Wikipedia:Reference desk/Science

March 1

Organisms

What causes organisms to be different in appearance?

Their DNA. StuRat 00:53, 1 March 2007 (UTC)

I'd go one step further and suggest it's their protein expression--VectorPotential^Talk 00:55, 1 March 2007 (UTC)

I'm going yet another step further and suggest Quantum Mechanics. 202.168.50.40 22:45, 1 March 2007 (UTC)

On another point of view, the reason their appearance is different is that the organisms are different shapes, sizes and colours, due to their growth into that shape. The growth and shape will depend on the way that cells divide, which direction they elongate, junctions between cells, how fast cells grow - or how big, or some parts dying (eg hair). The colours often depend on pigments such as chlorophyll carotene melanin haemoglobin. GB 03:55, 1 March 2007 (UTC)

To take the colour as an example in more detail, different species have different types of cells (called chromatophores) that can generate lots of different colours in the hair and skin. Mammals have only one type (melanocytes) that can make yellow/red or black/brown pigments (called melanin). This is why all mammals are variations of these colours (and white, of course, which is a lack of pigment). Fish, reptiles and amphibians have lots of different types of chromatophore that can make black, brown, yellow, red, orange blue, red, silver colours. By mixing these together you can get pretty much every colour you can imagine. This is why fish are much more brightly coloured than mammals. Rockpocket 18:28, 1 March 2007 (UTC)

Coilguns as infantry weapons?

Suppose that the problem of generating sufficent power over a long enough period of time to make it practical as an infantry weapon, would there be any advantages in replacing traditional rifles with coilguns? As I understand it, there is no recoil with a coil gun, which seems like an obvious advantage - larger caliber rounds could be used at a higher velocity with perfect accuracy. Would it also be possible to create an automatic coilgun/coil-minigun? --81.77.38.252 02:00, 1 March 2007 (UTC)

No, there would still be just as much recoil. We're talking about a conservative force; there is still recoil even though a magnetic field is being used to transfer kinetic energy to the projectile rather than a chemical reaction. Think about a permanent magnet and a chunk of ferromagnetic material (like iron). If you hold one in each hand and bring them into close proximity, do you only feel an attractive force on the iron? -- mattb @ 2007-03-01T02:30Z

Wouldn't an automatic coilgun also get extremely hot, extremely quickly? I could see coilguns being excellent as sniper rifles - large caliber, high velocity, no muzzle flash, no gunshot sound. Steel-jacketed, depleted uranium fragmentation rounds - yum! Now, we just need to figure out how to reduce the size of the battery required, so that it fits comfortably into the butt of the rifle, or attaches like a conventional ammo clip (as opposed to being a 150lb backpack)... ;) --Kurt Shaped Box 17:36, 1 March 2007 (UTC)

I've did some research on coilguns (trying to build one myself) and all sources indicate that coilguns take an extremely long time to charge. So automatic coilguns are out of the question. The range is also abysmal, and there is no rifling action to stablize the flight of the projectile, making it highly inaccurate. -- 我♥中國 03:12, 2 March 2007 (UTC)

Looking for quotation: only a small percentage of the general public will ever be able to master the skill of operating an automobile

Someone famous, like Karl Benz, was quoted saying something to the effect of: "only 1% of the general population posesses the physical coordination to be able to learn how to drive a car".

Something like that. searched for hours on Wikipedia and Google, but found nothing. I don't recall who said this, and am now doubtful it was Karl Benz, but I heard it in a documentary several years ago... though I can't remember anything else about the documentary.

I'm using it for a video about how throughout history, people have thought that technologies would be out of reach of the common people, but over and over again, technology finds widespread use. Any other good examples of this would be helpful, such as Kevin Kelly's quote from Wired that when the Internet was developed, nobody could've guessed that 99% of the content would be created, not by corporations and governments, but by the people themselves.

I don't know the source of that either - but were you aware of the British government's study that estimated that four computers would be enough to cover the computing needs of the entire nation? SteveBaker 03:10, 1 March 2007 (UTC)

Harrumph! You mean Douglas Hartree's estimate that three computers would be enough. As recalled by Lord Bowden in a 1969 lecture (to be found in the 1984 anthology "Mathematics: People, Problems, Results", edited by Douglas M. Campbell and John C. Higgins, ISBN 0-534-03201-X) (I hope this isn't long enough to be considered a copyright violation):

I joined Ferranti in 1950. They had nearly finished building the first digital computer ever to be made by a commercial firm in England and they asked me to see if it would be possible to manufacture such machines and sell them at a profit. Our machine could do simple arithmetic a thousand times as fast as a man with an adding machine, but it was not at all obvious that anyone would be prepared to pay a hundred thousand pounds or so for it. ...

I must remind you that this was in the days before IBM. I went to see Professor Douglas Hartree, who had built the first differential analyzers in England and had more experience in using these very specialized computers than anyone else. He told me that, in his opinion, all the calculations that would ever be needed in this country could be done on the three digital computers which were then being built -- one in Cambridge, one in Teddington, and one in Manchester. No one else, he said, would ever need machines of their own, or would be able to afford to buy them. He added that the machines were exceedingly difficult to use, and could not be trusted to anyone who was not a professional mathematician, and he advised Ferranti to get out of the business and abandon the idea of selling any more of them.

It is amazing how completely wrong a great man can be. The computer business has since become one of the biggest in the world. Hartree used to tell this story against himself as long as he lived, but I want to emphasize the fact that in 1951 it was much harder to see into the crystal ball than you might think. Ferranti needed a new product, and they were more hopeful than Professor Hartree, so I canvassed the optical industry, the aircraft industry, the civil engineering industry, and our newly established Atomic Energy Authority, and I found that they all faced the same problems.

If the calculations were short, they were done on desk calculating machines operated by clerks. During World War II, Professor Sydney Chapman asked the Home Office to teach long-term convicts to use adding machines for the war effort, but this admirable suggestion was rejected on the grounds that it was unfair to punish a man twice for the same offense and that it was bad enough to be in jail. Nevertheless, there were large numbers of professional calculating-machine operators, and Dr. Comrie had worked out complicated ballistic tables for the RAF on the National Cash Register machines which he had used to calculate the Nautical Almanac.

If the calculations were long and complicated, there were three overwhelming objections to the use of a computer. The machine usually broke down before it had finished the calculation, its memory was too small to hold all the data it needed, and, worst of all, it took so long for the mathematicians to get the program right that it was usually quicker (and cheaper) to get the calculation done by clerks, or to build the device the computer was trying to design, whatever it might be, and try it out. This was quite good enough for opticians who designed new lenses. But experimental aircraft are very expensive to build, and the test pilot takes his life in his hands ... I came to the conclusion that there were a few calculations that would be worth doing on a computer...

And I had to sell the wretched things ... I thought I had the most peculiar job on the world until I met a man on the Queen Mary who sold lighthouses on commission ...

--Anon, March 1, 2007, 08:33 (UTC).

Yeah - that's the one. I thought the government said they would need three computers in England - and possibly a fourth in Scotland. But that was from memory - I could easily be wrong. Anyway - thanks for the quote. That's exactly the thing I was thinking of. I concur about the difficulty of estimating these things. I worked on the team that invented the CD-ROM, we thought that 600Mbytes of storage would be more than enough for any conceivable application...now we have DVD's and they aren't big enough - so we are going to have to have BluRay-ROM and HD-DVD-ROM. I'm not going to make that mistake again! SteveBaker 16:00, 1 March 2007 (UTC)

After a cholecystectomy...

People who are having their spleen removed have to take vaccinations. Similarly, do people who have their gallblader removed have to take any kind of medicine post-surgery? Thanks in advance for answers, Jack Daw 03:03, 1 March 2007 (UTC)

No. The spleen has a function, called opsonization, in the immune system. That's why it's recommended that various vaccinations be performed before a splenectomy (if its not an emergency) and why people without a spleen are especially susceptible to infection by bacteria that require opsnization for an immune response to occur (i.e., encapsulated organisms). But the gall bladder has no immune function; it's basically just a sac for bile to collect in until it's used. In general, when it's gone, it's not missed at all. - Nunh-huh 03:46, 1 March 2007 (UTC)

Not eating large quantities of fat might be recommended for those who have had their gall bladder removed. This is good advice for everyone, but especially for them, as they may no longer be able to digest large quantities of fat, and it may come out as diarrhea, instead. StuRat 14:12, 1 March 2007 (UTC)

Sabertooth Tigers

The way I learned it when I was a kid, sabertooth tigers' fangs grew longer, and longer, and longer, until they got too long and killed the tigers. (Correct me if that's wrong.) I've heard a similar story about a breed of deer and their antlers. The thing that recently occurred to me is, how? How could that possibly happen? The whole point of natural selection in the first place is that the dangerous end of the spectrum gets weeded out, and species invariably gravitate towards the optimal level of any attribute if they possibly can. As soon as part of their population started dying from excessive long-toothedness, things would wander back in the other direction or stabilize. How did it happen, then? Black Carrot 04:54, 1 March 2007 (UTC)

I'm pretty sure that story about the fangs is an urban legend, or a prehistoric legend, or whatever.

