::I'm actually surprised that this "Titan test" is so public. And to think the UK newspapers are griefing us over posting the ending to ''[[The Mousetrap]]''! [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 14:18, 2 September 2010 (UTC)
::I'm actually surprised that this "Titan test" is so public. And to think the UK newspapers are griefing us over posting the ending to ''[[The Mousetrap]]''! [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 14:18, 2 September 2010 (UTC)
Actually I was asking the question from work, was not signed in, after 5 hours and 5 papers I solved it, the algorithm is n^3+3^n but I was not following any rule for solving it.And its not "that" public, I was looking specifically for"Titan Test"[[User:DSTiamat|DSTiamat]] ([[User talk:DSTiamat|talk]]) 16:08, 2 September 2010 (UTC)
Actually I was asking the question from work, was not signed in, after 5 hours and 5 papers I solved it. After a while I began to try combinations with 2^, as it didnt work I tryed 3^, and there I saw a pattern, the algorithm is n^3+3^n but I was not following any rule for solving it.And its not "that" public, I was looking specifically for"Titan Test"[[User:DSTiamat|DSTiamat]] ([[User talk:DSTiamat|talk]]) 16:08, 2 September 2010 (UTC)
== Ant? ==
== Ant? ==
Revision as of 16:20, 2 September 2010
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
I saw a shocksite of a man with all of his head below his eyes and forward of his throat (including his nose) missing. His jaw was gone, his molars were hanging on shattered bone stumps, his upper jaw and nose were carved away, and his tounge was just hanging there.
I think I recall seeing that picture. If it's the same one the OP was talking about, the man had most of his *face* below his eyes and forward of his throat missing - all that remained were a few bloody strips of flesh and his tongue hanging down, which gave him a cuttlefish-like appearance (I thought). I think that it was explained as a shotgun injury. Dunno if it was real or not. The guy was sat up and seemed very much alive. --Kurt Shaped Box (talk) 01:53, 29 August 2010 (UTC)[reply]
Oops, I misread the OPs question - I thought he had stated most the head above the eyes was missing! I must pay more attention to small details like that! 87.115.183.214 (talk) 23:33, 29 August 2010 (UTC)[reply]
Warning The OP may have viewed an injury worse than this but not as bad as this, and surgeons could fix neither by transplanting one of these. They are unpleasant pictures, I warned you!.Cuddlyable3 (talk) 13:35, 29 August 2010 (UTC)[reply]
A doctor friend saw a man who had been depressed and shot his jaw off with a rifle in a failed suicide attempt, and commented "He thought his life sucked BEFORE?" Edison (talk) 03:24, 30 August 2010 (UTC)[reply]
Your response is not sensible. You seem to be saying that if someone is clinically depressed, then he shoots off a portion of his jaw so that he is grossly deformed in view of others and has trouble eating, that he will not have more cause to be depressed afterwards. That is absurd. Edison (talk) 02:03, 31 August 2010 (UTC)[reply]
That is not at all what I'm saying. I am saying that depression has little to do with whether your life appears to objectively 'suck' to outside observers, and suggesting that it does is not only unprofessional for a doctor, but potentially harmful. Everything can seem to go your way, and you can still be suicidally depressed: the sort of misapprehension shown by that doctor leads people to avoid seeking treatment, and adds extra guilt on top of the other feelings of worthlessness. 86.161.108.172 (talk) 16:53, 31 August 2010 (UTC)[reply]
I think the black death was a bacteria. HIV I am doubtful as people get stuck living with it. Now since the question seems to be grouping strains of viruses into one for the count, I still think influenza would be it unless it's some slow, long-term thing like I don't know rabies. Are you ready for IPv6? (talk) 08:07, 29 August 2010 (UTC)[reply]
The traditional theory is that the Black Death was plague, caused by Yersinia pestis, as you say a bacterium (please, not "a bacteria"). However there are certain aspects of the historical record that seem rather different from the observed contemporary behavior of Y. pestis, and there's an alternative theory that the Black Death was actually a hemorrhagic fever, probably viral, along the lines of Ebola. I don't know if we'll ever really know. See theories of the Black Death. --Trovatore (talk) 10:16, 29 August 2010 (UTC)[reply]
HIV? No way "From its discovery in 1981 to 2006, AIDS killed more than 25 million people". Smallpox? Perhaps "Smallpox was responsible for an estimated 300–500 million deaths during the 20th century alone". Influenza? May be "Influenza spreads around the world in seasonal epidemics, resulting in the deaths of between 250,000 and 500,000 people every year,[7] up to millions in some pandemic years. On average 41,400 people died each year in the United States between 1979 and 2001 from influenza.[8] Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans." Nil Einne (talk) 09:46, 29 August 2010 (UTC)[reply]
Thanks for the stats. Smallpox is no longer killing, of course. I'd no idea that influenza still kills so many - I've always thought of it as a severe cold (though I know it is different). Why is there such a fuss over HIV if it is "relatively" harmless? (Sorry, don't answer that question, it was rhetorical. I do know that it is serious for those who catch it) Dbfirs12:17, 29 August 2010 (UTC)[reply]
The fuss over HIV is that it was 1. new, 2. behavior related, 3. totally mysterious at first, and 4. killed a lot of middle-class and rich people as well. From a straight-up epidemiological point of view, it is not nearly as problematic as many better known diseases, ones with easier cures, and so on. This is not new with HIV, of course — there are lots of phenomena like this, where the attention paid to certain risks (e.g. death by home invasion) far, far outweighs the actual incidence, compared with other risks that are perceived to be "normal" (e.g. death by heart disease), which are largely ignored. --Mr.98 (talk) 13:47, 29 August 2010 (UTC)[reply]
I would point out that in terms of current deaths, HIV is far from harmless. I didn't quote this but if you check the article it also says "In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children". Influenza may kill more then that in a some years, but from what I quoted not in an a more 'normal' year. As Mr 98 said HIV is new so it's not exactly surprising it doesn't win in a cumulative basis even if the population nowadays is far higher then historically but it doesn't mean it isn't currently a big deal. Smallpox is no longer killing which likely means even if it was the leader it will one day lose that position. Whether it ever was a leader and if so, when/if it lost that position I don't have enough info to speculate on but from the figures at hand it's not impossible smallpox may still leads. From the smallpox article "In the early 1950s an estimated 50 million cases of smallpox occurred in the world each year.[13] As recently as 1967, the World Health Organization (WHO) estimated that 15 million people contracted the disease and that two million died in that year", so it was still fairly major in the 50s, at a guess we could say 10-100 million people died from influenza since then. Of course when counting deaths you always have the problem many factors generally contribute to a death. For example people with AIDS have a far higher risk of death from influenza and a lot of other viral diseases (well many things I mention viral because that's what were discussing). Nil Einne (talk) 04:48, 30 August 2010 (UTC)[reply]
Sorry, let me clarify: HIV/AIDS in the West. You'll notice that now that it is primarily an African/Asian thing that the enthusiasm for activism has died down quite a lot. The initial Western reaction was not based on Africa/Asia at all. When something just afflicts the poor we have an easy time looking the other direction. When it starts to kill white guys in San Francisco, it becomes a national debate. --Mr.98 (talk) 12:35, 30 August 2010 (UTC)[reply]
Also in terms of the flu, I've heard it suggested before that a lot of people have no idea what the flu is and often when people think they have or had the flu, they just had a bad cold Nil Einne (talk) 07:51, 30 August 2010 (UTC)[reply]
Most of the time, not even their medical practitioners know, not really anyway. My cousin who's a physician tells me that in her experience they generally diagnose viral syndrome rather than influenza. The symptoms are so non-specific that you can't really be sure unless you actually isolate the virus from the patient, and that really doesn't change the treatment anyway, so why bother?
Of course sometimes you can be pretty sure, in a Bayesian sense — if you come down with flu-like symptoms in the middle of a flu outbreak (and they do isolate virus from enough patients to know about those), then you can place pretty good odds that you've got the flu. --Trovatore (talk) 07:57, 30 August 2010 (UTC)[reply]
The 1918 flu pandemic is estimated to have killed between 50 and 100 million people. Even if the Black Death was viral and killed a third of the population of Europe and Asia, it doesn't seem likely to have reached those numbers. Looie496 (talk) 16:46, 29 August 2010 (UTC)[reply]
Let me chime in again on Influenza, probably specifically Influenza A, the most common variety. The deal with influenza is that it spreads relatively easily from person to person without an intermediate vector. It spreads so easily, to stop it spreading you have to wash constantly; and even that's not 100% effective. Other major infections and diseases all generally went away with improved hygene in a very general, public health sense. Plague stopped being a huge deal when people stopped living with rats and fleas in their houses. Cholera went away when people stopped shitting in their water supplies. Smallpox went away via a combination of gradual immunity and active vaccinations. Most of the other big killers are bacterial or protist; for example Malaria may give Influenza a run for its money in terms of total deaths in history. Indeed, it looks like under curent conditions, it kills far more (between 1-3 million worldwide annually, compared to Influenza's 0.25-0.50 million), but it is caused by a protist. --Jayron3204:32, 30 August 2010 (UTC)[reply]
I seem to remember reading last year, during the big H1N1 scare, that hand-washing, beyond being "not 100% effective", doesn't really even help all that much with flu. Supposedly flu virions have a lipid envelope that isn't very survivable once it lands on something, so most flu transmission is airborne. No guarantee I got that right, and anyway I certainly don't want to discourage people from hand-washing — there are lots of other things it'll help keep you and others safe from. --Trovatore (talk) 09:48, 30 August 2010 (UTC)[reply]
The Major Bones , Muscles , Muscles Joints and Joint actions involved in Baseball batting
I need to Know about the Major Bones , Muscles , Muscles Joints and Joint actions involved in Baseball batting. Any info on how to optimize performance in Batting and what their biomechanical principles that apply to batting would also be really appreciated. —Preceding unsigned comment added by 175.39.13.5 (talk) 09:58, 29 August 2010 (UTC)[reply]
It is less than 24 hours since you first posted your question. Please read the section "When will I get an answer?" at the top of this page. Cuddlyable3 (talk) 10:51, 30 August 2010 (UTC)[reply]
Indeed - but in any case, these reference desks are manned by volunteers who do this for free. Sometimes we just don't have a good answer for you. I have no knowledge about batting - but meanwhile, I'd suggest reading our articles: Hand, Arm and Shoulder - which are more detailed than you might expect. Since all of the bones, muscles and joints in those parts of the body are involved in batting - that should give you a good start. SteveBaker (talk) 13:56, 30 August 2010 (UTC)[reply]
A better question would be: "what bones, muscles, joints and joint actions are NOT involved in baseball batting?" Seriously, you could start from the feet and lower legs, up through the thighs/hips, core muscles of the abdomen, trunk, and back, to the shoulder girdle, upper arms, out to the distal arms, and end with wrist action and hand grip. Then you would have described virtually all of the body's major bones, muscles, and joints. For some real references, you could look at these articles which describe the biomechanics and shoulder muscle recruitment involved. I can't really judge whether these references will really answer your question. Sports biomechanics is the study of physics in sports, and although the article doesn't specifically address the baseball swing you might be interested in following some of the external links for more information. A google search on "baseball swing mechanics" will find any number of sites purporting to help optimize your swing; many of these will probably want to sell you a video or something. --- Medical geneticist (talk) 23:00, 30 August 2010 (UTC)[reply]
Okay. Someone give me a straightforward, scientific, skeptical, Joe Nickell'esque debunking of how the corpse of Bernadette Soubirous can possibly keep up this Lenin-like appearance despite the body being "nearly 130 years old"??
I read the part in her article about the wax imprint of the face of course, but if that's just a wax imprint then where's her real face? and what about the body? The paragraph reads: "What struck me during this examination, of course, was the state of perfect preservation of the skeleton, the fibrous tissues of the muscles (still supple and firm), of the ligaments, and of the skin, and above all the totally unexpected state of the liver after 46 years. One would have thought that this organ, which is basically soft and inclined to crumble, would have decomposed very rapidly or would have hardened to a chalky consistency. Yet, when it was cut it was soft and almost normal in consistency. I pointed this out to those present, remarking that this did not seem to be a natural phenomenon." -- Ϫ09:59, 29 August 2010 (UTC)[reply]
You can't really "debunk" it, because there are instances where bodies are remarkably well preserved, even when you wouldn't expect them to be. You notice that the vast majority of saints and other religious figures aren't incorrupt: they decay like almost anyone else. I suppose you could do a study that looks at the rates of preservation among religious vs. non-religious folks (and presumably find that the rates are similar for a given climate and burial method), but I don't know of any such study. Such research would also be complicated by the fact that it's common to exhume saints (to collect relics, which in most cases are just bones), while pretty rare to dig up other folk. Buddy431 (talk) 19:46, 30 August 2010 (UTC)[reply]
"it was feared that the blackish tinge to the face and the sunken eyes and nose would make an unpleasant impression on the public" does not sound "incorruptible" to me. Sounds like they cherry picked evidence supporting their thesis that the supernatural was at work, and discarded that which didn't. --Sean19:08, 30 August 2010 (UTC)[reply]
For the same reason that your blood pressure does not blow your head apart when you stand on your head. The increase in pressure is a fraction of one atmosphere, and the blood vessels are adapted to deal with this. I expect that giraffes have modified valves to cope with the extra height. I'll check. Dbfirs12:06, 29 August 2010 (UTC)[reply]
While Dbfirs' answer is perhaps technically correct - it dismisses the problem far too lightly. The pressure of a column of blood 3 meters high is about 30 kiloPascals, but the giraffe's blood is normally at high pressure because when the animal is standing upright, the blood has to be pumped up to it's head, so you start with a blood pressure of around 40kPa above atmospheric at the heart and you have to add about another 30kPa to it when it's head is low to the ground. 70kPa is about 5 to 6 times normal human blood pressure! The Giraffe has evolved all sorts of special valves in the veins and arteries of it's neck to shut off the flow of blood when the head is tilted downwards precisely because of this problem. They also have incredibly thick-walled blood vessels in their legs - for the exact same reason. If a giraffe kept it's head down for too long, the lack of blood flow to the brain caused by those valves shutting would cause it to black out and soon die. When you watch them drinking, you can see that they have to work hard to avoid that exact problem. Giraffes are incredible examples of the lengths evolution will go to engineer a creature that's trying to fill a tiny specialized niche. SteveBaker (talk) 02:23, 30 August 2010 (UTC)[reply]
Yes, I did underestimate the biological technicalities. I was reacting to the Physics of "blow its head apart". Dbfirs08:32, 30 August 2010 (UTC)[reply]
Beyond postural changes, male giraffes fight by swing their heads against the necks of their rivals at high velocity[2], which should also send pressure waves along the blood passages. Edison (talk) 03:16, 30 August 2010 (UTC)[reply]
Well, perhaps such a mechanism might work - but the giraffe doesn't do that - it has special valves in the blood vessels in it's neck. SteveBaker (talk) 13:49, 30 August 2010 (UTC)[reply]
Does Japanese longevity still stand after fraud relevations?
Right. It means, they have some obvious problems in the system of counting. Are they big ones or small ones? It will take more checking to really find out for sure. However it seems unlikely that the general longevity question (which is dependent on more than number of centenarians) would be so warped by fraud as to be completely incorrect. --Mr.98 (talk) 15:24, 29 August 2010 (UTC)[reply]
The number of dead registered centenarians seems now to be in the thousands ([3], in German). Only if this is still just the tip of the iceberg (which seems possible) will Japanese life expectancy notably decrease.--Roentgenium111 (talk) 19:20, 29 August 2010 (UTC)[reply]
How can Japanese officials be so stupid as not to verify someone is still alive when their residence was turned into a park in 1981, as was reported for one supercentenarian, or no one has seen them in decades, but their welfare or pension checks still get cashed? Have any of the greedy and crooked relatives been arrested yet, or any of the lazy government officials fired? Edison (talk) 03:12, 30 August 2010 (UTC)[reply]
It's not being "stupid", it's just not having a mechanism in place to audit. Auditing costs money, time, personnel, too. If you assume the level of fraud is low (which it still might be, even with the scandal examples above), then at some point chasing down fraud becomes more expensive than just accepting it. (Without taking into consideration, either, the costs of false positives/negatives — is it worse to err on the side of cutting checks or on the side of denying them? Mistakes will happen one way or the other.) Obviously their system as it is seems to lack the ability to know for sure either way, which is a problem. But it's not "stupidity" so much as "bureaucracy", which is something of a different problem than lack of intelligence. The parts of the bureaucracy that are concerned with "is this address valid" have probably nothing to do with the parts that are concerned with "should we cut this check." --Mr.98 (talk) 22:12, 30 August 2010 (UTC)[reply]
I want to be sure, once and for all, that pool chemicals intended to highlight urine bright colors do indeed exist. Would someone please post a link to a shop that allows me to buy these chemical highlighters? (I don't trust Google to return the results I'm looking for with these keywords for some reason. You probably know how to search them better than I do.) --70.179.165.170 (talk) 16:00, 29 August 2010 (UTC)[reply]
Maybe only on December 14, 2000?
That's when Snopes last updated the article you linked to. Who's to say that no lab has invented the coveted chemical in the nearly 10 years since then? And if they still don't exist, how come they are impossible to develop with today's chemical science? --70.179.165.170 (talk) 18:55, 29 August 2010 (UTC)
I adjusted the layout of the OP's questions to avoid double headings. Cuddlyable3 (talk) 22:45, 29 August 2010 (UTC)[reply]
The Snopes article clearly states that such an indicator is possible (or at least plausible) and also gives several suggestions (that still sound pretty valid) why nobody is developing/mass-marketing it. It takes time+money+ability+opportunity to get something, not just "scientifically possible". The ball's in "whoever wants it"'s court to either get it done or find updated information that it's already been done; I doubt anybody is doing active research to find positive proof that it's impossible. DMacks (talk) 19:13, 29 August 2010 (UTC)[reply]
It may or may not be impossible - but you certainly can't buy such things. If you think of the concentration you'd need in the pool water to produce a noticable color - this would have to be a totally non-toxic chemical with non-toxic byproduct from the reactions. Anyway - it's an urban legend told to small children in a (probably vain) effort to stop them peeing in the pool. Since adults only pee about 1 liter per day - little kids probably a tenth of that. Urine is 95% water. Dissolve that in 100,000 liters or so of pool water...and you have 0.05 parts per million. Urine isn't toxic - and it actually kills bacteria. Why the heck would you fill the pool with some complicated chemical to prevent that? It's utterly ridiculous to imagine that you either would or could. So, no - it's complete B.S. SteveBaker (talk) 01:28, 30 August 2010 (UTC)[reply]
I read somewhere (unfortunately I can't remember where) that they tried this in a public pool somewhere and it had the opposite effect to that intended. Children actually came to pee in the pool to watch the comic effect of the "wake". Was this a genuine trial, or a spoof account? Dbfirs08:19, 30 August 2010 (UTC)[reply]
On a related note, my local swimming pool used to have posters claiming that the eye-stinging effect of the water wasn't due to the chlorine, but a reaction of the chlorine with urine. So, basically, "don't wee if you don't want your eyes to sting". Apart from the accompanying horror when you realise that your eyes always sting if opened underwater at this pool, is there actually any truth to this? 86.161.108.172 (talk) 11:51, 30 August 2010 (UTC)[reply]
Which part of "0.05 parts per million" didn't you understand?! No! There is no truth to it. Apart from the psychological consequences, this is a huge non-problem! SteveBaker (talk) 13:46, 30 August 2010 (UTC)[reply]
There is a problem with the reaction between chlorine in the water and various things (including urine, sweat and deodorant), the chemicals produced are called chloramines[4][5], particularly nitrogen trichloride, and they have a bad effect on eyes and breathing for some swimmers. This tends only to be a problem with the older style of pools with high sides, which allows these chemicals to reach sufficient concentrations to be a problem. Being heavier than air, they're concentrated just above the water surface, right in the breathing zone for a swimmer. Our local swimclub occasionally has to call a halt to training sessions when it gets too bad. Newer pools, with sides at water level don't have the problem. Mikenorton (talk) 15:12, 30 August 2010 (UTC)[reply]
Thanks. So, not quite as they described, but based on truth. This pool did indeed have high sides: one of the things the lowest swimming certificates judged you on was the ability to get out without sticking your knee in the overflow ledge! 86.161.108.172 (talk) 15:30, 30 August 2010 (UTC)[reply]
Those involved with "planetary protection" would take the possibility seriously. So far as I know however there has never been a demonstration of Earth life replicating under Martian conditions in the lab. Wnt (talk) 22:25, 29 August 2010 (UTC)[reply]
The atmosphere of mars is too thin to maintain liquid water on the surface for any extended length of time, so any drop of water on mars would quickly dry up and any life form present would presumably desiccate. There are perhaps some life forms which might be able to survive in this state for some time, but only in a suspended state, not in a living, procreating state. I can't remember where I heard it but I understand NASA goes to considerable lengths to ensure there aren't any life forms like bacteria and such on the probes and rovers and other stuff they send to mars, and anywhere really. Vespine (talk) 00:13, 30 August 2010 (UTC)[reply]
I was looking for an article on the amusing and awesome behavior of dogs-burying-bones, and all I found so far has been Hoarding (animal behaviour), which mostly discusses rodents and birds that cache a lot of food in the same place over time. Do we have any article on the behavior of canines burying bones? Comet Tuttle (talk) 20:27, 29 August 2010 (UTC)[reply]
Leopards drag their kill high up in the trees so they can eat at their leisure. Squirrels store their nuts and acorns in a tree hollow or bury them in the ground. Beavers collect piles of vegetation around their lodges in anticipation of the cold hard winter to come. Even people stock their pantries with enough staple to last for weeks.[6] Here are a couple of websites that explain why dogs bury their bones: This site says they want to soften the bones. This site notes that burying food and bones arises from the need to hide food from other predators. There are many other sites that offer answers here.Cuddlyable3 (talk) 22:39, 29 August 2010 (UTC)[reply]
I've had 5 different dogs over the years - not one of them ever buried a bone. I'm skeptical that this is such a common behavior as it's usually depicted. We did have a female Labrador who hoarded - it was pretty comical, if you gave her a snack when she wasn't particularly hungry, she'd wander around the house looking for somewhere to hide it...but she was entirely hopeless at it and generally settled for pushing it into a corner between a piece of furniture and the wall - but she never buried anything. SteveBaker (talk) 01:20, 30 August 2010 (UTC)[reply]
Our dog never buried a bone before we got a big enough yard. (She was maybe 6 at the time.) Then the instinct seems to have kicked in and she started burying them like mad. (Bones, toys, pig ears.) We were pretty surprised that she started to exhibit "classic dog behavior" of that sort pretty spontaneously after all that time. --Mr.98 (talk) 02:22, 30 August 2010 (UTC)[reply]
I've watched my share of documentaries about African wild dogs, wolves and dingoes and I don't remember ever seeing these wild specimens burying bones. It may of course have something to do with having excess food - a condition often encountered in domesticity but rarely encountered in the wild. As for burying bones to soften them, I think your average archaeologist would say otherwise! Richard Avery (talk) 06:52, 30 August 2010 (UTC)[reply]
The time scale is obviously different for the dog and the anthropologist, and, as we know, fossilization is not exactly a common occurrence anyway. My dog has buried pig ears, and that definitely softens them. (And makes them pretty nasty.) --Mr.98 (talk) 12:29, 30 August 2010 (UTC)[reply]
Acquired a male beagle 16 years ago. He frequently buried bones. Big beef thigh bones. Needed BIG holes. (Beagles and nice gardens do not coexist.) Acquired younger female beagle 7 years ago. When they were each given bones, the male always ended up with hers, after demolishing and/or burying his. Yes, a real cad! So she never buried bones. Older male beagle died three months ago. Now the female has started burying bones. Draw your own conclusions. HiLo48 (talk) 21:08, 30 August 2010 (UTC)[reply]
Coin
Is it possible for a normal coin (say, a US quarter) to land on its side after being flipped? My common sense says no but I can't see why (from a physics standpoint) not. Because a coin is really a cylinder with radius r and height h, so simplified maths would give that the chance of its landing on heads is r/[2(r+h)] on tails also r/[2(r+h)], and on its side h/(r+h). What am I missing? 76.235.109.75 (talk) 21:08, 29 August 2010 (UTC)[reply]
There is in fact at least one well-known movie whose main plot is set in motion when a flipped coin lands on edge. However, in the movie this happens because it's flipped onto a table or something and lands against the side of a book on the table. --Anonymous, 04:00 UTC, August 30, 2010.
