both the switch and the light bulb/tube is another matter. It makes sense for this reason, as well as for your own convenience, to leave them on rather than switching them off if it will only be for a short time. --Anonymous, 20:03 UTC, April 5, 2009.

Regarding cars, according to CNN [12]:

"It's probably a myth that goes back to the days when cars were equipped with carburetors, but many drivers believe that starting up and turning off your car repeatedly is a fast way to drain your gas tank.

"But because of modern fuel-injection technology, drivers actually save gas by turning off their engine than letting their car needlessly idle, says Consumer Reports' Paul.

"Granted it's probably not sensible shutting down the engine every time you get stuck in traffic, but if it looks like you might be at the drive-thru for more than 30 seconds to a minute, it's worth turning off your car, says Paul." A Quest For Knowledge (talk) 20:39, 5 April 2009 (UTC)

The lifetime of a compact fluorescent light, measured in burning hours, is far less if it is switched on and off frequently than if it is left on for several hours each time. CFLs are not recommended for motion detector light applications.The electrical energy would be reduced as for incandescent bulbs, is it is turned off when the light is not needed. Incandescent bulbs are not affected nearly as much in their lifetime burning hours if they are switched on and off frequently. Edison (talk) 03:10, 6 April 2009 (UTC)

I think that answers everything I need to know. Thanks. 90.193.232.106 (talk) 18:09, 6 April 2009 (UTC)

Wet hands and light switches

Are they really dangerous, like I was told as a child? 90.195.179.144 (talk) 19:46, 5 April 2009 (UTC)

Can they be? Potentially. If there's enough water present, then yes, you might be able to close a circuit and electrocute yourself on mains voltage. In general use, however, it's unlikely. If you've ever gotten a static shock off a light switch, then you're connecting to grounded metal rather than anything hot. Water on your hands, in usual amounts, isn't likely to connect you to anything more dangerous than that. That said, there's no good reason to go slinging water at a switch just to say "I told you so!" — Lomn 22:51, 5 April 2009 (UTC)

The usual problem with this kind of thing is that you get away with it most of the time - but if there is a problem in the light switch itself then you are in serious danger. It's definitely not a safe thing to do. In the UK, light switches that are in bathrooms, etc are mounted on the ceiling with a long pull-cord - this keeps the switch itself high up out of reach of wet hands. SteveBaker (talk) 03:22, 6 April 2009 (UTC)

Note that in bathrooms you are also likely to have wet feet, which increases the hazard if you do touch something electrically live with your hands -- what you especially don't want is for current to enter your body through your hand and exit to ground through your foot (or your other hand), passing through your heart on the way.

If there's something that almost all the time doesn't hurt you at all, but 1/1,000 of the time it kills you, is it correct to call it "really dangerous"? What if it was 1/100 or 1/10,000 or 1/100,000 instead of 1/10,000? Would you call it "really dangerous" then? Because this is the way that electric shocks from the household power supply are. There's not enough current to cause tissue damage by burning, the way you could get from lightning or a high-voltage line; if you get an unpleasant jolt, you let go and you're fine. But if the current hits your body the wrong way (and, perhaps, at the wrong time in your heartbeat cycle), your heart stops and you drop dead. I am not saying that 1/100 or 1/1,000 or 1/10,000 or 1/100,000 is the correct number there; I wasn't able to find statistics on that. But I am saying that it's not really clear how to answer the question. --Anonymous, edited 03:41 UTC, April 6, 2009.

swelling AROUND the eyes and diabetes

Hi Wikipedians:

I'm wondering if swelling AROUND the eyes (as in periorbital swelling/puffy eyes, like a blackeye without the blackness) have anything to do with type 2 diabetes.

I've looked over all the eye related complications of type 2 diabetes on the American Diabetes Association website, none of the conditions listed there seem to indicate swelling around the eyes.

This is just out of scientific curiosity and is not related to any medical issues.

Thanks.

65.95.97.197 (talk) 19:59, 5 April 2009 (UTC)

Oops, never mind, stupid me, it's an indication of Diabetic nephropathy. 65.95.97.197 (talk) 20:05, 5 April 2009 (UTC)

'Physalis Mottle Virus’

hey all, What are the implications of 'Physalis Mottle Virus’ on water quality and human health?? Is it dangerous?? what does its presence imply for potable water consumption....? Thanks.

CAnnB (talk) 23:07, 5 April 2009 (UTC)

Hi CAnnB. PhMV (Physalis Mottle Virus) is a Tymovirus, a plant virus. AFAIK, it has no effect on any animal, humans included. --Dr Dima (talk) 04:16, 6 April 2009 (UTC)

As for your last question - what you should really worry about is what else is in that water, and how it became contaminated. --Dr Dima (talk) 04:27, 6 April 2009 (UTC)

April 6

Boredom

Is it possible, either biologically or psychologically, to be literally bored to the point of death? I don't mean brought to the point of suicide, but sort of losing the will to live without being taken by any specific other cause. —Akrabbim^talk 01:28, 6 April 2009 (UTC)

It seems unlikely. We know that there are people have been kept in solitary confinement for many years (Richard Wurmbrand, for example - suffered extremes of this horrible torture for 14 years) - they suffer mental symptoms - but they don't die (at least, not from boredom). SteveBaker (talk) 03:18, 6 April 2009 (UTC)

Lightweight! These guys did 36 years of solitary in lovely Angola Prison. --Sean 14:02, 6 April 2009 (UTC)

According to this book and other places, it is believed that babies in orphanages die when they are not given any tactile stimulation. However, I haven't been able to find anything more concrete. I vaguely recall reading somewhere about the investigation of two orphanages in Victorian England; the one that was better financed supposedly had a 100% death rate because the caregivers were trained in the latest Victorian theories (i.e. no touching), while in the other, the adults received little or no instruction and interacted more with the babies, so some of the kids survived. I have no idea if this is true or just a story. Clarityfiend (talk) 06:00, 6 April 2009 (UTC)

You might find Atul Gawande's recent article in the New Yorker about solitary confinement enlightening on this point. --98.217.14.211 (talk) 14:16, 6 April 2009 (UTC)

Interesting, thank you. The defining factor here seems to be interpersonal interaction, rather than mere lack of activity. —Akrabbim^talk 15:53, 6 April 2009 (UTC)

RNA polymerase

How does RNA polymerase selects the DNA strand for transcription? —Preceding unsigned comment added by Mmpdsetti (talk • contribs) 03:13, 6 April 2009 (UTC)

• You want to read Transcription_(genetics)#Initiation. Basically, the RNA polymerase recognizes a promotor that is bound on a specific part of the RNA. Perhaps the 5'and 3'ends of the RNA fooled you into thinking the RNA strands were palindromic? = Mgm|^(talk) 08:04, 6 April 2009 (UTC)

since shorelines are fractal, how are they really (IN FACT) calculated, when we read figures about x miles of shoreline?

We often hear that shorelines are "fractal" -- which makes sense, since what would make them straight? But how then are the data for x miles of shoreline in FACT calculated? Do you just go inland until you CAN get a straight line, and just cut off many many many factors of jutting edges or what? THank you. —Preceding unsigned comment added by 94.27.225.22 (talk) 08:26, 6 April 2009 (UTC)

One possible method (which I believe is used) is to approximate the shoreline by a polygonal curve with each side about the same length. Of course, the result you get from this depends strongly on the length you choose for the sides, which is why different authorities often give wildly different figures for the lengths of coastlines and other non-straight borders. Algebraist 08:50, 6 April 2009 (UTC)

(after ec): Dr_Dima hypothesis number n+1: People who understand what a fractal is, and people who assign "shoreline length" a definite numerical value, form two non-empty disjoint (non-intersecting) sets. Seriously now, this reference explains how shoreline length is "measured" in practice. As expected, the word "fractal" is never mentioned, and neither is the systematic increase of the result with map resolution. --Dr Dima (talk) 09:00, 6 April 2009 (UTC)

Shorelines aren't truly fractal anyway. People like to imagine "shore line" as a fractal that is coherent all the way down to individual grains of sand. But really, even if you're standing on a beach, you'd be hard-pressed to draw a line in the sand at the "Shoreline". Not because of the infinite precision needed to describe a fractal, but because the ocean and even the beach itself are constantly in motion. Beyond a certain point there isn't any more precision to measure.

I'd wager that nowadays, It's entirely possible to define the length of a coastline with enough precision that the "fractal nature" of the coast doesn't make any difference.

How often this is done, I don't know. APL (talk) 13:40, 6 April 2009 (UTC)

That could introduce new problems, as the length of the shoreline changes when the tides goes out, and also after every storm (if a sandbar is connected or disconnected from the shore, does that change the length of the shoreline ?). StuRat (talk) 17:07, 6 April 2009 (UTC)

Exactly, what you're dealing with is an average. It doesn't make sense to talk about the fractal nature of an average. APL (talk) 20:26, 6 April 2009 (UTC)

I think it does. There's one fractal when the tide is out and another when it's in, and we'd average those. StuRat (talk) 19:42, 7 April 2009 (UTC)

well you know what people OUGHT TO DO? Just DRIVE DOWN THE SHORE, there is ALWAYS an easy way to drive along the shoreline, and just measure the difference the odometer shows at the end! 94.27.194.165 (talk) 15:45, 6 April 2009 (UTC)

That wouldn't work for fjords. I blame Slartibartfast. Gandalf61 (talk) 15:50, 6 April 2009 (UTC)

See Coastline paradox. --Heron (talk) 18:25, 6 April 2009 (UTC)

Easily solved. You drive an infinitesimally small car. Confusing Manifestation(Say hi!) 23:15, 6 April 2009 (UTC)

But wouldn't it take you an infinite amount of time to drive it around the coast? All of those tedious detours around sand grains...I bet you'd cheat and take shortcuts. SteveBaker (talk) 01:58, 7 April 2009 (UTC)

How about using the shortest path between the low-tide and high-tide lines? —Tamfang (talk) 05:20, 7 April 2009 (UTC)

Comorbidity of pulmonary and liver diseases

Hello. I'm trying to help out a friend who's studying Medicine to solve a medical case. I'm not going to give all the details of the case that's been assigned to her (lest you believe I am looking for medical advice), only those I believe are the most important. The pacient has rales, coughs and other pulmonary symptoms. The pacient also has abnormal liver test results, such as high GGT and alkaline phosphatase levels.

As I said, I am not going to ask for a specific diagnosis, but I would greatly appreciate if someone can give us a little push in the right direction, since we have been unable to find any disease which would cause both pulmonary and liver symptoms. Thanks a lot. Leptictidium (mt) 09:41, 6 April 2009 (UTC)

Chronic liver disease can present with numerous respiratory symptoms, see hepatopulmonary syndrome, though I'm not sure if that's mentioned in your case. In addition, in can result in elevated GGT levels, but I'm not sue about alkaline phosphatase levels. I'm not saying this is your answer, I'm not a doctor, but this is a logical option to consider. Cyclonenim :  Chat  10:43, 6 April 2009 (UTC)

Have you considered alcoholism? I mean, for your test case; not personally. Perhaps an alcoholic cardiomyopathy resulting in cor pulmonale to produce the respiratory symptoms; and alcoholic liver disease to cause GTT elevation. ALD and heart disease can both cause elevated ALP, as can many other things. The heart disease can also cause hepatic venous congestion and contribute to the deranged LFTs, particulary GGT as its a sign of hepatobiliary pathology moreso than pure hepatic pathology. You don't mention whether or not there's any other biochemical abnormalities, for example hypoalbuminemia, elevation of transaminases, hyperbilirubinemia (conjugated or not) - these would be useful to know. Also consider anything else that causes congestive heart failure, as the same physiology applies. Mattopaedia ^{Have a yarn} 02:59, 8 April 2009 (UTC)

Royal Society of Canada

Does the FRS(Canada) enjoy the same prestige as Memberships of American Academy of Arts and Sciences,French Academy of Sciences,Royal Society Of London,Royal Swedish Academy of Sciences,National Academy of Sciences and Pontificial Academy of Sciences(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 11:13, 6 April 2009 (UTC)

I don't have an answer about the FRS(Canada), but wanted to point out that the American Academy of Arts and Sciences may not be as prestigious as you think it is. Perhaps you're thinking of the United States National Academy of Sciences? --Scray (talk) 02:03, 7 April 2009 (UTC)

I must say I am surprised!According to the site American Academy of Arts and Sciences has more than 160 Nobel Laureates and 70 Pulitzer Prize winners amongst its membership and looking at the membership anybody who is anybody in US is a member!Surely that makes it perhaps one of the most sought after learned societies in the world apart from being the oldest learned society in the US!I was not so sure about the Royal Society of Canada.(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 09:35, 8 April 2009 (UTC)

Reference material for doctors

What materials do doctors use/refer to for diagnostic/differential purposes. In other words, for psychology/psychiatry you use the DSM-IV--this gives you criteria you must meet for certain disorders, possible treatment plans, etc. My question is, is there something comparable for the medical field? Thanks in advance for your help! Dimblethum (talk) 12:27, 6 April 2009 (UTC)

I'm just a layman but the last time I went to my NHS doctor in the UK, she used her computer after examining me. I realised later that she was looking up the recommended course of treatment. This is available publically online somewhere as I had a look at it, but sorry I've forgotten what it is called. In Britain patient records have been computerised, and apparantly this involves a classification system of some kind. I understand there are different classification systems used in the US. 78.147.28.51 (talk) 12:43, 6 April 2009 (UTC)

The ICD-10 from the WHO is what's used for general medical classification (and also used outside the US for psychiatry, rather tan the DSM-IV).Fribbler (talk) 15:33, 6 April 2009 (UTC)

Also see PubMed for which you can use Medical Subject Headings. For prescription drugs there's a pharmacological tome. Had the title when I started posting and now can't find it again, sorry. 76.97.245.5 (talk) 15:57, 6 April 2009 (UTC)

Depending on the doctor - and I suspect, the nature of the disorder you're being treated for - some doctors use Google. No, this is not a joke. However, upon re-reading your question, I feel that this probably doesn't address exactly what you're after. <.< 90.193.232.106 (talk) 17:59, 6 April 2009 (UTC)

Doctors use a variety of books, medical journals and internet resources. The Oxford Textbook series is widely used for reference, and all hospital libraries (in the UK) will have a copy of the Oxford Textbook of Medicine. I prefer Harrison's Principles of Internal Medicine; it is a little easier to read, and not just for reference. Again, Harrison's Principles is available everywhere. More recently, Uptodate.com has become a widely used web-based resource. In the UK, the British National Formulary is the definitive manual for drug dosing. [Declaration of conflict of interest: I am a pulmonologist and internist. I don't often read outside my areas of specialism.] Axl ¤ [Talk] 18:59, 6 April 2009 (UTC)

I agree with Axl. A great deal of medical training is learning to look things up and evaluate evidence. The list of reference sources is legion, as evidenced by the huge market for reference books and (increasingly) electronic media. While it's true that physicians use Google, it's often an indirect search for a specific reliable source or fact. Skills vary, of course, but good clinicians are very good at information retrieval. --Scray (talk) 19:51, 6 April 2009 (UTC)

@78.147.28.51. In Canada, the drug tome to which you were referring is called the CPS. // BL \\ (talk) 01:37, 7 April 2009 (UTC)

And in NZ, New Ethicals (randomly enough). Gwinva (talk) 03:49, 8 April 2009 (UTC)

If Sulforaphane is good for you, is sulphur dioxide beneficial also?