You're right, evolution would normally not engineer something so broken.

However, there's a lesser-known quirk about evolution which is that it does not work nearly so hard to optimize the characteristics of an organism after its reproductive age. If a creature gets increasingly crotchety or frail in its old age, its individual fitness may be diminished, but given that it has already passed its genes on to its offspring (or not), the fitness of the species is not compromised. An adult organism past its reproductive years may still care for its young, so there's indirect genetic pressure to keep it fit long enough to do that, but once the offspring can survive on their own, the fitness of the adults simply doesn't matter in an evolutionary sense. (And indeed that's why animals get old and die, at all.) So if this hypothetical fatally-too-long fang in the saber-tooth cat story were actually true, but if the fang only grew long enough to kill the cat after it had reproduced and raised its young to self-sufficiency, there wouldn't be any genetic pressure to "fix" the mistake. —Steve Summit (talk) 05:43, 1 March 2007 (UTC)

P.S. This page (linked to from our Saber-toothed cat article) discusses evidence that saber-toothed cats lived to an advanced age, quite possibly cared for and fed by other members of their pack even after they could no longer hunt. It doesn't mention anything about dying of too-long fangs. —s

I thought this was with rabbits, where the teeth keep growing forever...--Honeymane_{Heghlu meH QaQ jajvam} 05:49, 1 March 2007 (UTC)

First, there are animals which have teeth that grow forever, such as rodents. They just need to chew on things constantly to grind them down. There is another odd thing that sometimes happens, where a feature is selected for because it's important for mate selection, to the point where it becomes actually harmful to the species. The passenger pigeon is one example, where they would mate, in flight, by the millions. They would refuse to mate if the two birds weren't inside a cloud of millions of other passenger pigeons. This had the advantage of only allowing the fittest birds, those which could fight their way into the center of the cloud, to pass on their genes. However, when people came along this hurt them in two ways. These huge clouds of birds made easy targets for hunters with shotguns, who could kill dozens with each shot. Then, once the population was reduced to a certain point they no longer reproduced, as they never felt they were in the center of the cloud, because it wasn't dark enough due to the fewer number of birds. Thus, their evolution made them actually less fit to survive than other pigeons, and led to their extinction. I suspect that, had they had more time to adapt, a few mutant "deviants" which reproduced outside this cloud would pass on their genes and we would now have a "non-cloud" variety of passenger pigeon. Unfortunately, they couldn't adapt in time.

Other examples of absurd reproductive displays exist, especially in birds, such as the peacock or bower bird. It's hard to understand why a variety that put it's energy into building nests, feeding the young, defending the group, etc., wouldn't do better than one which puts so much energy into display.

I believe saber-toothed tigers, as well as many other large animals, were killed off in the Americas when people first migrated into the area and hunted them. Interestingly, many large animals, like lions and tigers, were able to survive in the Old World. I believe this is because they adapted as people slowly became a threat (as the people developed better weapons). Those which avoided people passed on the "timid" gene, and today most large animals avoid people. In the Americas, however, the people came in already with formidable weapons, and the large animals likely didn't see people as a threat, due to the animal's larger size, and were wiped out before they could adapt.

There are a few large animals which survived in the Americas, such as moose, elk, bears, alligators, and bison. I suspect those animals had places to hide that allowed them to survive. The moose and elk tended to live in northern Canada, too cold and treeless for large populations of people to exist and hunt them to extinction. Bears hibernate, so would be hard to find and hunt for good portions of the year. Alligators hide underwater and in swamps much of the time. Bison could hide in huge herds. A herd of a million bison was able to survive the onslaught by people, at least until firearms appeared. StuRat 13:51, 1 March 2007 (UTC)

Can I have some info on native New Zealand alpine flowers?

I have an assignment for biology and ive looked through all sorts of bookas and googled extensivley but i cant find any inormation on Raoulia and Celmisia, which are 2 native alpine plants from New Zealand. Can you help at all? Thanks xx 219.88.12.217 07:28, 1 March 2007 (UTC) Mia

We seem to be lacking in articles for both of these. Here's what I found:

• Kea bird that eats the seeds of both of those plants
• Asteraceae Family of daisy-like flowers that includes the Raoulia
• Tongariro National Park has lots of Raoulia plants: Raoulia albosericea covers an area of 165 km²

This topic seems awfully specific, but I'm still surprised that Wikipedia has so little information. Have you checked a university science or botany library? Nimur 08:32, 1 March 2007 (UTC)

I have found the following Raoulia Australis sites:

• Lots of facts
• Several photographs

It seems that the plant is a tightly-packed bush whose leaves grow so tightly that only their tips are visible. The plant grows on rocky outcrops at high altitudes (1200 - 1800 meters). It can survive in this rocky environment by holding water inside its close-knit inner branches. Nimur 08:51, 1 March 2007 (UTC)

The plant-geek community also likes to use Raoulia as a "stumper" - i.e. a piece of botanical trivia that only the most hard-core enthusiasts know. Nimur 09:24, 1 March 2007 (UTC)

Here is information on Celmisia semicordata:

• Lots of facts
• Some photographs

This is the "alpine daisy" or "cotton plant" (not to be confused with actual cotton). It grows natively in New Zealand, but has been exported throughout the rest of the world as a garden plant. It has white daisy-like flowers.

I realize I'm violating the you should do your own homework clause of the Science Reference Desk. These links easily popped up in Google (simply by searching for Raoulia and Celmisia, respectively. But oh well. Information is free. Perhaps a less lazy editor will create the Raoulia australis or Celmisia semicordata articles. Please be responsible with the above links; their information is probably copyrighted; respect the authors' creative wishes. Nimur 08:58, 1 March 2007 (UTC)

Cassiopeia A

A recent copy of 'Astronomy' and also your entry under this subject staes that this object (a neutron star) is 10 000 light years away from Earth. It also states that it exploded i 1667 and was first detedted in 1947.

Now, I understand that nothing can travel faster than light. So surely if it took 280 years for detectable radiation to reach Earth then Cas A must be +- 280 light years from Earth ?

198.54.202.250 07:36, 1 March 2007 (UTC)

I think you're misunderstanding the intended tone of the article. The supernova was first detected in 1947, this is the first time that we on earth observed cassiopeia A, and at that time it was supernova. There were no records of cassiopeia before this time. This was the first signting of this object. We have theorised that the Supernova started 300 years ago, this is the 1667 date, this is when it visibly started from Earth (but we could not detect it at that date, because of poorer astronomy techniques, or we just werent looking in the right place). All of the times on that page are "observed time" and don't take into the account that it's 10000 light years away, it's probably not still a supernova, but we still observe it as such. Capubadger 07:54, 1 March 2007 (UTC)

This is wrong. It was not a supernova in 1947. The visible event would have been short-lived and is theorized to have occured 300 years ago, but there are no clear recorded observations of it. In 1947 a bubble nebula was observed, which is the remnant after effect of a recent supernova. Based on the size of the bubble, they calculated the ~300 years. However, as Capubadger says neither date considers the 10000 year delay in travel time for the light to reach us. Dragons flight 09:36, 1 March 2007 (UTC)

Thanks, I'm learning too :) Capubadger 10:02, 1 March 2007 (UTC)

Yes, a supernova remnant is the general term for what is left after the supernova has ended. Many of them are quite beautiful, incidentally. StuRat 13:29, 1 March 2007 (UTC)

Capsule /pill Material....

What are the small round things inside a capsule called? They look like non-pariels to me but when I search, it only comes up as a bakery term for decorating chocolate and cake.