Australia's 50c coin is a dodecagon. While I've never seen one land on its side, an occasional game (particularly among drinkers) is that of trying to stack them on their sides on top of one another. It would seem quite likely that one could occasionally land on its side.
That's a reasonable linguistic question. I read side to mean the thinnest face. Neither heads nor tails. The question would make little sense otherwise. HiLo48 (talk) 23:20, 29 August 2010 (UTC)[reply]
A nickel can land on its side, but a quarter can't, because it has rounded edges -- you can't even make it stand on its side by setting it that way. As a general principle, if you can set up a coin on its side and have it stay that way, then there is some finite probability of it landing on its side when dropped and staying that way. Looie496 (talk) 23:23, 29 August 2010 (UTC)[reply]
Anything can be made to stand up if its center of gravity is vertically in line with a supported point (a local minumum). Now whether it's anything close to stable towards say even the merest breeze is a separate issue (Metastability) regarding how high the center of gravity is. You can stand a pyramid on its point if you're careful! More close to the "quarter has curved edges" issue, you can also stand an egg on its end (a curved surface), until it gets jiggled and rolls over. DMacks (talk) 02:22, 30 August 2010 (UTC)[reply]
Plenty of coins can stand on their edges. That's not the same problem as whether they can end up on their edges after a flip. The problem is, how do you kill the rotation? The coin can't land exactly on its edge, in order to end up there; it would just keep on rotating, and fall over. So I suppose it would have to land at an angle a bit short of upright, in the direction of rotation, with the rotation so nearly spent that air resistance or something can kill the remaining angular kinetic energy and angular momentum, simultaneously, just in time to have it rest on its edge. (You have to consider these a bit separately; it's imaginable, say, that the angular momentum could be counterbalanced by the straight part of the far edge of the coin, but if you don't dissipate the energy, the coin just bounces backwards and falls over in the other direction.)
This just seems virtually impossible to me — certainly far less probable than you'd get from the ratio of the areas. Most of the time, when a flipping coin lands, it is rotating far too quickly to have any way of ending up on the edge. Maybe if it bounced back and forth a few times, dissipating energy, but somehow bouncing high enough to get back to the edge? I just have trouble seeing how this can happen. --Trovatore (talk) 04:15, 30 August 2010 (UTC)[reply]
When I had a coin land on its side, it did so spinning, gradually slowing down. I assume it had bounced around until the axis of rotation was close enough to vertical. 86.161.108.172 (talk) 11:44, 30 August 2010 (UTC)[reply]
The old Threepenny-bit from pre-decimalized UK currency was remarkably easy to have land on-edge. It was a very thick 12-sided coin, and if you just took a handful of them and dumped them on the table, the odds were good that at least one of them would be balanced on-edge. SteveBaker (talk) 13:42, 30 August 2010 (UTC)[reply]
With a US quarter, it would be theoretically possible, but extremely unlikely unless it were to land on a deforming surface, such as deep sand. Googlemeister (talk) 14:15, 30 August 2010 (UTC)[reply]
I don't think it matters whether the cylinder (coin) is round or with 12 flat surfaces. Assuming the surface onto which the cylinder is dropped is perfectly level, the 12 flat areas don't contribute to the likelihood of the cylinder coming to rest on edge. Thickness matters because that enters into the the calculation relating the cylinder's dimensions to one another. Also the 12 sided "cylinder" would not be a cylinder. But the calculation required to determine likelihood of coming to rest in any particular orientation does not involve, I don't think, the length of the linear dimension of the 12 flat faces. I can't do the math, but I think it should only involve three factors—the width of the object, and its two faces (heads and tails), which are of course equal. Bus stop (talk) 21:28, 30 August 2010 (UTC)[reply]
Like Steve, I am old enough to remember threepeny bits and they were very easily stood up on their edge. It is possible that the flat edges do make a difference here. A rolling round coin that is also slightly tilting will continue to roll and tilt until it falls over. A coin with flat edges does not roll so readily as a round one, there is a potential hill to overcome each time it rolls over a corner. If the forward momentum is not sufficient get it over the next hill the coin will fall back onto the previous edge causing a small torque to be applied. On some throws of the coin this might just happen to be just enough to cancel, or sufficiently cancel, the torque due to the tilt of the coin, resulting in it being brought to an upright position. This cannot possibly happen with a round coin, so polygonal coins have a greater probability of standing up. SpinningSpark23:33, 30 August 2010 (UTC)[reply]
They were "very easily stood up on their edge" because the table or other surface was not level. Any amount of tilt will allow a perfectly round coin to roll. I am specifying that the surface be perfectly level. Also, as Steve said, the "threepenny-bit" was "very thick." If we substitute four-sided or even three-sided for twelve-sided I think it becomes more clear that the only calculations are the relative surface areas available upon which the object can come to rest. That involves the ratio of surface areas available to one another. There are a number of square units on "tails." There are a number of square units available on "heads." And there are a number of square units available on "edge." The ratio that we are concerned with is that ratio that relates heads/tails to edge. In all instances that that ratio is equal, there is an equal likelihood of the object coming to rest in its three varieties of orientation. Bus stop (talk) 00:44, 31 August 2010 (UTC)[reply]
The coins roll because they have been randomly tossed, there is no question of sloping tables, they will still roll even if the table is levelled with micrometers. You are making big assumptions saying only diameter/width ratio is important and I would not be so bold without a source to back that up. All sorts of other things can effect the outcome. Mass/diameter ratio, for instance, will vary with coin material and could be very significant for the likelihood of a coin with "sideways" velocity righting itself when it hits the table. I think I have given a reasonable possible cause why polygonal coins are more likely to right themselves which you have just ignored. You are taking too simplistic approach, only considering coins dropped straight down in a random orientation; the reality of tossed coins is much more complex and dynamic than that, spin vectors can have some surprising results in collisions. SpinningSpark16:51, 31 August 2010 (UTC)[reply]
How do the flattened sides of a polygonal object help it to stand in its least stable orientation? The flattened sides tend to prevent "rolling." The flattened sides don't help to prevent the object from falling into the orientation called "heads" or "tails." I think it is the width of the object alone that provides stability when it stands in its least stable orientation. I am not ignoring your reasoning. I think your reasoning is not likely to bias the outcome. Yes, the "coin with flat edges does not roll so readily as a round one," but that could just as likely mean that it falls over more quickly into the position of heads or tails. Bus stop (talk) 21:38, 31 August 2010 (UTC)[reply]
What you say is true for a stationary coin resting on the table. But this is too simplistic, I am suggesting that you ought to also consider the effect of angular momentum vectors for dynamically moving coins. For a coin that encounters a hump and starts to roll backwards, the vertical part of the vector (which it will have if the coin is leaning at all) will causes a rotation in the direction that puts the lean on the line of travel and with a sign that is tending to right the coin as it falls backwards. This is a consequence of conservation of angular momentum. The corners of a polygonal coin are like the coin has carried its own "humps" with it and will have a similar effect. SpinningSpark07:12, 1 September 2010 (UTC)[reply]
Coins that are not cylinders and which have an odd number of sides (like the 7-sided UK 50p coin) are rarely truly polygonal - they are properly called 'verved'. The flat-looking faces are actually short arcs of circles centered on the point on the opposite side of the coin. (Which is why having an odd number of sides is important here). What this means is that the "diameter" of the coin is constant and it will roll perfectly, despite not being circular. That's important for vending machines and such like. It's a clever idea. However, the old British threepenny bit had 12 sides - so it couldn't be verved, it didn't roll at all well - and so was rarely accepted by slot machine manufacturers. SteveBaker (talk) 13:00, 1 September 2010 (UTC)[reply]
Do we have any idea as to how difficult it would be to climb Olympus Mons on Mars, compared to climbing the highest mountains on Earth? Assuming that we were already on Mars and had spacesuits that didn't particularly restrict the movement of the mountaineers, I mean. The WP article states that it has a 'shallow slope (2.5 degrees central dome surrounded by 5 degree outer region)' - so does this mean that may actually be a less difficult climb, on a purely technical basis (sounds as though it's high - but really wide) than something on earth that is considered 'steep', such as K2? Would summiting at 27km be any different to a man in a spacesuit than walking at 'ground level' on the Martian surface? Do we know enough about the mountain yet to discuss this in a meaningful manner? --Kurt Shaped Box (talk) 22:10, 29 August 2010 (UTC)[reply]
There are cliffs along the basal bluffs in some places, but if you avoided them it would be technically a stroll, except for two factors. The first of course is the sheer height. The second is that because it is so high and massive, the expansion of the atmosphere when the daylight sun hits it is expected to generate very strong winds along the slopes. For what it's worth, if you have access to Google Earth, you can use it to get some pretty neat 3D views of Olypmus Mons from a variety of angles. Looie496 (talk) 23:13, 29 August 2010 (UTC)[reply]
As you've stated yourself, having a spacesuit is a bonus (I assume it will protect you from what the Mars' climate will throw at you)! It negates the main problems climbing in a hostile environment presents (cold, wind, lack of oxygen) and that's a major factor. If you didn't have to worry about environment even a novice mountaineer could probably climb most mountains on Earth. The only thing standing in the way would be mountaineering technique, but Olympus Mons is relatively flat. So if climate problems (other than perhaps the strong winds Looie mentioned) and the lack of steep ascents have been taken out of the equation then Olympus Mons would be more of a gentle hill walk. (I guess you'd need a lot of base camps for replenishing your spacesuit, sleeping, etc., unless technology was at sci-fi standards!) It would be cool to climb any mountain on Mars tho, I've been born a century too early! 87.115.183.214 (talk) 00:58, 30 August 2010 (UTC)[reply]
I remember a line from a sci-fi novel that went something along the lines of "There's no point in visiting a planet with a highest mountain unless you're going to climb it" - can't say that I disagree. Climbing the 'Great Wall of Iapetus' would probably be an awesome experience too. Actually, do you need a 'spacesuit' as such, on Mars - or would a helmet respirator and heavily insulated clothing (say, of the type they wear when walking in Antarctica) suffice at sane elevations? --Kurt Shaped Box (talk) 01:12, 30 August 2010 (UTC)[reply]
Mars has less them 1% the atmospheric pressure of earth. 0.6 kPa vs 100kPa on earth. So you'd probably need a pressure suit. Plus there's no magnetosphere, so I think you'd also be vulnerable to cosmic and solar radiation. Vespine (talk) 01:44, 30 August 2010 (UTC)[reply]
Even if you could just maybe get away without a pressure suit at the bottom of the mountain - you'd certainly need one at the top. The atmospheric pressure at the top being about 5% of what it is at the normal surface elevation of Mars...that's a pretty reasonable vacuum! It's not much of an exaggeration to say that the mountain sticks up above the top of the atmosphere. SteveBaker (talk) 02:15, 30 August 2010 (UTC)[reply]
Similarly , would it be way easier to climb Mt Everest if you had a similar space suit that "did not restrict movement" and kept you warm and oxygenated? Lack of oxygen and cold seem to be the factors that make attaining the summit of Everest rathr than the need to scale sheer cliffs. Edison (talk) 03:06, 30 August 2010 (UTC)[reply]
The Armstrong limit is the pressure that water will boil at, at body temperature. Mars's surface atmosphere is about 10% of that pressure. Thus you need a pressure suit to stand outside on Mars. CS Miller (talk) 09:30, 30 August 2010 (UTC)[reply]
Yes - but it is widely claimed that the skin (perhaps with a light elastic covering) is able to supply sufficient tension to prevent that problem. It's certainly marginal though. You'd definitely need a full-face mask to protect eyes, nose & mouth. SteveBaker (talk) 13:36, 30 August 2010 (UTC)[reply]
Would you also need full protective pants, to protect the other openings and/or mucous membranes? I imagine those areas would be deeply unpleasant in low pressure without adequate protection. 86.161.108.172 (talk) 15:23, 30 August 2010 (UTC)[reply]
You'd be in trouble if you wanted to breath though. Even pure oxygen, at martian pressure, would not sustain you. So you'd need to be breathing something pressurized. If you hope to breath both in and out you're going to need pressure squeezing your chest and abdomen roughly equal to the pressure of the air you're breathing. APL (talk) 21:05, 30 August 2010 (UTC)[reply]
Is that a fact? That the external air pressure on your body is a factor when expanding and contracting your lungs? I thought that it was an action purely driven by your own muscles... --Kurt Shaped Box (talk) 22:53, 30 August 2010 (UTC)[reply]
Getting to the top of Olympus Mons would be a major endeavour. It is 625 km in diameter, so even if it were completely flat it would still be a journey of many days to get to the top on foot. However, it is not completely flat and it is certain that many obstacles, some unforeseen, will be encountered on the way. The basal cliffs are 6 km high, true there are places where lava has flowed over them making them smoother, but at the very least this adds a substantial diversion. Similarly, the caldera has cliffs up to 3 km tall, although the highest point is not within the caldera so one could claim to have summited without actually getting to the centre of Olympus Mons. SpinningSpark12:06, 30 August 2010 (UTC)[reply]
Something else to make this easier is the low gravity on Mars, 35-40% of earth gravity. Assuming your high-tec space suit isn't very heavy, you should be able to travel twice as far as you could on earth with less fatigue. Googlemeister (talk) 14:09, 30 August 2010 (UTC)[reply]
That's not true. The moon astronauts (working under just 15% of earth gravity) reported that they were fatigued much MORE quickly than on Earth. SteveBaker (talk) 14:15, 30 August 2010 (UTC)[reply]
Apollo/Skylab_A7L suits operated at 3.7 psi, and while the atmosphere was pure oxygen to "match" the partial-pressure of oxygen at 1 atmosphere, these conditions are not ideal for intense climbing and physical exertion. Nimur (talk) 18:35, 30 August 2010 (UTC)[reply]
If you had a magic space-suit that didn't restrict your movements and never ran out of air, you could probably do most of it on a bicycle in under a week. Planing the route would be critical. APL (talk) 16:09, 30 August 2010 (UTC)[reply]
I notice that I'm able to see through my rectangular prism fishtank and see someone else looking into the opposite broad side, but I can't see through from my broad side at anyone peering through the two short sides, and vice versa. Why does this happen and at what angle between the glass panels does this 'blindspot effect' begin? If anyone has a pentagonal, hexagonal, etc. tank, perhaps you could register your visual experience -- I only see such shape tanks in the pet shop and they are empty so the effect doesn't apply. DRosenbach(Talk | Contribs)01:42, 30 August 2010 (UTC)[reply]
When light passed from one material to another, it's bent. If the amount of bend exceeds the angle required to exit the material then it's bent back - just like a perfect mirror. When you look through the parallel sides - the light is exiting at close to 90 degrees to the air/glass and glass/water boundaries - and the light coming from the person on the far side of the tank goes right through - so you can see them. When you look through two sides that are at right angles, the light will be passing through those boundaries at something more like 45 degrees - which is about the critical angle at which the light is totally reflected. It'll likely bounce around inside the tank until it's absorbed. SteveBaker (talk) 02:11, 30 August 2010 (UTC)[reply]
Without trialling this, I'd suggest the light would reflect off your broad side as it's beyond the critical angle thus the TIR mentioned, but I'd predict someone at the other short side would be able to see the reflection on that broad surface, i.e., the light would pass back out the other short side rather than being reflected around inside the tank indefinitely or until absorbed (could also depend on the absolute size of your fish tank which surface it left from). It would also depend on the angles of the incident light. If you put the person back and to the side rather than directly side on, and maybe vary your viewing position along that broad surface, you may be able to see them. FWIW the critical angle for water-air is about 49°, so if you're viewing angles are roughly 45°, it's more the glass-air boundary with a critical angle of about 42° (depending on the glass) that's causing you grief. --jjron (talk) 16:18, 30 August 2010 (UTC)[reply]
Electrocution?
What will happen if a piece of metal (say aluminum, conductor) is kept on a thick plastic/rubber matting ( insulated from earth ). A man stands barefeet on this aluminum plate. And a wire introduces high voltage (say 220 v) into the aluminum plate. Will the man get a shock ?
Jon Ascton (talk)03:43, 30 August 2010 (UTC)[reply]
First a disclaimer, do NOT attempt to perform ANY experiments with high voltage, it is extremely dangerous and quite easily lethal. What theoretically SHOULD happen and what could and might happen are two very different things. As for your question, if the person is electrically isolated from anything else, then no, there should be no electrocution. This is the same reason why birds can easily sit on bare high voltage wires without suffering any effect.Vespine (talk) 03:57, 30 August 2010 (UTC)[reply]
Yeah, I have seen birds sitting that way, safely. This video (from an item above in RD) http://www.facebook.com/video/video.php?v=148725461813437&ref=mf the guy's got killed because he is standing on a steel platform (roof of train) though it's a matter of inquiry if he is wearing shoes and why didn't insulation interfere in that case.