Sulforaphane is found in broccoli, cabbage and so on. Suplhur dioxide is used to preserve dried fruit etc. I make my own muesli using dried fruit, and I have been wary of sulphur dioxide. How likely would it be that if sulphoraphane is good for you, then suphur dioxide may be also? Would the metabolic pathways or the reasons for the benefit of the first chemical be similar to those of the second? Can this inference be made? 78.147.28.51 (talk) 12:50, 6 April 2009 (UTC)

If you really want to get into the details of this, you'll need to consult a doctor or some other appropriate professional. However, our sulfur dioxide article says that "[s]ulfur dioxide is an allergen to which some consumers are sensitive" and includes an EPA reference which notes that "SO₂ is associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death."[13] — Lomn 13:06, 6 April 2009 (UTC)

I had already read both the articles thanks. I'm hoping for an answer from someone with knowledge of metabolic chemistry or physiology. It is not a medical question. 78.147.28.51 (talk) 13:29, 6 April 2009 (UTC)

I don't think we need any specialist knowledge here. Sulforaphane (C₆H₁₁NOS₂) has a completely different chemical formula from sulfur dioxide (SO₂) and has a much more complex molecular structure. There is no reason to expect their metabolic effects be at all similar. Our sulfur dioxide article says "Sulfur dioxide has no role in mammalian biology". Gandalf61 (talk) 13:32, 6 April 2009 (UTC)

The common mistake here is thinking that molecules which contain the same element must be similar. This is not true, at all. The most basic example is table salt, sodium chloride, which is composed of a metal, sodium, which bursts into flame when it gets wet, and a poisonous gas, chlorine. Obviously salt isn't much like either of those. StuRat (talk) 17:01, 6 April 2009 (UTC)

Magnetic flux

I have a doubt regarding magnetic flux, and i would appreciate if someone bothers to explain me this concept.

Basically, there is no such thing as a magnetic monopole right, so the most basic thing we can analyze is a dipole. And the dipole has to be a point dipole, it can't be two monopoles separated by a distance, for that would mean monopoles exist. So the most basic entity, corresponding to a point electric charge, is a point magnetic dipole. And i can regard the dipole as two monopoles, very close to each other( the monopoles have to be very strong, or the dipole moment will be zero, so consider both the pole strength and the distance as limits , one tending to infinity and the other to zero). Magnetic flux is a count of the no. of field lines emanating through a surface. But whatever the surface i consider (even if it is open), i can say that the positive flux caused by the positive point pole will exactly cancel the negative flux of the negative pole, as they are very close to each other, so the net flux has to be zero! So the magnetic flux through any surface is zero!

I know i am making a mistake somewhere in the argument, and i would be happy if someone would point it out to me. Thanks in advance (going through this would have caused some effort). —Preceding unsigned comment added by Rkr1991 (talk • contribs) 13:26, 6 April 2009 (UTC)

I believe you are exactly correct, the net magnetic flux through any closed surface is indeed zero. See http://en.wikipedia.org/wiki/Gauss%27s_law_for_magnetism It states "The left-hand side of this equation is called the net flux of the magnetic field out of the surface, and Gauss's law for magnetism states that it is always zero." —Preceding unsigned comment added by 81.11.162.104 (talk) 13:50, 6 April 2009 (UTC)

Indeed! In a world without magnetic monopoles any closed surface you construct will have zero net flux. There are still surfaces with net magnetic flux through them: unclosed ones.

You can prove this from Maxwell's equations if you don't mind some vector calculus: you start with ${\vec {\nabla }}\cdot {\vec {B}}=0$ try integrating it over a general volume and then use the divergence theorem to see that the boundary surface has a zero flux.

But do we live in a world without magnetic monopoles? Maxwell's equations are pleasingly symmetric if we include them and Dirac showed that if magnetic monopoles exist electric charge is quantized. Pretty tantalizing... 163.1.176.253 (talk) 14:27, 6 April 2009 (UTC)

I just noticed that you had mentioned open surfaces and you're not correct in thinking they would lead to zero flux. It's not correct to think of our ideal dipole as two point magnetic charges separated by zero distance. If it were then the two fields, generated by each monopole, would cancel perfectly (and therefore there wouldn't be any field lines at all).

So, if you want to think about it in terms of two separated points we need to have two monopoles separated by some non-zero distance. This then leads to fluxes for open surfaces and zero-fluxes for closed ones. (Although, as magnetic monopoles don't exist we should probably not give too much importance to the microscopic structure of a dipole constructed with them. We should really be using either the dipole as the fundamental generator of magnetic field or current loops, which have a magnetic moment and the advantage of existing.) 163.1.176.253 (talk) 16:25, 6 April 2009 (UTC)

Pah! A "point dipole" is an oxymoron -- it is nothing. Two opposite moments at the same location give a net sum of zero. The principle that there is no magnetic monopole only means that any positive magnetic moment must be associated with an equal negative moment in the vicinity. Looie496 (talk) 01:54, 7 April 2009 (UTC)

Well let me put forth my question more directly. This is a question which was handled in my class. There is a cylinder of radius r and height 2L. A point dipole m is placed at its center. Find the magnetic flux through the top surface, the axis of the cylinder being vertical. My teacher did this using the formula of the field due to a point dipole... but i want to know what's wrong with my logic. Since it is a point dipole, i have to bring the 2 monopoles(imaginary) very close to each other, which means they should cancel out each other's field lines, so there should be no flux. What's wrong with my logic? —Preceding unsigned comment added by Rkr1991 (talk • contribs) 05:38, 7 April 2009 (UTC)

You can indeed get a magnetic dipole by taking 2 magnetic monopoles of opposite magnetic charge, and let the distance between the monopoles go to zero while you let their charge go to infinity. If the magnetic charges remained finite, the fields would cancel out, but the magnetic charges go to infinity. The field in the limit is not zero. It's like finding x*(1/x) in the limit for x goes to 0 : the limit is 1, even though you seem to multiply by 0.

The monopoles are very close to each other, but they are also very strong. Surely you derived the formula for the field due to a point dipole by calculating the limit for the field of 2 monopoles whose magnetic charge goes to infinity and whose separation goes to zero? If not, try to do so mathematically. You'll see the field does not become 0. —Preceding unsigned comment added by 81.11.162.104 (talk) 07:39, 7 April 2009 (UTC) Ok thanks--Rkr1991 (talk) 13:27, 7 April 2009 (UTC)

Earthquake radius

I guess I know the basic answer to this question, but I am wondering if I can get more detail.

The terrible earthquake that occurred in Italy seems to have an exceedingly small radius in which it was felt. Is there a reason for this? Is my perception incorrect?

The related larger question is, why is an earthquake in St Louis felt in Boston, while an earthquake in LA is felt perhaps as far as San Diego (if even that far), while an earthquake in Italy is felt for barely 40 miles? Apollo58 (talk) 15:25, 6 April 2009 (UTC)

Fault (geology), Earthquake are worth a look. For Boston particularly Earthquake#Earthquakes away from plate boundaries. 76.97.245.5 (talk) 15:37, 6 April 2009 (UTC)

It's also worth noting that the Richter scale is logarithmic. Italy's quake is being estimated between 5.8 and 6.3 (a factor of five, give or take, so there's a lot of uncertainty). The 1812 New Madrid earthquake, which originated near St. Louis and rang church bells in Boston, was an 8.0 or higher -- approximately 100 times more powerful. — Lomn 15:49, 6 April 2009 (UTC)

Also, this USGS source suggests that the Italy quake was perceptible at least 200 km from the epicenter, significantly more than the 40 miles you first note. — Lomn 16:15, 6 April 2009 (UTC)

There are two aspects to this Q:

1) How severe a quake is at it's epicenter. This has to do with the magnitude on the Richter scale, of course, but also the population in that location, the building codes, and the local geology.

2) How well it travels. This depends on the geology between the source and measurement location as well as the local geology at the measurement site. A deeper quake will also tend to be felt more evenly over a wider area, while a shallow quake will be much stronger in the local area. StuRat (talk) 16:53, 6 April 2009 (UTC)

Indeed. An interesting comparison puts this week's Italian earthquake magnitude 6.3 M_w, depth 10km against the 2007 Gisborne earthquake, of 6.8 M_L and depth of 35.6 km. The Gisborne earthquake was felt in Christchurch, well over 700km away, yet there was little damage in Gisborne itself, and only 1 related death. (Of course, the depth is not the only contributor to damage: a medieval city will sustain more damage than a modern town built to exacting earthquake building codes. Gwinva (talk) 04:11, 8 April 2009 (UTC)

Article: Science and technology in the United States

The article I mentioned above has almost no references or sources. For the article's quality, that's a problem that should be addressed elsewhere, but I'm looking for a good place to find some reliable sources on that topic. Thanks! Randnotell (talk) 16:12, 6 April 2009 (UTC)

While that article itself doesn't have references it's peppered with internal links. See if the linked articles have relevant information and whether that is referenced there. If it is you could either copy that ref. or leave things be as it is. (Latter option will almost guarantee the next "improve quality" editor stumbling over that article will scream murder. :-) 76.97.245.5 (talk) 17:26, 6 April 2009 (UTC)

Internal links cannot by themselves be used as references unless the fact in question is pretty obvious. It is also worth noting that there are long, synthetic paragraphs with almost no internal linking—which smacks of OR. There are also some major misconceptions. German scientists didn't leave Germany because Einstein urged them to, they left because the Nazis passed the Law for the Restoration of the Professional Civil Service that made them lose all their jobs. (Einstein didn't even flee Germany in the wake of Hitler—he had already left for a temporary position in the US, and after Hitler took power he announced that he wouldn't be coming back. That's not the same thing as fleeing.) (It also manages to totally omit any discussion of biology but that's another question.) It is... problematic to say the least. --140.247.242.83 (talk) 19:26, 6 April 2009 (UTC)

You can try my reliable sources search engine: [14] A Quest For Knowledge (talk) 19:28, 6 April 2009 (UTC)

A hypermiling question

I recently listened to a podcast about hypermiling and various fuel economy-maximizing behaviors. I drive an automatic Toyota Celica and have been hypermiling it for one fill-up so far; however, I'm wondering if constantly shifting into neutral is bad for my transmission? Presumably there's some general wear-and-tear, but is doing more harm than good in the long-run? -- MacAddct1984 ^{(talk &#149; contribs)} 16:14, 6 April 2009 (UTC)

Yes, it will do more harm than good unless you happen to drive down some very long hills (miles long), where the gas savings will be more significant. StuRat (talk) 16:39, 6 April 2009 (UTC)

Well, this last fill-up I went from averaging about 27 MPG (based on 9 data points, varying between 26-28 MPG) to 32.5 MPG, a 20% increase. As this was my first attempt, I suspect there may be improvement next time. I shift into neutral whenever suspect I won't need to accelerate for maybe 15+ seconds. How about shifting into neutral when stopped for at a traffic light? I have a feeling that the engine is working about the same fighting the brake in drive and spinning around incessantly in neutral. -- MacAddct1984 ^{(talk &#149; contribs)} 17:21, 6 April 2009 (UTC)

I read a report on the BBC website earlier this year, that shifting into neutral does not help fuel consumption; rather, it makes the car use more fuel because the engine thinks it should be doing something and starts eating fuel. The economical way they recommended was to keep the car in gear but to take your foot off the accelerator and drive it as long as possible without touching the pedals. --TammyMoet (talk) 18:35, 6 April 2009 (UTC)

In my above response, I definitely noticed an increase in MPG, granted it's only one data point so far. I can say that with my car, in neutral, the revs stay at about 700-800 RPM, in drive with my foot off the gas, it's about 1300 RPM. The problem with coasting in drive is that the car slows down much faster than when it is in neutral. -- MacAddct1984 ^{(talk &#149; contribs)} 19:37, 6 April 2009 (UTC)

But your fuel consumption is not proportional to RPM. If you have a car like mine with an instantaneous MPG meter - you'll see that you can have the tachometer wrapped around the end-stop

It's also very dangerous to let your car roll in neutral down long hills - you can't use engine braking (in a hurry) if you need to - and if you slow the car using the brakes, they may overheat, boil the brake fluid and then you'll have no brakes! If you want to do hypermiling - you're going to need a stick-shift car. Moreover, your 20% increase is much more likely from being acutely aware of your driving style than it is to do with rolling in neutral.

I did a proper scientific test (actually, as the result of a bet) in my first MINI Cooper'S (back when those cars only got 25-ish mpg when you drove them moderately agressively, as I usually do). What I did was:

1. Turned off the A/C.
2. Kept the tires slightly over-pressurized.
3. (most important) Never let the RPM get over 3,000 or under 2,000 (no easy feat!).
4. Kept my top speed down to 55mph.
5. Planned a route with the fewest stop-signs and traffic lights - even though it was ~10% longer than my usual commute.

By taking only those measures, I was able to squeeze 40mpg out of my 25mpg car...woohooo!

I love driving...but it was the most boring two weeks of my life!

Then I did some math...by driving like this, it was taking me 10 minutes longer to get to work each day - and 10 minutes longer to get home again. (People say that agressive driving doesn't get you there any quicker - but the science says "Bullshit"). Over the 560 miles I drove (56 miles per day) I used 14 gallons of gas - rather than the 22 gallons I usually used over that time. So at the cost of 200 minutes (3.3 hours) of my life, I saved 8 gallons of gas. At the time, gas was at it's most expensive - $4 a gallon...so I saved a princely $32. So - I was 'earning' about $10 per hour. Unfortunately, I earn $50 per hour - and at the time I was being paid for overtime work - so this represented a net loss of $150. Since I happen to enjoy being at work rather than creeping along the highway at 55mph - feeling uncomfortable because of the lack of A/C...it was actually a lot worse than that. But now - with gas under $2 per gallon, I'd only be saving $5 per hour - which means that I'd be paying myself less than minimum wage. So all of this nonsense doesn't make economic sense. If you are doing it - you're doing it for the greenhouse gas savings.

So now, I have the newest MINI Cooper'S - which does close to 40mpg with the A/C turned on and with my usual style of driving. This means that if I tried the experiment again - even if I got the same percentage mpg improvement - I'd be down to about $3 per hour.

My proper scientific conclusion is - don't drive a gas guzzler - get something with a 6 second 0-60 time and 140mph top speed - floor it at every red light if the car next to you is a VW Bug turbo, any kind of Scion or anything that says "Hemi" on the back. See if you can take cloverleafs at 80mph by following a proper racing line (um...you probably shouldn't try that in a Celica). Drive happy. SteveBaker (talk) 19:39, 6 April 2009 (UTC)

Your analysis avoids such things as time lost to more frequent refueling, possibly more frequent maintenance, and the occasional traffic accident ;-). --Stephan Schulz (talk) 20:12, 6 April 2009 (UTC)

Thanks for the lengthy reply, as always, Steve. Yes, the fact that I changed a bunch of variables at the start wasn't very scientific, so it is very possible that the change in driving style had more to do with it. Maybe I'll stop doing the neutral bit and see how much that actually changes things. Why keep the RPM over 2,000?