I assume they're the actual drug. The capsule is just a delivery method. I don't know if they have a specific name. Capubadger 10:05, 1 March 2007 (UTC)

Okay... than the actual drug inside a pill (in whatever form it is) can be called just "content", "material"? I am getting a kick out of it because the medical/pharmaceutical business has so many names for other things, yet the little round "pellets" inside a capsule have no specific name. Thanks

Pellets sounds good, But maybe someone in pharmacy can sound in.. Or you could try the language board. :) Capubadger 13:23, 1 March 2007 (UTC)

Pellets is right Mabris 22:03, 1 March 2007 (UTC)

I remember advertisements years ago for the decongestant Contac that said the pellets would enter your system at different speeds to give a longer-lasting effect, and it called them "tiny time pills". Obviously a phrase made up by the advertisemnt writer! --Anonymous, March 2, 00:40 (UTC).

List of countries with their positions on the world

Hello, I want to know, where are situated countries on the world. I found in Wikipedia only list of countries by northernmost or southernmost point, but there's only one coordinate. Could you write an article with list of countries and with their latitude + longtitude? Like this [[1]] , but with both their coordinates. Coordinates of centers of this countries would be great.

Thanks a lot, it's quite hustles. tomasslavicek[at]atlas.cz

The General Measures of Geography dataset from Harvard's Center for International Development includes coordinates of country centroids. -- Avenue 11:18, 1 March 2007 (UTC)

Coal pile fire

There is a big coal power plant close where my cousin lives. There is a big pile of coal close the coal plant. My cousin tells that there is often fire going on at the coal pile. When he saw the fire the first time he called fire department, but person in fire department said that they are aware of that fire, and people call them time to time about that, but the fire is normal and has been appearing for a long time, and it does not bother anybody. So they did not extinquish it. This is a rich country so surely it is not that fire department is too poor, stupid or corrupt to extinquist the fire, and surely if it would be hasard they would extinquish it - they just do not see it is needed to extiquish it. I would like to know how fire can be normal and okay. Does fire not eat coal away and therefore cause costs? Does it not pollute? Or is it possibly something else than real fire, like will o' the wisp or electricity or chemical luminance? Majji 11:47, 1 March 2007 (UTC)

The problem is it's extremely difficult to extinguish, especially if in a coal mine. Spraying water on it alone doesn't work. You would need to completely enclose the fire and rob it of oxygen. Perhaps some type of thick foam could do that. Even then, the coal is such a good insulator that the coals in the center would remain hot enough to reignite years later, whenever oxygen again became available. So, you would then need to drill holes into the pile and inject water in to cool those coals (being careful to avoid the superheated steam that comes out). This would also ruin the coal, however. StuRat 13:11, 1 March 2007 (UTC)

Coal has been underground for tens of millions of years, so I doubt that water from a fire hose would "ruin" it as it it wre a charcoal briquet which would fall apart. I know that there are long-burning fires in coal mines, but I do not understand a power company allowing a fire to burn up coal thay have purchased and mover to their generating plant. It would violate air pollution laws in most localities and the burning coal would be a disaster if it got placed on the conveyor belts into the plant. It is brought in a train car load or barge load at a time and placed in a coal pile. Bull dozers can be used to spread it out and fire hoses to extinguish a blaze. If it is a mine-mouth station then maybe it is a coal mine fire and not a coal pile fire. If there is a long-runnng fire in a coal pile at a power plant, one could complain to the CEO of the company, to the Environmental Protection Agency or state air quality board or equivalent if outside the U.S. Edison 15:07, 1 March 2007 (UTC)

It's not permanently "ruined", but would need to be spread out and dried before it could be burnt, and this would again cost more than the coal is worth. StuRat 17:44, 2 March 2007 (UTC)

It is not mine-mouth station. The coal is brought from another place by train. Fire department has known about the fire for years so if there would be something illegal about it they would have reported it further. In this country the officials are very strict about environmental issues, so they must somehow think the fire is not a problem for environment. By the way they are closing the plant soon, not because the fire, but because goverment tries to cut carbon dioxide emissions. No newspaper article or television story about its closing told anything about the fire. I have never seen anything about the fire in media. Its not always visible, so there are many people who have never heard of it even if they have seen the pile. Majji 16:49, 1 March 2007 (UTC)

It would be important to know what country. In some countries, I would suspect corruption. --Zeizmic 19:32, 1 March 2007 (UTC)

Sweden Majji 20:12, 1 March 2007 (UTC)

Per[2] and [3] the coal inside a coal pile may catch fire from spontaneous combustion. It combines with oxygen, producing heat, and the temperature gradually climbs until ignition temperature is reached inside the pile. During the heating phase ethane, methane, and hydrogen are released, creating the possibility of gas explosions. Thermal imaging can detect this before the fire is a big problem. Other sources show utilities routinely watering the coal. Fires in coal bunkers on old steamships were apparently common: they would shovel the burning coal into the furnace: end of problem. But burning coal going up the power plane conveyor belt to be pulverized is a huge problem. So if they got it put out, it might spontaneously reignite over and over. Steam explosions can be a hazard of using firehoses on a coal pile fire. Foe some stories of the fire fighting, see [4]. Edison 16:53, 2 March 2007 (UTC)

What is a string (in string theory) made from?

in "http://en.wikipedia.org/wiki/String_%28physics%29" the definition of a string is: "A string is an object with a one-dimensional spatial extent".

What is this "object" made of? (it cannot be meterial as this is the basic building block of any material, it cannot be energy as this is the basic energy carrier).

Is it possible the change the vibration of a string? how?

87.68.156.66 12:05, 1 March 2007 (UTC)

The superstring is a brane. [Mαc Δαvιs] X (How's my driving?) ❖ 12:16, 1 March 2007 (UTC)

It isn't really made of anything, and describing it as an actual string isn't really accurate. It's just what the action looks like. --Philosophus ^T 13:47, 1 March 2007 (UTC)

Nothing - it's just a mathematical description of the way things work at the lowest possible level of existance. Beware though - String theory isn't by any means a proven thing and the latest thinking is that perhaps it's a blind alley that too many people have been working towards. SteveBaker 15:51, 1 March 2007 (UTC)

Asking the reductionist question "what is it made of" has been such a successful strategy for such a long time in the physical sciences that it is eays to forget that it doesn't always have an answer. What is happiness made of ? What is the number 1 made of ? When we get to strings we have reached the bottom of the reductionist ladder (if string theory is correct). So strings aren't made of anything - they just are. Gandalf61 16:54, 1 March 2007 (UTC)

Strings are a way of mathematically modeling the behaviour of energy. Matter is the same as energy (E=mc²). In some ways, it is the answer to the question "what is energy?"

[Strings] are almost inconceivably small, 1020 10²⁰ times smaller than an atomic nucleus. For Brian Greene [...] strings appear as "tiny, one-dimensional filaments somewhat like infinitely thin rubber bands". [...] They are "minute loops of energy", says John Horgan in The End of Science (Addison-Wesley, 1996). "A string is just a loop drawn in space", offers Lee Smolin, in Three Roads to Quantum Gravity (Weidenfeld & Nicolson, 2001). It is not made of material at all. It is what material is. As for elementary particles, there is no real content to the question, what are strings made of? They just are.

— Jon Turney, Nature (link to source)

I think the actual string theory page is a little better at describing it than String (physics). It is also worth noting that string theory is still being developed, and its predictions are not well tested. --h2g2bob 19:23, 1 March 2007 (UTC)

I don't think that number "1020 times smaller than an atomic nucleus" is right. Shouldn't it be 10²⁰ times smaller? SteveBaker 22:14, 1 March 2007 (UTC)

Yep, sorry, it lost the superscript when I copied-and-pasted --h2g2bob 04:05, 2 March 2007 (UTC)

Some might say that String Theory has fallen out of mainstream physics. It has been in the works for nearly thirty years and still has no predictable results. Its primary attraction is its glamorous sounding terms (Calabi-Yau manifold!) and popular appeal, but it is not necessarily scientifically credible. Nimur 21:39, 1 March 2007 (UTC)

The trouble is that it's still unfalsifiable and it hasn't made any predictions that we're remotely likely to be able to test. At best it's a useless theory even if it turns out to be correct. SteveBaker 22:16, 1 March 2007 (UTC)

String Theory is the modern alchemy. Future generations will laugh at us for believing in stupid things like this (without physical evidence). The problem with string theory is the use of the word "theory". It's not a theory, it's merely a hypothesis. Sure it is very elegant, so is describing matter as being made from 4 fundamental elements AIR, EARTH, FIRE and WATER. 202.168.50.40 22:51, 1 March 2007 (UTC)