In the train example, even if he were wearing shoes, the train cable has a very high voltage and it's not unreasonable to think that the electricity would simply arc around the soles of his shoes. Dismas|(talk)04:53, 30 August 2010 (UTC)[reply]
yes, shoes seem not to be as good insulators as you would perhaps think, I suspect a lot of people who are electrocuted aren't necessarily barefoot. I have seen purpose built insulating floor mats rated to just a few hundred volts and they are made of heavy rubber about an inch thick. As for the rabbit, unless there's something we're missed, that does indeed seem like a gaff, earthing the plate by the way would still make no difference, it's the rabbit that needs a path to earth. Stepping on and off such a platform would be when you would get the shock, but if you jumped on and off in one go you would be alright, again: definitely NOT something you should try for yourself. Vespine (talk) 05:58, 30 August 2010 (UTC)[reply]
Any electromotive force has two output terminals. In his question, Jon Ascton says a wire introduces high voltage into the aluminum plate. OK, so one terminal is connected by a conductor to the plate. That makes us wonder if the other terminal is connected to anything. Whether or not the man on the plate is at risk of electrocution depends entirely on whether there is a risk of him becoming connected to the other terminal. If he is not connected to the other terminal there is no closed circuit in which current can flow and he is not at risk of electrocution. If he is connected to the other terminal, or if the other terminal is connected to Earth and he touches something other than the aluminum plate or insulating rubber matting, zappo! Dolphin(t)06:27, 30 August 2010 (UTC)[reply]
Strictly speaking, if you have enough voltage, you don't need a closed circuit. A human body has a certain self-capacitance. That is, even with nowhere for them to go, a certain number of charge carriers will flow in or out of the body as the voltage changes. Hook up an AC voltage source, and they'll flow both in and out, repetitively. Now you've got a current, even with nowhere for it to go. --Trovatore (talk) 07:45, 30 August 2010 (UTC)[reply]
I agree entirely with the comment about human self-capacitance. I can remember taking a class of 14-year olds to the Science Museum in Paris (Palais de la Découverte), where one of the workshops the staff put on for them could be described as "playing about with a BIG van der Graaff generator". So, as one does, they got a couple of kids to come and volunteer, and made their hair stand on end (this video shows the same sort of demonstration). As I was the teacher and I knew what was going to happen, I was paying more attention to the safety rules the staff were giving the kids. To be charged up to half-a-million volts or so, the kids were stood on plastic podia a bit less than a metre (say 2½ feet) high – you can see the same thing in the video. The one thing the staff insisted on was to say "you can come off the podium any time you like, but please tell us first." (I assume they had a special teenager-discharging capacitor in the podium that they could connect up through a decent-sized resistor as needed)
Now the charge you get from a van der Graaff generator is DC, a one-off with no external current source, but still enough to give you a nasty shock if you discharge it through the body's internal resistance: it seemed to take a second or two to discharge the kids safely through the podium, and they were charged up to far more than the breakdown voltage of a small air gap as they would have had if they tried to step off the podium fully charged. If that had been AC with a external current source, it could easily have reached fatal currents even without a route to earth. Physchim62(talk)10:48, 30 August 2010 (UTC)[reply]
It should be OK - but the devil is in the details. For example - if you were to step onto or off of the plate, one foot at a time - then for a moment, one foot is grounded and the other is on the plate - and you'd get zapped. But you see birds sitting quite happily on 10,000 volt power lines - and this is the exact same problem. SteveBaker (talk) 13:31, 30 August 2010 (UTC)[reply]
But from my personal observation birds do not sit on the really high voltage transmission lines, 110kV for example, at least not that I have ever seen. 65.121.141.34 (talk) 13:59, 30 August 2010 (UTC)[reply]
Linesmen who connect themselves to high voltage lines are aware of corona discharge, described as like a swarm of insects buzzing around them. Cuddlyable3 (talk) 15:11, 30 August 2010 (UTC)[reply]
As a teen I once touched a metal electrical outlet plate that was "grounded" to 110V AC, while sitting on a chair of polyurethane of the like. I became curious about it because the metal looked smooth, but felt rough, and took some time rubbing and staring at it trying to figure out the incongruency. I resisted the suggestion to test my idea about electrical leakage with a ground... but my friend who declared that "there can't be anything wrong with the wiring, my Dad put it in himself!" used a metal pole to quickly determine the truth. This is why the U.S. uses 110 V wiring. ;) Wnt (talk) 15:38, 30 August 2010 (UTC)[reply]
On the question of shoes mentioned a bit earlier, it depends on the material of the sole. Leather soles are going to do a poor job but most man-made materials are good insulators if they are thick enough for the voltage in question. Don't trust your life though, to footwear that is not specifically designed for insulation - the slightest flaw in a material at high voltage can lead to dielectric breakdown, and in this case, the death of the wearer. SpinningSpark15:38, 30 August 2010 (UTC)[reply]
For the same reason bread does not. Starch has different properties than sugar due to the long lengths of the sugar chains. Just like water has different properties than either hydrogen or oxygen, sugar has different properties than starch. When compounds interact chemically they form new compounds with very different properties. --Jayron3205:37, 30 August 2010 (UTC)[reply]
If I wash a starched shirt, will the starch come off?
Yes, it does help. Right there in the introduction. It says that they both committed suicide. If Harris shot Klebold then himself - then Klebold couldn't have committed suicide. SteveBaker (talk) 14:12, 30 August 2010 (UTC)[reply]
This shouldn't be filed in the Science section. Though the two might properly have placed themselves outside the scope of Humanities, it would seem the closest category. Wnt (talk) 15:26, 30 August 2010 (UTC)[reply]
Dylan's official autopsy report ruled (here) it a suicide. There was some speculation, given that he was shot by a single bullet in the left side of the head (rather than the right). However, it turns out that other footage showed him shooting a gun with his left hand, so it seems at least probable that he shot himself. As far as I know, there's no footage of them actually committing suicide. Buddy431 (talk) 19:28, 30 August 2010 (UTC)[reply]
And at all who rushed in saying "yes, they obviously shot themselves, look at our articles" (that has about one line about them killing themselves and doesn't say anything about how it was done), I say shame on you. A basic Google search would have shown that we don't really know for sure whether either of them shot themselves, and that there is legitimate controversy especially over Mr. Klebold. Especially you Steve: arguing from a linguistic standpoint? Over a single sentence that's been in our article for who knows how long, and would still be substantially correct even if one had shot the other? For shame. Buddy431 (talk) 19:34, 30 August 2010 (UTC)[reply]
For shame? WTF? Read what I actually wrote - not what you think that I wrote. I said that our article does contain that specific information...and it does. It doesn't take more than a single sentence to answer the OP's question. You may care to dispute whether our article is correct or not - but DO NOT reprimand me for doing precisely what the Ref Desk's mandate is - which is to find data primarily within the encyclopedia and tell our OP's where to go read it for themselves. If you think the article is incorrect then go there and fix it - but meanwhile, what I wrote is true, correct and in line with what we do here at the reference desks. You should not come here and put me down for doing what you have completely and utterly failed to do. You talk about some nebulous google results without pointing to where they actually are - we don't know whether your answer is backed by reputable sources or from some bunch of random conspiracy theorists. Now apologize dammit. SteveBaker (talk) 19:36, 31 August 2010 (UTC)[reply]
Sounds like a great piece of information (that the details of who shot whom or whatever is not known) to add to the relevant wikipedia articles. With WP:RS citations for alternative theories or at least statements that the exact sequence of events isn't known, or is disputed, or... DMacks (talk) 20:59, 30 August 2010 (UTC)[reply]
Eric was carrying thisDylan had the TEC-9Oh, wait, the "wound was consistent with 9mm ammunition" but they were both carrying 9mm weapons. And Dylan had the TEC-9; Eric was carrying the carbine, which is a lot less easy to fire into the left side of your head, aiming slightly downwards! Wikiscient(talk)10:14, 1 September 2010 (UTC)[reply]
The autopsy and other reports concluded that they committed suicide - that each shot himself. Given the notoriety of the case, they would have put their best experts onto resolving this matter - so I don't think your opinions and guesses based upon the flimsiest of evidence stack up against that amount of expertise. Rather than guessing - and confusing our OP with highly in-expert opinions, I strongly suggest you read those reports. SteveBaker (talk) 12:46, 1 September 2010 (UTC)[reply]
Relax, Steve. Your response is addressed exclusively to me, does not discuss the OP's question in any way, involves your own opinion as to what "they" would have done, and suggests that you have not looked very closely at the cited sources yourself. If you would like to comment further on my response to this question or my behavior at this desk generally, please do so on the talk page or on mine, not in answer to an OP. Wikiscient(talk)13:04, 1 September 2010 (UTC)[reply]
The autopsy report link does bring some science into this: unfortunately, the science is only that the wounds were "consistent with" self-infliction. That does not mean that they were proved to be suicide. Note that both wounds were "through-and-through", so ballistics can only be done by figuring out which bullet went with which suicide and digging it out of the wall. I don't know if this was done - there must have been a lot of bullets in those walls. But apparently DNA can be extracted from bullets [7] so even if all you had was a box of loose bullets from the room and the ballistics samples from the guns, you still should be able to figure out whether each boy was shot with his own gun. I don't know if anyone has done that, or if anyone cares. Wnt (talk) 18:20, 1 September 2010 (UTC)[reply]
And I maintain that we probably will never know for sure who actually shot Mr. Klebold, and that at some point it doesn't really matter. They certainly "Killed Themselves" in a collective sense, which is probably the best we can do in this case, especially after over 10 years. Buddy431 (talk) 23:26, 1 September 2010 (UTC)[reply]
The OP's question can be put as "Whose finger pulled the trigger?" that caused Dylan's death for which there is no living witness. The autopsy reports can not definitively rule out either Eric or Dylan as answer to the question. The only way it might be found is by a further forensic investigation. A hypothetical line of investigation is to try to find the lethal bullet that might both be traceable to one boy's gun and carry a detectable DNA trace from Dylan, as Wnt noted. Any such forensic investigation seems unlikely because of its minute chance of success, and the unnatural expense of employing a Crime lab where there is no prospect of an arrest. Wikipedia cannot speculate what if anything such investigation might discover. The question is likely to persist unanswered, like the theory of the shooter on the grassy knoll.
Pure water is indeed a relatively poor conductor, but nearly all water outside of purified/distilled de-ionized water in a laboratory or similar specialized setting contains additional substances (mostly 'salts') which, even in trace amounts, provide ample ions with which to conduct electric current. 87.81.230.195 (talk) 16:54, 31 August 2010 (UTC)[reply]
By the way, don't be so "sure" about that heater killing you. It very well could, but you could saved by GFCI protection (or whatever they call it in your country), and predicting the flow of electricity in a mass of water is not so simple. Mythbusters did some experiments on this. --Anonymous, 19:53 UTC, August 31, 2010.
Any way to cut a steel cable with common tools?
Can you cut relatively thin steel cables using tools people are likely to have at home? I've tried cutting a thin cable but was surprised that even though it looked about the same diameter as a comparable galvanized wire, it's a lot harder to cut. Stores that sell steel cables have hydraulic cutters, but most people don't have a reason to buy and keep one at home. Any suggestions? —Preceding unsigned comment added by 96.227.60.170 (talk) 12:47, 30 August 2010 (UTC)[reply]
Bolt cutters work pretty well and would be the first tool I'd reach for. If you have an angle grinder with a decent cut-off blade, you'd get through it with that too (wear eye protection - there will be lot's of pretty sparks!) - I suppose you'd eventually get through it with a Dremel tool with a cut-off disk - but it might take a while. Failing that, often you can untwist the cable such that the individual wires can be cut separately - and then all you need is a pair of wire-cutters and a lot of patience! If all else fails, a hacksaw will (eventually) get you through it. SteveBaker (talk) 13:25, 30 August 2010 (UTC)[reply]
Bend it many many times, and it'll break. It's possible to do it pretty accurately if you use two pliers to do the initial bend. Ariel. (talk) 17:47, 30 August 2010 (UTC)[reply]
Sounds like it could be made from strands of tempered high-carbon steel much the same as Piano wire. If you have a domestic gas cooker (or some such) and heat a small loop to cherry red and take it out the flame s-l-o-w-l-y, that will de-temper it and thus easer to sever. --Aspro (talk) 22:42, 30 August 2010 (UTC)[reply]
Deep Blue vs. Deep Blue
(I questioned whether this was "Computing" or "Science," and decided on "Science," since it is not, like most of "Computing," a practical question.)
If Deep Blue were to play chess against another Deep Blue, is it likely that one of them would be the winner (rather than a draw), and if so, what would determine which one was the winner? (E.g., random chance, or who goes first, or ...?)
(This need not be specific to Deep Blue's architecture — feel free to apply to other super chess A.I.s. that play against identical algorithms or machines. That is, it is not Deep Blue vs. Deep Junior that I am interested in, but Deep Blue vs. Deep Blue or Deep Junior vs. Deep Junior.) --Mr.98 (talk) 15:31, 30 August 2010 (UTC)[reply]
The received wisdom in chess is that the white pieces have a slight advantage, but the majority of grandmaster games end in draws. So I would say the most probable outcome of like machine playing like is a draw. However, if the machine has a flaw against a particular defence, the Sicilian Defence say, then that can be exploited by always playing the Sicilian Defence when black. Such tactics can be used against a human of course, but humans tend to learn from their mistakes after a while (albeit a long while in some cases) so the answer might come down to whether the machines are capable of learning from their mistakes. Such a pair of machines might produce some novel and interesting games. However, Deep Blue, had no such capability, except by human programming between games to eliminate previous mistakes, and would fall into the same trap over and over again. Deep Blue achieved the results it did mostly through brute force computation of positions. If Deep Blue had the programming to exploit the mistakes it itself made then the winner would be black or white depending on whether the mistake was with the white or black pieces. If however, it did not have such programming (most likely, since if the programmers allowed for a particular mistake to be exploited they would likely program Deep Blue not to make the same mistake itself) then the likely result would be that the mistake, even when made, would be overlooked by the opponent machine and a draw would result. SpinningSpark16:05, 30 August 2010 (UTC)[reply]
I don't remember if it was the first or second Deep Blue match, but the one that I watched a documentary about pointed out that the programmers continued "improving" the program in Deep Blue throughout the match. In that sense, the human programmers could learn from mistakes and try to improve the performance. At that point, Deep Blue is just a tool and it is a game between the programmers of one tool against the programmers of another tool. -- kainaw™16:14, 30 August 2010 (UTC)[reply]
They were not allowed to make improvements while a game was ongoing. The improvements were made between sets of games - although Kasparov famously claimed that IBM were cheating to explain his loss of the match. SpinningSpark16:30, 30 August 2010 (UTC)[reply]
It should of course be noted that there are routine computer-on-computer chess matches ([[i.e. World Computer Chess Championship, Chess Engines Grand Tournament, etc.), though generally not with the same program against itself. I'm sure that such games have been run though. Anyway, I see no reason why we could predict one outcome over another; a chess game is typically quite assymetric, such that I'm not sure that it would make much of a difference that both sides are running the same engine. I could be wrong though. Additionally, some engines can "learn" (such as by adding positions to a Transposition table), which, as Spinningspark, might make an interesting set of games. In this regard, though, there's nothing special about having identical machines, other than that they'll assign the same values to the same positions. Buddy431 (talk) 19:17, 30 August 2010 (UTC)[reply]
You can pit chess computers against each other and find out! Many chess programs allow you to pit computer opponents against each other. Many even allow you to choose the engine - for example, GNU Chess/XBoard allows you to install any chess computer engine that speaks Chess Engine Communication Protocol. See our list of chess engines and the free and open-source software ones - there are dozens of common engines that can be "hot-swapped" in to an XBoard graphic chess interface. These engines can play against each-other or against humans. You might also want to read about how chess is "rated": Chess rating system. "Winning" is too simplistic - chess ratings are statistical monstrosities based on performance over many games. At best, you could determine whether an algorithm, playing against itself, were consistently susceptible to the same attacks, or if it were only susceptible to random strategies. And, you could compare different algorithms against each other. Chess engines often have tunable parameters, like "search depth", that will affect their performance on various hardware; so if you want to set up a maximum computer-time limit, your hardware will affect the outcome as much as the software engine. Nimur (talk) 19:33, 30 August 2010 (UTC)[reply]
You should read Feng-hsiung Hsu's book "Behind Deep Blue". He was the leading designer of the machine. It's an interesting read (not least because Hsu claims not to play chess - or even be particularly good at it!) He describes how they would routinely use Deep Blue to play against itself in order to find bugs, tune performance and automatically create certain tables that the machine used. Chess isn't a symmetrical game - there is a big difference between playing white and playing black - normally, white is on the offense and black is defending - so a machine that was better in defense than offense might well win more often against itself when playing black than white...for example.
More than that, in a sense, Deep Blue is always playing against itself - what happens when it is trying to figure out a move is that it will mentally try every possible legal move - then use it's own algorithms to try to guess the best response it's opponent could come up with. That way it can see which of move produces the weakest "best possible" response from the opponent. But since it's own algorithms are this imaginary opponent - it is reasonable to say that it's always "playing against itself".
You have uploaded it to Commons, not here on Wikipedia so you need to ask on Commons. The best thing to do is upload it again with the correct name and then request speedy deletion of the old file. Instructions here. SpinningSpark18:13, 30 August 2010 (UTC)[reply]
Thanks all. I think that photo represents exactly the same type we have in Yemen, Trovatore. I will upload it again with the name of agave, unless you don't have further comments.--Email4mobile (talk) 21:52, 30 August 2010 (UTC)[reply]
Is it possible to test if the universe/multiverse is infinite?
This is more philosophy than science. If you cannot detect something in any way and it cannot detect you in any way, does that something exist? The universe can expand faster than the speed of light. We can only detect a small portion of what might exist due to the limitation of the speed of light. Similarly, only a small portion of the universe can detect us due to the limitation of the speed of light. If you decide that anything that is mutually excluded by the speed of light doesn't exist, the universe is what we can detect and it is finite, but growing. If you decide that things we cannot detect (and cannot detect us) do exist, it is not possible to know if the universe is infinite or finite because we have no means of detects what might be the edge of the universe. Step this up to the theory of multiverses and you just make the problem more complicated with the same stipulation. If you limit this what we can detect, it is finite but growing. -- kainaw™18:40, 30 August 2010 (UTC)[reply]
Your second question begs the question: Is "universe" and "reality" the same thing? Can the universe be finite and reality infinite? Can the universe be infinite and reality finite? Notice that I ensured to include mutual detection in the answer above to handle many concepts of reality. What if something can detect us but we cannot detect them? What if something can change what we consider reality but we cannot detect it? Again, this falls more into philosophy than science. -- kainaw™18:44, 30 August 2010 (UTC)[reply]
A closed universe of the FLRW type would be expect to have a spacetime that is locally curved everywhere. We can observationally test for this. If we detect a non-zero positive curvature it would be strong evidence suggesting the universe is finite (even if it much larger than the size of the observable universe we currently live in). This would be akin to someone deducing that the Earth is round by watching ships sail over the horizon, even though they can't begin to see the shape of the entire Earth. It wouldn't be an absolute proof since the shape of the universe could change to something other than a FLRW type out beyond the regions we are able to measure, but it would be good evidence. So far though, it appears that the curvature of the universe is consistent with zero. This suggests either that the universe is infinite, or if it is finite then it is much much larger than the observable universe we are currently able to study. Dragons flight (talk) 18:58, 30 August 2010 (UTC)[reply]
Until we account for the missing mass (dark matter) then we are unlikely to be able to test very well for the cosmological periodicities which might indicate a closed space. Occasionally, someone will come up with evidence for periodicities but I'm not sure if there has ever been a literature review of those. Why Other (talk) 19:29, 30 August 2010 (UTC)[reply]
No, because the assumption is invalid. You want Liquid breathing.
To be more precise, pressures at which non-cryogenic air is liquid are not compatible with mammalian cellular life. Even if they could be gradually equalized, the molecular moments of inertia necessary for many of the biochemical cycles (e.g. Citric acid cycle, etc.) and proper operation of proteins, enzymes, and nucleic acids would be fatally affected.
Even if those problems could be overcome, breathing liquid air would still suffer from a similar problem involved with breathing other oxegenated liquids: the inability to remove enough carbon dioxide at liquid viscosities. Removal of sufficient amounts of CO2 is a problem of the air commons as well as individual terrestrial animals. Why Other (talk) 21:57, 30 August 2010 (UTC)[reply]
There is no pressure "at which non-cryogenic air is liquid". At least if you believe this link, the critical temperature of air is −190 degrees Celsius, which I think qualifies as "cryogenic". Above that temperature, no matter how much you compress air, it will not liquefy (though it may acquire viscosity and other characteristics similar to that of a liquid). --Trovatore (talk) 22:45, 30 August 2010 (UTC)[reply]
If air were liquid... it would be a liquid. I assume what you mean is, if a liquid had the oxygen content of air, or higher, could you breathe it? For that I refer you to liquid breathing, but for photos you'll need to turn elsewhere: [8][9](but ignore all rumors of "blood substitutes", the idea is absurd and the experiments deadly)
Why did clear polypropylene become whitish after melting & resolidifying?
I took a clear plastic container lid made out of polypropylene and cut it into small pieces and placed those pieces in the "dish" of a crushed and inverted aluminum soda can and placed the setup in a toaster (not microwave) oven at 450 F for 20 minutes until all the plastic was in clear liquid form. I took it out of the toaster oven and almost immediately as it hardened, it began to whiten to the point that when it was cool enough to handle, it was almost but not totally opaque; I could see the shadow of my finger through the ~5mm thick piece of plastic. What's the story there? —Preceding unsigned comment added by 166.137.11.190 (talk) 19:33, 30 August 2010 (UTC)[reply]
Two guesses: The original material was crystallized, and the melt was amorphous. Or perhaps you have lots of air bubbles in the melt. Also, all polypropylene I've seen has been opaque. Ariel. (talk) 20:20, 30 August 2010 (UTC)[reply]
We have an article on polypropylene that says "When polypropylene is biaxially oriented, it becomes crystal clear". I'd say that biaxial orientation is destroyed when you heat/cool small pieces of PP using a toaster oven and a crushed aluminum can. Also, I suspect that the Opacity_(optics) of the result might be due to the introduction of Crystallographic_defects. SemanticMantis (talk) 20:25, 30 August 2010 (UTC)[reply]
Candle dynamics / design, wicking
In short, if I use a piece of common jute twine as a `wick', what sort of candle could this support? (The goal here is to recycle old candle stubs into new candles, using commonly available household items).
I am familiar with capillary action in the simple context. Candle wicks work on this principle, but it seems to me that candle dynamics are not so simple. Several factors must come into play to make a self-sustaining candle, e.g. wick design, melting point/viscosity of the wax, diameter of the candle, and boundary materials.
The article states that braided cord works better, which makes intuitive sense, but I know from personal experience that twisted cords still wick, if not as well. The bigger issue is this: a mordant is applied to make most wicks, and "Without mordanting the wick would be destroyed by the flames and the flow of melted wax to the flame would cease."
I have a hard time accepting that mordants are strictly necessary, and the mordant article doesn't even mention flame-retarding effects.
Shouldn't there be some candle diameter/wick diameter/container material that would allow me to make a candle using some common type of cordage as a wick?