My commute to work is only about 10 minutes; however, I do a decent amount of highway driving a month (~800 miles) for work, visiting clients. For the record, I think those who turn their engines off completely while driving are insane. -- MacAddct1984 ^{(talk &#149; contribs)} 20:27, 6 April 2009 (UTC)

Well, 2000 rpm is what's recommended for my car - yours may be different. But in general - if the rpm is too low (and presuming it's doing work) - then the engine will be 'lugging' - which is when the sides of the piston to slap against the walls of the cylinder...it is extremely damaging to the cylinder walls. The car can safely idle at those low revs - but as soon as it has work to do - it needs more revs. Hmmm - oddly, we don't have an article about that...just a one-liner in a disambiguation page. It's not generally a problem in automatic cars because the transmission keeps the revs in the efficient range - but when you start messing around shifting it yourself - you get the worst of the stick shift and automatic approaches. Note: The cost of replacing your engine will make any amount of marginal gas savings irrelevent - so be careful. SteveBaker (talk) 00:30, 7 April 2009 (UTC)

Just for the record you should NEVER turn your engine off in a modern car while it's in motion. The steering may lock and you'll lose power assistance for the brakes and steering - extremely dangerous. Exxolon (talk) 21:06, 6 April 2009 (UTC)

Driving habits make a huge difference, but I agree with those above- there's no plausible explanation on why shifting into neutral would improve your mileage. Turning the engine off entirely would plausibly improve mileage, but it's dangerous, as pointed out above. Friday (talk) 21:15, 6 April 2009 (UTC)

You're talking automatic transmissions only, right? I can get a substantial improvement in "coast time" by dropping my manual Camry out of gear, because I'm no longer in compression. At one point in my commute, I crest one bridge over a crossroad, shift into neutral (which drops the engine speed from 2100 to 900 rpm), and can coast 7/10 of a mile to my exit, still hitting the cloverleaf at about 40mph. There's no plausible explanation for that? --DaHorsesMouth (talk) 22:33, 6 April 2009 (UTC)

Check the engine braking article. Exxolon (talk) 22:49, 6 April 2009 (UTC)

Sure, maintaining speed so you have it later can improve your mileage. What I mean specifically was, you're not using more gas in engine braking than you are just idling. Friday (talk) 14:57, 7 April 2009 (UTC)

I strongly disagree with DaHorsesMouth - doesn't matter whether it's stick or automatic. The "Gas pedal" is called that for a reason...it (essentially) controls how much gasoline is going into the cylinders. If your foot is not on the gas pedal, then it doesn't matter a damn whether you're in neutral at 900 rpm or in 4th gear at 3000 rpm...you're not using significant amounts of gas in either situation. If you have a car (like my '09 MINI Cooper'S) that has an instantaneous MPG gauge, you can prove this for yourself. If you take your foot off the gas pedal, then the reading goes to 99mpg (it's a two digit display) and then about half a second later, flips to flashing '-- mpg' irrespective of the RPM because the amount of fuel that's being used is zero and your MPG is infinite (or at least off the charts). Sliding into neutral doesn't do much (if anything)...and it's potentially dangerous. SteveBaker (talk) 15:23, 7 April 2009 (UTC)

I think all he was saying is that he slows down more when in gear, not that coasting in gear uses more gas than coasting in neutral. If you slow down when you didn't want to, and then have to give it some gas later, that uses more gas than not accidentally slowing down in the first place. Is the gas consumption really zero? I assumed the engine was still getting the same amount of gas it would get when idling, but I suppose I have no particular reason for having assumed that. I suppose a sufficiently-smart engine wouldn't bother injecting any gas at all, if it's not needed. But I don't know whether engines are commonly that smart. Friday (talk) 17:28, 7 April 2009 (UTC)

Leave the car in gear and coast. This is engine braking, all modern fuel injected cars will completely shut off the injectors when you are engine braking, using no fuel. Also driving habits make a big difference, the harder you press the gas, the worse the MPG will be. That's about it.Extide (talk) 20:51, 7 April 2009 (UTC)

Centre of gravity

Hi! Where is the centre of gravity of the bow (weapon)when it is in passive state? Thanks! —Preceding unsigned comment added by 84.52.162.94 (talk) 18:04, 6 April 2009 (UTC)

That would depend on the bow. They come in all sorts of shapes and designs. It would also depend on whether you mean strung or unstrung when you say 'passive'. Algebraist 18:08, 6 April 2009 (UTC)

If you call the grip the front of the bow, then the center of gravity for a strung bow is going to be behind the grip. The center will move further back once it is drawn because the ends of the bow are pulled further from the grip. I am ignoring the contributions of the arrow in this case. Sifaka ^talk 18:37, 6 April 2009 (UTC)

But your first claim does not necessarily hold for a recurve bow. --Stephan Schulz (talk) 19:01, 6 April 2009 (UTC)

Violet scent

Is there any simple chemical (ester, perhaps?), that makes the characteristic scent of violets? Thanks, --Dendre (talk) 18:48, 6 April 2009 (UTC)

Perhaps Ionone per this website (see entry for 1905). Our article claims that ionone is a rose smell though. Rmhermen (talk) 19:01, 6 April 2009 (UTC)

Actually, our article on Ionones claims that one variety of Ionone is responsible for the rose smell. It seems entriely reasonable that a different Ionone or mixture thereof could be responsible for the violet smell as well... --Jayron32.talk.contribs 19:43, 6 April 2009 (UTC)

Another probe to Uranus?

Will we eventually send another probe to Uranus and Neptune? If so when? 2020? 2030? So far on Voyager 2 have been there.--69.228.146.223 (talk) 19:02, 6 April 2009 (UTC)

According to exploration of Uranus and exploration of Neptune, there are no current planned missions. I should think someone will send something eventually, if civilization survives long enough. Algebraist 19:14, 6 April 2009 (UTC)

We don't provide medical advice here. ;-) Axl ¤ [Talk] 22:27, 6 April 2009 (UTC)

I really don't want to make the obvious joke here. It's killing me not to... URGH... Probing Uranus? Did he at least buy you a nice dinner first? Too late... --Jayron32.talk.contribs 00:04, 7 April 2009 (UTC)

If Uranus was named in 1781, when was the first off-color joke published about its name? (Perhaps something like "Gosh, with my new telescope, I believe I can see Uranus!"). Understandably, with the correct pronunciation there is no humorous effect in such observations as 1902 "one with good eyesight can easily see Uranus without artificial help" or from 1914 "A remarkable thing about Uranus is that it is enveloped in a dense atmosphere of enormous extent." Edison (talk) 21:40, 7 April 2009 (UTC)

Garrison Dam

If Garrison Dam on the Missouri river in North Dakota failed catastrophically, how long would it take for the flood to reach the next dam down? Is it likely that this would cause a failure of the second dam as well? 65.121.141.34 (talk) 19:03, 6 April 2009 (UTC)

There are simply too many unknown variables to answer that. Some things that would influence the outcome is whether most of the water ends up going downriver or whether it can spread out; how fast the dam fails, how much debris it will carry, whether the other dams have been softened by rains; ice flow; etc.. The engineers probably allowed for some margin of error, but thing can always go wrong. 76.97.245.5 (talk) 11:04, 7 April 2009 (UTC)

Just curious, are there any examples of this kind of sequential dam failure? Rmhermen (talk) 16:13, 7 April 2009 (UTC)

I do not know of any, which is why I am thinking of using something like this for a disaster type book. 65.121.141.34 (talk) 16:55, 7 April 2009 (UTC)

See Banqiao Dam. -Arch dude (talk) 17:46, 7 April 2009 (UTC)

Fear of Abandoment

First - should psychology be under the Science Reference Desk? Second - What are the treatments for Fear of Abandoment? Has one treatment been more successful than other? --Reticuli88 (talk) 19:27, 6 April 2009 (UTC)

If we recommended treatments to you for any medical condition, that could be construed as advice. It would be irresponsible to make any statement which would encourage you to take a course of action which could end up being wrong. The best advice we could give you is to seek the advice of a qualified medical professional. --Jayron32.talk.contribs 19:40, 6 April 2009 (UTC)

Not seeking treatment for myself nor anyone. Just an objective question. --Reticuli88 (talk) 19:44, 6 April 2009 (UTC)

Perhaps our articles on Obsessive Love, Delusion or Anxiety may have some sources to help you out. We are not qualified to give you any advice, as psycological illnesses are extremely complex and treatments of any sort may vary greatly. Livewireo (talk) 20:15, 6 April 2009 (UTC)

The main treatments would be tranquilizers, cognitive behavioral therapy, or psychoanalysis, probably. Looie496 (talk) 02:07, 7 April 2009 (UTC)

Hammer Striking a Nail

Quick/dumb question: Why is it when you strike a nail (or any metal) with a hammer really hard there are sparks? —Preceding unsigned comment added by 24.171.145.63 (talk) 21:29, 6 April 2009 (UTC)

As a result of the impact, small pieces of iron or steel are shaved off and frictionally heated; so much so that they ignite and burn in air. Surface to volume ratio increases as the particle size decreases, therefore these particles burn much more readily than any "macroscopic" iron or steel objects. --Dr Dima (talk) 21:46, 6 April 2009 (UTC)

It is interesting to note that sufficiently small, unoxidized iron particles ignite spontaneously in air. So, frictional heating may not even be required (although it certainly helps). See pyrophoricity. --Dr Dima (talk) 21:56, 6 April 2009 (UTC)

I wouldn't say it's friction at all. If small bits of metal stick up on the nail when it is first struck, there will be an enormous pressure applied to those bits, causing them to heat enough to glow or even melt and splatter out. They then rapidly cool and solidify in the air. StuRat (talk) 19:05, 7 April 2009 (UTC)

Thanks! —Preceding unsigned comment added by 24.171.145.63 (talk) 22:05, 6 April 2009 (UTC)

Sparking is mostly true for steel hammers, a brass hammer will spark far less, or not at all, which is why they are used in emergencies when flammable gasses are in the area. 65.121.141.34 (talk) 13:39, 7 April 2009 (UTC)

Self-induced synesthesia?

I've recently been reading a lot about synesthesia as well as self-hypnosis. I found a study (http://www.medindia.net/news/Hypnosis-can-Induce-Synesthesia-Study-43347-1.htm) in which researchers claim to have induced Grapheme-> color synesthesia in their test subjects and I was wondering if the same would be possible via self-hypnosis. Further, would it by possible to induce sound->color synesthesia, assuming one has perfect pitch? Thank you! 128.252.254.7 (talk) 22:02, 6 April 2009 (UTC)

There are certain non-prescription medications which have been shown to induce synesthesia, but use of these is against the law in most jurisdictions... --Jayron32.talk.contribs 00:02, 7 April 2009 (UTC)

Thank you for answering; however, I was wondering if it was possible to induce grapheme->color synesthesia via self-hypnosis. Thank you! —Preceding unsigned comment added by 128.252.254.7 (talk) 00:54, 7 April 2009 (UTC)

The paper in question, PMID 19175754, was only published last month, which isn't really enough time for people to have weighed it and evaluated its implications. Looie496 (talk) 02:14, 7 April 2009 (UTC)

I remember reading about that study. The popular reportings suggest that the study considered grapheme-colour synaesthetes to be unable to see a black grapheme printed on a background of the related colour. I found this baffling based on my own experience of and readings about synaesthesia. No doubt there is some group of people for which this is true, but I don't think it's representative of synaesthesia in general. Is the actual study more nuanced on this? 80.41.115.101 (talk) 19:33, 7 April 2009 (UTC)

Global warming

Rather than we're destroying the planet couldn't global warming just be the sun going through what a star does when it becomes middle aged, i.e. become warmer and expand and bring its heat closer to the earth. I know we dont help but the idea of the sun being closer to us seems so much more viable to me. —Preceding unsigned comment added by 92.232.184.222 (talk) 23:09, 6 April 2009 (UTC)

See Stellar evolution. The kind of aging of the sun you describe takes place on the magnitude of 1,000,000,000's of years. Global warming is taking place on the order of 10's of years. Demonstrably unrelated events. Now, the sun does show small fluctuations in energy output, both increases and decreases, and sometimes on short-time periods, but the current trend in global warming has not been correlated to any such changes. It has, however, been nicely correlated to an increase in carbon dioxide levels in the atmosphere, AND to increases in industrialization... --Jayron32.talk.contribs 23:28, 6 April 2009 (UTC)

Yeah - the timescale of the present change is vastly too quick to be a 'natural' thing. Also, if you plot a graph of temperature gain versus CO2 levels - they track each other very closely. The correlation is close to perfect. Correlation doesn't mean causation - but we have plenty of reasons to show causation too. There is really no doubt left - none whatever - not a shred. We're beyond the "Is this really happening?" and "Is it a natural event?" thing...now it's down to "Can we fix it?", "How bad will it be before we do fix it?", "How much will it cost?" and "How can we pursuade China and India to do their part?"...sadly, we still get a dozen questions of this kind for every one of the latter - and that's a sad, sad measure of the success of the evil corporations who are trying to bury the facts under a whelter of FUD. SteveBaker (talk) 00:07, 7 April 2009 (UTC)

Well, there are natural events which can cause climate change on the time scales we're seeing now, such as giant meteors and supervolcanoes. However, we haven't had either of those events recently, so we know that's not the issue. StuRat (talk) 15:44, 7 April 2009 (UTC)

Yes, it's possible that changes in the Sun are the primary cause of global warming. Mars is getting warmer [15], Jupiter is getting warmer [16], Triton (Neptune's largest moon) is getting warmer [17] and even Pluto is getting warmer [18]. Meteorologist John Coleman, founder of the Weather Channel, states that global warming is primarily the cause of the Sun getting hotter [19]. This topic was discussed on Penn and Teller's Bullshit! program [20]. Although they stopped short of claiming that the idea that mankind is responsible for global warming is bullshit, they did say that it smells like bullshit (watch all 3 parts of the episode and the extra's for Penn and Teller's complete take on this issue). A Quest For Knowledge (talk) 03:34, 7 April 2009 (UTC)

I'm pretty sure he meant the effect of the sun getting hotter, not the cause. Global warming couldn't possibly cause the sun to get hotter.--KageTora (talk) 18:49, 7 April 2009 (UTC)

Dear OP: The previous respondent prefers to take the word of two comedians and a TV weather show anchor over hundreds and hundreds of qualified climatologists and scientists of all kind who are essentially unanimous on this point. You may judge his/her ability to answer questions of this kind accordingly. Sadly, I'm not allowed to use the phrase "total idiot" at this point (oops!). (Actually - it's just one comedian - the other one doesn't say much.) 14:55, 7 April 2009 (UTC)

I watched that episode of BS!, and it should be noted that it was made some time ago, before all the evidence was in. What they essentially said on the show was that global warming may or may not be occurring due to human activities, and that all the evidence was not in (at that point). Now it is, and it is pretty much clear to every scientist not on the payroll of a major polluter that global warming is a real problem. StuRat (talk) 18:43, 7 April 2009 (UTC)

According to a column Penn wrote last year [21], his position is "I don't know". A Quest For Knowledge (talk) 20:24, 8 April 2009 (UTC)

There is also some theory I saw on some science channel about the temperature of the galaxy being warmer in the spiral arms than in between (obvious, warmer near stars and colder away from them) and how that affects the overall temperature of the solar system as it passes through denser and less dense areas of the galaxy. That would mean that it could be a warm spot in the galaxy, not necessarily the sun getting warmer. Since I really have no interest in this theory, I didn't reserve any brain cells to remember what program it was or who was stating the theory. I vaguely remember that they had rather nice graphics (which is why I watched it). -- kainaw™ 03:56, 7 April 2009 (UTC)

"Planetary warming" is a myth promulgated by certain so-called sceptics. Of course, on average about half of all bodies in the solar system will get warmer at any one time due to orbital dynamics (elliptical orbits will move them towards and away from the sun). We do not have reasonable climate estimates for any of the farther solar system bodies. We only know about Pluto for 1/3rd of a Plutonian orbital period ("year"). The "warming" on Pluto, for example, is an extremely indirect measurement of atmospheric density during two occlusion events of stars -the atmosphere was thicker the second time, which may mean that more of it had thawed from the frozen state, which may mean that Pluto was warmer (or not). But Pluto, at that time was (and still is) fairly close to the sun, so of course it's expected to warm. Mars is not significantly warming - does anyone ever look at the second page of that NatGeo article? Jupiter is not getting significantly warmer, it very likely goes through a periodic event of wind system reorganization that makes some parts of it much warmer (and others cooler). And you might want to read the Triton article for yourself - there is no hint about increased solar output, but the warming is driven by atmospheric and albedo changes as the the moon goes through an unusual orbital alignment. We cover most of this with sources in the global warming FAQ. --Stephan Schulz (talk) 06:26, 7 April 2009 (UTC)

April 7

Toads and warts

Is it true that handling certain species of toad will cause an outbreak of warts in a human? I was told this as a child and it has stuck with me. I have never, ever touched a toad (or frog, just in case) in my life up to this point because of it. It's not that I feel that I've missed out on anything important growing up, but I'm wondering now if I have been misled. :) When I say warts, I mean the typical warts that humans suffer from, not a reaction to toxins in the toad's skin that causes something that looks a bit like warts to come up. --84.71.174.88 (talk) 01:09, 7 April 2009 (UTC)

No. Toads cannot cause warts in humans. This is an urban legend. Warts are caused by a variety of viruses. The relevant viruses are not carried by toads. JoshuaZ (talk) 01:42, 7 April 2009 (UTC)

It's more like sympathetic magic: toads have warts, therefore toads cause warts. Looie496 (talk) 02:16, 7 April 2009 (UTC)

No. See List_of_common_misconceptions#Biology. Axl ¤ [Talk] 09:21, 7 April 2009 (UTC)

It should be noted that this particular item is currently unsourced. Me and several other editors are attempting to find reliable sources for this article, but this item may be removed shortly. A Quest For Knowledge (talk) 12:31, 8 April 2009 (UTC)

The problem is that the term "warts" is used to refer to different things. The warts on a frog are more like what we call moles, which are not usually caused by a virus and therefore can't be passed on to others. StuRat (talk) 15:39, 7 April 2009 (UTC)

When you say "frog" do you mean "toad"? In these parts, our frogs are pretty smooooth. --Scray (talk) 21:03, 7 April 2009 (UTC)

Yes, I meant toads. StuRat (talk) 14:58, 8 April 2009 (UTC)

hearing

I went to a rock concert about a year ago and had tinnitus for 3-4 days after that. I want to go to another concert in a couple months and was wondering if there was a way that I would not get that ringing in the ears, or to keep the duration of the ringing shorter, and still enjoy the concert without muffling the music. 12.216.168.198 (talk) 02:48, 7 April 2009 (UTC)

I find that earplugs do an excellent job of reducing volume to enjoyable levels without muffling the music -- in fact, I tend to find the audio quality better once so filtered. Plus, no ringing! I prefer the cheap disposable foam variety for this sort of thing. — Lomn 03:02, 7 April 2009 (UTC)

I know a lot of professional audio people (I work in the video games business). They value their hearing above all else (One guy calls his ears his "golden moneymakers" because without them he has no career!) - yet they also enjoy listening to and playing music more than any people I know. They each have reusable ear plugs that are created especially for each individual by an audiologist who measures their ear canals. These earplugs attenuate the volume of the sound to a huge degree - but do so in a way that's completely uniform across the entire audio spectrum. This means that they still hear all of the nuances of the sound - and can ascertain the timbre, etc precisely as well as someone with unprotected ears. It also allows them to wind their audio systems up to higher volume levels so they get the satisfying 'gut feel' of the bass notes (and the all-important neighbours calling the police to complain about the noise)...without wrecking their hearing. They point out that every time you expose your ears to loud music, you erode your hearing a little bit more - and if it's loud enough to cause temporary deafness or tinnitus - then you have certainly damaged your hearing in a way from which it will never fully recover. So there is a STRONG recommendation that if you go to concerts or play instruments - to wear earplugs every single time - and that you should buy the best ones you can afford. SteveBaker (talk) 14:48, 7 April 2009 (UTC)

I agree with the earplug recommendation. If you're worried about looking uncool, get some earplugs which are skin-colored and put them in right before the music starts (say during a trip to the bathroom). If you put them in too early everyone will wonder why you can't hear. You don't have to worry about taking them out immediately afterwards, though, as people will attribute any lack of hearing acuity on your part as being due to damage to your hearing from the concert.