I agree. Although Alchemy started to get a bit problematic when they had to have fire ('phlogiston') have negative mass in order to make the masses in some reactions work out correctly. Then some reactions "let the fire out" and some "absorbed fire" - it all became rather arbitary. I wouldn't really say it was elegant - although (aside from the negative mass of phlogiston), they basically had the right idea - they just needed a lot more elements than the four they settled on. String theory is nothing if not elegant - and the fact that we can't test any of the things it predicts is really just unfortunate - that doesn't make it wrong. There is a long history of the more elegant theories winning out over the ikky complicated ones. The main problem I have with the theory is that if it's not going to predict anything, it's just not very useful. Since so many great minds have spend so many of their best years working on it, it may well be remembered chiefly as a tragic waste of human effort. SteveBaker 02:49, 2 March 2007 (UTC)

Wow, I didn't know so many experts on theoretical physics monitored this board Not every scientist in the field agrees with the criticisms expressed above. The article String theory says "String theory as a whole has not yet made falsifiable predictions that would allow it to be experimentally tested, though various planned observations and experiments could confirm some essential aspects of the theory, such as supersymmetry and extra dimensions." Robert Goddard's notions of sending rockets into space and Einstein's Theory of Relativity were similarly disparaged, as was the Newton's finding that a prism separated light into the various wavelengths. One use of string theory is to provide a nice exposure for Brian Greene . Edison 17:23, 2 March 2007 (UTC)

Yes. But each of your examples were falsifiable. Goddard actually built a rocket. Newton actually built a prism. Einstein didn't do much, but he gave predictions about certain phenomena that were empirically tested (the 1919 astronomical observations come to mind). I've had the chance to hear Brian Greene speak (both in "public" format and in theoretical-physicist mode), and he makes a few hand-waving references to a new hadron collider at CERN in the next few decades, but as far as I'm concerned, his work is primarily a mathematical concoction, not really a scientific theory with testable results. Perhaps "testable results" is a bit too vague, so I will rephrase it in stronger terms. Science, as a whole, uses experimental studies to guide our abstract understanding about our universe. Without experiment, abstraction has no relevance to reality. So when a theory does not have "testable results," that means it has no real manifestation in our universe. I find it very hard to stomach a "fundamental theory" which does not explain anything, no matter how many fancy pictures, graphs, equations, or diagrams it may include. Nimur 19:19, 2 March 2007 (UTC)

suicidal behaviour

what i want to know is that how can we explain this behaviour of commiting suicide if our gene is selfish. how can it command to end life before time if life is so important for any species. and is this kind of action reported in any domestic or wild animals. can we say that only human brain is so emotionally developed that we can think of such actions.

It is possible that the death of an individual can further the spread of the genes of that individual, by helping those genetically related to that individual to survive. However, this is rarely accomplished by suicide in nature. Most often, death occurs by "old age", which really means the individual's genes have programmed them to die at a certain age. The most dramatic example of this is in salmon, which live for several years, and are at their healthiest when jumping up waterfalls to return to their breeding grounds. Then, after they mate, apparently a chemical switch is thrown and they die "of old age" in a few hours, providing food for the young salmon that carry their genes. Another method used is homicide, when members of the same species kill off those which have outlived their usefulness. Those female insects which kill the male after mating come to mind here. Predation also kills off the old in many species, leaving more food for their offspring to survive. Reproducing and dying also helps to increase the rate at which a species can adapt, and thus furthers it's survival. Suicidal behavior in humans is sometimes in the form of not wanting to use up resources needed by their relatives, but more often seems to be a "brain malfunction", where a young person could go on and contribute and pass on their genes, but chooses not to. This is a consequence of having a complex brain; more complex systems have more frequent malfunctions.

Note that some multi-cellular organisms don't die "of old age", however, such as certain trees. I believe, in those species, the advantages of age (such as the old tree being taller than trees of other species and thus being able to capture the sunlight) outweigh the disadvantage of taking resources from those individuals genetically related to themselves, which makes fewer survive and reduces the rate at which that species can adapt. StuRat 12:41, 1 March 2007 (UTC)

• I know very little about suicidal behavior in animals apart from the fact that the story about lemmings is a myth. I would consider ants suicidal, but they only run into their own death if it saves the rest of them. Just because our genes are programmed for survival doesn't mean we have to do it. People also have free will. Only the chemicals needed for cognitive processes are coded in our DNA, not our thoughts. - Mgm|^(talk) 13:48, 1 March 2007 (UTC)

The selfish gene theory does not imply that the organisms in which they are found are selfish. Instead, it is the idea that genes compete with other genes for survival, rather than organisms competing with other organisms of their species. − Twas Now ( talk • contribs • e-mail ) 17:45, 1 March 2007 (UTC)

According to selfish gene theory, its not even survival that is the gene's primary interest, per se, its propagation. Therefore once the genes have propagated (by reproduction) it might be in the interest of parent organism to sacrifice itself if it increases the chance of its offspring (or any relative that contains its genes) surviving. Especially if the parent is past reproductive age. If resources were scarce, the suicide of a parent could make sense in a selfish gene strategy (consider the classic "you'd be better off without me" suicide note). Some hive animals, like certain ants and bees, will have members that will go out on what are essentially "suicide missions". The complex genetic relationships between the Queen and her hive means that this actually makes a lot of sense in terms of selfish gene theory, even though it appears very unselfish on the face of it. The excellent book, The Selfish Gene explains. Rockpocket 18:16, 1 March 2007 (UTC)

Yes, good clarification. But when speaking of genes, there isn't really a distinction between propagation and survival. At the gene level, propagation is survival. The Selfish Gene is a wonderful book. − Twas Now ( talk • contribs • e-mail ) 23:02, 1 March 2007 (UTC)

Indeed, good clarification of the clarification. I should have been clearer and said "its not even survival [of the organism] that is the gene's primary interest, per se, its propagation [of the gene itself]." Rockpocket 02:46, 2 March 2007 (UTC)

Regarding numerical weather prediction modeling

Sir I am a research student working on numerical weather prediction .I want to know about meteorological data, that which type of data used to run a numerical model.is it surface or upper air data.

Both. Also, ocean currents and temps are critical, especially in predicting hurricanes. StuRat 13:31, 1 March 2007 (UTC)

And ionospheric measurements! Nimur 21:43, 1 March 2007 (UTC)

oxen or bulls grazing habits

I have observed that horses graze by uprooting the grass. When we send them out to graze in a grassy paddock, it quickly turns from geeen to brown.

Cows can graze in fields for a whole season and it reamins green. I guess that is beacuse they only eat the top of the grass.

But do bulls graze like horses or cows? Does the male cow uproot the grass when grazing? —The preceding unsigned comment was added by Akivaw (talk • contribs) 16:37, 1 March 2007 (UTC).

I'm sure they feed bulls a form of protein instead over here :] Hidden secret 7 17:08, 1 March 2007 (UTC)

And they used to feed cows sheep-brains over here :-S I'm pretty sure bulls eat like cows. Skittle 19:02, 1 March 2007 (UTC)

Since a cow and bull are the same species, I think they would have similar eating habits. Cattle and horses are quite distantly related. − Twas Now ( talk • contribs • e-mail ) 17:33, 1 March 2007 (UTC)

I know that different types of grazers shear the grass at different heights. Some are less destructive than others. I don't know which animals eat which amounts, though. I really wish I had taken a class in animal science in school... Nimur 21:58, 1 March 2007 (UTC)

Fat and exercise

If one exercises enough, is it okay to consume a lot of fat? --Masatran 16:47, 1 March 2007 (UTC)

cholesterol might be a problem, and you could affect other parts of your balanced diet, but it might work :) Hidden secret 7 17:07, 1 March 2007 (UTC)

If you are going to exercise a lot, it is generally better do consume carbohydrates. It sort of depends on the intensity of your workouts though. − Twas Now ( talk • contribs • e-mail ) 17:32, 1 March 2007 (UTC)

Some might say that if you partake in a low carb diet to induce ketosis, you can eat all the fat you want.Mabris 21:57, 1 March 2007 (UTC)

The suspected link of low-carb diets to osteoporosis might be one of the unfortunate sideeffects of that approach. ;) -Wooty Woot? contribs 22:23, 1 March 2007 (UTC)

The bad breath and bowel irregularity are more immediately unfortunate ;) Mabris 22:48, 1 March 2007 (UTC)

The short answer is NO. Even if you ran a marathon everyday, this does not give you a licence to eat KFC everyday. The simple reason is that you would eventually die from a heart attack caused by the clogging of your arteries. Just because you are skinny does not mean your arteries cannot clog up. 202.168.50.40 22:41, 1 March 2007 (UTC)