You can make a candle wick from a cotton ball, just take some, and twist it into a cord. Make sure it's real cotton though, not plastic (try to burn some). Jute might not work as well because it's coarse. A finer thread works better as a wick. It's not very hard to make a wick, and it does not require complicated calculations, or mordant. I've seen wicks made of fiberglass too, but they need a holder, so will work for oil, but not wax. Ariel. (talk) 20:17, 30 August 2010 (UTC)[reply]
In the 1960's candle wicks contained some lead to keep them upright, so that molten wax could rise in the wick and vaporize to burn efficiently. A mere piece of limp string might fall over in the pool of melted wax and be extinguished. The characteristics of the carbonized wick are important to the success of a candle. Modern wicks should still have a characteristic carbonized ash which stays upright to facilitate vaporization of the wax and efficient burning, even in the absence of heavy metals. Edison (talk) 01:49, 31 August 2010 (UTC)[reply]
Google books shows portions of lots of books with guidance on candle making. Braided wicks are said to be better than just twisted wicks, and the wick size must be appropriate for the candle diameter: too small and it will go out. Too big, and it will make a big sooty flame that will leave soot on the wall and ceiling. See [10] for instance. Edison (talk) 14:13, 31 August 2010 (UTC)[reply]
For earth-like life, water is necessary, but not sufficient. Other materials are necessary for organic molecules to form: carbon and nitrogen, at least; and probably phosphor, sulfur, sodium, chlorine, and many other chemical elements. If you are willing to accept a very abstract definition of "life", then the specific requirements for it to exist are much more open to interpretation. Nimur (talk) 22:09, 30 August 2010 (UTC)[reply]
Define "simple". Simple prokaryote bacterias are made of water, fat, a few proteins, and some nucleic acid - (see bacterial cell structure) - they're essentially nothing but a flimsy bag full of simple chemical compounds. More advanced life-forms are just "additionally complicated" bags. DNA is a very complicated compound, by comparison to, say, H2O. But, it is naturally created from simpler sub-compounds called base pairs. In turn, these are created from simpler sub-compounds called nucleotides. Those are made up of individual organic molecules, which are made of individual atoms. At some point, we reach such simple compounds that the molecules can not be said to be alive. Where do we define this line? At what point does the chemical reaction cross the threshold of sufficient complexity to be called "alive"? And what about hypothetical life-forms that are not carbon-based? We have a discussion on the definition of life that brings up important definitions and presents many viewpoints on the issue of abiogenesis. Whatever your belief is about the origins of life - whether you think that life started on Earth, in space, or even if you are a creationist, you must have some kind of answer to the abiogenesis problem... and granted, this is a very challenging question. Most scientists believe that the presence of carbon, water, phosphor(us), sulfur, nitrogen, and so on, plus billions of years and exposure to lightning, cosmic rays, radiation, and solar heating, is a sufficient amount of time for a few of these atoms to "randomly" bump together in such a way to create a self-sustaining and replicating chemical reaction - the beginnings of the basic metabolism of a simple life form. Scientists debate exactly how long and what materials are absolutely necessary. Nimur (talk) 00:40, 31 August 2010 (UTC)[reply]
Much is said about the presumed improbability of a self-replicating molecule just popping into existence out of simpler compounds. But is it really that improbable? The important thing to remember when thinking about the abiogenesis issue is that in addition to a very large timescale, life might have formed in any drop of suitable liquid on any suitable body in the entire universe. Throughout the enormous number of random 'bumps between atoms' that have happened in the entire universe over the entire time since the big bang - only one of those had to result in a viable self-replicating molecule to result in life as we know it. It happened (probably) here on Earth because it must have done or we humans wouldn't be here. Using the 'anthropic principle' to explain things that we don't know the answer to is generally considered 'iffy' - but in this case, it's precisely the right answer. When we talk about "the entire universe" in this context, we don't even have to limit ourselves to "the observable universe"...whichever part we evolved in is by definition within the visible universe.
So let's crunch the numbers: There are 1023 stars in the observable universe - and the lower bound estimate for the entire universe is 1023 times larger - if an average star has 10 moons or planets with water - then there are 1047 possible places for life to form - if random chemical 'bumps' happen to every molecule in the surface of the planet about every few microseconds then over the past 10 billion years each one will have been bumped 1023 times - and if the volume of the earth's ocean is a reasonable 'typical' volume then there are 1023kg of water (plus loads of other 'stuff') - but we also know that life might have formed deeper in the Earth's crust - since Avogadro's number is 6x1023 we can probably estimate that there are 1046 molecules around on a typical planet that are doing the bumping. Multiply that out and you have 1047+23+46=10116 possible opportunities for that first self-replicator to have randomly formed. (I love how all of those constituent numbers are around 1023!)
If you seriously stop to consider the size of that number, it would be truly remarkable if some kind of self-replicator didn't spontaneously arise at least once at some point in the universe! (Of course, if the universe is infinite (which it very well might be) then the abiogenesis event has to have happened an infinite number of times - so it's not just overwhelmingly probable - it's an absolute certainty).
Just as with evolution - this process is completely inevitable and it would take a rather large intellectual leap to imagine constraints that would somehow have prevented this abiogenesis event from happening. We may not know the details yet - but the statistics are beyond reproach. We KNOW that the abiogenesis event had to have happened - it's just too improbable that it couldn't have happened.
@Chemicalinterest: You are incorrect. Life is certainly composed (in part) of some exceedingly complicated compounds (although quite a lot of the composition is simple stuff). But that doesn't mean that life wasn't created from simple compounds...it obviously was. All of the atoms that make up our bodies ultimately came from basic elements formed in fusion reactions inside a star and thrown out into space in a supernova. It follows that even the most complex compounds such as DNA and RNA must have formed by some means from the most simple possible building blocks...the raw elements. The only real question here is what processes made that happen. SteveBaker (talk) 22:28, 31 August 2010 (UTC)[reply]
That covers the favorite topic of... evolution and the origin of life! I believe that their is more to life than 1018 carbon atoms and 104 nitrogen atoms and 1015 oxygen atoms, etc. etc. --Chemicalinterest (talk) 00:23, 1 September 2010 (UTC)[reply]
Well, you can believe all you want; but if you can't explain what "more" there is, then your belief isn't really scientific. Life really is just lots of very complicated, self-replicating chemical interactions. How complicated is it? So complicated that we can't re-create all of them in the best chemical laboratories (yet); or simulate them on the best and most powerful computers. But really complicated does not mean "happened because of magic." Life originated, and the reactions took place, because like all chemical reactions, the conditions were suitable for that set of reactions to occur. Nimur (talk) 18:20, 1 September 2010 (UTC)[reply]
I was just wondering on how it would be possible to create a cordless vacuum cleaner... but then it hit me as quite obvious that how would it be supplied with power? Well, is this even feasible? 99.114.94.169 (talk) 21:59, 30 August 2010 (UTC)[reply]
There's no problem transfering usable energy across an area without wires: see PS10 solar power tower, which is rated at 11 megawatts output. The problem is getting in the middle of that energy transfer! Now a standard U.S. 12-amp vacuum cleaner consumes 1.44 kilowatts input, but let's imagine that the cordless model is smaller, and so only consumes one kilowatt. What's a kilowatt? It's the power of the Sun's radiation on a square metre (10 sq. ft.) of the Earth when the Sun is directly overhead: so imagine going sun-bathing at midday on a clear day in the tropics, and your whole body still isn't receiving a kilowatt (your exposed surface area is a lot less than a square metre). Now imagine the beam that has to power your vacuum cleaner, which is much smaller than you are, and imagine what would happen if you got in the way of the beam! Physchim62(talk)01:42, 31 August 2010 (UTC)[reply]
All that wirelessly transmitted AC is wonderful, unless you consider that electromagnetic radiation just might have bad effects on human tissues. I do not care to be in the middle of an electrical transformer. Edison (talk) 01:44, 31 August 2010 (UTC)[reply]
You could run a vacuum cleaner on an internal combustion engine... No cords needed and you could have a vacuum cleaner that probably could suck your carpet clean off the floor. You would need to find a way to vent the exhaust out of the house though so you don't get carbon monoxide gas. Googlemeister (talk) 13:01, 31 August 2010 (UTC)[reply]
There'll be no carbon monoxide if you use hydrogen as the fuel. Of course, there are a few technical problems with that too!
Another way to store energy on board a device is a tank full of compressed air, or liquefied air at cryogenic temperatures. Or it could be superheated water that is kept from turning into steam by the pressure in the tank. In each case the air or steam from the tank is used to drive cylinders as in a standard steam engine. At least two of the three versions of this system -- the compressed air and the superheated water -- have been used in real life for fireless steam locomotives in industrial facilities, and compressed-air power was even used for public transit vehicles (streetcars, mostly in Paris). But the need for a heavy tank and heavy equipment to recharge it makes all of these impractical for a small appliance too.
--Anonymous, 20:03 UTC, August 31, 2010.
That Tesla photograph always bugs me. There's clearly a wire leading out to the light-bulbs. Who's to say it's not powering them? (Tesla certainly wasn't above taking a staged photo if it got him some funding.) APL (talk) 14:49, 31 August 2010 (UTC)[reply]
I'm writing an essay about why it is not a good idea to mix unknown chemicals in the laboratory (we do this every year for a different rule, as part of the "Laboratory Safety" unit). I'd like to provide a concrete example of a very dangerous reaction that could occur if random chemicals are mixed "to see what would happen", but I can't think of anything at the moment. Could someone help me out? BTW These should be chemicals you can find in a high school chemistry laboratory. 76.230.225.80 (talk) 23:04, 30 August 2010 (UTC)[reply]
Pouring water into sulfuric acid is also used as a common example of a dangerous reaction that can happen in the lab. The reaction is highly exothermic so can boil and splatter acid onto anything nearby. Vespine (talk) 01:32, 31 August 2010 (UTC)[reply]
I thought of two chemicals which create a highly sensitive explosive compound when mixed, which once almost blinded me when an ounce of the mixture exploded in a glass jar when I merely started to unscrew the lid, but I decided that the information would only encourage bad behavior. I spent months removing glass shards from my hands. There are probably some still in there many years later. Edison (talk) 01:42, 31 August 2010 (UTC)[reply]
Hopefully Wikipedia can prevent injuries by reminding children not to make that stuff in a glass jar. Or anything else even conceivably explosive. I happen to know that you can leave a kid alone with a container of screw-cap test tubes and harmless reagents for less than five minutes, and end up with him barely avoiding blinding himself because while you weren't looking he filled up the tube, capped it tightly, and pulled out a lighter from his pocket... Wnt (talk) 21:41, 1 September 2010 (UTC)[reply]
Mixing concentrated sulfuric acid and either concentrated hydrochloric or hydrobromic acid seems like a clever way of getting "even more acidic or specifically corrosive" (maybe in analogy to aqua regia?). Except one tends to produce clouds of HX gas and the other maybe also lots of X2 vapor if I recall. That latter is a nice visual demo because of the colors. How about "I'll neutralize this strong ammonium hydroxide solution with conc. HCl!"? Start with slightly warmed solutions. You don't even need to get as far actually mixing them--just tilt one towards the other so the vapors start to mix--and you get a large white cloud forming that settles as a fine powder on all surfaces. As a bonus, you don't create a chemical waste problem: the powder is water-soluble and not corrosive--probably wash down the drain or trashcan disposal--and the concentrated reagents are not consumed, diluted, or converted into other hazardous materials. Obviously nobody should try these at home and/or without appropriate protective gear, etc. etc.DMacks (talk) 06:25, 31 August 2010 (UTC)[reply]
I mixed conc. HCl and dilute ammonium hydroxide to produce a slight smoke. X2 would probably not form for HCl, because H2SO4 isn't a strong enough oxidant. Bromine would be produced though. Nice toxic suffocating corrosive bromine vapor. oror --Chemicalinterest (talk) 16:27, 31 August 2010 (UTC)[reply]
The screaming jelly baby is a common school chemistry demonstration in the UK. It involves heating potassium chlorate in a boiling tube to melt it (to melt the KClO3, that is, not to melt the boiling tube!), then dropping in a jelly baby - a source of sugar, to be oxidised by the chlorate. CLEAPSS reminds teachers in its notes on potassium chlorate that while KClO3 + sugar is safe if performed according to the instructions, KClO3 + sulfur and KClO3 + phosphorus are explosive mixtures and are therefore illegal to prepare. See also Armstrong's mixture, which is primarily KClO3 + P.
Have you seen these two terms used in some scientific application? If so, it would help us if you describe the scientific application so that we can explain the difference in a way that is meaningful for your application. If not, your question should be re-posted at the Language Reference Desk WP:RD/L. Dolphin(t)02:08, 31 August 2010 (UTC)[reply]
When talking about light speed, we almost say it is invariant and it is rarely described in some sites as absolute (for instance: Principle of Invariant Light Speed).--Email4mobile (talk) 03:01, 31 August 2010 (UTC)[reply]
Not sure if this is what you want, but absolute usually refers to a limiting invariant. Thus, 'absolute zero' is the invariable lowest limit of temperature, while other temperatures (such as the boiling point of water at standard pressure) are invariant without being absolute. but without knowing the context of your question, it's hard to be sure if that helps. --Ludwigs203:40, 31 August 2010 (UTC)[reply]
One could say that the speed of light is an "absolute maximum" speed, but this is usually taken for granted and is seldom spelled out in those words. "Invariant" just means that it doesn't change, but note that only the speed of light in free space is invariant. Light "speed" actually depends on the medium through which it is travelling. Dbfirs08:19, 31 August 2010 (UTC)[reply]
Light only travels in a vacuum, and at only one speed. If it runs into say an atom it gets absorbed and (perhaps) re-emitted -- at light speed, back into the inter-atom vaccum. Wikiscient(talk)08:38, 31 August 2010 (UTC)[reply]
Well, yes and no. Yes, for the particle description of light. For the wave description, not so much. How can they be true at the same time? Not so easily. You have to swallow one or more of the various weirdnesses of quantum mechanics.
By the Copenhagen interpretation, I think you would say that the light wave, in matter, is a superposition of various possible world lines where the photons are absorbed and re-emitted, as you say — but there isn't necessarily a fact of the matter as to which of these (mutually incompatible) world lines is the one that "really happened". --Trovatore (talk) 09:25, 31 August 2010 (UTC)[reply]
Yes, thanks for the correction on interpretation. I've put "quotes" round "speed". The word is used informally to mean "speed of propagation", as in the experiment to "stop light". Dbfirs18:28, 31 August 2010 (UTC)[reply]
Solar system
When was the last time Jupiter, Saturn and Neptune were in line from Sun, estimated years to next time planets will form straight line from Sun, how does this effect earth's orbit--Golfforgeorge (talk) 04:37, 31 August 2010 (UTC)[reply]
It's called an astronomical syzygy and it's really not that hard to look up past and future planetary alignments, if you're interested, GIYF. And no, the planets are so far apart that there is no appreciable effect on earth's orbit.. Vespine (talk) 06:49, 31 August 2010 (UTC)[reply]
This link, http://www.space.com/scienceastronomy/solarsystem/planets_align_020402-1.html , talks about the alignment in April, 2002 of the Sun, Mercury, Venus, Mars, Earth, and Saturn -- and says that in the next 100 years there will be only three other times when at least five planets are so closely aligned: September 2040, July 2060, and November 2100. (You can also find astronomy software online that will calculate the dates etc. of various planetary configurations for you, if you want.) Wikiscient(talk)08:02, 31 August 2010 (UTC)[reply]
It should also be noted that such predictions only work on relatively short (centuries or millenia) timeframes. When extrapolated over longer time periods, the system degenerates into an n-body problem, and becomes chaotic. That's because over long time periods, the total of the small gravitational effects of the planets on each other begin to add up, and aren't negligible anymore. --Jayron3205:43, 1 September 2010 (UTC)[reply]
The lack of progress in motor vehicles
It seems to me the US can't depend on car manufacturers to help progress cars into efficient vehicles. So we should be hopeful of independent means, right? The porn industry changed the way we look at movies, and NASA has used space to aid the progress of medical and other scientific technology. Likewise, Richard Branson is pushing civilian space traveling like no one has (or would, if it weren't for him). So why on earth is the combustion engine still even being used? Why hasn't NASCAR or F1 or whatever independent racing corporations invented the car that has 80–90% (or better) efficiency, awesome MPG ratings, etc etc? What on earth does NASCAR do with all the advertising money they get from those six thousand decals on every car? How come cars are so ... embarrassing? – Kerαunoςcopia◁galaxies04:37, 31 August 2010 (UTC)[reply]
It seems to me that this request is asking for opinions. The Science Reference Desk does not provide opinions so it is likely that the OP will not receive satisfying responses. Dolphin(t)04:45, 31 August 2010 (UTC)[reply]
Hmm... what if I rephrase the question with less whining involved (my fault): Is there any evidence that actual, verifiable work is being made to progress the internal combustion engine into something entirely different and far superior to what it is now by the actual corporations who make them? Students and science contests don't count. – Kerαunoςcopia◁galaxies05:11, 31 August 2010 (UTC)[reply]
Thanks for both responses. From what I've heard from owners of hybrids, they're somewhat of a sham. I wouldn't consider them "far superior" by any means. I was hoping someone might know if there are plans in the works to eliminate the internal combustion engine entirely. I just feel like it's 2010 and we're still stuck in the 40s or something. – Kerαunoςcopia◁galaxies06:53, 31 August 2010 (UTC)[reply]
Battery electric vehicles can be extremely efficient if the batteries are charged by some sustainable source such as solar or wind power. But if the batteries are charged from the mains supply that same efficiency will never be available because at the source is a heat engine of some sort. It depends to a large degree on what you have in mind when looking for improvements. For example, are you looking for improved thermal efficiency and are willing to sacrifice in the area of capital cost? Or are you looking for reduced greenhouse emissions and are willing to contemplate increased nuclear waste? Or are you looking for reduced weight and are willing to sacrifice in the areas of capital cost, thermal efficiency and greenhouse emissions?
When designers go looking for improvements they need to know the criteria for determining merit. Similarly it would be good to define some criteria for determining merit here. Dolphin(t)07:29, 31 August 2010 (UTC)[reply]
Battery electric vehicles are just as efficient when the batteries are charged for ANY source. Although coal and petroleum-fired generation plants pollute, they are still much better than having lots of IC-engines since the former are concentrated sources and can thus their pollutants be more easily controlled and contained. -- Sjschen (talk) 14:41, 31 August 2010 (UTC)[reply]
If you compare car engines from 40 years ago, they have improved a lot, especially in the power they can make, and reduction in noxious emissions. Graeme Bartlett (talk) 11:38, 31 August 2010 (UTC)[reply]
It's a little unfair to be too critical. The manufacturers of cars (and their engines) are reacting to what the public will buy and at what price. If everyone in the world refuse point blank to buy a car that does less than (say 40mpg) then within a very short period of time, all cars would be able to do 40mpg. But because people will still buy cars that only do 20 to 25mpg - and there are no laws to prevent their manufacture, there is no incentive for things to improve.
Secondly, as others have pointed out, there are hard theoretical limits to the efficiency of heat engines. Also, there aren't many other readily available energy storage systems with the 'energy density' of gasoline. Over the years, people have made all-electric cars, hydrogen cars, pneumatic cars, clockwork cars, propane powered cars, steam-powered (wood/coal/oil fuelled) cars, cars that ran on chemically treated sawdust, etc...but none of them have enough energy density to compete with gasoline. So unless the general public are prepared to live with less range/acceleration/interior-space or less weight (which probably means less safety equipment) - there isn't a whole lot that can displace gasoline until we have laws to force a change - or until it becomes so seriously un-cool to drive a gasoline powered car that nobody will do it anymore.
Thirdly, a lot of the problem is with infrastructure. The technology for hydrogen powered cars already exists. There are many working prototypes of hydrogen powered cars and they work pretty well. But if there is nowhere within 20 miles of my home and/or office that sells hydrogen in the bulk and with the filling convenience that I need, I can't buy a hydrogen car. This produces a chicken and egg situation - there are almost no hydrogen filling stations in the world - so there is no market for hydrogen cars - so there is no incentive to build the filling stations.
Breaking the infrastructure problem is something that can be solved with electric cars - electrical outlets are everywhere! But electric cars don't solve the energy density problems - so you're likely to be stuck with 100 mile(ish) range or (vastly overrated) hybrids until some truly magical battery technology comes along.
Right now, there are ridiculous legal restrictions that prevent some of the technology we do have from being used! I drive a MINI Cooper - and in Europe there is a version that automatically cuts the engine when you stop the car - and then when you pull away again, starts rolling the car forwards using the starter motor rather than immediately restarting the engine. Only when you reach a certain speed (10mph or so) or if the battery starts to run low, does the engine actually start running. This is a ridiculously simple thing to do - it's hardly more than a software change - but it means that in stop/go traffic, you have an electric car. It could be retro-fitted onto most modern cars - and would cost almost nothing to do. However, it's illegal in the USA! So my car is perfectly capable of doing this - but prevented from actually doing it by a software change they had to put in to meet US regulations. Aaaarrrggghhhhh!!!!
(Only partly a reply to Steve.) An article I have read puts an emissions rating of about 100g/km on electical vehicles, based on the way the United Kingdom generates energy. On the development front, Volkswagon's "L1", an internal-conbustion machine, gets 39g/km, or 180 miles per gallon. It's not quite your average car, however, but you can't say they're not trying. On the more achievable side, the article (quoting Richard Parry-Jones) suggests that cars running at about 70g/km should be mainstream by 2025. By comparison, the average UK car (and that includes what Americans would call "SUVs", and cars more common here) gets about 150g/km, it says. I think that's about 30 MPG, but I'm not sure (it would depend on other factors, I would imagine). - Jarry1250[Humorous? Discuss.]20:14, 31 August 2010 (UTC)[reply]
(ec - also only a part-way reply to the above): as long as the United States produces most of its electricity using coal and natural gas ((see this Department of Energy table for details), switching to electric cars will actually increase the carbon footprint per each mile traveled. (Coal is a much dirtier fuel than petroleum in many ways). So if the objective is to reduce greenhouse gas consumption, electric cars won't do this - what they will do is break down the dependence on petroleum. There are many reasons to make this transition; but it is not accurate to say that carbon emissions would be lower. Nimur (talk) 20:20, 31 August 2010 (UTC)[reply]
I think you're missing the point though. Cars are fairly long-lived things. Cars that are 10 years old are still on the road. While it's obviously important to get fossil fuel power generation switched over to wind/solar/wave/hydro/nuclear - we shouldn't wait for that to happen before we start to switch the world's fleet of cars & trucks over to electrical power. In fact, it can be argued that the additional profits made available to power generation companies would hasten their ability to invest in new technology. Another argument (which I'm a bit dubious about) is that by centralizing the pollution to one large facility (as opposed to a bazillion separate tiny ones) would make it easier to capture the pollution and fix it. However, that has not historically been the case - cars have cleaned up their emissions considerably over the last few decades - power plants, much less so.