Another suggestion is to not sit right in front of any speakers. Obviously, this doesn't work if the concert enforces assigned seating, unless you know where the speakers will be when you choose your seats. However, avoiding speakers will only reduce the hearing damage, not eliminate it. You still need earplugs for that. StuRat (talk) 15:25, 7 April 2009 (UTC)

Certainly the inverse-square law applies here! If you can double your distance from the nearest speaker - the sound energy will be one quarter as much - but because our ears are logarithmic devices, it won't seem four times quieter. However, this doesn't really change the answer - if you like music and would like to be able to continue to enjoy it - wear earplugs. With decent earplugs - and hearing that hasn't already been fried by going to too many Motörhead concerts - you can easily hear normal conversation with the earplugs in...that's also a consequence of the logarithmic nature of our hearing. With good earplugs, things don't really sound that much quieter. SteveBaker (talk) 16:19, 7 April 2009 (UTC)

Distance from speakers certainly matters, but not only distance, as most speakers are highly directional. Therefore, sitting an equal distance to the side of a speaker isn't nearly as bad as in front of it. Intervening objects, such as a post or the heads of other concert-goers, may also block some of the sound. StuRat (talk) 19:34, 7 April 2009 (UTC)

As for why there aren't regulations which limit the volume at concerts to levels that won't damage hearing, there I am baffled. StuRat (talk) 15:31, 7 April 2009 (UTC)

There are such regulations in (for example) the UK - but the levels aren't set low enough to be 100% effective. SteveBaker (talk) 16:19, 7 April 2009 (UTC)

Plus what would be a safe level of noise for1 minute may not be safe if you have 3 hours of that noise level. 65.121.141.34 (talk) 16:53, 7 April 2009 (UTC)

Some musicians use "high fidelity" earplugs by Etymotic Research [22]. The frequency response is preserved while lowering the dB level. We cannot give medical advice, and specifying "safe" noise levels seems to fall in that category. For general information, you might check OSHA for the noise levels employees can be exposed to for varying durations under U.S. regulations. This regulation does not guarantee complete safety for persons exposed to noise levels under the curve. But they are an improvement over the old days when every construction worker, person who fired guns, soldier, or especially boiler maker was deafened to varying extents. Did you plan to carry a calibrated dbA slow response meter with you? Else, how would you know the sound pressure level? Edison (talk) 20:59, 7 April 2009 (UTC)

Why do massive objects in space don't look like they are moving?

Small objects in space look like they are moving, while massive objects don't. Why is this? 98.221.85.188 (talk) 04:36, 7 April 2009 (UTC)

I'm not sure what you mean. They look that way to whom? —Tamfang (talk) 05:15, 7 April 2009 (UTC)

I think that the OP means that when you travel, small things such as trees move when you look at it while larger (and probably distant) objects such as landmarks and the Moon doesn't appear to move even if you are travelling by car.--Lenticel ^(talk) 06:28, 7 April 2009 (UTC)

The appearance of moving results from the object appearing at a different angle at different times. So for a distant object to appear to move it will have to move a significant fraction of its distance away, so for something like the moon, you would have to move hundreds of kilometers to notice the change in its angle compared to say the stars. For distant stars there is even less movement in the sky, Astronomers can use parallax to find out how far away stars are. Graeme Bartlett (talk) 06:40, 7 April 2009 (UTC)

It's especially noticable with large aircraft. When you look at an airliner slowly drifting across the sky - it's hard to imagine that it's belting along at 400 mph! Partly that's because perspective has reduced the angular rate of speed relative to your eyepoint - the other part is that being such a large object, it takes more time to travel it's own length than a little cessna or something - which is going maybe a quarter the speed but is ten times shorter in length. Another problem with anything high in the air or in space is that there are typically no nearby, stationary objects for you to compare against. This is a problem that plagues science fiction movies and TV shows - even when the Starship Enterprise is zipping along at several times lightspeed - the stars in the background ought to appear dead still for hours at a time...but they don't - they move and even have parallax! That's totally unrealistic (even in a 'classical universe' with no relativity and no speed-of-light limit) - but that's the only way they have to convey speed. There is often a similar problem with size - you see spacecraft disappearing behind planets and moons - when in reality, even a gigantic craft would have shrunken to an invisible dot long before it could be far enough away to get around a planet that's thousands of miles in diameter. SteveBaker (talk) 14:36, 7 April 2009 (UTC)

In Star Trek, they use "warp factors", which apparently are not just the number of times the speed of light they are going. If this was the case, then, traveling at say Warp Factor 5 would still take them years to get anywhere (although it might not seem so to them, due to time dilation, but they just ignore that). It seems to have been a logarithmic scale of some type, with Warp Factor 1 being the speed of light and Warp Factor 10 being infinitely fast. They did violate this principle and go over Warp Factor 10, on at least one occasion, though. They could typically travel to the nearby stars (let's say 10-100 light years away) in a matter of hours (again, ignoring time dilation). If we assume the typical trip to take 1/1000th of a year, that would give us speeds in the range of 10 thousand to 100 thousand times the speed of light. In at least one episode, they did go all the way to the edge of our galaxy, though, which implies speeds well into tens of millions of times the speed of light. At such speeds, you should notice some apparent movement of the nearby stars, but perhaps not as much as is shown. StuRat (talk) 15:05, 7 April 2009 (UTC)

They use at least two sets of warp factors in star trek (geek warning, but I'm sure I'll be beat). In Voyager, Warp 10 = infinite velocity. In other series, I think they've gone to at least warp 16-17, which, of course, wasn't anywhere near infinite velocity. -- Aeluwas (talk) 15:43, 7 April 2009 (UTC)

All Next Generation era series use the new system, the Original series and Enterprise use the old one. There is no clear rule for the old system, but the fan-devised rule of them is that warp factor W means a speed of c*W³. --Tango (talk) 17:37, 7 April 2009 (UTC)

In space, it's the distance to the objects that determine how fast they appear to be moving, as explained previously. But you asked about the size of the objects. It just works out that small objects we can see are close and large objects are far away. If the Moon was as far away as a star, we couldn't see it. If a star was as close as the Moon, we would all be dead. StuRat (talk) 15:18, 7 April 2009 (UTC)

Star Trek - Science or fiction?

While looking at this image, it occurred to me that the "lettering" of the quadrants was rather strange. Instead of going either clockwise or counter-clockwise, the quadrants are put in order from right to left, then criss-cross, and then go right to left again. Since Star Trek often tries to keep some slight grasp on science (theoretical or not), I'm left wondering where they got this mapping scheme. Is this based on anything in the real world or is this just a oversight on the part of the writers? Dismas|^(talk) 05:21, 7 April 2009 (UTC)

I'm not sure why this particular arrangement was chosen, but there are sometimes good reasons to eschew traditional ordering (obligatory xkcd). Also, why would a clockwise (or counterclockwise) arrangement be any more sensible? – 74  05:46, 7 April 2009 (UTC)

A counterclockwise arrangement would follow along the lines of the quadrants of a coordinate plane. Dismas|^(talk) 10:17, 7 April 2009 (UTC)

Certainly; but there is no scientific basis for that arrangement either—it is used by convention (i.e. because it has been used before) and because it roughly corresponds to polar coordinates (another arbitrarily-chosen system). Tellingly, only one octant is commonly labeled: the first octant (+,+,+). – 74  11:21, 7 April 2009 (UTC)

If you're looking for an explanation that would be plausible 'in-universe', the order of labelling follows the chronological order of exploration (by human beings); it also sorts the quadrants by increasing (mean) distance from Earth. I don't know of any explicit canonical reference which describes the labelling system, but you might try poking around over at Memory Alpha. TenOfAllTrades(talk) 12:30, 7 April 2009 (UTC)

• Entertainment Desk answer:

I've seen every episode of every Star Trek show (except the animated series) and all the movies, and I do not believe they ever mentioned the physical layout of the quadrants. I always assumed that consecutive letters were in order around the galaxy and therefore it was gamma that was opposite alpha, and I would have noticed if they said something that meant it was different. The image is only sourced to a web site and it might well have been created by a fan or writer who just made an assumption about what the labeling was. The fact that it relates to both Deep Space Nine and Voyager suggests that it is non-canonical.

• Science Desk answer:

Nothing in astronomy labels quadrants with letters. Where the details of an object are known well enough to talk about locations within it or on its surface, numerically expressed coordinate systems such as latitude and longitude are used.
--Anonymous, 20:10 UTC, April 7, 2009.

Not to sound like a total nerd, but in one of the episodes (in Voyager I think) where a prop map of the galaxy has the quadrants labeled. I don't recall the exact episode, but I bet that Memory Alpha would know where it is. 65.121.141.34 (talk) 20:46, 7 April 2009 (UTC)

Vacuum flask

I was reading the Vacuum flask article and I came across this line:

A typical domestic vacuum flask will keep liquid cool for about 24 hours, and warm for up to 8.

Assuming the cool liquid has the same temperature difference from ambient temperature as the warm liquid does, how does this make sense?

This statement makes less sense if you think about common temperatures. Take ambient to be 20ºC, the cool liquid to be ice water (0ºC) and the warm liquid to be boiling water (100ºC) then surely it would take longer for the hot liquid to equilibrate than the cool liquid. Am I missing some thing here? —Preceding unsigned comment added by 130.194.164.217 (talk) 06:10, 7 April 2009 (UTC)

"Cold" doesn't flow; heat does. Take a point source located in a vacuum—all radiation produced will travel outwards radially and be lost. Now, take a point sink inside a vacuum—any radiation produced outside the vacuum is quite unlikely to strike the point sink. In real life, the interior dimensions are significantly larger than a point, but I'd suspect the principle still stands. – 74  06:33, 7 April 2009 (UTC)

If it's convenient to talk about cold flowing - we can. The math still works. Just as we talk about electricity flowing in the opposite direction than which the electrons are actually moving...it doesn't matter. Rigid thinking in science is not good. Very often, profound insights can be gained by kinda tipping your head sideways and squinting a bit! SteveBaker (talk) 14:26, 7 April 2009 (UTC)

"Lax" thinking is the kind of thing that generally leads to profound errors, not insights. In situations where the directionality of flow is irrelevant then you can use "cold" flow somewhat interchangeably (but with dubious benefit). However, in cases like this where directionality is important "cold" flow only confuses the issue. Science is all about precise (or "rigid") exploration of the world, and I am quite surprised by your dismissal of valid scientific principles in the interest of "convenience". – 74  21:17, 7 April 2009 (UTC)

It's only lax thinking if you don't understand the underlying mechanism. Low level atomic vibration/motion is what we call "heat". That vibration spreads to other atoms that are moving less quickly - and we talk about heat moving from hot to cold. However, when those fast moving atoms pass on their energy to the slow ones - they are slowed down in the process so talking about the reduction in motion spreading from the slow moving atoms into the fast moving atoms is no more or less valid than the "conventional" description of heat travelling from hot to cold. So long as you understand this, you can just as validly talk about the 'coolness' flowing into the hotter material as the other way around. This isn't "lax thinking" - it's unconventional thinking - looking at the problem in another way and possibly gaining some insights. It's truly just a matter of convenience to decide to talk about flow in one direction or the other. As I pointed out (and you've carefully ignored) we do this all the time when we talk about electricity flowing from + to - rather than from - to + as is "really" happening if you watch the electrons. However, we're quite happy to talk about the motion of "Electron holes" in the conventional direction as a way of making sense of the 'reversed' direction. Same deal with heat and cool. Far from "dismissal of valid scientific principles" I'm using those very principles in a way that might well make the explanation clearer. I should probably say something about being "quite surprised by your rigid thinking and lack of comprehension of underlying scientific principles"...but I'll let your imagination fill in the details (if you have an imagination that is). SteveBaker (talk) 13:18, 8 April 2009 (UTC)

It most certainly *is* less valid in the case of radiation, where a second material is not necessarily located in close proximity (and needn't exist at all). The "fact" that "electron holes" may be used to make some explanations of circuits simpler (personally, I've found it only adds confusion) has little to no bearing on heat transfer; an (equally pointless) counter-example would be darkness/light. But, if you insist on confusing the issue, I apparently cannot stop you. – 74  16:38, 8 April 2009 (UTC)

"Close that refrigerator door, you're letting all the coolth out !". StuRat (talk) 14:31, 7 April 2009 (UTC)

Yes, you are missing some physics. Radiative thermal losses (integrated over the entire spectrum) are proportional to temperature to the fourth power, see Stefan-Boltzmann law. Hot object in a warm environment loses energy faster than a cold object in the same environment gains energy, assuming the surface properties of the two objects are the same. Vacuum flask coating is not equally reflective at all infrared wavelengths, so the dE/dt ~ T₁⁴ - T₂⁴ approximation is not really accurate; but qualitatively it should work. --Dr Dima (talk) 07:28, 7 April 2009 (UTC)

You're also missing what people mean by keeping cool or hot. It would be considered cool if it is a bit cooler than ambient, but it would have stopped being hot and become warm or tepid in between getting to ambient temperature - and it would do that quicker because of the bigger temperature difference. Dmcq (talk) 09:58, 7 April 2009 (UTC)

I agree with all of our previous answers. The deal is that the vacuum inside the flask only stops losses due to conduction & convection (and even that, not completely since it's not a hard vacuum and there is a connection between interior and exterior at the neck of the vessel). It does little to prevent loss due to radiation (although they do apply a mirror coating to the glass of the inside vessel and use shiney metal for the exterior). But because the radiation from the warmer outside of the flask into the interior is happening at a lower temperature than the radiation from a hot liquid inside to that exact same exterior temperature - then the losses are faster. That taken with the undoubted truth that 'hot' liquids have a bigger temperature delta to the outside than the outside does to a cold liquid inside - so any conduction paths (which depend on temperature DIFFERENCE not absolute temperature) will be less significant in the cold case. Add to that that we care more about how hot our coffee is than how cold our soda is...this easily explains the factor of 3x difference. I'm actually rather surprised it's not more than that.