When looking at how your food effects your health, there's an important difference between saturated fat and unsaturated fat. Looking strictly at weight gain or loss, all that's important is the calories you take it versus those you burn- it doesn't matter where they came from. Friday (talk) 22:50, 1 March 2007 (UTC)

You can't exercise enough. Estimates for burning off a pound of fat include: hiking to the top of a 2,500-story building, running 60 miles, spending 7 hours cleaning animal stalls. Exercise is a terribly difficult way to lose weight and some would say it is insignificant. Hard exercise for one hour can lose you an ounce of fat. Fat is the most energy-dense substance the human body and any organism can use, it packs 4 million calories, or 4,000 food calories per pound, 15 times more than TNT. Eating fat does not equal heartattack, but it will increase your chances. That Atkins Diet, I believe does not work by principally inducing ketosis, but instead by just cutting your food intake, like about every diet. It just cuts the dieter's calorie consumption. [Mαc Δαvιs] X (How's my driving?) ❖ 03:28, 2 March 2007 (UTC)

Liquid Nitrogen

If one was to put about 0.1 to 0.2cc of liquid nitrogen in a small container that is completely sealed, for how long will the nitrogen stay in the liquid state? If it does stay liquid, will it perpetually stay cold? Thank you. —The preceding unsigned comment was added by 68.39.175.57 (talk) 21:43, 1 March 2007 (UTC).

If the container is strong enough and has no leaks and it's pretty full then the liquid nitrogen will stay liquid forever - even at room temperature. If it's warmer than it's boiling point then it'll start to boil - the gas that comes off will rapidly increase the pressure - because boiling point goes up as the pressure goes up, it'll eventually reach a pressure at which the liquid won't boil - even at room temperature and you'll have liquid nitrogen at room temperature. Of course the pressure might be rather high - so if your container isn't strong enough, it might explode or something. But it won't stay cold forever - that's just not possible. SteveBaker 22:08, 1 March 2007 (UTC)

One would advise caution when opening said container :) Mabris 22:46, 1 March 2007 (UTC)

Yeah, gotta watch out for the kaboom effect. DMacks 22:49, 1 March 2007 (UTC)

A minor note—the critical point of nitrogen is only 126 kelvin (about -150 C). Above the critical point, no material remains a liquid, regardless of the pressure. So even in your infinitely-strong container, the nitrogen will be a gas (albeit a high-pressure, high-density one) that uniformly fills the entire volume of the container well before it reaches room temperature. TenOfAllTrades(talk) 23:19, 1 March 2007 (UTC)

With a supercritical gas there will be no point where you could see a liquid condense, or boil. However in our example the density of the fluid will be so high that it would have liquid properties. GB 01:31, 2 March 2007 (UTC)

Also, even if the equilibrium point is a gaseous state, there is a time when there is a liquid state and a gaseous state. The temperature and pressure will affect the rate of evaporation. 171.64.91.48 03:59, 2 March 2007 (UTC)

THE FUTURE is wild?

How accurate is the "the future is wild" series and what did they base their predictions on? —The preceding unsigned comment was added by 74.102.217.142 (talk) 22:01, 1 March 2007 (UTC).

We'd have to wait a few million years to ascertain the accuracy. They simply took what is known about evolution and presented examples of what is possible. This is not what is likely, as nobody has the foresight to predict such things.Mabris 22:42, 1 March 2007 (UTC)

It's a great show, BTW!Mabris 22:43, 1 March 2007 (UTC)

They get their predictions from the same place Science Fictions writers get theirs. From a bottle of scotch. 202.168.50.40 22:47, 1 March 2007 (UTC)

It's a wonderful inspiration, scotch. − Twas Now ( talk • contribs • e-mail ) 22:58, 1 March 2007 (UTC)

Population?

How come in the last century the human population grew incredibly fast, and how come their are so many chiniese people? —The preceding unsigned comment was added by 74.102.217.142 (talk) 22:05, 1 March 2007 (UTC).

Maybe start here? Mabris 22:28, 1 March 2007 (UTC)

Cheap Oil. Cheap oil means that a human using machine can do the work of a 100 slaves. Furthermore, cheap fertilizers (made from oil) has cause the increase in output of agriculture and this has enabled the production of cheap food. Increase in health standards globally means more children survived into adulthood. Furthermore a lot of people are religious and does not practise population control. 202.168.50.40 22:34, 1 March 2007 (UTC)

I've read that modern medicine and agriculture are the biggest reasons for the post industrial boom. Mabris 22:44, 1 March 2007 (UTC)

1. Exponential growth
2. good agricultural technology for thousands of years = lots of people, leading back to #1.

-- 我♥中國 03:08, 2 March 2007 (UTC)

chemistry problem

if 15 mL equals .6784 grams, then how many grams does 575000 mL equal? (in grams) —The preceding unsigned comment was added by 76.188.176.32 (talk) 22:09, 1 March 2007 (UTC).

The reference desk will not do your homework for you. As a pointer, though, how many grams are in 1 mL? — Lomn 22:21, 1 March 2007 (UTC)

I do not know how to convert grams to mL.

You don't have to for the question. It's simply saying something similar to "if 6 drinks equals a six-pack, how many drinks are in fifteen six-packs?", which is simple division you most likely learned in 5th or 6th grade. -Wooty Woot? contribs 22:25, 1 March 2007 (UTC)

And that is the point of the homework! Look carefully at the first thing you said, "15mL equals 0.6784 grams". From that, you are supposed to work out how many grams are in a mL. You then convert 575,000 mL into grams using the number you worked out. You can't look up how many grams in a mL, because it depends on what material is being measured (mL measure volume, grams measure mass). You have to work it out each time you have a question like this. Skittle 22:28, 1 March 2007 (UTC)

I have figured out that 1 grams equals .0452 mL (i think), but does that mean that i multiply the numbers 575000 x .0452 to *get the amount of grams?

You'll want to double check what you're calling grams and what you're calling mL, but you're on the right track.Mabris 22:36, 1 March 2007 (UTC)

Saying 1 gram = .0452 mL means that the density of the substance is .0453 mL/gram. Density is very very important - it converts mass to volume! So if the density is .0453mL/gram, and you know the volume of the substance is 575,000 mL, then how would you find the mass of the substance in grams? (hint: look at the formula for density and try to manipulate it into an expression of the form mass = volume and density). -sthomson06 (Talk) 22:38, 1 March 2007 (UTC)

Thank you I understand completely now!

• Be careful. How about 1 mL =.0452 gram rather than the other way around? It is like the difference between lightning bugs and lightning bolts, or full credit and partial credit. Then multiply 575000 mL times .0452 grams per mL.Edison 06:27, 2 March 2007 (UTC)

Dark Matter

If dark matter makes up a substantial amount of every galaxy, why doesn't it accrete into the equivalent of dark-matter stars? Does dark matter interact on the stellar or planetary level, or is it just found in interstellar space? Does it fall into celestial bodies of mass like the sun?

I realize that this might be something that nobody knows, but it seems like a fairly basic question. Jolb 22:28, 1 March 2007 (UTC)

Good question. Perhaps it's to diffuse to aggregate? Maybe bits of dark matter are too far apart for gravity to over expansionary forces. That's just a guess. Mabris 22:34, 1 March 2007 (UTC)

The wikipedia article on the Milky Way says, "Most of the mass of the Milky Way is thought to be dark matter, forming a dark matter halo of an estimated 600-3000 billion solar masses (M☉) which is concentrated towards the Galactic Center.[6]" If it interacts gravitationally like normal matter, that doesn't seem too diffuse to aggregate...Jolb 22:49, 1 March 2007 (UTC)

Good point. If it aggregated around "normal" matter, it would also be hard to identify it by traditional gravitational lens type effect (I think...) Mabris 23:02, 1 March 2007 (UTC)

It goes the other way around. Dark matter doesn't aggregate around "normal" (baryonic) matter, normal matter aggregates around dark matter. If the current theories are correct - and not everyone believes them, let's be clear - the filaments (image) and clusters map out where galaxies formed, due to the (far larger) gravitational attraction of the dark matter.