As for your claim that "Coal is a much dirtier fuel than petroleum in many ways" - well, yes, perhaps in "many" ways - but not in the one very specific way that most concerns us...CO2 production. A 4-stroke steel car engine has a maximum possible theoretical efficiency of 37% - and most cars manage around 18% if 'normally aspirated' and 20% if supercharged or turbocharged. Contrast that with coal fired power stations which actually achieve 33% and natural gas stations which get about 50%. The trouble is that it's not that simple. It costs energy refine oil into gasoline - it takes more energy to haul it to gas stations which are widely and inconveniently scattered. It takes less energy to get raw coal onto a 2 mile long train and haul it to just one destination - which is probably situated conveniently close to the mine.
But coal is more of a nuisance than just the CO2 - all of the ash piles (which are more radioactive than the vast majority of the waste produced by nuclear power!) - the damage they do to the water table, the sulphur compounds they generate into the air...lots and LOTS of nasty side-effects.
But for sure, we need to start switching our cars over to electricity in the hope that we'll be ready when clean electricity DOES start appearing.
Well, the way I see it, even if electric cars initially are fueled by coal, there is the probable eventuality of switching to nuclear energy or geothermal or wind some other source of energy. In other words, electric vehicles have an "exit strategy" from the polluting fossil-fuel base. So, they are advantageous for that reason. But in the short term at least, petroleum is a more efficient fuel - economically, thermodynamically, and so on. I think these issues all elucidate the trouble with the OP's original question: "progress" is very hard to define, because it depends on the timescales involved and the ultimate objective we are aiming at. Nimur (talk) 01:48, 1 September 2010 (UTC)[reply]
Vision at the speed of light
This is more fiction than real world science but I'm curious none the less...
If it were possible for a person to move at the speed of light (without any other physiological changes than just whatever gave them the ability to do this), how would their vision be affected? After all, we see because light hits our retinas but what if we're moving at that speed. Then would we only see what was directly in front of us since those photons would be going directly into our eyes? Dismas|(talk)07:56, 31 August 2010 (UTC)[reply]
At light speed, length contraction makes everything have zero length. Any photon you encounter (that would let you see in the first place) would be blue-shifted to infinite energy, or red-shifted to zero energy. Human eyes can detect neither, so you wouldn't see anything. 157.193.175.207 (talk) 08:01, 31 August 2010 (UTC)[reply]
Two photons colliding head-on do so with infinite(x2?) energy...?
You wouldn't have time to see anything. The proper time experienced along any path at the speed of light is zero. This might sound theoretical, but it has a serious consequence — it's how it was originally recognized that neutrinos have nonzero (rest) mass. If they had zero mass, they would have to travel at the speed of light; in that case, they could not change flavor, because there would be no time in which the change could happen. But there aren't enough electron neutrinos coming from the Sun; only about a third as many as there should be. The explanation offered was that they are changing flavor on the way to Earth. But then they must have mass. --Trovatore (talk) 10:00, 31 August 2010 (UTC)[reply]
The time issue is nasty. The instant you hit lightspeed - the entire universe would be over for you. Whatever ultimate fate befalls the universe is where you are. The incoming energy issue is also fatal - you get hit by an infinite number of photons and each has infinite energy...that'll ruin your entire day right there! The universe would have contracted to zero dimensions along your line of flight - so you'd be everywhere in the universe at once - which would guarantee you'd smack into a star or something...at the speed of light! (Ouch!) Everything you can possibly imagine about this is utterly and instantly fatal. Fortunately, it's impossible, so this is one less thing to worry about! SteveBaker (talk) 18:36, 31 August 2010 (UTC)[reply]
That explanation of neutrino oscillation is incorrect. A particle of zero mass won't oscillate into some other flavor, but neither will a particle of any definite mass. There are three neutrinos with well defined masses that don't oscillate into each other (ν1, ν2, ν3). The three traditional named neutrinos (νe, νμ, ντ) are mixtures of those and do oscillate into each other, which means that the mixtures have no definite mass, which means that ν1, ν2, and ν3 don't all have the same mass. It follows that they don't all have mass zero, but the value zero plays no special role in any of this. -- BenRG (talk) 22:19, 31 August 2010 (UTC)[reply]
Hmm, OK, that's interesting, but just the same, doesn't it independently follow from zero proper time that there can be no oscillation? --Trovatore (talk) 22:29, 31 August 2010 (UTC)[reply]
I don't think the universe is "over for you" when you hit lightspeed, in terms of time dilation. Remember, from your perspective it's the universe moving at lightspeed, and it is not moving forward in time. Of course, that infinitely blueshifted light may mean the universe is over for you in a more mundane way!
There's a nice simulation video of the changes in angle as you accelerate toward lightspeed... somewhere... eventually all the light compresses toward a point. I didn't find that today. (But while looking I did find the most glorious crank theory of gravity I've ever seen, complete with a comparison of spin-2 graviton theory to Adolf Hitler... [11]) —Preceding unsigned comment added by Wnt (talk • contribs) 18:58, 1 September 2010
No, you're missing the point. Take any two events along a lightlike path; what's the interval between them? It's zero. And that's the same as the proper time experienced by an observer along that path. So such an observer does not experience time passing at all.
The bottom line is that there is no such thing as an inertial frame of reference traveling at lightspeed. You can't set up such a coordinate system at all; you'd have to divide by zero. --Trovatore (talk) 19:11, 1 September 2010 (UTC)[reply]
Hmmm... I did miss some points. An observer "at lightspeed", i.e. in the limit as he approaches lightspeed, should perceive a vast swath of the universe flatten down to a two-dimensional disk moving past him at the speed of light (Lorentz contraction). But time for that seems frozen. The key thing that we're neglecting is that reaching lightspeed involves acceleration, and lots of it. From the perspective of outside observers the acceleration to speed up that last little bit is very small, but the mass is enormous, and so an enormous amount of energy is involved. From the perspective of someone traveling "near" lightspeed, adding another 0.9c involves a tremendous amount of acceleration - and of course, even an object moving relative to him at 0.9c is still slower than light in every frame. So we're talking about just incredible amounts of acceleration, over and over. This is discussed a bit in [[12]], but the formula they give there "t' = t(1 + Φ / c2)", with Φ = gh, confuses me - there's a unitless "1", and it seems like the clock-ticks could go negative for objects behind the accelerating observer.
I am not well-versed in general relativity, but I think that the gist is that you can't really just reach the speed of light and your life is over. Rather, you can burn your Star Drive at full blast and watch time gradually slip away for as long as you like, never reaching lightspeed. Wnt (talk) 00:56, 2 September 2010 (UTC)[reply]
Direction of Earth's Revolution
Suppose one were "above" the plane of the solar system, such that, when looking at the Earth, one saw primarily the northern hemisphere. From this perspective, would the Earth appear to revolve clockwise or counterclockwise about the sun? —Preceding unsigned comment added by 203.97.79.114 (talk) 11:17, 31 August 2010 (UTC)[reply]
I'm afraid you're not answering the question I asked. You've both told me about the Earth's rotation about its own axis; I'm asking about its revolution about the sun. —Preceding unsigned comment added by 203.97.79.114 (talk) 11:44, 31 August 2010 (UTC)[reply]
I would argue that the first diagram doesn't, since there's no way to tell if we're viewing the day side or the night side of the Earth. The second does, though. —Preceding unsigned comment added by 203.97.79.114 (talk) 12:00, 31 August 2010 (UTC)[reply]
Sure enough! The image's own description page has it ("Earth is shown as viewed from the Sun; the orbit direction is counter-clockwise (to the left)") but the caption on the image in the article doesdid not. Fixed, good catch! DMacks (talk) 12:12, 31 August 2010 (UTC)[reply]
Wait, no, it would be going from left to right regardless of which side you were on, as long as you kept north as up. I disagree with your caption. —Preceding unsigned comment added by 174.91.10.238 (talk) 16:50, 31 August 2010 (UTC)[reply]
...same confusion (wrong technical term for poster's actual question) that got several of us off in the wrong direction (so to speak) with the answer. DMacks (talk) 18:16, 31 August 2010 (UTC)[reply]
There is of course nothing except our own interpretation that makes north "up" and south "down", it would be just as valid to call the Antarctic "up", it's purely because theres people in the northern hemisphere who sit more on top of the globe then below it. However it's so ingrained on every single map and every globe that even I in Australia struggle to make the switch just in my head. Vespine (talk) 23:56, 31 August 2010 (UTC)[reply]
"Reverse osmosis"
Should "reverse osmosis" really be called "reverse osmosis," as if it's the reverse of osmosis? Osmosis is the movement of water across a semipermeable membrane from an area of high water potential to an area of low water potential. If I've understood reverse osmosis, all they are doing is increasing the pressure on one side of the membrane with the "dirty" water, so that the water moves across to the clean side. But since water potential is already defined in terms of pressure, among other things, the water is still just moving from an area of high water potential to an area of low watert potential. So it's still just regular ol' osmosis, right? 76.24.222.22 (talk) 11:37, 31 August 2010 (UTC)[reply]
Yep, thermodynamically it's just regular ol' osmosis: as you say, the chemical potential of the water is increased on the "dirty" side of the membrane so that it's higher than the chemical potential on the "clean" side. It's called "reverse" osmosis because most people think of osmosis as water moving the other way, so that solute concentrations on the two sides of the membrane are equal, but that is just a limited conception of osmosis. Physchim62(talk)12:48, 31 August 2010 (UTC)[reply]
Alternatively, osmosis is defined as the movement of solvent from the low concentration side to the high concentration, then the opposite is correctly called reverse osmosis. Dbfirs17:51, 31 August 2010 (UTC)[reply]
I have a theory on what the crystal skulls actually are
i would like someone to contact me about the crystal skulls it may be that its a far feched theory but i believe they hold some sort of message could you please contact me asap as i believe i know the key to opening this infomation.. thankyou contact me on (e-mail address removed) —Preceding unsigned comment added by 86.139.245.30 (talk) 12:23, 31 August 2010 (UTC)[reply]
We don't contact people by e-mail, and you should not post your e-mail address here. I have removed it, to combat spam. --Mr.98 (talk) 13:10, 31 August 2010 (UTC)[reply]
Wikipedia is specifically not interested in ideas you have just dreamed up (see WP:NOR) - this reference desk is for asking questions and getting answers - not for recruiting people to listen to whatever ideas you've had. If you had a specific question about the crystal skulls that our article was unable to answer - then it would be appropriate to ask it here. SteveBaker (talk) 18:28, 31 August 2010 (UTC)[reply]
His email address is still available in the history. Aren't these supposed to be permanently removed? I'm just curious. – Kerαunoςcopia◁galaxies18:57, 31 August 2010 (UTC)[reply]
Permanently removing ANYTHING from Wikipedia is amazingly difficult. Even an admin can't completely eradicate data from the system - it takes yet higher levels of system privilege to do that. Here on the ref.desks we seem to have evolved a system whereby we simply remove the email address from the current version and leave it in the history. IMHO, that's a waste of time - if our OP's wish to leave their email addresses and risk getting spammed - that's their own call. I leave my email address exposed on my User page and I've not noticed any change in the volume of spam I get as a result. Anyway - what really matters is that we're not going to email answers to people - much less get involved in some kind of private debate. SteveBaker (talk) 21:46, 31 August 2010 (UTC)[reply]
Anyway it's how we generally handle things. The issue is less a bot going through the history looking for addresses (what a waste of time!) than it is the many pages that mirror "active" content and put it all over the place. --Mr.98 (talk) 00:48, 1 September 2010 (UTC)[reply]
This section doesn't mention that certain measure may be OK only for spherical glass - problem and not for cylindrical
Also if you want a lot of angry, vocal testimonials from unfortunate people who have had permanent eye damage from the surgery, google lasik disaster or the like. Comet Tuttle (talk) 16:28, 31 August 2010 (UTC)[reply]
Someone deleted this question as a request for "medical advice". However, general discussion of a medical procedure, including its risks, is well within the scientific purview of Wikipedia - it's no different than the question above about whether you can be electrocuted by standing on a 220V plate. As always, be disclaimed that we can't tell you what to do. Wnt (talk) 04:15, 1 September 2010 (UTC)[reply]
Is it a myth or a fact that it works only on cases with spherical lens and not cylindrical lenses ?
Well, slightly to that side of vertically down, if by North Pole you mean the point of intersection of the meridians. Incidentally, in scientific terms, the North Magnetic Pole is really a south pole, which is why the "north" of the magnetized needle is attracted to it. At some unknown time in the (arguably fairly near) future, it will probably flip and become a true north pole. Dbfirs17:45, 31 August 2010 (UTC)[reply]
Actullay if you take a compass that's constructed for use by the equator and use it in for example Sweden, the needle would point a little downwards scraping the compass floor effectively making it less usable. Instead they come with a small counterweight adjusted for the latitude where it's intended to be used, so the needle will stay horizontal. The needle will be attracted more and more downwards as you get clooser to the north pole. Moberg (talk) 14:41, 31 August 2010 (UTC)[reply]
There are "three-dimensional" compasses if that's the right term, they should exactly point downward ?
Right - but a dip circle is really just a sideways compass. They take some trouble with the bearings - but aside from that, it's nothing special. If you imagine a "3D compass" (maybe a needle mounted on a ball-and-socket joint or something) then as you'd approach the magnetic north pole, the needle would continue to point towards it - but more and more weakly - and start to dip downwards more and more strongly. Right at the pole, the 'pointing North' force has dropped to zero and the thing would point straight down at your feet. SteveBaker (talk) 18:24, 31 August 2010 (UTC)[reply]
I think the above explains it very well, but it may be worth just mentioning that that there isn't really a single "point" where you are exactly at the north pole. Well there is but you'd be hard pressed to figure out you are there if all you had was a compass. If you look at the diagrams at Earth's magnetic field it becomes easier to see that it's more of a north "zone" rather then a point. It's not like your compass is pointing to your front, then you take a couple of steps and all of a sudden it's pointing backwards, or even worse, spins like a top, like I've seen depicted on more then one occasion. Even with a special compass like Moberg suggests, when you are in the "zone" walking in any direction would not make much noticeable difference. To really work out if you are right on the north pole, I think you'd probably have to plot several points around a fairly substantial area and then derive an average. Vespine (talk) 00:31, 1 September 2010 (UTC)[reply]
Yes, indeed. The amount of force rotating the needle in a horizontal plane drops off dramatically - even at 100 miles from the magnetic pole. You need an increasingly sensitive compass at those latitudes to get any reading whatever. The dip angle is more useful though - but (as you say) it's still not exactly sensitive enough for accurate navigation. There are lots of additional complications - for one, the earth isn't a perfect dipole and the magnetic poles wander around a lot from year to year. Right now, the magnetic south pole is out in the ocean somewhere - it's nowhere even close to the true pole about which the planet rotates.
But the ambiguity in our latitude/longitude/heading system at the poles is very real. There is an old puzzle that goes:
Q: A hunter leaves his tent, walks one mile south, one mile east, shoots a bear and then walks one mile north to arrive back at his tent...what color was the bear?
A: White.
Most people think that the North pole is the only place that this story would work - but actually, there are a bunch of places near the South pole where the story would work just as well...except that there are no bears there. It takes a bit of a mental stretch to visualize where those places are though! The easiest ones to imagine are points that are one mile North of the line of longitude that wraps around the south pole and is exactly one mile long - so in walking east for one mile, the man makes a complete lap of the pole and ends up following his own footsteps back for another mile, heading north. However, there is another place that's one mile north of the line of longitude that's a half mile long...then the man makes two laps of the pole as he walks east before returning to his tent. SteveBaker (talk) 04:38, 1 September 2010 (UTC)[reply]
A warning in advance...we can't give medical advice here. That said, we do have an article on anti-obesity medication, which covers a big range of drugs. Find the one you're interested in on the list, click its article and see if it has overdose information on the page. You'd have to be more specific with exactly what drug you're interested in to get a more detailed answer. Vimescarrot (talk) 15:56, 31 August 2010 (UTC)[reply]
The hazards of overdosing on individual drugs will vary depending on the drug. Members of a class of drugs such as "diet pill" will not necessarily have the same, or even similar, hazards. -- Ed (Edgar181) 19:44, 31 August 2010 (UTC)[reply]
How To Pronounce "Feynman"
Sorry if this question is a bit trivial, but I couldn't find anyone pronouncing his name. Even his online lectures have edited out the start, where he presumably introduces himself. My questionn is, quite simply, after reading Surely You're joking and starting on the Feynman Lectures on Physics (I need to improve my calculus skills), it struck me that I don't know how to pronounce his name, having seen it only in print. I had a look at the article, but couldn't make head 'nor tail of that IPA stuff. Two options presented themselves to me: "fine-man", or "fain-man" (Fain rhyming with vain). In case it matters, I would pronounce it with an english accent, living as I do in England. Thanks very much.--HarmoniousMembrane (talk) 16:01, 31 August 2010 (UTC)[reply]
You're quite correct. Indeed, carefully listening to this video to see how he pronounces that semi-vowel, I would write it FINE-muhnn (as you might expect from someone from New York). But I'm a native speaker of British English (of the Northern English variety), so pronouncing non-stressed "man" as "munn" is second nature to me ;) Physchim62(talk)23:18, 31 August 2010 (UTC)[reply]
Sadly, I find that script fails to read the 'Feynman' IPA: it doesn't give anything for /a/ and fails to read /aɪ/ as a diphthong :( A shame, since it's a good idea. 86.161.108.172 (talk) 21:53, 31 August 2010 (UTC)[reply]
That is unfortunate. It definitely needs some love as I haven't found it to be useful for non-English IPA at all. Still better than nothing, though, IMO. --Sean18:26, 1 September 2010 (UTC)[reply]
Did humans evolve from something with more nipples, or did cats evolve from something with fewer nipples, or did they both evolve nipples independently from a mammal that didn't use nipples, like a platypus? —Preceding unsigned comment added by 174.91.10.238 (talk) 16:40, 31 August 2010 (UTC)[reply]
Humans and cats almost certainly didn't develop nipples independently; they are both Eutherian mammals. However their evolutionary histories split around 100 million years ago (humans belong to Euarchontoglires, cats to Laurasiatheria), so there was a lot of time for differences to develop. Looie496 (talk) 17:40, 31 August 2010 (UTC)[reply]
Re-reading, I think the question has not been clearly answered yet, especially as two different taxonomies have been used which might confuse. So here is some more:
Fossil records suggest that the platypus, cats and man derived originally from the Eutherian group. A new group diverged away from this when the modified sweat glands (that produced the proto-milk) evolved into clearly defined nipples. Palaeontologist have named this group Epitheria (but perhaps not for this reason alone). Cats and man came from this later group which divided several more times. Fossil evidence further suggests that, the animal from which man evolved from was quite small. Evolution appears to disfavour small litters in small animals and so it is thought likely by some that these animals would have at least one pair of nipples in order to suckle larger litters. However, by the time they had split off again and finaly evolved into primates the number had been reduced to one pair and single births. Fossils do not usually record soft tissue so the actual stage of evolution that this happened can only be guesstimated at. So, it is quite likely that originally several sets of nipples evolved all at once in the common ancestor of 'human and cat' and then reduced down to the one pair in man today.--Aspro (talk) 20:23, 31 August 2010 (UTC)[reply]
You might be right, as I first did this before man first walked upon the surface of the moon, and jeans where something one wore... and my memory is going! Which taxonomy are we taking about? Fossil evidence is dependant on morphology. Looking at the genes and their occurrence in other animals don't over lap exactly with fossil evidence. The two taxonomies don't yet match perfectly (but they could go on to explain horizontal transmigrations and other esoteric theories). The OP asked a simple question and I think we have answered that now. --Aspro (talk) 23:16, 31 August 2010 (UTC)[reply]
The sub section: Fossil-based family tree of placental mammals shows the palaeontological tree. It might come down to tectonics and the geological dates of continental separation. Which group does the platypus not belong to? Molecular phylogenetics however, cannot state, what they state as all 'fact', as they have not a shred of hard evidence (i.e. fossils). Modern mammal (aboriginal man) only arrived 60,000 years ago. --Aspro (talk) 23:57, 31 August 2010 (UTC)[reply]
The one problem with doing it by tectonics is figuring out how the opossum managed to get all the way to the Americas. Unless it was already there before all of the placental mammals showed up. --174.91.10.238 (talk) 03:06, 1 September 2010 (UTC)[reply]
Marsupials are now thought to have developed first in South America, probably after it had split off from Africa (in the breakup of Gondwana) but while it was still connected to Antarctica and Australia. The ones in Antarctica have vanished for obvious reasons. Opossums, and other South American mammals such as armadillos and sloths, did not reach North America until the land bridge opened around 10 million years ago. Looie496 (talk) 04:12, 1 September 2010 (UTC)[reply]
The platypus is not a placental mammal, it lays eggs. Monotremes are generally believed to have branched off at the earliest node that has surviving offshoots, earlier even than the branching between placentals and marsupials. Looie496 (talk) 03:57, 1 September 2010 (UTC)[reply]
Actually, a question that has always interested me is when breast tissue migrated to the chest. in every non-primate I can think of (including most monkeys) nipples are situated on the belly, and often (as with cows) on the lower parts of the belly - on humans, chimps, and gorillas, though, they are placed over the rib cage. I can see the evolutionary advantage of this (allowing an infant to be fed while held in the arms, which makes it possible to walk and feed a child at the same time), I just don't know where the evolutionary spit for it lies. --Ludwigs222:32, 31 August 2010 (UTC)[reply]
The article nipple claims that humans develop additional nipples that regress during fetal development. Unfortunately it provides no source. I found this paper, which examines tissue from uncertainly dated 14-18 week old fetuses, and finds no evidence of milk line segmentation (barely of the milk line at all). But they are looking too late - mostly, they complain about lack of availability of fetal samples. I'd hoped that other countries wouldn't have this ethical notion that it's OK to abort a fetus but not to look at the tissue afterward (at least, not if it could benefit scientific knowledge or human health...), so I wouldn't rule out that the Wikipedia article really did have some valid source for events around 4-6 weeks development. Wnt (talk) 19:06, 1 September 2010 (UTC)[reply]
Not really true. Consider a pig (and lots of other animals are similar) - see here for example. The nipples go pretty much right up to just below the front legs, similar to the location in humans. I'd also argue most (all?) primates have nipples up on the chest, not the belly - consider even something relatively distantly related like a lemur, those nipples are right up there. It's also wrong to say they're on the chest to allow "an infant to be fed while held in the arms, which makes it possible to walk and feed a child at the same time" - not many non-human primates could accomplish this, even our close cousins chimps and gorillas are knuckle-walkers, which would make this scenario almost impossible. Most likely the ancestor had multiple nipples, with the extra ones lost and just the upper ones retained. The small number of young raised by primates at any one time - usually one or two at most - would mean no need for the extra nipples and they would be selected against. Retention of the upper nipples would be favoured as it would allow for 'nursing' the young to feed while in dangerous positions like high up in trees. --jjron (talk) 14:28, 2 September 2010 (UTC)[reply]
In the US there is a formal process to survey tornado damage and estimate intensity (managed by NOAA, I believe). Unless there is a similar process in Ireland, there may be know way of accurately knowing the intensity of most tornadoes in Ireland. Dragons flight (talk) 21:33, 31 August 2010 (UTC)[reply]
Climatologically speaking there is very, very little chance that this will happen. Violent (F4-F5) tornadoes are rare outside of the United States, and this does not mention that strong tornadoes form that often in the UK or Ireland. Also, if my memory serves me correctly the only locations that have a tendency to suffer strong-violent (F2-F5) (relatively) frequently are the United States, Canada, Australia, Bangladesh, and parts of mainland Europe (don't take this at face value, my memory may be wrong). The list of European tornadoes says that the strongest British tornado is probably the London Tornado of 1091, which should give an idea of what strength Irish tornadoes could have. Ks0stm(T•C•G)01:14, 1 September 2010 (UTC)[reply]
I don't think this can be worked out from a formula because it depends on how the focus mechanics are designed. Theoretically, to focus on something closer you'd just turn the focus knob more, however you'll hit a mechanical limit long before you hit a optical limit to how far you can turn the knob. Vespine (talk) 23:28, 31 August 2010 (UTC)[reply]
Cats' senses
hi. I asked this question as a follow up to a different question but nobody responded. How much do the acuity of the senses vary between house cats and wild cats (such as cougars, lions, tigers, etc.) and I read the article but I didn't understand how exactly a cat's vision is inferior to a humans in light. Are they nearsighted, farsighted? Or do they see blurrier? Or what? 76.229.235.27 (talk) 23:22, 31 August 2010 (UTC)[reply]
The Cat senses article says: "Testing indicates that a cat's vision is superior at night in comparison to humans, and inferior in daylight."