SteveBaker (talk) 14:26, 7 April 2009 (UTC)

Some Stanley "vacuum flasks" in recent years had finely powdered carbon in the "vacuum" space. A pinhole leak in the outer liner caused the fine carbon dust to spew out, reducing visibility if it happened in a moving auto. If it had lower than atmospheric pressure, why wouldn't air leak in instead of the carbon powder leaking out? Dewer's first vacuum flask in 1892 had a silvery mercury coating. In a vacuum flask without a silvery coating, a liquified gas evaporated 1/5 as fast as in open air; with the mercury coating, the evaporation was reduced to 1/33 the free rate. There should be a small hole in the lid of the inner container to avoid any pressure buildup. The flask allowed Dewar to transport liquified air on a rail trip from London to Cambridge to show it off. The outer of the flask was packed in dry ice to liquify the mercury and reduce the mercury vapor pressure. Edison (talk) 20:37, 7 April 2009 (UTC)

True area of a country

Hello, fellow Wikipedians. It has for a long time bugged me that it seems, when we measure the area of an... area, country rather, that we take the flattest approach. In truth, every hole and rise will result in a greater area, and so a 500km^2 country that is completely flat will have less area than a 500km^2 country that has, say, a mountain on it.

Afghanistan for instance, to point to a place where we know the intricate shapes and forms of their mountains, has a much higher area than is stated in its proper article, likewise Norway, whereas Western Sahara's real area isn't too far from its measured area - not off by as much as in other cases, at least. Are anyone able to measure area in this way, "real" area as it might be called? Thank you for your help. 62.128.252.85 (talk) 11:19, 7 April 2009 (UTC)

You may be interested in How Long Is the Coast of Britain? Statistical Self-Similarity and Fractional Dimension. While that concerns the length of a coastline, the problem is analogous. -- Coneslayer (talk) 12:00, 7 April 2009 (UTC)

"True" or "real" area of a country is an interresting concept. Did the September 11 attacks reduce the real area of Manhatten? Cuddlyable3 (talk) 13:49, 7 April 2009 (UTC)

This is emphatically NOT the same as the 'coastline' problem. When we talk of the 'area' of a city or a country or whatever - we're not talking about the total area of everything contained inside of it - we're talking about the area of the city when it's projected downwards onto an idealized spheroid at mean sea level. Where my house is built, I have 1.2 acres of land - most of it slopes steeply at about (let's say) 45 degrees - which means that the ACTUAL area is about 1.4 times bigger which is close to 1.7 acres. But I'm taxed on 1.2 acres, the law regarding the amount of land I needed to build a 2 storey house said I had to have 1.2 acres...everyone talks about it being 1.2 acres. So taking the more reasonable definition of 'projected area' - even though the "coastline" of that area might be fractal in nature and it's length is therefore indeterminate, the area bounded by that fractal has a well-defined value that lies between limits that can be determined to arbitary precision by examining a more and more detailed coastline. That's the opposite of the coastline problem - where the more closely you look at the coastline, the longer it becomes and the less accurately you can determine the answer. Now, if you ARE talking about the area of everything inside the city - then indeed you are looking at a fractal-type of problem which is kinda similar to the the coastline problem in that you ultimately need to sum the areas of each blade of grass - and so forth...however, that's a fairly bizarre interpretation of the word for any practical purpose. SteveBaker (talk) 14:04, 7 April 2009 (UTC)

It seemed to me that the "bizarre interpretation" was the exact point of the question, which is why I brought it up. As you add up all the extra area due to terrain, your area gets bigger and bigger as you go to smaller scales (cracks in the mountain, etc.). BTW, are surveyed areas really projected to MSL? So a flat parcel surveyed at 1 acre in Denver is really slightly bigger than 1 acre? -- Coneslayer (talk) 14:14, 7 April 2009 (UTC)

Technically - yes - but the error is so spectacularly microscopic for a flat piece of land that the errors in measurement completely dwarf that. SteveBaker (talk) 15:43, 7 April 2009 (UTC)

I agree that the approach the original poster was asking about would lead to both the fractal issue and the problem of the area changing due to strip mining, landscaping, etc., so isn't practical. Whether the current measures are taken the way SteveBaker said is an interesting question. I suspect that in many cases the area of a plot of land is simply determined by measuring the distance along the edges (straight-line distance, through the air, not measured along the ground). I doubt if any adjustment for elevation is used. StuRat (talk) 14:29, 7 April 2009 (UTC)

When they surveyed the plot for my house, they determined the latitude/longitude for each corner of the lot and stuffed that into a piece of software that calculated the area. The altitude wasn't taken into account - and they certainly don't use tape-measures to just measure the straight-line distances between the corner markers...at least not in Texas. SteveBaker (talk) 15:43, 7 April 2009 (UTC)

Of course they don't use tape measures. I believe modern surveyors have a device which uses the speed of light to measure the distance (do we have an article on this ?). I can't see them using a GPS device to measure the latitude and longitude, as they just aren't accurate enough. Being within a few feet is fine for driving directions, but lousy when marking property lines. StuRat (talk) 19:24, 7 April 2009 (UTC)

Actually - they did use GPS - but not the regular satellite-only kind. They plant a special 'base station' at a known location and use 'differential GPS' which is accurate down to a millimeter or so to accurately measure the position relative to that base. In the case of a plot of land, they don't care much where it is (at least not to great precision) - but they do care how big it is...because that's what determines the taxes you pay, etc. What they actually did at my house was to check the position of a big steel spike that's driven into the ground at one corner of the lot using some kind of conventional measurement system with theodolites and such measured from a nearby road. Then they positioned the GPS base-station onto that spike then walked off to the other corners of the property with their differential GPS and got accurate numbers relative to the base station and hammered in more spikes. Then they hooked up the GPS widget to their laptop and got a number for the area. No elevation data. There is no way they could have used lasers or whatever - the terrain is WAY too rugged for that. You'd have to take down at least a hundred trees to get a line of site, even over the flatter parts! (Then my neighbour dug up one of the spikes because he claimed it was 20' away from where it should be...he ended up paying a $1000 fine and came close to going to jail when he argued with the police...don't do that!) SteveBaker (talk) 01:17, 8 April 2009 (UTC)

I didn't say they use light, but rather the "speed of light", which, of course, applies to the entire spectrum. I suspect that the "differential GPS" device you mentioned uses that method, with radio waves or some other frequency. I would have thought they would need to take differential elevation into account, as well, when determining the area of a piece of land. For example, if you have a 240 foot long lot which is 70 feet lower at one end, that will give a distance of 250 feet between the two points when measured at those different elevations. That's enough error that they might be rather concerned. StuRat (talk) 14:54, 8 April 2009 (UTC)

You do not get more hectares or acres of land by digging a hole and piling up the resulting dirt. See the 1902 "Manual of instructions for the survey of public lands... which included the oath to be taken by assistant surveyors:"...we will level the chain upon even and uneven ground, and plumb the tally pins..." U.S. Supreme Court Reports from 1901 says "...the mode of measuring will be to level the chain, as is usually done with chain carriers when measuring up and down mountain sides, or over other steep acclivities or depressions, so as to approximate, to a reasonable extent, horizontal measurement, this being the general practice of surveying wild lands in Tennessee." "Leveling the chain" can be done by physically keeping the chain horizontal, or by trigonometry on cliffs and steep river banks based on use of transits or other optical instruments. Only informal measurement, like a farmer dividing by his own efforts a 40 acre field into 2 twenty acre fields, might be done up hill and down. In such informal measurements, the farmer might cut a "pole" 16.5 feet long and walk along flipping it end over end to measure off "poles" or he could level it. "A "Gunter's chain was 66 feet long, equalling 4 "poles" or "rods." A British surveying book from 1881 compares the "levelled chain" and the theodolite for measuring slopes, and notes how hard it is in practice to perfectly "level the chain". Edison (talk) 19:54, 7 April 2009 (UTC)

Surveying and Aerial survey may have the info Stu was looking for. While it might be of statistical interest (or bragging rights) to measure surfaces at an angle, for most practical purposes the more level the area the more usable. (OR we have an brook in back with a slope of about 60 degr. You'd have to either dig things up or fill it in to do anything with the lot but admire the view.) 76.97.245.5 (talk) 20:18, 7 April 2009 (UTC)

Relationship between Thermodynamic Entropy and Cosmic Dark Energy?

What is the relationship (if any) between Entropy and Dark Energy The temperature-dependent term for Entropy is an important thermodynamic determinant in most bio/chemical reactions. Yet astrophysicists rarely discuss or estimate its role in determining the balance of cohesive/dispersive forces at work in the cosmos. Why is this? Is Entropy Dark Energy by another name? Has the dispersive effect of an Entropy increase in the cosmos (but outside a black hole!) been quantified -- I assume that it cannot be just ignored? 19Grumpah42 (talk) 13:08, 7 April 2009 (UTC)

Have you read our articles on entropy and dark energy? They should not be considered analogous. As dark energy is presently theorized to be doing work (accelerating the expansion of the universe), it is specifically not "the unavailability of energy to do work". — Lomn 13:28, 7 April 2009 (UTC)

temperature goes up as you dig down.

The temperature goes up as you dig down, like with the Kola borehole. If one was to dig a straight level tunnel starting at 1,000 ft under a 12,000 ft tall mountain, would the tunnel be far warmer in the middle then on the outside ends, or does the temperature only start going up when your hole is below sea level? 65.121.141.34 (talk) 14:22, 7 April 2009 (UTC)

It depends entirely on where you dig. If you start digging on a 12,000ft volcanic mountain, it won't take long to hit hot rock. If you start digging on a 12,00ft pile of granite, it will take a long time to hit hot rock. The Earth's crust is not uniform and there are hot spots under it. -- kainaw™ 14:26, 7 April 2009 (UTC)

If your mountain is made of a 'hot' granite, i.e. with a high concentration of radionuclides, it could be quite hot due to its internal heat production from radioactive decay. Whatever the actual value of the geothermal gradient beneath your mountain, it would get hotter along your horizontal tunnel, the only question is 'how much?'. Mikenorton (talk) 14:41, 7 April 2009 (UTC)

Since most of the heat underground is either generated at the point where it's measured (by radioactivity and tidal forces) or underneath, the question is if the heat is kept where it is or allowed to radiate away on the surface. Therefore, the more insulation there is between a particular location and the surface, the hotter is should be. Horizontal distances would be the same as vertical distance, in this regard. However, solar heating means that the surface is sometimes hotter and sometimes cooler. On a hot day, it will be cooler underground or in a tunnel through a mountain. This effect will be much greater than the quite gradual effect of increasing temp with distance from the surface. StuRat (talk) 20:17, 7 April 2009 (UTC)

For a practical example, I have here a nice little book: the 2000 English translation Historical Tunnels in the Swiss Alps: Gotthard Simplon Lötschberg of the 1996 book Historische Alpendurchtische in der Schweiz by K. Kovári and R. Fechtig, published by the Gesellschaft für Ingenieurbaukunst (Society for the Art of Civil Engineering) there. This quotes a 1906 report saying that when constructing the original Simplon Tunnel, "the temperature of the rock rose rapidly from about 40 °C [that's 104°F] at distance 6340 m [3.94 miles] into the tunnel at the start of the period of observation to about 52 °C [125°F] at 7300 m [4.54 miles]. From there the increase in temperature was more gradual until at about 9100 m [5.65 miles] from the north portal it reached its highest value of 56 °C [132°F]" (that would be near the midpoint of the tunnel). From the accompanying diagram, the depth of rock above the tunnel at the three positions mentioned was roughly 1,200, 1,500, and 2,200  m respectively, or about 4,000, 5,000, and 7,200 feet.

The book does not mention the particular source of geothermal heat applicable to this tunnel, but a geological diagram shows that it is mostly in schist and gneiss, both of which are metamorphic rocks that may or may not be formed from granite. To deal with the heat, cold water was pumped into the tunnel and sprayed into the air. Many tunnel projects experience quantities of ground water flowing into the tunnel and in this case that water, which was at 12°C (55°F), was put to good use.

--Anonymous, 20:41 UTC, April 7, 2009.

Venusian thought experiment

Well, let's imagine our Solar System 4 billion years ago, with a little twist.

Let's say Venus and the Earth were pretty close to actually being twin planets 4 billion MyA. Same conditions, same [almost] everything. Time goes by, and eventually life evolves on Venus about 80 MyA before the same thing happens on Earth. Morphologically, you can imagine Venusian life to be as similar or as different from life on Earth as you wish, the only condition is that they must have the same vital requirements as we Earthlings.

Geological time speeds by, with both Earth and Venus having their share of diversity booms and extinction. Because Venus had a 80 MyA headstart, intelligent life evolves on Venus while the Earth is still in the Middle Cretaceous (ok, it doesn't have to be that way, but imagine it is).

While dinosaurs still rule the Earth, Venusians discover fire, erect buildings, create the movable print and eventually start burning fossil fuels. Like on Earth, they keep on pumping CO₂ and other greenhouse gases into the atmosphere for over a century. Even though they notice they've damaged the planet, it's too late to do nothing because they've already triggered the melting of permafrost methane, which in turn triggers a runaway heating. In the end, temperatures rise to the point that all life on Venus is scorched to death.

80 million years go by, and the weak but constant surface effects on Venus erase any trace of civilisation on that planet. Now, we only see a barren desert spreading everywhere. Even their spaceships won't be a witness before us, since either their orbit has decayed and they have been destroyed, or they are many lightyears away in interstellar space. Therefore, nothing remains to remind us of what happened to Venus and what may happen to us.

Okay then, end of the story. What is the scientific evidence for or against this possibility? What are the oversights I may have made when inventing this little tale? Or, on the contrary, is it possible that it might have happened? Leptictidium (mt) 14:30, 7 April 2009 (UTC)

I think the biggest flaw is the implausibility of "twin planets" as laid out at the open. Venus' surface atmospheric pressure is 90 times that of Earth and it's 97% CO₂. We colloquially refer to Venus as having a "runaway greenhouse effect", but there's no plausible way for humans to accidentally get from our global warming scenario to something akin to Venus. To be clear, Venus has over 200 thousand times more atmospheric CO₂ than Earth. We're speculating that Earth's change in CO₂ concentration peaks at give-or-take double present levels. Now, applying that much CO₂ to a Venusian atmosphere raises its concentration from 96.5% to 96.5004%. Clearly, the same mechanic could not apply. What is catastrophic for Earth isn't statistically measurable for Venus. — Lomn 14:56, 7 April 2009 (UTC)

But Earth's atmosphere had much more CO2 and was much much denser in the past, i.e. before those pesky cyanobacteria turned well-behaved CO2 into toxic oxygen and complex organic molecules. See Earth's_atmosphere#Evolution_of_Earth.27s_atmosphere and Oxygen Catastrophe. --Stephan Schulz (talk) 15:12, 7 April 2009 (UTC)

Did the Venusians develop any space travel technology? If so, is it possible that there might still be satellites in orbit after 4 billion years 80 million years? I would think that they would have tried to leave some sort of record of their existence. Perhaps place satellites in orbit around all the major bodies in the Solar System (all the planets and the Sun). Actually, knowing that there's life on Earth, I would imagine they would send some probes down here as well as the Moon. In fact, why not move to the Earth? If the Earth's atomosphere isn't habitable for Venusians, perhaps Earth can be Venus-formed. A Quest For Knowledge (talk) 15:22, 7 April 2009 (UTC)

If you carefully construct a scenario in which there is no scientific evidence (as I think you tried to do) then there won't be any scientific evidence. If you don't do that - then there would be. It's kinda meaningless. If I had to specifically poke holes - I'd point out that if these Venusians were even a little ahead of where we are technologically - they'd be sure to have sent craft to the lagrange points of (at least) Venus - those locations are in principle accessible to our technology - and their equipment would still be sitting there pretty much intact even after millions of years because the lagrange points behave as if there were gravity pulling things towards that location (although that's not really what's going on) - so their positions would be stable and easily located. Of course you can just write that maybe the Venusian religion forbids sending things to the lagrange points and we're back with no evidence again...but that's true of anything we might come up with. SteveBaker (talk) 15:32, 7 April 2009 (UTC)

Or a large chunk of rock could have randomly flew through the Lagrange point taking the satellite with it. 65.121.141.34 (talk) 15:45, 7 April 2009 (UTC)

BTW, this is a pretty interesting premise for a science fiction story. If this is an original idea from you, you might want to run out to find a lawyer and see about getting a copyright on it. A Quest For Knowledge (talk) 15:37, 7 April 2009 (UTC)

You cannot get a copyright on an idea...--Stephan Schulz (talk) 15:40, 7 April 2009 (UTC)

And if you could, you'd have to fight my prior claim from years back. The basic idea is a fairly obvious one and I'm sure it's occurred to many people independently. Algebraist 15:47, 7 April 2009 (UTC)

Well, I'll try and clarify a few things.