As to why they don't collapse, stop and think about why galaxies don't collapse - all those gas clouds, stars, planetary systems. They're kept in orbit around everything interior. Dark matter essentially only interacts gravitationally, so (naively) it behaves the same. It's not static and about to fall, it's in constant motion, as everything else is. Think of a galaxy as a little solar system, but with a billion dark matter dust flecks or planetesimals orbiting between, alongside and beyond each planet. The exact answer also depends exactly what dark matter is, of course - did you read cold, warm and hot dark matter? Highly energetic particles needn't be strongly bound to (in a well-defined orbit around) anything. Conversely, MACHOs would probably exist in quite slow, ponderous orbits, for example. Spiral Wave 01:01, 2 March 2007 (UTC)

Many steps in the accretion of small scale structure (e.g. stars and planets) involve non-gravitational processes. For example, collapsing gas clouds dissipate energy through thermal radiation. Similarly planets are built out of small rocks, etc. that are individually held together by chemical bonds rather than gravitational bonding. Strictly speaking neither of these processes is necessary for structure formation, but they greatly accelerate the process. If dark matter truly doesn't participate in any electromagnetic processes, then it would be much less likely to clump on small scales.

And yes it could fall into stars and other matter, but if it can't interact chemically, then it could essentially fall straight through and come out the other side. Even so, some experiments do seek to look for evidence that there might be dark matter trapped in the middle of the sun or the Earth. Dragons flight 05:59, 2 March 2007 (UTC)

Coldest Metal

What is the coldest metal or substance at ambient (room) temperature.

ie., at room temperature, a metal will feel colder than wood or plastic.

Thank you, --Cduffner

I believe that silver has the highest heat conductivity among metals, so that would give it the "coldest" feel. Note, though, that metal just feels colder than wood or plastic, since it draws heat from your skin more quickly. Mabris 23:08, 1 March 2007 (UTC)

As Mabris says, metals feel 'cooler' because they conduct heat away from your skin more rapidly than most other materials. We have a modest list of thermal conductivities; higher conductivities mean a cooler feel. Silver is the highest among metals; pure diamond is actually even better (but more expensive). TenOfAllTrades(talk) 23:13, 1 March 2007 (UTC)

Helium II has an insanely high thermal conductivity, but, of course, is not present as a solid at room temperature. Mabris 23:18, 1 March 2007 (UTC)

I agree that silver is the best candidate in one sense - but unless it's really in close contact with your skin, it might not pull heat out of your hand (say) as fast as a liquid that could follow every crease and crinkle. So I'd suspect that the liquid with the highest thermal conductivity would feel the coldest. I'd bet on that being mercury because it's also a metal...but I don't know for sure. But if we head out that way, a liquid that would rapidly evaporate at some temperature between room temperature and the temperature of your skin would pull heat out of your hand even faster...but perhaps I've strayed beyond the parameters of the question. SteveBaker 02:32, 2 March 2007 (UTC)

Basic 'design flaw' in beetles

If you flip them onto their backs, they cannot right themselves. Going back to the 'sabertooth tigers' thread, where User:Honeymane mentioned that "evolution would normally not engineer something so broken", why is it that beetles have been so successful whilst still exhibiting this obvious weakness?

It's a similar situation with turtles and tortoises when it comes down to it - just on a larger scale. --Kurt Shaped Box 23:03, 1 March 2007 (UTC)

The inability to right itself is due to the heavy shell they carry (for beetles and turtles both). The survival advantage conferred by the armoring outweighs the disadvantage in getting upright. Most beetles and such can right themselves, though, given enough time. I imagine that at some point in history there were creatures so heavily armored that the balance of advantage was negative (they were well protected, but too often got stuck upside-down), and those creatures have since died off. Mabris 23:13, 1 March 2007 (UTC)

Yeah, what was the name of that dinosaur that looked like an armadillo with a long tail that ended in a bony (spiked?) club? That thing was built like a tank... --Kurt Shaped Box 23:19, 1 March 2007 (UTC)

Ever seen a click beetle? (I'd provide a link here if I wasn't so technologically challenged). Beetles "in the wild" most often can and do right themselves just by flailing around til they flip back over. Certainly on a flat surface, in the lab, this would be difficult to impossible but in thier native habitat I don't see where being flipped over would be that much of a disadvantage.216.209.110.186 11:30, 2 March 2007 (UTC)Canis sylvaticus

Polacanthus? Or you thinking of Doedicurus, which was actually an armadillo? Mabris 23:26, 1 March 2007 (UTC)

Ankylosaurus - that was it! I had a toy one when I was a kid, though mine looked much more like a cross between a turtle and an armadillo than the one pictured in the article... --Kurt Shaped Box 23:34, 1 March 2007 (UTC)

Consider the Glyptodon. Cheers Geologyguy 00:33, 2 March 2007 (UTC)

Imagine the havoc that could be wrought be an armored seagull. Mabris 23:45, 1 March 2007 (UTC)

Na. Armour would affect their speed, agility and flight-capability. Now, if gulls were ever to evolve opposable 'thumbs' and learn to co-operate, we would be in trouble... --Kurt Shaped Box 23:51, 1 March 2007 (UTC)

But they can right themselves. Isn't evolution neat! --Cody.Pope 00:22, 2 March 2007 (UTC)

Quick enough to save themselves from whatever predator(s) just flipped them over? --Kurt Shaped Box 00:52, 2 March 2007 (UTC)

Not sure about beetles, but adult turtles have very few predators (young turtles, sure -- but they compensate by having so many eggs; turtles being an r-selected species). The large tortoises, which have the most difficulties getting up right, are almost extinct as a result of humans but otherwise they have no predators that would flip them over. --Cody.Pope 01:31, 2 March 2007 (UTC)

Enthalpy of Solution

What is the enthalpy of solution of Potassium Nitrate? It is not in our article. Can this quantity be calculated from solubility or some other parameter? Nimur 23:58, 1 March 2007 (UTC)

According to the Handbook of Chemistry and Physics, the enthalpy of solution for KNO3 is 34.89 KJ/mol or 8340 cal/mol at 25 degrees Celsius. I suppose this could be calculated by maybe taking the difference of enthalpies of formation for NO3 and KNO3, but I'm not sure.

March 2

Colours relation to wavelenght

Can I ask another question here? Daniel Dennett mentions that it is studied that each colour does not match with a certain wavelenghts, and so colour does not correlate with wavelenghts, unlike usually people thinks. He says also that certain colour can be produced with very different kinds of light with different wavelenghts. This is against what I have been told on school. Can you explain me how light creates colours according to this what Dennett said. Majji 00:28, 2 March 2007 (UTC)

One important distinction to remember is that between the color(s) of light itself (its wavelength or combination of wavelengths) and the way one perceives that light (its effect on the eye or other receptors). The articles on color and color vision are useful. DMacks 00:39, 2 March 2007 (UTC)

I answered a very similar question a few weeks ago on the Miscellaneous section of the reference desk. What with all the mess with archives recently, I can't figure out how to link to it - so I'll just do a quick copy/paste:

There are certainly things that our senses fool us about. We know for absolute certainty that we don't see "reality". One of my favorite examples is the colour "Yellow". Our eyes only have receptors that are sensitive to colours near red, green and blue. Since pure yellow (such as you might get from a Sodium street lamp) is somewhere between red and green on the spectrum, our red and green receptors are both weakly stimulated and our brains have learned that when this happens, we should label the colour "Yellow" - however, if you mix red and green light (for example on that computer screen you are looking at right now which only has red, green and blue light emitters...no yellow), that also stimulates both red and green sensors in our eyes and we say "Yellow" - despite the fact that there is no yellow light anywhere around. We teach ourselves that (when mixing light) "Red + Green = Yellow" - this is nonsense. Red + Green equals just that - Red plus green. It only looks yellow because our eyes respond to red+green in the same way they do to true yellow light.

This leads us to some interesting observations. There are animals out there (notably some species of shrimp and (oddly) the Goldfish) who have many more colour receptors than we do (some shrimp have twelve, the goldfish has seven, we humans just three). Such a creatures have a sensor that directly percieves true yellow light - so for them, the colour that is a mixture of red and green as seen on a TV screen or computer monitor would not look yellow - but some other colour that we can't even begin to imagine. So there are colours out there - perfectly normal colours within the visible spectrum - that we can't see correctly.

We could get a sense of how dramatic a difference this might be by imagining someone who had a form of colour-blindness that produced no green sensitivity. They would see pure green light as something that would very weakly stimulate their red and blue sensors - which would appear to them to be a darkish shade of purple...but to us "normal" people, it's pure green. So go back to thinking about that goldfish: the yellow on our computer screens and the yellow in a sodium street lamp are as different to them as green and purple are to us! It's exactly like the whole human race were colourblind...compared to the humble goldfish.