"Night vision" in mammals mostly involves "rod cells" in the retina; cats have more of these rod cells in their retina than humans do. But that means they have proportionally fewer cone cells than humans, which are the cells in the retina that specialize in responding to relatively bright light. These cone cells are also more "tuned" to respond to color, detail, and rapidly changing images. So it is in those ways that cats have "inferior" bright-light vision than humans, because they are relatively specialized for seeing in low-light conditions. Wikiscient(talk)07:19, 1 September 2010 (UTC)[reply]
I'm looking for a decent star map, not to go stargazing with, but more to understand the "geography" of the sky better. I'm not interested in deep space objects, just visible stars. I would like all the constellations labeled (that is, the entire region on space assigned to each constellation demarkated as well). I want the Declinations and Right ascensions labeled at reasonable intervals (every 30 degrees or so, like you see latitude and longitude labeled on a map of Earth). I'd also like the Milky Way shown, and a lines showing the ecliptic and celestial equator. Basically, I want a map of the sky like you'd see a map of the whole Earth (something like the Mollweide projection, I guess). Here's sort of what I want: [14], but I don't really care about the Caldwell objects, and I want a lot more of the stars labeled, and the declinations and right ascensions labeled. I would have thought such a thing would exist on the internet, but I'm having trouble finding something like I want. Does anyone know of anywhere I could find such a thing? Buddy431 (talk) 01:04, 1 September 2010 (UTC)[reply]
Celestia is not a "map" as much as a "simulated planetarium." But it has a very nice user-interface; you can stay at Earth and view the sky from Earth, with or without constellations, text labels, and so on (many options are configurable). Celestia also has a very effective 3D mode that allows you to zoom around in space. The novelty of their approach is the "exponential" zooming - so when you get out far from earth, your speed changes to dynamically match the difference in scale-lengths at large astronomical distances, always tuned to be relevant to whichever scale you're viewing at. It's a great way to see the "geography" of space in 3D. Nimur (talk) 01:57, 1 September 2010 (UTC)[reply]
It's not online, but the "SC001 Constellation Chart" (supplemented by SC002 and SC003 for the polar regions) seems to be pretty close to what you want and is used in a number of introductory astronomy courses at colleges. The publisher's Web site—the maps in question are the bottom three items on the page—indicates that the maps are certainly cheap, each costing about the same as a plain cup of coffee at Starbucks. Deor (talk) 11:00, 1 September 2010 (UTC)[reply]
Thanks. The SCoo1 looks pretty good, I might go ahead and order it. I have Celestia, but I haven't done much with it. It runs pretty sluggishly on my computer. Buddy431 (talk) 23:22, 1 September 2010 (UTC)[reply]
Eyesight and social development
Is it possible that poor eyesight can affect a child's social development in areas such as making friends and daily social interactions? If so, is this also true for adults? Is their any documented evidence for this? Thanks. Clover345 (talk) 01:10, 1 September 2010 (UTC)[reply]
Children are cruel when it comes to finding weaknesses in others and exploiting them ruthlessly. It would be quite surprising if they did not do so for people with poor eyesight. Did you never hear one child calling another "Four Eyes"? Heck, adults can be pretty cruel too - Dorothy Parker is famous for saying "Men seldom make passes at girls who wear glasses."...how do you think that would affect a typical 13 year old girl? There is plenty of anecdotal evidence (hubpages.com/hub/Eyeglasses-and-Your-Child-How-I-Overcame-the-Four-Eyes-Jokes - for example) - but surely we don't need much to be convinced of the fact. The real question is what the long term impact might be - and that's nowhere near so clear. SteveBaker (talk) 04:13, 1 September 2010 (UTC)[reply]
It's possible, sure, but I think it may not be significant - children make fun of -everything- (names, freckles, ginger hair, socio-economic class, gender, those funny pants someone wore one day...), so I imagine it would be difficult to tell the signal for the noise regarding a specific effect that glasses would have. Anecdotally, I started wearing glasses when I was 10-ish, and never really noticed that they impacted my social development (being quiet and reading a lot seemed to have more of an effect). I'd be curious if there are any actual studies on this...Quietmarc (talk) 12:54, 1 September 2010 (UTC)[reply]
Speaking as a spectacles wearer since the age of seven, my OR observation is that because spectacles can easily be broken by accidents in physical play and sports (such as a ball striking the head) or by the deliberate violence of bullies, and because this can entail prolonged inconvenience to the victim and expense to their (consequently displeased) parents, children who wear spectacles may tend to shy away from vigorous sports and social interactions, and be more fearful of bullying behavior, leading to a less assured and more introverted personality. It's difficult to tell from the inside if my solitary and bookish nature (snap, Quietmarc!) was a consequence or merely a corollary: I too would be interested in any research in this area. (87.81 posting from . . .) 87.82.229.195 (talk) 13:53, 1 September 2010 (UTC)[reply]
I don't think so. In fact I feel more secure since I begun to wear glasses (at about 14), I think girls find me more interesting with glasses on. Many have in fact protested at my idea of contact-lenses. Jon Ascton (talk)17:51, 1 September 2010 (UTC)[reply]
Massive Stars
there are many stars in the galaxy
likewise sun is a star
a few days before a star named "aura" was discovered which is many times bigger than the sun and also has more mass comparable to sun.
how is it possible?
because scientists have estimated that any star with greater mass than the sun may not exist.
and there are many galaxies in the universe.
so is there possibility to have many other stars which are brighter than sun? —Preceding unsigned comment added by Gwen dollen (talk • contribs) 04:35, 1 September 2010 (UTC)[reply]
As you can see, the sun is about in the middle of this diagram
The statement "scientists have estimated that any star with greater mass than the sun may not exist" is wrong. Models place the upper limit for stable stars at well over 100 times the mass of the Sun. --Wrongfilter (talk) 08:53, 1 September 2010 (UTC)[reply]
The sun is nowhere near the largest kind of star - in fact (as you can see from the diagram over on the right here), it's somewhere roughly in the middle of the range. Our sun is a very average kind of a star - nothing special at all. About half of the stars out there in our galaxy and in other galaxies that are near enough for us to study are larger than the sun. About half are brighter than the sun. I don't know where you got the idea that scientists don't believe that - but you are most certainly incorrect. SteveBaker (talk) 12:20, 1 September 2010 (UTC)[reply]
Yeah, I have to disagree with Mr. Baker as well. Most stars are actually rather smaller than the sun (see Sun: it's estimated that the sun is larger than 85% of the stars in the Milky Way). It's also the case that most of the stars that we study are at least comparable to the sun, simply for the reason that those are the ones that we can see and study the easiest. However, being in the 85th percentile still leaves a lot of room at the top for some truly massive stars. Our article List of most massive stars lists R136a1 as the largest, at about 250 times the mass of the sun. Interestingly, most of the prominent stars in the sky are decidedly atypical. The 1st and 4th brightest stars, Sirius and Alpha Centauri are comparable in magnitude to the sun, and are bright due to their proximity to Earth. On the other hand, stars like Canopus, Rigel, Betelgeuse, Beta Centauri are a fairly good distance away (over 100 ly), and are just huge, massive stars that put out a lot of light. These types of stars are definately not common, but because they are so visible, they are much better studied and more well known than even a very close, but dim star, like LHS 292. Buddy431 (talk) 23:20, 1 September 2010 (UTC)[reply]
Bok choy, at least here in NZ, often refers to Chinensis or "Chinese mustard". However, the term in Chinese can also be used for its relative the Napa cabbage. Choy sum literally means "vegetable heart", the tender insides of such veggies. sonia♫07:13, 1 September 2010 (UTC)[reply]
I was reading today's article on the Balaur. The dromaeosaurs were around for over 100 million years. It seems to me that there was not much significant change (evolution) in this group considering the very long time they were around. In fact the Age of the Dinosaurs was an extremely long period and while there clearly were many different varieties of dinos, there really does not seem to be any real significant difference in the grand scheme of things. This is in comparrison to the genus homo which has only been around for 2.5 to 3 million years (or, a small per centage of time compared the dinosaurs). So, my question is: why did the dinosaurs not develop (evolve) into a "higher" form (intelligence, technology, etc.) as we humans have in such a fraction of the time we have been around? —Preceding unsigned comment added by 142.46.225.77 (talk) 13:44, 1 September 2010 (UTC)[reply]
Well, I think you have to throw out the window the idea that there wasn't much variation in dinosaurs. There was. Plenty. We don't have evidence of all of it, because fossilization is a tricky thing, but we have tons of reason to believe that there was a lot of variation. They evolved to fit into basically every niche, including air and sea. I'm impressed by Archaeopteryx — it seems to me at least as impressive, evolutionarily speaking, as developing a big brain. Perhaps even more so; high intelligence is just scaling up an existing property (plus a little bit more). Feathers? Light bones? Flight? That's some impressive stuff.
As for why didn't dinosaurs evolve higher intelligence and technology — you might as well also ask why no other forms of life except for basically a small subset of primates and maybeCetaceans evolved very impressive brains, much less technology. Insects have been evolving longer than dinos or mammals, yet they are probably not much more intelligent now than they were 300 million years ago. The reason is quite simple: it's not at all clear that high intelligence is worth the tradeoff. It requires a big brain, which is extremely physiologically taxing. (Human brains account for 2% of our body rate, yet require 15% of our cardiac output, 20% of our total body oxygen consumption, and use 25% of our glucose consumption.[15]) Even for Homo, our big brains didn't lead to total domination for quite awhile. (Note that chimpanzees and bonobos and gorillas, though they have massive brains compared to most of the animal kingdom, are not exactly living high on the hog in the way that even Homo erectus was. They can't just pick up and move to the other side of the Earth if they run out of food in their niche, for example.) High intelligence is one possible way to lead to massive gene flow, but it's not at all the easiest way. Insects do just fine, evolutionarily, without them, on their breed-and-feed model. To use a very bad mode of reasoning, one might suggest that if high intelligence and technology was so obviously beneficial from a gene's eye view, we'd see more than basically one species that had it.
Lastly, you shouldn't see evolution as teleological. It doesn't lead in one direction. It's not like "high intelligence/technology" is the "goal". Evolution has no goal other than gene flow. That's it. High intelligence is a means to that end, as are big horns, the ability to hunt at night, the ability to fly, the ability to blend in with your surroundings. It's certainly the case that with enough high intelligence and technology, one species can basically rule over most others. But even that took hundreds of thousands of years, and by some arguments, we aren't quite as mighty as we think we are. (Insects still probably have us beat, and have laid us low more than a few times in our history.) Humans are the odd, weird case, not the normal case. There's still a lot we don't know about why we evolved the brainpower we did — it is awfully excessive, and goes well beyond what we would need to for basic hunter/gatherer lifestyle. --Mr.98 (talk) 14:38, 1 September 2010 (UTC)[reply]
"High intelligence is a means to that end, as are big horns, the ability to hunt at night, the ability to fly, the ability to blend in with your surroundings." Ahh, but high intelligence lets humans have all those abilities through tool use such as, spears, night vision goggles, airplanes, and camouflage. If it gives all of those benefits at once, is it safe to say that we are the first species on this planet to "win" the game? Googlemeister (talk) 15:06, 1 September 2010 (UTC)[reply]
We clearly win in an engineering contest, which I think is your point. As far as winning an overall game, well, we're just going to have to wait and see, aren't we? I'm putting my money on the Empire of Bacteria to outlast us and therefore "win" on another set of criteria. Comet Tuttle (talk) 15:51, 1 September 2010 (UTC)[reply]
If we're going by species, we're sunk. There are species several orders of magnitude older than us that are still around. We'd have to wait for them to become extinct and -then- start counting down the millions of years before Homo sapiens (or even Homo in general, I guess) is even in the running. Quietmarc (talk) 16:28, 1 September 2010 (UTC)[reply]
We only 'win' if we spread farther than the other life. It's entirely possible that we've already accidentally contaminated Mars or Venus, so bacteria may be beating us in that respect as well. APL (talk) 16:44, 1 September 2010 (UTC)[reply]
But bacteria wouldn't have been able to get there unless an intelligent technological species evolved to get them there. And chances are, bacteria could survive better on Venus than mammals could, given the surface conditions. So if you choose to consider bacteria and space-faring apes as a sort of single "symbiotic organism" for interplanetary travel, where the bacteria are the "reproductive organ"; and the technological apes' only meaningful function is to propel the reproductive organ forth (by inventing metallurgy and learning fluid-dynamics to build the necessary rockets)... then we can say that Earth Creatures have cooperatively worked together as a single organism to colonize other planets. Once the bacteria establish a foothold, they can proceed, over billions of years, to evolve back in to "higher forms" of life that can re-invent interplanetary travel. I see no reason why this contravenes the established norms for biological classification - it's just a different methodology for defining "species" and "reproduction" that scales to cosmological timescales; individual organisms and in fact entire species become mere sub-components of the larger life-cycle. Various SETI researchers have proposed such schemes, sort of "Gaia hypothesis"-esque. Nimur (talk) 18:32, 1 September 2010 (UTC)[reply]
We should remember that the creatures which survived the great Cretaceous extinction are those that were capable of making it through a major disaster, by hibernation or maybe by flying to the other end of the Earth. So the extinction of the dinosaurs made way for a world of species more able to survive change ... I wonder if they are also more able to cause it.
When we look to the evolution of humans, we see 1) two million years of Ice Ages, and 2) the extreme variations of wet and dry near the Okavango Delta, which is (give or take a country or two) the location where modern humans arose. I think it is striking that humans seem particularly capable of moving through muddy terrain, sort of like the lechwe or the famous bipedal Chacma Baboons, and I am inclined to think that many of our species' predecessors originate from the area.
What humans have done with this lineage is to take on an invasive character, equipped with such things as fire and clothing to change the landscape and move beyond traditional boundaries. Perhaps intelligence is the highest elaboration of this invasive program, allowing humans to change the Earth beyond all bounds of ecology. Wnt (talk) 17:59, 1 September 2010 (UTC)[reply]
Nobody is arguing that high intelligence doesn't open up a lot of doors, or that humans haven't compensated for our pathetic qualities with technology. But that's probably not why we evolved the intelligence in the first place, in any case. Nor does it necessarily lead to long-lasting gene flow. Since humans invented civilization, they've come close to wiping themselves out a number of times, in a relative blink of an eye compared to the dinosaurs, insects, and so on. There's a very real argument to be made that too much intelligence is a bad thing — if you can make weapons of mass destruction (nuclear weapons, new forms of virulent pathogens, evil nanobots — heck, just excessive carbon output) you run the risk of self-extinction. Cockroaches on the other hand will probably always be here. Anyway, it's food for thought, lest we congratulate ourselves too quickly, ten thousand years of civilization onward. In any case, there is no "winning" in evolution in any strict sense. The last species alive doesn't get a prize. I don't mean to be nihilistic, but there is no reason to evolution from a scientific point of view, it is just something that happens when conditions are right, the same as when a star undergoes fusion when you put enough mass together. --Mr.98 (talk) 22:33, 1 September 2010 (UTC)[reply]
99942 Apophis side effects
Assuming 99942 Apophis has entered the Earth's vicinity in 2029 or 2036, with a minimum distance separating between the two surfaces of about 1000 km (i.e. height). What could be the expected consequences affecting Earth's parameters like gravity, angular momentum and linear momentum. Do you think there will be some significant changes the we feel them directly (the day length for instance)? I will come back after fasting is over lol.--Email4mobile (talk) 14:34, 1 September 2010 (UTC)[reply]
Significant, no. Apophis is far too small to impact the length of the earth's day in any amount that would be noticeable to someone without an atomic clock with micro-second accuracy. Now, if apophis were to impact earth, I suppose that it might alter the length of the day a smidge if it impacted at a shallow angle adding angular momentum to the earth, but in that scenario, a barely shorter or longer day would be of minor consequence what with all the death and destruction. Googlemeister (talk) 15:00, 1 September 2010 (UTC)[reply]
Assuming no collision or atmospheric entry, no, there will be no changes in any of the above observable by the unassisted human. However, it is reasonable to suggest that Earth's momentum might be measurably affected -- such things aren't really uncommon (certainly not on astronomic time scales). Earth's gravity won't be affected, as its mass won't change. Even while Apophis passes 1000 km overhead, the effect of the moon's gravity on Earth's surface will remain about 15 million times more powerful than Apophis'. Long story short, unless there's an impact event, there will be no impact (as it were). — Lomn15:00, 1 September 2010 (UTC)[reply]
Apophis is 14 orders of magnitude less massive than the Earth: it will have about the same effect as a single bacterium passing within a foot or so of an average adult human, i.e. none at all. Physchim62(talk)15:08, 1 September 2010 (UTC)[reply]
I think the poster wants to see the nasty, so here goes:
Angular momentum (scalar magnitude, assuming a strike directly perpendicular to the Earth's axis which probably is a lie) is the product of these 2.7 x 12.59 x 6371 x 10^10 kg = 2.17 x 10^15 kg km^2 /s
Angular momentum of the earth (calculating a different way, L = I ω, using a moment of inertia formula I found on Yahoo answers which I hope is the right one = 2/5 m r^2 * (2 pi/T)
Where m (Earth) = 5.978 ^ 10^24 kg, radius = 6371 km, T = 86400 s (1 day)
L = 2/5 * 5.978 ^10^24 kg * 6371 km * 6371 km * 2 * 3.14159 / 86400 = 7.058 * 10^27 kg km^2 /s
Ratio of the asteroid's angular momentum vs. Earth's = 2.17 x 10^15 / 7.058 * 10^27 = 3.074 * 10^-13
Thus the loss of time for 1 year = above ratio * 86400*365.25 = ( 31557600 s * 3.074 * 10^-13) = 9.701x10^-6 s
What would happen if two stars were to "crash" into each other? Would they form a single, larger star, or would it upset the fusion reactions and cause a supernova, or would the stars just pass straight through one another with no major changes or what? Googlemeister (talk) 15:10, 1 September 2010 (UTC)[reply]
(ec) We have no Stellar collision article, surprisingly. Our Type Ia supernova article, in the Formation section, says, "Collisions of solitary stars within our galaxy are thought to occur only once every 107–1013 years; far less frequently than the appearance of novae", and goes on to say that one "likely" scenario out of the possible scenarios, involving a binary system as one of the colliders, is that you end up with two white dwarfs; it supplies 3 references about stellar collisions. Comet Tuttle (talk) 15:39, 1 September 2010 (UTC)[reply]
US penny coin composition
Are US pennies really composed of bronze? My science textbook says that. I always thought that they were zinc with a copper plating (after 197x, of course). --Chemicalinterest (talk) 15:33, 1 September 2010 (UTC)[reply]
Hi, I've been looking into QR codes for a few days (yup, that includes reading the article on Wikipedia). You can use a QR generator to generate a qr code from a url, or text. It reads the url and generates a code designed to direct the follow-up user to that url.