1. When I said twin planets, I meant at the beginning. That means that Venus CO₂ would be 97%, but maybe as a result precisely of all the permafrost methane melting and triggering a positive feedback.
2. Yes, they did have space travel technology. But someone said above that they would be a little more advanced than we are now – no, in my thought experiment the 80-million-year old Venusians would be just as advanced as we are, only 80 million years earlier.
3. @ SteveBaker: I am not asking for evidence regarding the fact that this happened, but rather what information we have which may suggest it could have happened (or could not, for that matter).
4. Finally, a question: would it be likely that, with all meteors, comets, etc. flying around, artifficial satellites survived for so long in the Lagrangian point? Leptictidium (mt) 15:54, 7 April 2009 (UTC)

The Lagrangian point of what system? Earth-Moon, Sun-Venus, ...? —Tamfang (talk) 17:39, 7 April 2009 (UTC)

There ought to be atmospheric spectroscopic evidence. I would think at least some telltale organic molecules would remain even in the oxidizing atmospheric conditions. Also there would have been a lot of water on Venus to support life originally (assuming life on Venus operates on similar principles). Venus' atmosphere has a rather low water content (0.002% Water vapor compared to earth's ~ 1% water vapor). Venus' high temp would make liquid water on the surface unlikely. The article Venus says the best hypothesis as to what happened to the water Venus was hypothesized to have in the past is that the evaporated water "has dissociated, and with the lack of a planetary magnetic field, the hydrogen has been swept into interplanetary space by the solar wind." Is 80 million years enough time to get rid off an ocean's worth of water via that method? I'm not sure it is. According to Carbon, Earth has a total of about 40000 gigatons or 4 * 10¹³ kilograms of carbon dissolved in water, in the atmosphere, as coal and oil, and locked up in biosphere. That carbon would make about 1.5 * 10¹⁴ kilograms of carbon dioxide if I did my math right. There is 4.8 × 10²⁰ kg of atmosphere on Venus according to Atmosphere of Venus and around 95% (assuming by weight) of it (~4.6 × 10²⁰ kg) it is carbon dioxide. That amount of carbon dioxide is about 6 orders of magnitude greater than the amount of carbon dioxide that all the Earth's sources of carbon that I mentioned above would make. While I am not sure the Earth figure includes other sources of carbon like carbonate containing minerals (probably not), Venus has a ridiculously large amount or carbon dioxide nonetheless. That discrepancy makes me wonder if Venus' atmosphere could have ever not had a significant amount of carbon dioxide as there would had to have been a large amount of something that could have bound all of that up previously. If the rest of that carbon dioxide did come from carbonate minerals, again, is 80 million years enough to decarbonate enough of it to account for present day atmospheric concentrations? Also if that process was still going on, if you could get a spiffy probe to the surface to bore a deep hole, you might be able to tell. Sifaka ^talk 17:56, 7 April 2009 (UTC)

Sorry, but you're about a century too late with your sf scenario. Of course when Percival Lowell, H.G. Wells, and Edgar Rice Burroughs were at it, the conceit was that since Mars was further from the Sun than the Earth, it cooled and developed first, and had the old civilization, while Venus was still in its version of the Mesozoic.

Sorry to dash cold water on your idea, but there is utterly nothing that would support your scenario. At Venus' distance from the Sun, lower gravity than Earth, and long diurnal rotational period, liquid water could not naturally collect on its surface, without which life is not going to get a foothold.

B00P (talk) 00:54, 8 April 2009 (UTC)

Now it can be revealed: it was Venusian UFOs that abducted our dinosaurs. Cuddlyable3 (talk) 17:42, 8 April 2009 (UTC)

How common is runaway global warming?

Some people say that we will soon trigger, or already have triggered, runaway global warming, and once it happens it's nigh-impossible to stop. How often does this happen? How bad is it when it does? — DanielLC 16:42, 7 April 2009 (UTC)

I would say we have a severe deficiency of data considering we don't have an experimental control group, or a large enough population of planets with temperature data to get any kind of statistically relevant result. My WAG is that it is rare. 65.121.141.34 (talk) 16:48, 7 April 2009 (UTC)

Runaway global warming is, as far as I know, still something of a vague theory with several possible mechanisms - the Clathrate gun hypothesis being the most prominent I've seen, i'd recommend that article as a good starting point. There simply isn't enough data to make a solid answer to your question: past periods of large-scale warming can be as easily attributed to solar variations that we simply have no control over. ~ mazca ^t|c 17:18, 7 April 2009 (UTC)

see Interglacial. -Arch dude (talk) 17:22, 7 April 2009 (UTC)

Since the Earth's been hotter than this before and cooled down, obviously something must eventually kick in to bring temperatures back down. However, temps could get dangerously high until that happens. StuRat (talk) 19:57, 7 April 2009 (UTC)

And, while we don't have evidence of runaway global warming due to greenhouse gases, there is plenty of evidence of other dramatic climatic changes both in the Earth's past and on other planets. Mars, for example, appears to have once had quantities of liquid water. StuRat (talk) 20:07, 7 April 2009 (UTC)

Mars could certainly lose all its liquid water without high temperatures due to a dissipated atmosphere, even if the temp stayed around -20F, so I would like to see additional evidence before I would count Mars. 65.121.141.34 (talk) 20:39, 7 April 2009 (UTC)

I was using Mars as an example of "other dramatic climatic changes", not "runaway global warming". StuRat (talk) 14:22, 8 April 2009 (UTC)

There are certainly two parts to this - right now, we undoubtedly have global warming - far more rapidly than any of the 'nut-job' theories can explain. This much is established fact. What we don't know is precisely is whether it's reached the runaway stage yet - and if it hasn't, then by how much can we risk pushing it before it does? There is a small amount of legitimate doubt as to whether the runaway effect even exists - but the vast majority of serious experts claim that there is at the very least, a huge risk that the climate will run-away from our ability to control it by any means whatever.

There are a fair number of feedback mechanisms involved - things like that snow is white an shiney and reflects sunlight away from the earth - as the earth warms, the ice melts and is replaced by something darker (ocean or dirt) which ceases to reflect sunlight away and absorbs it instead. This extra absorption causes more temperature increase - which causes more ice to melt. Those kinds of mechanisms are what could kick us into 'runaway' global warming - a scary situation where even if we stopped all CO2 production instantly - the earth might continue to get warmer. But we don't really have a firm knowledge of which (if any) of those mechanisms are removing our ability to recover. It seems that the arctic ice sheet is melting far faster than we predicted - and that is perhaps evidence of a runaway effect at the North Pole. However, when all of that ice is gone - the effect will cease to run-away. Since the ice at the North Pole is floating, it doesn't make much difference to global sea levels when it melts - so aside from the ecological damage (say goodbye to polar bears, for example - they are going extinct within our lifetimes) - the net effect is limited.

The same effect happening at the South Pole would be VASTLY more dangerous - because there is a lot more ice locked up there - and it's sitting on land well above sea level - so when it melts, it pushes the ocean levels higher.

Then (as previously mentioned) we have the methane clathrate business - where (essentially) there are deep ocean deposits of frozen methane which will melt when the ocean temperatures rise - thereby releasing methane into the atmosphere - which is a MUCH nastier global warming agent than CO2 - causing more temperature rise - causing more clathrate to melt. A couple of ships have detected methane bubbles coming from areas where these deposits may be found...so there is a definite possibility that this has already started to run-away. That happened at the end of 2008 - so it's very possible that we're already too late.

Also, as temperatures climb - the warming of the ocean causes the water to expand - making the sea levels rise faster than you'd expect from ice melting alone. As the ocean inundates land, the darker water absorbs more heat than the land would - and (worse still) has a higher thermal inertia - so it locks the heat in so it doesn't radiate out into space again at night as much as it used to. This increases temperatures - which melts more ice, clathrates and increases the volume of the existing water still more.

At some point, the increase in water levels will start killing off green plants - which means less CO2 is absorbed and more gets into the atmosphere. This is somewhat tempered by the increase in green algea in the oceans - so maybe that's not a feedback mechanism - but we don't know that for sure.

The point is that there are MANY mechanisms - and they are all feeding back on each other. So the melting of the northern ice-cap might not be directly serious - but because it increases the absorption of sunlight - it may be enough to kick one of the other mechanisms into high gear. Estimating the consequences of such complex interactions is very tough. The consensus of opinion between serious researchers is that we'll see between 7 meters and 22 meters of water level increase over the next 100 years. Either of those would be extremely nasty for humans...and devastating for most non-human life.

As for what it would take to recover - it is indeed true that the planet has recovered from worst in the past - but that's always been at the price of mass extinction of plants and animals - and it's taken hundreds of thousands of years to do that. So this potential recovery in the future isn't something we have to care much about - it's unlikely that human civilisation could survive in anything like a recognisable form in the face of that kind of destruction.

SteveBaker (talk) 20:36, 7 April 2009 (UTC)

Let me clarify my question. I want to know how common sudden changes in climate are. I'm not asking about extremes in climate or about how sudden climate change can happen. If they all lead to Extinction events, there couldn't be much more than 20 in the last 540 million years, right? If so, we'd need to be changing the climate at hundreds of thousands of times its normal speed to have an appreciable chance of triggering it in the near future, right? If runaway climate change won't cause an Extinction event, don't we have more important things to worry about? — DanielLC 23:02, 7 April 2009 (UTC)

We ARE changing the mean temperature at hundreds of thousands of times it's normal speed - and that's pretty much exactly what the problem is! We've increased global temperatures by a couple of degrees over a hundred years. In the past, that's something that's taken a million years to happen 'normally'. So yeah - we're doing this 10,000 times faster than 'normal speed'. That high rate of change makes it impossible for evolution to keep up - so the polar bears don't have time to evolve to do without icebergs. Also, it means that any natural feedback (such as algea in the ocean evolving to consume more CO2 in warmer waters) cannot kick in. It's precisely because it's happening so fast that it's such a major problem. If we had 10,000 years to plan for this change, we could gradually move cities inland, breed crops that would thrive in higher temperatures and so on...but at the present rate of change, there simply isn't enough time. If we kick the climate into 'runaway' mode - then the rate of change (and the AMOUNT of change) will kick up into a higher gear and we'll truly be in deep doo-doo. SteveBaker (talk) 13:01, 8 April 2009 (UTC)

If current theories are correct, sudden climate change has happened many times in the past, leading to mass-extinction events. Though I think you are referring to a sudden (few hundreds to a few thousands of years) warming as opposed to a sudden cooling.

Right now it is a purely hypothetical phenomenon, though purely hypothetical doesn't mean wrong; it just means it's never happened before while us humans were around to see it and our computer modeling skill is insufficient to say how much CO₂ will lead to how much warming over how long a time with precision. Sudden runaway warming may have never happened before on this planet. Some people theorize that Venus was the victim of runaway global warming which occurred when its hypothetical oceans started boiling off (although I'm not sure how widespread that theory is accepted).

Steve already went over most of the mechanisms which can re-enforce the warming, but there are many important factors that could check or even reverse a speedy warming (forgetting all that The Day After Tomorrow BS). And most importantly (IMHO), there is the whole problem with clouds: no one is really sure whether clouds will increase, decrease, shift geologically or temporally, or stay the same with a warming planet. And daytime clouds cool the earth, while nighttime clouds warm the earth. What I'm trying to say in a very roundabout way is this: It could happen, and it may have happened in the past, but we just don't know. -RunningOnBrains 00:11, 8 April 2009 (UTC)

I'm referring to any climate change, even if temperature remains constant. You'd think there'd be some way to tell. It doesn't effect how glaciers freeze or anything like that? Anyway, is the idea that it would cause an extinction event a myth? If it would, it couldn't have happened very often. Is there at least a known lower limit on how recent the last runaway climate change was? — DanielLC 01:45, 8 April 2009 (UTC)

At high rates of change, (like over hundreds of years rather than millions), evolution can't keep up. Animals and plants will die rather than adapt. Hence a mass extinction event. Just as the giant meteor that killed the dinosaurs caused mass extinction - so will abrupt climate change. However, in a gradual change (gradual - over geological timescales, that is) - plants and animals will evolve to take advantage of the new conditions and although the warmer world would be a very different place, there would be no sudden kill-off of species. In either case, however, the 'new' world might not be a place where humans could thrive...and that's the ultimate concern here. SteveBaker (talk) 13:01, 8 April 2009 (UTC)

It should be said that while some plants and animals will die out in a changed climate, others will prosper, simply because the climate they like becomes more common. Tropical plants are already expanding their ranges into traditionally temperate zones, for example. People also don't need to evolve to adapt, we can either move or alter our environment with things like air conditioning. Of course, global warming will still cause enormous problems, and maybe kill off a substantial portion of the human race (many of those living in Bangladesh, due to flooding, for example), but extinction of the human race isn't the threat here.

Note that while "runaway global warming" may or may not occur, "global warming" (without the "runaway" part), is definitely already happening. The difference is that regular global warming would be reversible if we stopped adding greenhouse gases to the air. Unfortunately, I don't see that as ever happening, or at least not until we use up all the fossil fuels. StuRat (talk) 14:41, 8 April 2009 (UTC)

why is water transparent and ice white?

Mathityahu (talk) 17:53, 7 April 2009 (UTC)

From ice, "It can appear transparent or an opaque bluish-white color, depending on the presence of impurities such as air." Certainly from my experience, some ice is basically transparent, and some is quite opaque. Friday (talk) 17:58, 7 April 2009 (UTC)

Ice is pretty transparent when it doesn't have air cavity impurities in it. The reason why your ice cubes for instance don't look transparent all the time is that rather small air bubbles and other impurities get trapped in the structure of the ice which scatter the light making it appear opaque. I could be wrong, but I think that there are several neutrino telescopes which take advantage of Antartic ice being clear over long distances, like the IceCube and Radio Ice Cerenkov Experiment. Sifaka ^talk 18:13, 7 April 2009 (UTC)

In addition to air bubbles, there's also fractal planes which make ice look white. I believe that ice, if chopped up into tiny pieces, will look white even if this is done in a vacuum. StuRat (talk) 19:50, 7 April 2009 (UTC)

You might be interested in the Blue ice (glacial) article. --JGGardiner (talk) 22:10, 7 April 2009 (UTC)

Little cracks and air bubbles reflect light in random directions. White pigment reflects light in random directions. They look the same. — DanielLC 01:39, 8 April 2009 (UTC)

April 8

Make OH Hydroxide

Is there a way to create OH(hydroxide) with household or easy-to-get inexpensive materials?The Successor of Physics 04:24, 8 April 2009 (UTC)

Yeah, dissolve Crystal Drano or Red Devil drain opener in water, and you get lots of it. (Disclaimer: if you create an explosion or burn yourself, you have only yourself to blame.) Looie496 (talk) 04:51, 8 April 2009 (UTC)

Indeed. In ordinary distilled water there are trace amounts of detectable hydroxides (about 1 x 10^-7 mol/liter on average). This is true in the purest of water, due to a reaction known as the autoionization of water. Drano will give you GOBS of the stuff, but is also highly caustic and toxic (you can get nasty chemical burns as it turns your skin into soap), and adding straight Drano to water is highly exothermic; it could heat the water to boiling, and it could spatter or splasg, at which point you could be covered with a highly caustic boiling solution. Not fun. Just about any high-pH substance will contain reasonable amounts of measurable hydroxide. Ammonia-water is basically a solution of ammonium hydroxide, and even simple soap, like say dishwasher liquid, will generate some hydroxide ions without being too dangerous. If you explained why you were interested in generating hydroxide, perhaps we could give you more direction... --Jayron32.talk.contribs 12:38, 8 April 2009 (UTC)

Well, actually all these responses seem to be about OH- . If TSoP really wants OH, as requested, that's a different kettle of fish. --Trovatore (talk) 00:23, 9 April 2009 (UTC)

Since he asked for hydroxide, we assumed he meant OH^-. The uncharged ·OH is the hydroxyl radical. TenOfAllTrades(talk) 00:38, 9 April 2009 (UTC)

Why does accelerating a charged particle produce radiation?