If you think about this in terms of sound instead of light, it's as if we heard the note "C" either when someone played a "C" or when someone played a chord containing "B" and "D". Our eyes can't tell the difference between "Yellow" and a "Red/Green" chord.

If you want to get freakier still - there is an interesting genetic condition called tetrachromaticity which can occur very rarely in humans (I believe there is just one known, proven case - an elderly lady in England who was tracked down using genetic testing). Tetrachromats have two different sensors in the green area of the spectrum that work at slightly different frequencies - so the person has FOUR types of colour sensors instead of the usual three. This lady sees colours that (as far as we know) nobody else in the world can see! Many tests have convinced researchers that she can indeed do this and the genetic disposition of colourblindness and other genetic markers in her history explain perfectly how this rare situation came about. Interestingly, she works in a shop selling knitting yarns and she has remarked on how her sensitivity to colour mismatches is significantly better than anyone else she's ever met.

SteveBaker 02:24, 2 March 2007 (UTC)

Tetrachromacy migh benefit from that info, it it can be reliably sourced. Rockpocket 02:38, 2 March 2007 (UTC)

Our perceptions do not map monotonically to physical stimuli. "Color" exists in the eye and brain, not in the physical stimuli. If we stare at a red object for half a minute, then look at the complementary colour, a shade of blue-green, we will perceive a supersaturated blue-green not found in nature, and contrariwise. The Worldbook Encyclopedia of the 1960's had an example of a picture of Abraham Lincoln printed in the complements of natural colors. If you stared at it for half a minute, the color See the American Flag afterimage at [5] If we put a hand in cold water, then put it in warm water, it will feel scalding hot when otherwise it would just feel warm. I heard of a man who was color blind in one eye and had normal color vision in the other. Colors clearly do not correspond linearly and monotinically to wavelengths, since in the CIE colorspace a given color sensation in the interior of the space can be identically created by an infinite number of combinations of two or more discrete wavelengths. This is clearly borne out by a century of color matching experiments. The sensation of white can be created by the admixture of an infinite number of combinations of complementary colors. Freaky: If you look at your image in a mirror in a perfectly dark room and flash a photoflash, a stationary afterimage which looks perfectly natural of yourself is seen, but if you move, the image remains a stationary ghostlike image. Freakier: If you stare at a rotating spiral for half a minute, the movement detection cells in your brain become fatigued. If you then look at another person, their face will appear to flow inward or outward depending on which way the spiral was turning. There is a double spiral demo at the following site, but do not look at it if you are troubled by vertigo or other problems from visual stimuli. [6] Edison 06:15, 2 March 2007 (UTC)

I don't know of any good colour pictures of Lincoln to demonstrate this - so I'll use another of our erstwhile leaders. So stare fixedly at the center of the picture for about 30 seconds - then look at the blank part of the screen next to it. Tadaaaa!

SteveBaker 19:08, 2 March 2007 (UTC)

Seeing light while pressing eye

People usually thinks that to see there must be photons. But if you are in totally dark room with no photons there, and you push your eyes outer side, you see round light at inner side of field of vision. This is not hallucination, because hallucinations are created by brain. It is rather experience of something real, perception of pressure on your eye. Somehow vision cells acts like they would receive photons, even though there are none. What it is this experience called then? Is this an instance where you can see touch instead of feeling it? Majji 00:37, 2 March 2007 (UTC)

Sounds like you're seeing phosphenes. DMacks 00:41, 2 March 2007 (UTC)

Yes, phosphenes caused my mechanical stimulation of the retina. It's safe to do. [Mαc Δαvιs] X (How's my driving?) ❖ 03:09, 2 March 2007 (UTC)

I'm not sure it is universally safe. Some people at risk for detached retinas should probably avoid such experiments. Note that if the pressure is toward the bottom of the eyeball, the phosphene is seen at the top, since the retina receives an upside down and backwards version of the world due to the optics of lenses. For me, looking to the extreme left has always caused phosphenes as well as pulsed ringing in the ears, implying involvement of the auditory nerve. No such effect from looking to the extreme right, We are all unique beings. Edison 06:06, 2 March 2007 (UTC)

straitening light

is there a way to perfectly straiten beams of light using lenses or such ?

the point woult be to straiten the focal point of a parabolic mirror capturing sun light to achieve transmition of all the light to another point

would this be possible? —The preceding unsigned comment was added by 216.113.96.83 (talk) 00:39, 2 March 2007 (UTC).

Perhaps a collimating lens? The question is a bit confusing though...all beams of light are essentially straight to a first approximation, all that changes is the direction they go. So one just needs to design a mirror or lens shape such that each beam coming from "whatever source you're using" gets reflected and/or refracted such that it goes off in "whatever direction you want". DMacks 00:47, 2 March 2007 (UTC)

what experiments ave been done on sun light collimating and what documentation could i see ?(so far i avent found any)

What you are really asking is whether light can be preventing from dispersing as divergent rays. The answer is YES - and you're going to kick yourself when I tell you that it's called a "Laser". Lasers can transmit light over vast distances without losing energy. But you can't make one with a simple mirror because there is no way to make a mirror accurate enough. You also need light all of one frequency to avoid other ikky problems. SteveBaker 01:54, 2 March 2007 (UTC)

Lasers are not perfect rays, though. They have some divergence. 171.64.91.48 04:03, 2 March 2007 (UTC)

Yep they do diverge a little. But they bounced one off a reflector that one of the Apollo crews left on the moon. From a lab on the surface of the earth - out to the moon and back - about 800,000 km, and (if I recall correctly) the beam only diverged to a diameter of a meter or so. Some of that would have to have been due to imperfections in the reflector - so the laser was probably quite a bit better than that. SteveBaker 04:24, 2 March 2007 (UTC)

I think what you are asking is a very common thing. Fiber optics is probably the largest application both for coherent and non-coherent light transfer. It is not collimated in the strictest sense but loss is limited. The article mentions using fiber to transfer sunlight from outside buildings to inside. --Tbeatty 04:57, 2 March 2007 (UTC)

Flipping turtles/tortoises

Has any predator (besides man) ever grasped the concept of working cooperatively to flip a turtle or tortoise much heavier than any one individual onto its back in order to make a kill? --Kurt Shaped Box 00:55, 2 March 2007 (UTC)

Unless you can break the shell (to get at the yummy turtle meat) it doesn't much matter if you can flip it. I don't see any way reproducible way that a group of animals could cooperatively crack the shell. However, I have heard that single eagles will pick up moderately sized turtles and drop them from altitude in order to break them open. Dragons flight 06:13, 2 March 2007 (UTC)

Hahahah I have an image of tens of meerkats working together to flip a galápagos tortoise. Capubadger 08:15, 2 March 2007 (UTC)

Care to upload it to imageshack[7] or Wikipedia/The Commons? [Mαc Δαvιs] X (How's my driving?) ❖ 18:21, 2 March 2007 (UTC)

This is a thinly veiled seagull question. We should not indulge it any further. Nimur 19:24, 2 March 2007 (UTC)

Drinking water and losing weight

Does drinking a lot of water cause you to lose weight? PitchBlack 01:03, 2 March 2007 (UTC)

Probably not - but it could very easily kill you. See Water intoxication. If you drink too much water, it can dilute your blood dangerously and kill you. There have been many cases of this happening - so DON'T DO IT! SteveBaker 01:50, 2 March 2007 (UTC)

You will not lose much. It takes one big C Calorie to heat 1 litre of water one degree. SO say if you drank 10 litres of zero degree water, you would only use about 37 * 10 Calories - 370, which is not a huge amount. You could turn down the heat a few degrees to get the same effect. GB 01:56, 2 March 2007 (UTC)

The idea, as I understand it, is that if you drink a fair amount of water, especially before meals, you will get full on it and wont have to eat as much to be sated. Thus, you lose weight. 70.108.199.130 02:10, 2 March 2007 (UTC)

SteveBaker may have over-reacted. It takes quite a bit of water to start feeling the effects of water intoxication (it states how many liters in the article). Drinking water, per conservation of mass, will increase your mass the more you drink it. The ways your body gets rid of it are primarily renal, solid waste, sweat, and exhale. [Mαc Δαvιs] X (How's my driving?) ❖ 03:08, 2 March 2007 (UTC)