However my question is this (thus?): Could I design the QR code first (perhaps including simple text, only a handful of characters in the design), and then use that QR code to throw up a random url that I could then set up a redirect on?
Excuse me for repeating your question back at you in my own words, but I think what you're asking is: can the black and white squares which form QR codes be rearranged to appear meaningful or decorative to humans, without the code ceasing to produce some data when given to a computer, and ideally without it ceasing to be valid as a URL (however garbled)? That's an interesting question. I see that under QR_code#Variants there is a mention of a variant called Design QR, which sounds like the sort of thing. 213.122.46.180 (talk) 16:42, 1 September 2010 (UTC)[reply]
Unfortunately, it appears like those "open standards documents" at ISO are locked behind a serious paywall. But a site for losers like us without money to waste on every passing thought ([16]) says that the http:/ and www and com and / and such all have to be in the barcode. And remember part of the barcode is an error correction code, which will be whatever it comes out as. Maybe someone with full access to the standard and crunching through a lot of possibilities could come up with something stunning... maybe not. Wnt (talk) 17:31, 1 September 2010 (UTC)[reply]
To paraphrase the article and earlier responses: there are some parts of the code that are required - like the version information and the data-timing and data-alignment marks. But the rest is "user-space." If you wanted to draw out a pattern, and then decode it to determine the URL, you could do it. But you can't be completely free-form: your pattern must include the spacers, alignment marks, and timing marks. And if you want to use a URL, you need to prepend your server-address. This would still leave you with a lot of blank space - you could draw your pattern of choice within the blank area; decode the whole thing, and then use that as your URL suffix. Nimur (talk) 19:51, 1 September 2010 (UTC)[reply]
Excellent, thanks for all the replies - I had to skip out shortly after posting the query yesterday,apologies for not returning sooner. I'll look in to what you have suggested Nimur - I have come across a BBC QR code that has the logo in a pixelated form at the centre of the code, and a Japanese website that creates QR codes with proper images in the centre on some examples, and other examples that use reversed out colours to suggest images or text. Cheers all, if I come across something interesting on the topic I'll put it on my talk page or in the QR Code article talk. Darigan (talk) 08:49, 2 September 2010 (UTC)[reply]
AIDS and stem cells
suppose some researches discover how to grow any body parts they wish from stem cells. Would it be possible to completely fry the immune system of an AIDS sufferer and start again from scratch, or would that be too dangerous?--178.167.247.73 (talk) 16:21, 1 September 2010 (UTC)[reply]
Possibly, but we're not a magic ball. We can't really guess what will happen in the future. There are unbelievably plentiful viruses and bacteria in the air to take advantage of a host with no immune system, so such a procedure would have to be conducted in a completely clean room -- something that's pretty difficult to achieve. If you try and remove cells and add new ones simultaneously, there's a chance that the virus would just transfer itself to the newer stem cells once they mature into T helper cells. Regards, --—Cyclonenim | Chat 17:01, 1 September 2010 (UTC)[reply]
As I'm sure you know (but probably forgot) the HIV virus also exists in body fluids. So the immune system would have to be knocked out for at least the time it takes for all the viral copies to disintegrate extracellularly. Then there'd have to be a way to, as you say, "completely fry" the immune system. I don't think there's a current method of killing all immune system cells without killing the individual, so it's not just an issue of using stem cells to replace the immune system -- we'd have to find a way to kill off all the white blood cells without utterly destroying the body. DRosenbach(Talk | Contribs)17:06, 1 September 2010 (UTC)[reply]
Unfortunately, this isn't possible with today's technology... using chemical agents or radiation to "fry" the immune system are actually frying quickly dividing cells in general because of the type of DNA damage they cause (which is why they're used to treat cancer). More slowly dividing cells are less affected, though, and tend to survive. Therein lies the problem: even if we eradicate the bone marrow in an HIV+ individual, the virus can persist in long-lived macrophages that have taken up long-term residence in various tissues. Those are an awful lot more difficult to fry... – ClockworkSoul03:33, 2 September 2010 (UTC)[reply]
It depends. The active ingredient might have gone so it might not do what it's supposed to. Or it could have become dangerous, making you sick, giving you an alergic reaction or even killing you.--178.167.247.73 (talk) 16:44, 1 September 2010 (UTC)[reply]
What will exactly happen in case of Alprex (I hope we are not crossing the dangerline into prohibited field of medical consultation)
We shouldn't give medical advice, especially when we know full well that no doctor is going to advise patients to take expired pills, even if it's probably just CYA. The problem is, nobody has tested such pills on patients, so what happens is a matter of surmise. Wnt (talk) 17:36, 1 September 2010 (UTC)[reply]
As a quibble, I call [citation needed] on your assertion that "no doctor" is going to do this. Consider a situation where over the counter drug X has always had an expiration date of 4 years from manufacture, and then one drug manufacturer contracts the expiration date to 3 years without changing the formulation, and without explanation. Is this for a medical reason, or in order to get consumers to purchase the big bottle of their pills more frequently? I'm not suggesting this is common, but it's easy to envision doctors seeing through such a scheme and advising their patients accordingly. Comet Tuttle (talk) 17:57, 1 September 2010 (UTC)[reply]
"No doctor" is doubtless a slight exaggeration, since there's always some exception - but not even Palestinians receiving aid on the Gaza Strip want expired drugs![18]
Actually, Wnt, the US Military tested drug expiration, and found that with optimal storage many drugs last MUCH longer, even a decade longer. Most drugs are given an automatic 1 year expiration, and no one checks them for longer times. Ariel. (talk) 18:36, 1 September 2010 (UTC)[reply]
In the United States at least, pharmaceutical companies have almost no say in what expiration dates go on pill bottles. Expiration dates are highly regulated by the FDA. The FDA requires analytical studies to evaluate the stability of the active ingredient under a variety of conditions. The time at which the amount of active ingredient falls below a specified percentage determines the expiration date. The statement above "Most drugs are given an automatic 1 year expiration, and no one checks them for longer times" is completely inaccurate. —Preceding unsigned comment added by 148.177.1.210 (talk) 20:21, 1 September 2010 (UTC)[reply]
Here is an Inspection Technical Guide: Expiration Dating and Stability Testing for Human Drug Products. The FDA is legally obligated to test drugs intended for human consumption. If a drug has a mislabeled or incorrect expiration date, or otherwise deviates from these guidelines, this consititues "cause to initiate regulatory action against the product and/or the responsible firm." The FDA is not a mindless bureaucracy - they actually do regulate the food and drug industry. Their mandate "...requires that test methods be reliable, meaningful, and specific, section 211.165 (e) gives more guidance by stating that the accuracy, sensitivity, specificity, and reproducibility of test methods employed by the firm shall be established and documented. Section 211.194 (a) (2) further requires that all testing methods used shall be verified under actual conditions of use. Testing procedures must include a stability indicating test which will distinguish the active ingredient from any degradation products and be able to make a reliable estimate of the quantity of any degradate." Nimur (talk) 22:51, 1 September 2010 (UTC)[reply]
Well, I'm ignorant of this field, but right after the section you quoted, that page goes on to say "The stability indicating test does not have to be the assay method used to determine product strength", and I don't see anything there stating that the expiration date is determined by the time at which the active ingredient amount falls below some percentage. Your assertion I sort of want to challenge here is that the pharma companies have "almost no say" in expiration dates. Comet Tuttle (talk) 06:33, 2 September 2010 (UTC)[reply]
If I take a 3 volt battery and appropriate bulb, dutifully attach the battery positive end to one of bulb's but instead attaching the negative to bulb earth it (bulb's other end). Should not theoretically it light up ? Why not ? Jon Ascton (talk)
You connected one terminal of the bulb to battery positive. How did you connect the battery negative terminal to "earth?" Various earth or ground connections can have varying resistances. There might be anywhere from 2 ohms to hundreds of ohms resistance between two wires which are "connected to earth," depending on whether the earth connection is a short wire stuck in the ground a few inches, a 20 foot ground rod driven into moist earth, or a cold water pipe connected to a municipal water system. What is the other terminal of the bulb connected to? Is there a complete circuit? Did you connect the other bulb terminal to "earth," and how? Edison (talk) 17:38, 1 September 2010 (UTC)[reply]
I didn't do anything with battery's Negative. Just battery's + is connected to bulb. Bulb's other end is earthed.
Changing the absolute electrical potential of an object doesn't really change it much. In thunderstorms the potential of the ground can shift by tens of thousands of volts (I think), but all you feel are tiny, barely annoying sparks from springs in a bed. Also see earth potential rise. A tiny tiny current flows from battery to ground, then the + side of the battery is a volt and a half less +, and the - side is a volt and a half more -, and then the current stops because the potential is equalized. In theory I suppose you could have a commutator that very rapidly switches from the + side to the minus side of the battery, and harvest these tiny currents as the battery goes up and down a full 3 volts each time, but I have no idea if this is doable in reality.
Bottom line: it takes very little current to make a very large change in voltage, if you don't have a completed circuit. Wnt (talk) 17:46, 1 September 2010 (UTC)[reply]
There is no such thing as an absolute electrical potential. Voltage can only be defined with respect to a reference point -- it is always relative. Looie496 (talk) 17:58, 1 September 2010 (UTC)[reply]
Well, surely there could be, in theory. There must be some way to measure the average potential of the Earth based on its effect on the charged particles of the solar wind, for example. Wnt (talk) 18:02, 1 September 2010 (UTC)[reply]
No, there can't be even in theory. As our electric potential article explains: The potential energy and hence also the electric potential is only defined up to an additive constant: one must arbitrarily choose a position where the potential energy and the electric potential are zero.Looie496 (talk) 19:17, 1 September 2010 (UTC)[reply]
I have to concede I was mistaken above - establishing the potential at which the charge on the Earth would be zero does not mean establishing that this is a true absolute zero voltage. For example, even if you pegged Earth to stay uncharged somehow, if you ran a long, conductive, uncharged, insulated cable out into deep space, any charge on the solar wind surrounding the Earth would still create a potential difference.
Even so I am still suspicious that some way to define zero voltage should exist, at least at the cosmological scale, that somehow averages all the positive and negative charges in existence. After all, gravity potentials have an established zero point in uncurved spacetime. In an earlier discussion it was suggested that electromagnetic forces can be modelled as a curvature of space, just like gravity. If so, there should be some point at which space is defined to have zero curvature, just as with gravity - this being the zero voltage. Wnt (talk) 21:32, 1 September 2010 (UTC)[reply]
My understanding of absolute potential is the energy required to move a unit charge from infinity to the point in question. Infinity is an unhandy place to connect a test lead however, so potential difference to a more convenient reference is used instead. SpinningSpark12:08, 2 September 2010 (UTC)[reply]
There has to be a complete loop - starting at battery +, through the bulb and back to battery -. A part of that loop can run through the earth - but it still has to be a complete loop. So you have to connect battery - to earth, one side of the bulb to earth and the other side of the bulb to battery +. That's theoretically enough - but in practice, you have to have really good earth connections - especially since your battery is just a few volts. SteveBaker (talk) 18:12, 1 September 2010 (UTC)[reply]
I can't find mention of it online, but I've held in hand an outlet tester with a single prong and a small light, which lit up when touched to the live AC wire using only the capacitance/inductance elements contained within a very small plastic shell. Wnt (talk) 18:36, 1 September 2010 (UTC)[reply]
Like this? It's a type of Electrical tester pen (see article for several different types and their operating principles. The one I have is all-plastic (no exposed conductor), so perhaps it detects stray voltage? I can actually trigger it even on non-powered circuits by moving it rapidly along certain conductors (stops reporting when I hold it still). DMacks (talk) 18:42, 1 September 2010 (UTC)[reply]
That's not the "pen-tester" that Wnt is describing. Wnt's tester consists of a neon lamp is series with a high value resistor. One end is connected to the user via a metal plate in the end of the handle. The lamp is lit when (a small) current flows through the user's body to ground. These devices are dangerous, there is necessarily no isolation from the mains voltage. They are mass produced very cheaply to a low standard. Throw it away. SpinningSpark12:02, 2 September 2010 (UTC)[reply]
Low frequency variation in professional music production?
Why is it that with professionally produced music, the final product seems to have less apparent frequency variation over different mediums (different speakers, headphones,, etc.), whereas in amateur music production there is apparently a much wider variation?
In case that isn't clear, to re-phrase it: Some speakers may have more or less bass or treble. Now, if you listen to a professional production, whether on speakers or headphones, it sounds about the same. If you listen to an amateur production, however, there seem to be a big difference. Aspects of it may sound more or less muffled, tinny, or hissy, depending on the type of speaker. ☯Zenwhat (talk) 16:51, 1 September 2010 (UTC)[reply]
This is probably observer bias. Have you actually quantifiably measured this? No matter what the source - whether it is professionally produced or amateur-recorded music, or even white noise, the speakers will imprint their frequency-response on the signal. Perhaps you can't tell the difference as easily when the music is professionally produced, but it is most certainly still there. If you want to test this, you can mic your speakers (play the same song through two or three different speakers), and run the signal through a software-spectrum-analyzer (like the one in Audacity). It is also plausible that the produced music was tested and specifically tuned up (e.g. by equalizing) so that its perceived sound quality was less susceptible to poor speakers. But the actual frequency response played out definitely depends on physical characteristics of the speaker: the amplifier electronics, the loudspeaker magnet and physical parameters, the cabinet, and so on. Nimur (talk) 19:54, 1 September 2010 (UTC)[reply]
I am definitely not an audiophile, so treat this suggestion with due caution. What makes amateur music sound that way (to me) is often the amount of "air" on the recording. We don't seem to have an article under that name, but I'm referring to the echo-y noise that comes from having the mic too far away from the sound source (mouth, guitar, etc.). Higher end systems may be cleaning the sound to reduce that noise, while cheaper systems would not. Since professional music doesn't feature much "air", you'd only notice the difference when listening to amateur recordings. Matt Deres (talk) 20:44, 1 September 2010 (UTC)[reply]
Help identifying a fish
Can anyone help me identifying the fish to the right? I took the photo about a year ago in the local aquarium, when I went there again today, the fish wasn't there anymore so I couldn't find out what species it is. It actually walked around on its leg-like front flippers, I'd love to learn more about this species. -- Ferkelparadeπ18:06, 1 September 2010 (UTC)[reply]
Thank you - we could use it in an article if we knew for sure what species it is. And thanks to everyone for helping to identify it, from comparing photos it looks like it is some species of frogfish. Fascinating stuff, I had no idea there were so many walking fish species -- Ferkelparadeπ12:58, 2 September 2010 (UTC)[reply]
Need medical term
Can't find medical term for a "scratch" caused by a sharp object to, i.e., chin BUT DOES NOT BREAK SKIN but leaves a red mark for a couple or three days. Need a medical term for paper. —Preceding unsigned comment added by 99.38.131.71 (talk) 18:25, 1 September 2010 (UTC)[reply]
Abrasion is the common medical term for a scratch on the skin. Most ICD9s related to this use abrasion. Friction burn is often used when a lot of friction is used, but that is not the case here. -- kainaw™18:34, 1 September 2010 (UTC)[reply]
You go to the source of the sound and investigate. If you have been around firing ranges, the sound of a firearm is distinctly different than a firecracker. Describing the difference is like trying to describe how a coronet sounds different than a trumpet. Words do not help much. Listening makes it instantly clear. The "kapow" of a firearm is two sounds in one. The "bang" of a firecracker is only one. If it is being fired at you, the sound is even more distinctive. It has a ring to it. -- kainaw™18:52, 1 September 2010 (UTC)[reply]
Yikes! I'd think being shot vs watching a fireworks display would have a more noticeable difference than "the sound is kind-hard-to-describedly different. DMacks (talk) 18:59, 1 September 2010 (UTC)[reply]
One can find video and audio of various firearms on the internet to get a sense of how gunfire actually sounds. Audio clips would be a good addition to the various firearm articles here on Wikipedia, if somebody could safely set up a sound recording system at a firing range. Nimur (talk) 20:02, 1 September 2010 (UTC)[reply]
Though they sound different on an (enclosed) range than they do in the open air. When I worked at Diemaco, for example, I was treated to an extreme version of this when they tested the C3 sniper rifles, which are fired in an extremely narrow range. The sound from each shot bounced back and forth down the tube creating a sound not unlike that made by shaking a musical saw - quite different from what they sound like in the open. Normal small arms aren't affected as much, but echo will still play a big part in the sound. Matt Deres (talk) 20:14, 1 September 2010 (UTC)[reply]
Interestingly, it is not possible to faithfully record a gunshot. All you get is klink sound. That's why in movies the sound of firing is added when the film is edited. Jon Ascton (talk)20:11, 1 September 2010 (UTC)[reply]
That is sometimes true. Please cite a source when you make claims on the Reference Desk. This article discusses the "microphone shutdown" phenomenon when using a microphone that wasn't designed for the purpose of recording gunshots, but notes the shutdowns were hard for them to duplicate. Comet Tuttle (talk) 21:05, 1 September 2010 (UTC)[reply]
(ec)Apples and pairs. Binary is a counting system. I2/5 is a barcode. I'll hazard a guess, fwiw, that the advantage of I2/5 is efficient use of space. It encodes numbers using the black lines and the spaces between them. If it used only the black lines, then the spaces would be redundant so far as passing number information is concerned, and would serve only as boundaries for the black lines. That being the case, the length of the barcode would have to be longer than would be the case if the white space function as boundaries and pass number information. More generally, there'll tend to be applications for which each "ridiculous coding method" is most appropriate. --Tagishsimon(talk)19:01, 1 September 2010 (UTC)[reply]
Talking of Barcodes, I too have a question. Generally, or perhaps as a matter of rule, barcodes are black lines, thick and thin, against a while background. Will the barcode work if you change (color-reverse) it i.e. you place white lines on a black background ? Jon Ascton (talk)19:08, 1 September 2010 (UTC)[reply]
Doubtful. The standards all require a "quiet area" (blank margin) that would be a "completely not-blank" margin in the negative-image ("all dark" isn't "all light"). Would be easy enough to digitally process such an image, but would have to do so before any attempt at decoding. DMacks (talk) 19:14, 1 September 2010 (UTC)[reply]
No. I've tried it myself (I use a barcode printer all the time at work and have played extensively!). I'm sure there's a more technical answer, but it really comes down to this - you wouldn't want your reader to be able do that because it would make it too easy to misread the barcode. When it comes to coded information, failing is much better than misreading. Matt Deres (talk) 20:21, 1 September 2010 (UTC)I've moved my comment to make it clear who I was replying to. Matt Deres (talk) 23:43, 1 September 2010 (UTC)[reply]
To Tagishsimon & DMacks: I was thinking that since interleaved 2 of 5 can only represent numbers anyhow, it would be much easier to represent those numbers using binary. DMacks' theme works, but I was thinking of using alternating lines and spaces, with wide lines or wide spaces representing 1 and narrow lines or spaces representing 0. This seems much more intuitive and readable than interleaved 2 of 5. --99.237.234.104 (talk) 19:52, 1 September 2010 (UTC)[reply]
That would make a non-uniform width--might be difficult to design forms or other fields to hold that sort of image (11111 would be 2x as wide as 00000) and/or to have users who need to scan them recognize something that isn't a uniform-sized object. You could do it with constant-width "black+white" ("wide-black narrow-white" vs "narrow-black wide-white") but then you're costing 50% of your data density. So heck, why not just use that whitespace for some data instead of just a fixed-width buffer. And then suddenly you're dealing with interleaved patterns:) DMacks (talk) 20:11, 1 September 2010 (UTC)[reply]
(ec) Binary might be intuitive, but not easy to design simple and cheap scanner-electronics for (especially because it is not at all resilient to error). These barcodes provide built-in redundancy, error-detection, and easy "start of signal" indications. To give one simplified example: in binary, how do you know when you're reading all zeros, and not just "no signal" ? There is insufficient information density, and so you need metadata or out-of-band signaling to start and stop the message. Barcodes must (by definition) contain this metadata in-line - so they need a more sophisticated coding. 2/5 also guarantees fixed linear length for the code, so it is sort of a monospaced font for numeric coding. Nimur (talk) 20:23, 1 September 2010 (UTC)[reply]
Simply put the problem is run length. If you have too many bars in a row the scanner can't read it. The purpose of the codes are to limit the number of identical bars in a row. See Run-length limited for some examples and discussion. Ariel. (talk) 22:24, 1 September 2010 (UTC)[reply]
Plane Crash
When an airplane (say Boeing 747) crashes how exactly do people inside it die ? Due to intense heat or the jerk ? Is the death swift or slow and painful ? Are they aware of what is happening to them ? Jon Ascton (talk)18:59, 1 September 2010 (UTC)[reply]
Note: I placed the same question on this RD a few minutes ago but it mysteriously vanished ! I'd like to know who did that and why ?
It depends on how it crashes. If it's going fast and crashes on land nearly everyone will die simply from impact. If it's a slow crash landing people who are standing up will die, but people sitting down in the brace position should be fine. If it's somewhere in between different numbers of people will die. Pretty much the same thing goes for water, except more people are likely to die. The materials planes are made from must actually extingiush fires, so they can't catch fire. Aviation fuel, however, can, and as there's so much of it, it can turn a crash site into an inferno and kill people who survive the crash.