What is the actual physical reason for this? —Preceding unsigned comment added by 118.139.4.222 (talk) 06:29, 8 April 2009 (UTC)

Acceleration in general (including linearly)? Or only circular? The latter is Cyclotron radiation or Synchrotron radiation, caused by the deflection or bending--centripetal acceleration--not just increasing speed. DMacks (talk) 06:58, 8 April 2009 (UTC)

Yes particularly circular acceleration. Why does bending the electron create radiation? 130.194.167.195 (talk) 07:31, 8 April 2009 (UTC)

The explanation is the same whether it's circular motion or accelerating linear motion. A radiating field consists of disturbances in both the E and H fields, perpendicular to each other. The H field is the time derivative of the E field, and the E field is minus the time derivative of the E field. This is a self-reinforcing relationship that causes an EM wave to propagate indefinitely through space. A charge moving at constant velocity won't create this relationship, because the E field is changing linearly and so the H field, which is the derivative of the E field, is constant. Changing E + static H --> no radiation. If you have an accelerating charge (whether that acceleration is linear or circular doesn't matter), then both the first and second derivatives of E are non-zero, so now you have changing E + changing H --> radiation.

Synchrotron radiation is just a special case of this. If the charge is going round in a circle then all the radiation comes from a finite area instead of being spread out in an infinite line. This makes it a more convenient source for experiments. --Heron (talk) 18:04, 8 April 2009 (UTC)

optical reflection distortion in tempered glass in automotive

dear sir,

I want to know which standards/methods has to follow to check optical reflection distortion in tempered glass. As per my information it is present in DIN standard , but i dont know it . I want to know the standard no. and why this occure during production of automotive glass and how to judge it. —Preceding unsigned comment added by Ravscapc (talk • contribs) 07:28, 8 April 2009 (UTC)

could a fast enough solar-powered car catch more sunlight?

Imagine if you had a raindrops powered car. It would make sense that if it were going very fast through raindrops it would be catching more of them. Is the same thing true of a solar-powered car going fast thorugh sunlight versus being stationary? 79.122.72.101 (talk) 08:01, 8 April 2009 (UTC)

Check out this derivation of the "simplified total wetness equation" by the BBC News. The answer is yes, but since the speed of (sun)light greatly exceeds that of your car (unless it's a really fast model), you'd only get an ultra teeny tiny improvement. Clarityfiend (talk)

No. Regardless of speed of your car, your car will measure speed of light to be same, and number of photons hitting the solar cells will be same and hence gathered solar energy will be same. In fact, if your call travels too fast (relativistic speed), your car will put on more mass, making it difficult to drive faster using the same quantity of solar energy. manya (talk) 09:13, 8 April 2009 (UTC)

Manya, I'm sorry to say that we're not discussing the change in the speed of light here and I think you have misunderstood the question, although what you mentioned about relativistic effects is true. My answer would be yes, and essentially the same as Clarityfiend's answer.The Successor of Physics 09:45, 8 April 2009 (UTC)

(@Superwj5: I have un-struck Manya's answer that you so rudely struck-out. We do NOT go around striking out answers we don't agree with unless they flagrantly break the WP:RD rules. If you think a previous answer is wrong - you must explain why you think it's wrong - not just cross it out...after all - you could just as easily be wrong - and in this case (as it happens), I think you are entirely wrong. Please consider your knuckles firmly rapped!) SteveBaker (talk) 12:48, 8 April 2009 (UTC)

Actually - I believe Manya is correct and Superwj5 has not considered the matter carefully enough. The speed of light is constant in all reference frames - so the car sees the speed of light coming from the sun as being the same no matter what speed it's travelling at. However, there would be a 'blue-shift' in light coming from in front of the car and a red-shift from the rear - and I think that means that the light coming from the front has more energy (I'm not 100% sure about that - with relativistic stuff, it gets complicated). But that only applies when the car is driving towards the sun - whatever that effect was, it would cause you to lose energy when driving away from the sun. When the sun is vertically overhead or off to one side - there is no benefit either way. Photons are in no way like raindrops! However, it's pretty clear that whatever the effect is, it's entirely negligable at all 'reasonable' speeds. SteveBaker (talk) 12:48, 8 April 2009 (UTC)

The Michelson-Morley experiment indicates that a light source that is directly overhead remains overhead regardless of horizontal motion of our car. Hence there would be no change in the energy collected by a horizontal planar solar cell.Cuddlyable3 (talk) 16:57, 8 April 2009 (UTC)

I'm fairly certain that there's another effect that causes light moving perpendicular to the observer to blueshift. I think it also makes the light move in the opposite direction of the observer from their point of view, which is contradictory to what Cuddlyable3 said, so can someone double-check this? By the way, the OP was comparing this to hitting more raindrops, rather than hitting them harder, so maybe we should also think about how many photons hit. — DanielLC 17:21, 8 April 2009 (UTC)

DanielLC is confirmed with Relativistic aberration. Is anyone up to drawing some diagrams to illustrate this article? It could really do with picturesque adornment. Relativistic beaming talks about the variation in apparent intensity at different directions. Graeme Bartlett (talk) 21:51, 8 April 2009 (UTC)

why isn't the segway a unicycle?

i don't get why the segway isn't a unicycle, wouldnt it have to do the same job just with half the parts?

also why not sit over a ball (like an old mouseball) then it could roll in 2 dimensions instead of just 1 + turning? 79.122.72.101 (talk) 08:21, 8 April 2009 (UTC)

1 wheel would be less stable than 2 wheels. I know it does the gyroscope/whatever thing but it'd increase the workload on it. The ball would add more friction, making it require more 'effort' (power) to move it around. The wheel has a small amount of surface in contact with the path/road, whereas a ball would (I expect) have more. 194.221.133.226 (talk) 08:37, 8 April 2009 (UTC)

why would you expect it would have more contact? A plane is tangent to a wheel in only 1 point, and it is also tangent to a sphere in only 1 point. How much friction there is would just depend on what PSI you pump the wheel/sphere to, wouldn't it? (the more it sags the greater the actual touching surface area). Why would 1 wheel be less stable than 2 wheels? People are able to ride unicycles... 79.122.72.101 (talk) 08:42, 8 April 2009 (UTC)

Riding on a plane needs minimum 1 or 2 wheels. Riding on a sphere needs minimum 3 wheels (which you find inside an old mouse), that's 4 frictional contacts including ball-to-ground. Cuddlyable3 (talk) 16:43, 8 April 2009 (UTC)

But riding a bicycle is much easier than riding a unicycle, because balancing on a bike is much easier...Also it seems from reading the Segway article that it constantly rotates/moves both wheels to maintain its position - I suspect on 1 wheel that would be harder to achieve (and potentially much the same on a ball). 194.221.133.226 (talk) 09:18, 8 April 2009 (UTC)

The segway doesn't use a gyro to make it balance - it rotates the wheels forwards or backwards to keep them under the center of gravity of the segway+rider. That's why you lean forwards to make it accellerate and backwards to make it stop or reverse. If you watch a segway when it's just sitting there, perfectly balanced, you can see the wheels moving microscopically to keep the thing balanced. The gyro inside is just it's way to measure how it's moving. Hence, to make a unicycle segway with just one wheel would be impossible because the wheel can't rotate sideways to keep the unicycle vertical in the side-to-side direction. A human unicyclist has to supply lateral balance by leaning from side to side. A segway that rolled on a ball could possibly fix that - but now it would need two sets of motors and two sets of gyro's - one for forwards/backwards motion and another for lateral balance. This would make it considerably MORE complex - not less. It might also make it exceedingly difficult to ride because when you leaned a little sideways - the "ballway" would tend to roll in the direction you're leaning. Since you need to lean into corners in order to keep your balance - the ball would presumably rotate such as to keep you vertical - which would result in you failing to turn corners at all (I think...it's confusing!). Anyway - on complexity grounds alone, it's a bust. However - having said that - you might want to check out Uno (vehicle) - which is almost a unicycle "motorbike" that balances in the forward/backward direction using technology similar to the segway and uses a split center wheel to manage lateral balance...you need to read the article to understand it in more detail. SteveBaker (talk) 12:32, 8 April 2009 (UTC)

I think you're assuming that the Ballway would not change heading. (And perhaps it wouldn't, That would not be easy to build.) If you're leaning purely to the right you want the Ballway to sidestep to the right, but if you're leaning forward and to the right, then it's entirely acceptable to travel in an arc. That would keep you balanced.

Ideally the Segway's wheels do exactly what you would do with your own feet. When you walk, you lean forward a little, and then move your feet forward to keep them "under" you, the segway attempts to do the same thing with its wheel. (I rode one once. It's a weird feeling. It felt like the thing was reading my mind.) Since humans are perfectly capable of leaning into a turn I don't see why a Ballway couldn't do the same. APL (talk) 16:40, 8 April 2009 (UTC)

If it had a ball, it would have to be able to move forward/backward, left/right, and clockwise/counterclockwise. That's three degrees of freedom. You can only lean forward/backward and left/right, so you'd have to have another degree of freedom to control it. It's possible to make it so you can control it with just the two degrees of freedom, but you won't be able to do everything that it's mechanically capable of, for example: if you make it so you lean forward and to the side to make it turn, how do you make it go diagonal? It's mathematically possible to map three dimensions completely to two, but you'd up with a ridiculous control system (see space-filling curve). — DanielLC 17:13, 8 April 2009 (UTC)

That extra degree of freedom really isn't a problem though. The Segway only uses the balance/leaning thing to do acceleration and deceleration. For steering, you have a twist-grip thing. Because the same mechanism is used for controlling the gross motion of the segway as is used to make it balance - you really can't make leaning be the control for steering in our ballway. When you lean sideways - the machine MUST roll sideways (without turning) or you'll fall off! I imagine our ballway would have to have some kind of additional controller for rotation - just as the segway does. Hence, y concern is that when you use this additional controller to rotate the beast - you'll be forced to lean into the turn to counteract centrifugal force - and when you do that - the lateral balance system would roll you sideways - making your turn into a messy affair indeed! In fact, you'd have to take turns pretty gently because with the machine FORCING you to ride upright (because as fast as you try to lean, the machine counteracts that) - the centrifugal force in a turn would throw you off. SteveBaker (talk) 18:09, 8 April 2009 (UTC)

I'm unconvinced. Even if your analisys is correct, there's no reason the software couldn't compensate for this. Afterall, it's a 100% predictable effect. (If you lost the ability to go forward at high speed, change heading, and add an additional diagonal component all at once, then there's no great loss. I'm not confident I could do that with my own two feet. Let alone a computerized beach ball.)

But I'm not sure you are correct. Imagine if you used an accelerometer to measure your "levelness". The force from gravity as a result of your lean would be the same as the centripetal force from the turn, exactly balancing it out. That's why we do it.

Since the segway is designed to mimic the actions of our own two feet, I don't know why anyone in their right mind would program a 'lateral balance system' that would attempt to keep you strictly upright while you were cornering.

The logic of the Segway and other self-balancing systems has always been "Move the wheels towards the center of gravity." That would still work. The tricky part with the BallWay would be determining which way the user should be facing. I think some inteligent rules could catch most cases. APL (talk) 19:53, 8 April 2009 (UTC)

it seems you're thinking the ballway wouldn't have handlebars (which would define "which way the user should be facing") but why not? You think it should just be a platform? no way, that's why the segway isn't like a skateboard (no handelbars) but a scooter (has handlebars). shouldn't the ballway have some too? .... wait, do you mean determining which way the whole contraption should be facing? just face it whichever way is set by the handlebars then? i dont really get your point of concern... 79.122.72.101 (talk) 22:30, 8 April 2009 (UTC)

If you google for "electric unicycle" and take the first link found, there are instructions for making your very own. The site has some info about balancing. This is a proper unicycle too, unlike the Uno (vehicle). I can ride a unicycle and when I was learning, I never had any problems with side-to-side balance once I could get some forward motion. --80.176.225.249 (talk) 22:59, 8 April 2009 (UTC)

Quantum harmonic oscillator

what is the perfect defination of Quantum harmonic oscillator ?Supriyochowdhury (talk) 10:12, 8 April 2009 (UTC)

I don't really understand your question, but it might be answered by our article quantum harmonic oscillator. Algebraist 10:20, 8 April 2009 (UTC)

why the wave function corresponding to the E-nu for a simple harmoic oscillator are nondegenerate.Supriyochowdhury (talk) 10:23, 8 April 2009 (UTC)

why would they be degenerate? Degeneracy in a quantum-mechanical system is usually a consequence of a symmetry of some sort. Now, consider a quantum harmonic oscillator (a spinless particle in a one-dimensional parabolic potential). What kind of symmetry do you suspect here? Why would you expect any two or more states to be degenerate? If you are thinking about x => -x symmetry, it leads to no degeneracy as it produces no new states that are linearly independent from the "old" ones. Or do you mean something else? You can make the states degenerate if you ascribe your particle a nonzero spin, but that is just adding another dimension. Conversely, you can add another spatial dimension, that would also make your states degenerate. Is that what you want? Think about it. --Dr Dima (talk) 19:36, 8 April 2009 (UTC)

Mom's perception

Do mothers have a distorted perception of danger? Are they influenced by any hormone to watch carefully for danger?--217.12.16.53 (talk) 10:51, 8 April 2009 (UTC)

Due to maternal instincts, a mother may be more risk averse regarding the child's well-being than the child. So the negative implications of a factor that would increase the child's risk carries a higher "weight" than the positive implications of a factor that equally decreases the same risk. I'm not sure if that's a distorted perception. Regarding the hormone, oxytocin (which is released during labour and breastfeeding) is thought to influence the maternal bond. From the article:

"Rat females given oxytocin antagonists after giving birth do not exhibit typical maternal behavior. By contrast, virgin female sheep show maternal behavior towards foreign lambs upon cerebrospinal fluid infusion of oxytocin, which they would not do otherwise."

See the article for the refs. Zain Ebrahim (talk) 11:31, 8 April 2009 (UTC)

A squalling baby is incredibly irritating but a mother seems to have hearing uniquely sensitive to that sound combined with specific mental (protective) and neurophysical (lactation) responses. I observe that a cat mother seems to have very little idea of how many kittens she has, which may be a source of worry that one may be lost, but is content if she has sniffed them all. Cuddlyable3 (talk) 16:22, 8 April 2009 (UTC)

Is it possible to predict an unknown element's attributes?

I'm interested in creating believable fictional elements, sort of like how people create believable fictional worlds with defined orbital distance and such. The only problem is that there doesn't seem to be any information on this topic, anywhere.

So is there a reliable, or at least somewhat believable, method to determine which attributes an element could have? What, exactly, causes an element, or compound containing a certain element, to be more prone to acidity, magnetism, and other features? What about its appearance--thickness, weight, color? Can these kinds of properties be determined or assumed from basic knowledge such as atomic weight, number of electrons, placement on the periodic table or relation to other elements, etc.?

Basically I'm just looking for guidelines. What can one realistically expect from an unknown element? What are the possibilities? What defines the possibilities? Is the lack of information on this subject due to the fact that an element's properties cannot be predicted accurately, or just because nobody else cares? —Preceding unsigned comment added by 97.104.210.67 (talk) 13:09, 8 April 2009 (UTC)

At this point, the only unknown elements in this universe will be very unstable. Generally, an element will be somewhat similar to the elements in the same column on the periodic table. Noble gasses are pretty inert, Halogens are rather reactive etc. 65.121.141.34 (talk) 13:18, 8 April 2009 (UTC)

It's not certain that all super-heavy elements (and their isotopes) will be unstable - there may be an island of stability. Dog Day Today (talk) 13:32, 8 April 2009 (UTC)

I should note that when the periodic table of elements was created, it functioned very well at predicting elements' properties. Dmitri Mendeleev was able to predict some of the properties of ekasilicon (germanium), ekaaluminium (gallium), ekamanganese (technetium), and ekaboron (scandium) just from their positions in the periodic table. Once you knew where your new element fits on the periodic table, you can semi-convincingly determine its chemical properties. -- 128.104.112.117 (talk) 14:40, 8 April 2009 (UTC)

Yes and No. "Yes" because you can predict anything you like (and you would have to work hard to predict something that someone somewhere would not reject as unbelievable). "No" because fictional creations are speculations not predictions (if by luck they turn out to be true then they are no longer fictional). The believability of a fictional element is increased by incorporating some known physical chemistry. Example 1: Dilithium crystal in Star Trek is supposed to be an element with atomic weight 87 and remarkable properties in crystal form. There really is a dilithium molecule but the rest is believable fiction. Example 2: Superman has problems with Kryptonite which is a fanciful element with no more than a name similarity to Element no. 36. Example 3: Melange (fictional drug) is a substance that plays an role in Dune (novel) but is IMO the least believable example. If your aim is to invent an element for a story I suggest that its "entertainment value" is more important than its believability to chemists. Cuddlyable3 (talk) 16:05, 8 April 2009 (UTC)

Your question covers interesting areas of science. Scientists do care about predicting the properties of elements, particularly to test the abilities of computational chemistry and to search for possible allotropes and polymorphs not yet discovered experimentally. I imagine atomic physics does a great deal of computational and theoretical work trying to predict and understand the properties of atoms of as-yet-undiscovered elements.

One very important use of such interplay of theory and experiment is that it tells you if your theory is along the right lines. The fact that the periodic table allowed Mendeleev to accurately predict the existence and properties of undiscovered elements suggested it reflected something very fundamental about atoms. Science works on cycles of:

• do an experiment
• make a theory to explain the results
• predict some new results with your theory
• do experiments to see if the predict results actually happen
• if yes, the theory is good (for now); if no, need to modify or abandon the theory.

If you want to create believable but fictional substances, you might be better off inventing fictional compounds rather than fictional elements - there's a lot more scope for undiscovered possibilities that would be stable - new compounds with unexpected properties are being discovered all the time.

Ben (talk) 17:07, 8 April 2009 (UTC)

The problem with inventing new elements is that the definition of an element basically revolves around the number of protons it has. Since that's a simple integer - and all of the elements up to well over a hundred are already 'known' - the only imaginary ones you can possibly have will need an ungodly number of protons. Sadly - it's all to easy to predict their properties...they fall apart in an alarmingly small number of milliseconds producing fairly boring elements and perhaps some stray radiation in the process! All of the very high numbered elements do that. There is some theoretical discussion of an 'island of stability' - a region where even an ungodly number of protons might hang together if the number of neutrons were just right. We don't yet have a way to make these high-atomic-weight elements right now - but the fact that we don't find them in nature is indicative that the island of stability either doesn't exist or is exceedingly hard to reach. This is really only theoretical - but I suppose you could use it as the basis of your fictional account. Personally, I agree with Benjah-bmm27 - you are better off thinking of imaginary compounds. There are (effectively) an infinite number of possible compounds - and we are only just learning of the near-magical properties of some of the weirder ones. Things like carbon nano-tubes, for example. Sadly - the prediction of their properties (especially the really weird ones like nano-tubes) is virtually impossible - which is what keeps chemistry from becoming a branch of physics! SteveBaker (talk) 18:02, 8 April 2009 (UTC)

Wow, what a reply. Thank you, everyone, this is all really helpful stuff. I should've thought to ask this here a long time ago! 97.104.210.67 (talk) 20:14, 8 April 2009 (UTC)

Alternative engine vehicles

I would like a list of all currently available hybrids, electrics, or PHEVs that can currently be ordered or will be available with the 2010 model year. —Preceding unsigned comment added by 198.176.41.2 (talk) 13:11, 8 April 2009 (UTC)

In what location? Some may even be sold in only one section of a single country (as was true of the GM EV1). The Category:Green vehicles looks like a good place to start but I doubt that we have a premade list of all current models anywhere. Rmhermen (talk) 13:46, 8 April 2009 (UTC)

Effect of Centrifugal Force on Oceans

putting back in own heading again...Matt Deres (talk) 20:20, 8 April 2009 (UTC)
As the earth rotates, centrifugal force causes ocean water to be deeper at the equator than at latitudes farther north or south. Has the greater depth at the equator due to this been calculated? One result of this effect will be that as global warming increases, flooding of land areas will be worse near the equator and less in areas farther north or south. – GlowWorm. —Preceding unsigned comment added by 98.17.41.22 (talk) 15:23, 8 April 2009 (UTC)

What we call flooding is relative to the normal coastlines that already include effects of tides and centrifugal force. Holland is far from the equator but would be among the worst hit by a global rise in sea level. Cuddlyable3 (talk) 16:29, 8 April 2009 (UTC)

The Centrifugal force really does have an effect, but the effect is felt by the whole planet, not just by the oceans. The earth as a whole is not sufficiently rigid to hold its shape against centrifugal force. Yes, the ocean surface at the equator is farther from the center of the earth than is the ocean surface near toe poles, but this si also true of the ocean bottom. see geoid. -Arch dude (talk) 21:37, 8 April 2009 (UTC)

Yes; the interior of the Earth is fluid and the entire Earth can be thought of as a sphere of liquid rotating in space in hydrodynamic equilibrium, with a thin solid crust. The centrifugal force makes the radius at the equater bulge out 21.3 km (13.2 miles) greater than at the poles. Except for local features such as continental plates the crust follows this surface of equilibrium (geoid), so the oceans are no deeper on average at the equator than at the poles. --Chetvorno^TALK 06:15, 9 April 2009 (UTC)

OK, that's a good point about the earth itself bulging at the equator. But as more water is added to the oceans because of melting polar ice caps due to global warming, centrifugal force will bring more of the water to equatorial regions compared to areas farther north or south. And yes, Holland may still be severely affected. So will the city of New Orleans in the US. Bangladesh is closer to the equator, and a great deal of the country is at a very low level, so it may loose a significant part of its area. At least it will be slow flooding, so the people will be able to get out. – GlowWorm. —Preceding unsigned comment added by 98.17.41.22 (talk) 07:00, 9 April 2009 (UTC)

Chemistry and lock, have any relation?

16:52, 8 April 2009 (UTC)bsm (=bimellahalrahmanalrahim) We must draw a plan for hacking door`s look that relate to chemistry any way, at least a little relation. we saw very ways but they are physically, completely. if there is any way or starting point?80.191.15.10 (talk) 16:52, 8 April 2009 (UTC)

Brute force! Destroy the lock with explosives, melt it, or dissolve it with Hg.

Ben (talk) 17:09, 8 April 2009 (UTC)

Freezing with liquid nitrogen could make the metal brittle and easy to fracture.Freezing could also inactivate the battery used for operating an electric lock, if it keeps a solenoid energized to hold it locked. Edison (talk) 17:30, 8 April 2009 (UTC)

Solids are solid and strong things are strong because of the bonds among their atoms. Take a solid, strong thing like a sledgehammer or crow-bar, for example. Or bones. Muscles contract because of chemical energy being released, so use those muscles to move those bones and kick down the door, swing a sledgehammer at it, or pry it open. DMacks (talk) 17:50, 8 April 2009 (UTC)

AKA MacGyver gets lazy? --Trovatore (talk) 22:19, 8 April 2009 (UTC)

Make a replica of Humphrey Davy's 1808 vintage "Great Battery," which was constructed with 2000 pairs of zinc and copper plates in individual tanks of dilute acid. It could produce about 2000 volts and over an ampere, and an arc from it could vaporize all known substances. It operated by electrochemistry so it should fall within the assignment. Just (carefully! extreme hazards from electric shock, acid, and high heat, as well as likely damage to the corneas and retinas) use a couple of electrodes to create an arc and burn away the lock. Or use an oxyacetylene torch (again, chemistry) to do the same thing in a more modern way. Edison (talk) 22:39, 8 April 2009 (UTC)

why don't we use the sun as a fusion generator?

i dont mean to be difficult but it seems that space is empty as you just have to fling something and then wait. so it's only a matter of waiting (and flinging in the exact correct trajectory) that separates something from earth orbit from the sun. so the sun is a huge fusion generator, and except for a bit of a wait after you've flung something at it, it is as easy to get to as earths orbit. so why dont we use it as close fusion generator? (sorry if i am misunderstanding something basic -- ive gotten a lot of flack elsewhere recently and have tried searching. thanks. 79.122.72.101 (talk) 22:12, 8 April 2009 (UTC)

The Sun already puts out as much energy as we actually want it to. If it put out more than it does, global warming would be an even worse problem than it is now. The difficulty is collecting that energy. --Trovatore (talk) 22:17, 8 April 2009 (UTC)

you don't see a difference between being as near to a huge fusion reaction as you want, 1 foot, 100 feet, 10000 feet, 100000 feet, etc, versus being able to build as large a solar panel as you want? i think there's a huge difference between having it in a few square meters and having it dispersed all over earth... 79.122.72.101 (talk) 22:34, 8 April 2009 (UTC)

That aside, it might be an interesting calculation to see how much energy would eventually be returned from 1 kg of hydrogen delivered to the Sun, versus the energy it takes to get it there. My intuition is that the return would be many orders of magnitude less than the investment, but I haven't actually run the numbers.

On another note, if you don't mind a bit of waiting, please send me a million US dollars. I'll pay you back one dollar a year, for a billion years. You get a 100000% ROI! --Trovatore (talk) 22:26, 8 April 2009 (UTC)

what? it doesn't take very long to get to the sun! also, you are discounting prevailing interest rates. 79.122.72.101 (talk) 22:34, 8 April 2009 (UTC)

In case we haven't yet been specific enough, solar energy is the term you're looking for. Anything we flung at the sun would return as such, and we've already got more sunlight than we can convert. This doesn't even get into the problems of getting something not just to the sun but to fusion depth (most of the hydrogen in the sun won't ever be fused) or of collecting the energy once it's created (the Earth receives less than one half of one billionth of the Sun's output). — Lomn 22:35, 8 April 2009 (UTC)

Follow-up fun. Burning one mole of hydrogen (w/ required oxygen) produces 242 kJ. Fusing that same one mole of hydrogen produces 2.7 billion kJ.[23] So fusion is better, right? Except that, as noted above, the Earth doesn't intercept all of the sun's output. Divide by the one part in 2.2 billion that we receive from the sun and that fusion nets us 1 kJ -- one half of one percent that of simple combustion on Earth (and well before we consider the point Trovatore raised regarding energy costs to move the hydrogen). No, sending stuff into the sun doesn't do anything to meet energy needs. — Lomn 22:45, 8 April 2009 (UTC)

Eh, the sun's already fusing; there's no need to fling *any* hydrogen. I believe the question here involves placing a satellite around the sun to harvest more of the generated energy and send it back to Earth. This concept has been explored in science fiction before (Asimov comes to mind), but I'm not aware of any practical research. Trovatore has it right though—any additional harvested energy sent to Earth would potentially cause an increase in global warming. – 74  01:08, 9 April 2009 (UTC)

Oh, well, if you could somehow collect the energy up close, and then (perhaps even harder) transmit it back to Earth efficiently, you could power an awful lot of stuff without aggravating global warming. Most likely you'd actually alleviate global warming, because you could replace carbon-emitting sources.

What I thought the OP wanted to do was increase the total power coming out of the Sun, so as to be able to get more power out of the same area of photovoltaics or solar-thermal generators here on Earth. That would aggravate global warming.

But getting the power back to Earth in a usable form seems completely infeasible to me. It's not like you can string up a high-voltage line. There have been proposals, kind of blue-skyish but at least semi-serious, to put solar-power satellites in orbit and beam the energy back to Earth in some sort of microwave beam. But that's from very much closer. Trying to put a power satellite in low Sun orbit and from there put a microwave beam direct on the collection station, rather than (say) the entire county surrounding it, strikes me as outside the realm of engineering possibility. (But don't let that stop you, OP; if you can figure out how to do it you could be wealthy indeed....) --Trovatore (talk) 01:51, 9 April 2009 (UTC)

My favorite concept is to put antimatter factories in low solar orbit and bring the "batteries" down the Beanstalk. —Tamfang (talk) 03:33, 9 April 2009 (UTC)

my god, you people thought i wanted to hurl hydrogen at the sun??? it boggles the mind. the sun has more than enough fuel. MY QUESTION IS SINCE IT'S A WORKING FUSION GENERATOR WHY DON'T WE USE IT AS THOUGH IT WERE IN OUR BACKYARD? Because the only thing separating the sun from our back yard (ie Earth's orbit) is a bit of a WAIT while our gear hurtles, AT NO ADDITIONAL FUEL COST, through space.

Space is a near vacuum. You hurl something and it goes "forever" (if you avoid colliding with something). So the difference between GETTING RIGHT HERE and GETTING WAY OVER THERE is 0 grams of rocket fuel -- just a bit of a wait.

So the way I figure, if the Moon happened to have a continuing fusion reaction, we would damn well harness that. So since the Sun is just as close (minus the bit of a wait getting there -- but at 0 fuel cost, just a correct initial trajectory), why don't we harness THAT? Seriously. 94.27.175.226 (talk) 09:35, 9 April 2009 (UTC)

We thought you meant that, because that was our best guess as to what you were talking about. Now I have no idea what you are talking about. What exactly are you proposing? Algebraist 09:41, 9 April 2009 (UTC)

to clarify, if there were a working, large-scale, self-sustaining fusion reaction on the moon, you don't think we'd be using it? My question is, why not do the same with the sun, it's the same as getting to the moon except a longer wait... 94.27.175.226 (talk) 10:01, 9 April 2009 (UTC)

April 9

Ethanol Train

I took the family to a tiny nearby town for lunch, which just happened to be hosting some sort of event about an ethanol train sponsored by the EPA. I took my son (who loves trains) to walk around the engine and check it out, but nobody was there to talk to. I've been trying to find more information, but I can only find two things: articles calling ethanol a "train wreck" and articles about a train shipping ethanol that derailed. Can someone point me to some information on the EPA's ethanol train? -- kainaw™ 03:57, 9 April 2009 (UTC)

Making the search more specific by searching for the phrase "ethanol-powered locomotive" avoids the sort of false hits you're talking about. I find one hit that might be relevant, which says a company called AHL-TECH is developing one. They have a web site at ahl-tech.com. --Anonymous, 4:07 UTC, April 9, 2009.

Or you can exclude terms which are in those false hits. I had good luck with "ethanol train -wreck -crash -derail": [24]. StuRat (talk) 05:50, 9 April 2009 (UTC)

Did you? The hits I looked at in that search all seem to be about ordinary trains shipping ethanol. --Anonymous, 8:28 UTC, April 9, 2009.

Weird example of relative size

I was reading a periodical piece on the new Planck craft when I came across this comparison:

Regions of the sky that today are separated by twice the apparent diameter of the full moon were once packed into a space much tinier than the diameter of a proton...

I've got no problem with the inflation theory itself, but I can figure out why they would choose to use "twice the apparent diameter of the full moon" when explaining relative size. I understand that angular diameter is usually used to describe the size of objects in space, but how is it any more useful/easier to understand than absolute measurements (e.g. the distance from the earth to the moon) in this case? Thanks! 124.154.253.25 (talk) 05:46, 9 April 2009 (UTC)

ESP

Can we actually believe in ESP ? Has it been proven to exist ? Are feelings like Instinct and hunches scientifically backed? For example, can say a mother possibly know that perhaps an accident is going to happen to her child, who is say a thousand miles away ? What is Science's viewpoint on this ? Rkr1991 (talk) 07:16, 9 April 2009 (UTC)

You can believe in what you want, but this is the science desk and if you're talking from a scientific point of view, the answer is no. See extrasensory perception. The prize offered by James Randi may also be of interest. As to "How can a mother know", the answer is that she can't. People imagine things all the time and sometimes, by coincidence, they happen. --Anonymous, 08:34 UTC, April 9, 2009.

Coma

What are the reasons that doctors will sometimes deliberately/purposefully place a patient into a medically induced coma? What does this do? What is the benefit? What scenarios (health problems) would typically lead to this medical treatment? How do they induce the coma? Thanks. (Joseph A. Spadaro (talk) 08:24, 9 April 2009 (UTC))

The induced coma article is rather short, but did you read it? --Anonymous, 08:36 UTC, April 9, 2009.