If you're sucked out of the plane at altitude you will die of freezing and hypoxia over about 30 seconds. If you are sucked out at a survivable altitude you will probably survive until you hit the ground. If you die on impact it would just be a quick jerk. If you die from smoke inhalation you wouldn't notice you'd just feel sick. Burning would be agony.--178.167.247.73 (talk) 19:14, 1 September 2010 (UTC)[reply]
Space exposure suggests 90 seconds for outer space (and mostly due to low pressure, not cooling to due low temperature or due to low-pressure-evaporative effects). Seems like "about 30 seconds" is too short an estimate. DMacks (talk) 19:21, 1 September 2010 (UTC)[reply]
178.167, I have some serious doubts about "The materials planes are made from must actually extinguish fires, so they can't catch fire." (my italics) and "If you die from smoke inhalation you wouldn't notice you'd just feel sick" [citation needed] Planes (an airliner or 747 in the OPs example) tend to burn pretty well actually. It has no doubt improved greatly, in new designs, but there is still material that can burn on possibly the majority of flying planes. Passengers baggage(in-hold and carry-on), clothing and duty free alcohol for example, (perhaps less so now under current 'limited liquid carrying' regulations) polyurethane seat cushions and similar used to be used. Not all planes meet the latest regulations that are required of new aircraft, an old 747 for example could be what 20+ years old? (educated guess! It's 5.30 AM here, have nodded off over keyboard and need to get more sleep so I have limited time to get refs myself), but there was a 'celebrated' case, Saudia Flight 163 of a Lockheed L-1011-200 TriStar, landing in Saudi Arabia in 1980 with a fire on board, "At the time the incident was the second deadliest single aircraft disaster in history". I think the plane was virtually burnt out, article doesn't seem to say. Obviously on that one there was plenty to burn. My readings of descriptions of on board fires refer to extremely thick, choking, and blinding smoke/fumes not something you would not notice! Burning would be agony, but apparently passengers are most often unconcious from inhalation of fumes beforehand (and one would wish so! Sorry for opinionating!) See also: Category: In-flight airliner fires220.101talk\Contribs20:06, 1 September 2010 (UTC)[reply]
You've asked a complicated question that depends on several factors. Do you crash into water? Into concrete? Onto a field? All of those determine the force of the impact and the disintegration of the aircraft. It also depends on the angle of impact (clearly a head-on impact with the ground is more instantly devastating than a slanted one after engines fail!). As for whether death is slow and painful or quick and painless, wouldn't that also depend on the position you're in on the aircraft? I'm afraid this is a question one cannot answer without specifics. Regards, --—Cyclonenim | Chat 19:12, 1 September 2010 (UTC)[reply]
No, no, no. That's not it ! That was the "gunshot" question, I deleted it on purpose because it somehow appeared twice. That's not it. What I am talking about is "Airplane crash" question Jon Ascton (talk)19:24, 1 September 2010 (UTC)[reply]
The complete history of this page (as with every page) is available for you to browse to see exactly who removed it when--no mystery about it. There are technical glitches we occasionally see where two people posting at nearly identical times results in the second one replacing the first rather than simply compounding the changes, and other things like that. Remember to WP:AGF and see what you can figure out from the history. DMacks (talk) 19:30, 1 September 2010 (UTC)[reply]
For the main question, our article on aviation accidents and incidents is a good starting point. Fatalities will vary by style of accident -- burning seems reasonable for a ground collision or controlled crash on ground whereas it's less relevant to a midair collision or ocean landing. I expect the primary causes of death are fire, then impact shock while in the aircraft, then free-fall from height. — Lomn19:16, 1 September 2010 (UTC)[reply]
Regarding the missing question, I suggest that in the future you use the "new section" link at the top to add a new question rather than manually editing it into a previous question; that will help prevent such edit conflicts. Of course, it won't prevent you from deleting your own question. — Lomn19:16, 1 September 2010 (UTC)[reply]
If you're sitting with your seatbelt on you're almost guarunteed to survive a controlled crash landing. You're also likely to survive other low-angle crashes. If the plane starts tumbling after impact youneed to be strapped in or you will die. Crashes where the plane crashes almost vertically will kill everyone on board though.
And parachutes would be a disaster. Planes fly so high that you would die in that atmosphere. In an accident you couldn't jump to early or you would freeze and suffocate. You couldn't jump too late or you would hit the ground and die. There is only a tiny window, and if the plane is plummting towards the ground nobody is going to be able to jump. In the event of an impact people are far mroe likely to survive strapped in to their seats than standing up waiting to jump.--178.167.247.73 (talk) 19:32, 1 September 2010 (UTC)[reply]
We really need a source for this "people would die" thing. HALO jumps are performed from altitudes in line with airliner operating environments. While those personnel use oxygen bottles, it would not be unreasonable for airliners to add those along with parachutes were it otherwise useful. — Lomn19:39, 1 September 2010 (UTC)[reply]
OK so you're sitting in your seat and suddenly the engines fail. How can 300-500 people all get into parachutes, oxygen tanks and thick thermal overalls before the plane impacts? Even if they manage that they won't all be able to get out the doors in time. And if they're caught standing up when the plane hits death is certain. Better to be sitting down strapped in and have some chance.--178.167.247.73 (talk) 19:43, 1 September 2010 (UTC)[reply]
That's moving the goalposts. You're claiming that people will die because of the altitude, and DMacks and I have called you on it.
To address the point, though, it appears that rate of decent of an unpowered 747 isn't much different from that of a powered 747. I calculate that you get about 15 minutes of glide time from 35000 feet down to 10000 (that's conservative, as is 10000 for "lowest parachute threshold"). 15 minutes is a plausible amount of time to evac an airplane -- though as noted elsewhere, parachutes are a silly idea for an airliner. — Lomn20:06, 1 September 2010 (UTC)[reply]
It's not moving the goal posts, he's just making an unstated assumption. The point is at those altitudes specialized equipment will be needed. (To say nothing of the specialized training!) His argument is that there would not be sufficient time for hundreds of untrained individuals to put on that equipment, therefore he's assuming that they would have to make the jump with simpler, lower-altitude equipment. If they used that equipment "too early", they'd die. APL (talk) 22:13, 1 September 2010 (UTC)[reply]
They're very useful. Perhaps not in a full-on collision with the ground, but it keeps you in your seat during intense turbulence and it keeps you safe during emergency landings. As for parachutes, far too impractical to put on in an emergency situation and if you are unlucky enough to be in a plane that blows up mid-air, then you'll probably die from the fireball or, as mentioned above, from hypoxia/hypothermia. Parachutes won't help there. Regards, --—Cyclonenim | Chat 19:34, 1 September 2010 (UTC)[reply]
Seat belts are collectively very effective, particularly for their price and weight. Naturally, they're not Magical Safety Beans that protect from all forms of danger. Mythbusters also tested the brace crash position a few years back and found that it substantially reduced the shock of a crash landing, if I recall correctly. As for parachutes, there are several problems. First, most accidents are at takeoff or landing, where parachutes are useless. Second, airliners aren't built to allow passengers to safely bail out (the D. B. Cooper thing put a stop to that). — Lomn19:35, 1 September 2010 (UTC)[reply]
Parachutes seem like a good idea, but I think weight alone would make them impractical. Likely to render a lot of flying unprofitable without also noticeably raising fares. A person once advocated having the entire passenger cabin seperate from the rest of the aircraft and parachute 'safely' to the ground. This idea has obviously not caught on. 220.101talk\Contribs20:19, 1 September 2010 (UTC)[reply]
Would putting a parachute on the entire fuselage actually be safer than making a controlled emergency-landing? A "parachute" is just a method for controlled descent. So are wings. Airplanes already have those. The problem is what to do when the aircraft's pre-designed, engineered safety systems fail.Nimur (talk) 20:54, 1 September 2010 (UTC)[reply]
Nimur, I may be 'misreading' your comments here, but I wasn't advocating the "Aircraft Passenger Safety Capsule" concept. The idea was the parachute/s only attached to the 'capsule' that seperated from the wings, tail, engines etc in an 'emergency', say uncontrolled engine fire. The idea seems unworkable in practice. (& The more I think about it the less practical it gets!) ;-) - 220.101talk\Contribs21:12, 1 September 2010 (UTC)[reply]
The FAA and the NTSB make accident and incident reports available to the public. They collect statistics on all incidents that occur in the United States (or involve American aircraft or American airspace or American passengers - actually, the boundaries of how they cover international incidents are kind of fuzzy). But they make all this data public, including final investigation reports that explain cause of aircraft accident and cause of death if there were fatalities. So if you are curious for a specific aircraft, like the 747, you can find full investigative reports. Wikipedia also has a section on accidents and incidents for the Boeing 747 and a full list of Boeing 747 hull losses (with quick summaries of fatalities and cause of accident). You can use this to guide your search through the FAA's list of specific incident-reports. Every incident is unique; but common causes of death are fires and traumatic impacts, depending on circumstances. For example, China Airlines Flight 611 links to a report that indicates many recovered passengers showed signs of traumatic decompression, serious fractures, and massive impact trauma. TWA Flight 800, which exploded in the air, links to this NTSB report, that states: "Injury and burn patterns to the victims as well as some body locations suggest that there was a severe break up of the passenger cabin early in the crash sequence." They clarify,
“
Although some of the accident airplane occupants may not have received injuries that were instantaneously fatal, all occupants received fatal injuries; therefore, the accident was considered nonsurvivable. Sufficient remains were recovered of 202 of the 230 occupants for investigators to make a determination of the level of severity of the injuries received. The following severity criteria was used: severe trauma was defined as "trauma that resulted in instantaneously fatal injuries"; moderate trauma was defined as "trauma that resulted in fatal injuries that could not be determined with certainty to be instantaneously fatal"; and minimal trauma was defined as "trauma in which fatal injuries were present, but not considered instantaneously fatal." On the basis of these criteria, investigators determined that 183 of the 202 occupants received severe trauma injuries, 15 of the 202 occupants received moderate trauma injuries, and 4 of the 202 occupants received minimal trauma injuries. Occupants identified as receiving minimal trauma injuries were all assigned to seats in zone C of the airplane passenger cabin; two of these four occupants were recovered from the surface of the ocean during the first hours after the accident.
Parachutes for airplane passengers is one of those perennial suggestions. The usual cited problems are (a) the weight of all that gear; (b) the impracticality of instructing all the passengers, on every flight, about how to put on the gear; (c) the impracticality of instructing all the passengers, on every flight, on how to properly execute a parachute jump; (d) envisioning what would occur with actually exiting the plane; (e) extensive aircraft redesign necessary (try opening a 747's doors at 30,000 feet. Go ahead, push as hard as you want). If the plane is "at altitude" and is able to fly straight and level enough for people to jump out with a parachute, then the passengers are going to be at less risk if they sit down with their seat belts on and the pilot executes an emergency landing. The Gimli Glider incident at 26,000 feet is the nice example. On the other hand, this company is selling whole-aircraft parachutes for small general aviation aircraft. Comet Tuttle (talk) 21:19, 1 September 2010 (UTC)[reply]
Jon: The reason why your question 'disappeared' (it's actually still there) is because you asked it at Wikipedia:Reference desk/Archives/Science/2010 July 1#Plane Crash not here (see [20] for proof). I was looking at the archive earlier today (in fact looking in my browser history only a few minutes after you asked) and noticed your question and was surprised I didn't recognise it and particularly that there was no answer at all, did notice it had been asked just recently until you asked again here. I presume you ended up at the archive from the link above on the expiration of medicines (that was how I did anyway). Nil Einne (talk) 02:23, 2 September 2010 (UTC)[reply]
The red-brown compound is the anhydrous form. Most hydrated forms are deep purple, a clearer purple than the sample in the picture. At a guess, the sample in the picture is already partially dehydrated; I'm not suggesting that the picture uploader made a mistake in the compound. Physchim62(talk)02:27, 2 September 2010 (UTC)[reply]
Yes, but it's very dangerous. Knocking somebody out means inducing a concussion, which is likely to produce headaches, dizziness, and difficulty concentrating for weeks. At worst it can cause a skull fracture, hematoma or cerebral hemmorhage that can be fatal. The TV thing of somebody being knocked out, being out for a while, then staggering to his feet and going about his business, would be quite exceptional. Looie496 (talk) 22:53, 1 September 2010 (UTC)[reply]
-EDIT: some answers above were deleted now my post doesn't make sense, this wasn't referring to Looie- That last answer is a bit creepy dude! I think both of those answers are not very appropriate.. I think a more appropriate answer is NO the MOVIES DO NOT REALISTICALLY depict how to knock someone out or what happens to an average person when they are punched or knocked out. There have been several widely reported cases in Australia over the last few years of people DYING from being punched in the head once. David Hookes was probably one of the most publicised ones because he was somewhat of a local celebrity. Vespine (talk) 23:24, 1 September 2010 (UTC)[reply]
I agree with Vespine. Movies and comic books convey the impression that a person can be readily rendered unconscious by a single blow with the fist to the chin or the head; and shortly afterwards the person regains consciousness with no side-effects! This impression is entirely unrealistic. A blow from the fist is unlikely to render the victim unconscious, but it is highly likely to leave the victim extremely angry! When a person is rendered unconscious by a blow to the head there is usually some side-effects, and it is not uncommon for there to be long-lasting injury. Dolphin(t)00:08, 2 September 2010 (UTC)[reply]
Actually, as a child I was knocked unconscious twice, under circumstances that closely resembled the movie scenes (i.e. fallen off sliding board, woke up and felt alright while being carried to the nurse). As a child I also saw an apparent "Vulcan nerve pinch" done (though apparently by pinching either side of the spine, rather than the shoulder) under circumstances where it didn't seem likely to be a practical joke. But I know, this isn't evidence. Wnt (talk) 00:32, 2 September 2010 (UTC)[reply]
Thank you for the replies. As I understand it, it would be easy to knock someone out by hitting them in the head with a hard object, but they would not recover as easily as shown in movies/TV. It is not likely to knock someone out by hitting them in the face with a fist. Bubba73(You talkin' to me?), 02:03, 2 September 2010 (UTC)[reply]
What you're missing in the summary is that it's not easy to "knock someone out" in such a way that you have any degree of confidence that you won't kill the person. If your main concern is, say, to stop an attacker, in a situation where you can justifiably kill him to stop him from doing whatever he's doing, then it's just a matter of making the blow hard enough. If you put further constraints on it, it's not so straightforward anymore. --Trovatore (talk) 02:09, 2 September 2010 (UTC)[reply]
I know this is fictionalized and these disease is just a plot element but are there any real diseases that fit Selma's affliction in the abovementioned film? 76.199.146.176 (talk) 23:56, 1 September 2010 (UTC)[reply]
Does anyone know of a flat, rather than round, thrust vectoring system that can vector in the yaw besides the X-36? And does anyone have a picture of the X-36's thrust vectoring system? --TheHighFinSpermWhale03:00, 2 September 2010 (UTC)[reply]
Shrinking helium
In last Sunday's Ask Marilyn article, Marilyn vos Savant discussed helium escaping from balloons. I understand the microscopic porous nature of the balloon, but I'm skeptical of the following statement: "Helium contracts as the temperature drops, which allows gas to slip through the pores of a balloon more easily."
It's a complex process. When a gas contracts because of temperature dropping, the molecular density increases; that is there are more molecules per unit volume of the gas, which may mean more collisions with pores. Of course, as the temperature drops, so does Root mean square speed of the molecules, which may mean less collisions with the pores. Of course, under a first approximation (ideal gas), these effects should exactly cancel. Since real gases behave slightly differently than ideal gasses, its quite more complex, and one effect may predominate over the other. The relevent discussions could be found in the articles Effusion and Graham's law, though the effusion article seems to lack some. --Jayron3204:52, 2 September 2010 (UTC)[reply]
The rubber around the balloon also contracts, and presumably, so do the pores. The walls should actually be slightly thicker as the balloon contracts. Gas transmission rate through the balloon-wall is much more complicated than a simple application of the ideal-gas law. I'd stake my bet on an empirical measurement of gas escape rate as a function of temperature; there are so many relevant factors (gas thermal velocity; pore size; collision rate; rubber material properties, etc) that trying to model them from fundamental physics is unlikely to be accurate. Nimur (talk) 05:35, 2 September 2010 (UTC)[reply]
How do you calculate energy from a pressure difference?
For example a hurricane has an eye 100km by 1km high, so a volume of 1.6×10^11 cubic meters, and a pressure of, say, 950 millibars, compared to 1013 millibars for the air around it. How much energy is contained in that pressure difference? Ariel. (talk) 05:40, 2 September 2010 (UTC)[reply]
Another related idea is Elastic_potential_energy#Elastic_Internal_Energy_in_Compressible_Gases_and_Liquids. Remember that the Gas constant can be expressed in Volume*Pressure OR as Energy, Joules and pascal*cubic meters are (I think) equivalent units. I think the relevent issue is that the potential energy is proportional to either PdV or VdP; that is under a constant pressure changes in volume represent a change in energy; while under a constant volume, pressure differential would be the relevent relationship to energy. So, I think (and I could be wrong here) that this is as simple as volume of the eye * pressure differental across the eyewall; corrected for units. Since m3*mbar is technically an energy unit, you could leave it as that, or you can do the dimmensional analysis, and change it to joules or kilojoules or whatever. --Jayron3206:00, 2 September 2010 (UTC)[reply]
Doing that gives me an energy of 1×10^15 joules (about a quarter of a megaton of TNT), which seems low (this says hurricanes release 6×10^14 J/second, and hurricanes can last at least 2 or 3 days on land). But I'm surprised that it doesn't depend on the density of the air. Wouldn't a heavier fluid contain more energy? Moving a given volume of water takes more energy than moving a given volume of air. Maybe not - I guess with a heavier fluid you need to move fewer atoms to produce a given pressure? Ariel. (talk) 06:07, 2 September 2010 (UTC)[reply]
The actual masses of the particles are irrelevent for this particular calculation; pressure and temperature already account for mass in their inherant formulation. The pressure is merely the force acting on a surface; that force doesn't care whether its a smaller particle moving fast or a heavier particle moving slow; its the same force so its effect on the energy should be the same. Also, that potential energy you have is instantaneous potential, that is the energy of the storm right now Besides dissipating energy, a storm also accumulates energy over time; that 1E15 Joules of energy you just calculated is not the total energy availible to the storm, since it will continue to gather energy even over land. On the balance, the storm loses more energy than it gains over land, but that's only because the rate of dissipation is greater than the rate of accumulation; the rate of accumulation is not zero. --Jayron3206:22, 2 September 2010 (UTC)[reply]
That page says "When a tropical cyclone passes over land, it is cut off from its heat source and its strength diminishes rapidly." Seems to me that hurricanes must store energy somewhere else besides the pressure gradient, maybe in all the moisture they carry with them. Ariel. (talk) 06:39, 2 September 2010 (UTC)[reply]
Again, that doesn't mean that the energy accumulation over land is zero, only that it is much smaller than the energy accumulation over water. The energy is stored in both the pressure gradient, and in the internal energy of the gasseous water molecules, as compared to the internal energy of liquid water. If you want to know ALL of that energy, you'd also need to know the temperature of the air in the defined volume; that temperature should equal the dew point (the air should be saturated) so you can then compare that to the vapor pressure of water at that temperature, which can then be used to find the partial pressure of the water vapor, which can be used to calculate the total mass (or moles, whatever) of water vapor in the air. You can then use that to calculate the energy differential between the gasseous and liquid water; i.e. the latent heat of vaporization. However, your question only dealt with the energy stored as the pressure gradient. --Jayron3206:48, 2 September 2010 (UTC)[reply]
Yes it did because I thought that was all of it. I'm going to try calculating the water energy tomorrow (unless someone wants to do it for me :) BTW thank you for the replies. Ariel. (talk) 06:56, 2 September 2010 (UTC)[reply]
Another idea (just popped into my head); a third, probably non-negligible source of energy is gravitational potential energy. After all, you just raised a HUGE mass of water rather high into the air, this height differential should itself be a possible source of potential energy. --Jayron3207:00, 2 September 2010 (UTC)[reply]
Falling stick
A straight vertical rod of length l, when pushed, slides for a little while and then topples from the vertical position. What will be the velocity of the upper end when this end hits the ground?
My approach was to use the work due to torque (∫τdθ = (1/2)Iω2) about the end touching the ground, but I don't think this is right. If axis I'm using is accelerating (and if there's friction, it should be accelerating), then won't I have to take into account ficticious torques? But that would mean knowing something about the friction, no? 74.15.136.172 (talk) 10:45, 2 September 2010 (UTC)[reply]
To me this looks like a much simpler question. The horizontal component seems to be neglected, what with the "push" and the "sliding" and all. But for the vertical component, you know that the stick starts with the potential energy g*(l/2)*m (m=its mass, irrelevant) and no kinetic energy (neglecting horizontal). When it hits the ground it has zero potential energy and (neglecting any energy dissipated in friction) kinetic energy 1/2 m v^2. So v (on average) = sqrt ( 2/m * m/2 * l * g) = sqrt (lg). If one end is stationary, then the other end should be twice that. Unless I forgot something. Wnt (talk) 14:10, 2 September 2010 (UTC)[reply]
Mathematical sequence
Hello PPL, whats the best approach for solving mathematical sequences like 1 4 17 54 145 368 945 ___? , the ones that are in IQ tests?Is there any kind of logical one? Or just trying blindly? TY much and sorry for my english.194.138.12.146 (talk) 12:41, 2 September 2010 (UTC)[reply]
For integer sequences, taking forward differences is a good place to start. If you don't see a pattern in the first forward differences, take forward differences again, rinse and repeat. Or, if you get impatient, you can look up the sequence at OEIS. Gandalf61 (talk) 12:55, 2 September 2010 (UTC)[reply]
I didn't see the pattern in the forward differences, even after looking at the entry - maybe I needed to compare something other than adjacent terms? But the ratios tell you something is up that is more complicated than an xn+1=axn+b sort of thing:
Actually I was asking the question from work, was not signed in, after 5 hours and 5 papers I solved it. After a while I began to try combinations with 2^, as it didnt work I tryed 3^, and there I saw a pattern, the algorithm is n^3+3^n but I was not following any rule for solving it.And its not "that" public, I was looking specifically for"Titan Test"DSTiamat (talk) 16:08, 2 September 2010 (UTC)[reply]
![[14]](https://commons.wikimedia.org/wiki/File:CaldwellStarChart.svg){kind=link}