According to the article: "Consuming as little as 1.8 litres of water (0.48 gal) in a single sitting may prove fatal for a person adhering to a low-sodium diet, or 3 litres (0.79 gallons) for a person on a normal diet". The questioner is talking about losing weight - and might well be doing some kind of low-sodium diet (either deliberately or inadvertantly) - and I could easily see that a mere 1.8 liters might well fall into their category of "drinking a lot of water" - furthermore - 1.8L is the fatal dose...I would imagine that severe (albeit non-fatal) things could happen with lesser quantities. I'd really like to avoid this reference desk being the first to kill one of it's questioners! SteveBaker 04:13, 2 March 2007 (UTC)

A lot lower than I expected. I'm not sure there are a lot of people that would drink half a gallon or 80% of a gallon in one sitting, but it seems reasonable to say it could happen. [Mαc Δαvιs] X (How's my driving?) ❖ 18:20, 2 March 2007 (UTC)

1.8 liters is only something like 7 eight ounce (250ml) bottles - there are plenty of people who would drink a six pack of beer in one sitting - why not water? If you look at the bottom of the water intoxication article you'll see a list of people who have died from this condition. There was an especially tragic one just a few weeks ago here in the USA where a lady was participating in a radio show contest "Hold your wee for your Wii" where they were offering to give away a Wii game console to the contestant who drank the most water without going to the bathroom. She was the mother of three small boys and did it to try to do something nice for them...stoopid, stoopid, stoopid. People have no clue how dangerous this can be! SteveBaker 18:52, 2 March 2007 (UTC)

How is it then that one (especially me) drink obscene amounts of beer during a night of binge drinking and only wake up with a hangover?

Oscillation

Is there a name for something (if something exists) that oscillates between being matter and energy according the Einstein’s equation such as the oscillation of energy between electrostatic and electromagnetic fields and how fast would this oscillation be? 71.100.171.80 01:34, 2 March 2007 (UTC)

Most matter is stable and does not convert into energy. Unstable matter such as the neutral pion can decay into electromagentic gamma rays, but then it does not oscillate and reform pions, as the chance of the two photons colliding is very low in the present universe. In the first microseconds after the big bang the background radiation may have been high enough to recreate matter, but it would be formed chaotically, not oscillating. However you may be thinking of the wave nature of matter, matter wave. GB 02:01, 2 March 2007 (UTC)

No, I'm thinking of oscillation or perhaps a stable form of energy we only call matter in the form of various atomic particles which may actually be a self-captured wave of energy (oscillating electromagnetic and electrostatic fields) where the path of propogation through space is merely diverted from straight to a circular path by the electromagnetic phase being 180 degrees out of phase with the electrostatic phase such that they become "locked" together at certain diameters as what we call a "particle" of matter. Something troubles me about not being able to describe matter as a "captured" form (wave) of energy and to describe the mechanism of its capture if Einstein's equation is true. (Which I don't doubt it is.) 71.100.171.80 02:29, 2 March 2007 (UTC)

No - nothing gets turned around in a circle to make a nice spherical particle - it's not like that at all. The wave that corresponds to a particle is a Wave packet. SteveBaker 04:06, 2 March 2007 (UTC)

Take a look at virtual particle. Particle/anti-particle pairs appear for short periods, then annihilate each other. These virtual interactions are important in analysis of particle interactions using Feynmann diagrams. Gandalf61 10:41, 2 March 2007 (UTC)

Yes, as for the concept of oscillation that came to mind virtual particles are essentially only different in that they represent a single rather than a cyclic existance, if my understanding is correct. As for describing particles in a more intuitive way the term that pops into mind to describe this concept of matter (particles) being merely variable duration spheres of energy formed by the interaction of energy's counterparts of electromagnetic and electromagnetic fields from their interaction at a frequency that jumps to near infinity resulting in sherical particle formation: a particle thus being described as perhaps as virtual energy; if you will. 71.100.171.80 12:21, 2 March 2007 (UTC)

Hair Growth Question

This is pretty plebian for the fairly technical Science desk, but I don't know where better to ask. I'm a highschooler who goes to a school with a no-facial-hair policy. This hasn't been much of a problem for me because all I've got in the way of facial hair is a slow-growing faint mustache, which is easy enough to shave, and a little hair in what might be called the goatee area (chinnish) that, if left unhindered, would probably grow out into a bizarre and conspicuous chin patch. Nothing really between the sideburns and goatee. I figure that'll come in in a year or two. The thing is, I just tried out, and have been given reason to believe I might have been accepted, for a school play where the characters are supposed to be sporting Miami-Vice style two-day growth. The question was whether anti-balding products, such as Rogaine etc, might be an ok idea if I wanted to stimulate hair growth around the regular beard area? My face isn't completely hairless there, just not enough to grow a legit beard, and I'm guessing that if I did this play half a year to a year from now, this wouldn't be a problem at all. So is that a good or bad idea? Any other suggestions?

Probably a bad idea, as Minoxidil should only be used on the scalp (see more details here) and it would take many months to show any effect anyway. There is little one can do to increase facial hair (short of injecting hormones). I would suggest you use makeup to generate stubble for your role. Rockpocket 02:32, 2 March 2007 (UTC)

Hope you don't feel embarrassed! I could imagine it, but, eh, you should be fine. [Mαc Δαvιs] X (How's my driving?) ❖ 03:03, 2 March 2007 (UTC)

I agree - makeup for stage needs to be somewhat exaggerated anyway - so even a real stubble might not be enough to look good. Also, unless you have very dark hair, your growth could be fair-coloured anyway. But it's stupid to mess with treatments like that unless you have to - there are health risks and side-effects with these things. Just so you think carefully about that - look at the list of side-effects for Minoxidil:

• acne on the area where it is being used as a topical solution

Yeah - that's gonna look real good for Miami Vice!

• headaches and/or lightheadedness
• very low blood pressure
• irregular or fast heart beat
• blurred vision
• chest pain

I don't think it's worth the risk just for a play!

SteveBaker 03:49, 2 March 2007 (UTC)

Googling theatrical makeup "beard stubble" led to a sponge for applying makeup to create such an effect at [8] Crepe wool and spirit gum are also classic standbys. Remember that it only has to look good from 20 feet and farther (or whatever your staging implies). Edison 05:59, 2 March 2007 (UTC)

Wait, you're doing Miami Vice for a high school production? [Mαc Δαvιs] X (How's my driving?) ❖ 06:24, 2 March 2007 (UTC)

Amiodarone and D5W

I am an instructor who helps teach paramedic students. We teach our students to mix amiodarone in D5W -- one student wants to know why D5W and is it OK to mix with normal saline? I've looked all over wikipedia and also at the manufacturer's website but can't find the answer. Futrmd2009 03:00, 2 March 2007 (UTC)

Wikipedia and the persons who answer questions here cannot give any medical adice, because the person giving the advice might be a physician, or he might be a teenage prankster. They might give well-meaning but incorrect advice, or they might give malicious advice. You will have to determine for yourself the reliability and validity and verifiability of the information there. The life of a patient might depend on getting medical advice only from qualified health practitioners. Edison 05:51, 2 March 2007 (UTC)

The questioner isn't asking for advice, he's asking for information. The reason amiodarone is given in D5W is simply tradition; that's the way the protocols were developed. As you know, amiodarone dosing is critical as to speed and concentration as well as in its interactions with various drugs and intravenous tubings. Because some drugs given in emergency situations are incompatible with (precipitate out in) normal saline, it's easier to use D5W. But even though amiodarone and NS are not incompatible per se, D5W is used in the manufacturer's literature and in ACLS protocols, and you really need to follow these rather than improvise. By the way, the manufacturer, like all U.S. pharmaceutical companies, has people whose only job is to answer these questions, and you can rely on the information being correct, so you should shoot off an e-mail to them. -Nunh-huh 13:58, 2 March 2007 (UTC)

Here's a good start. Skip to the background section where they talk about amiodarone. Dextrose is an osmotic agent. --Tbeatty 06:22, 2 March 2007 (UTC)

"is it OK to mix with normal saline?" sure sounded like asking for advice which might be implemented by health care personnel. Edison 16:13, 2 March 2007 (UTC)

Most information can be acted upon. That doesn't make it advice. The information being asked for was "is it contraindicated to administer amiodarone in Normal Saline, and if not, why do most people administer it in D5W?" - Nunh-huh 17:08, 2 March 2007 (UTC)

We hope a trained paramedic or medical professional will not use Wikipedia as the guideline for safety, regardless of what is posted here (advice, information, articles, or otherwise). Nimur 21:08, 2 March 2007 (UTC)

email

How can I email a page from Wikipedia. There seems to be no link to "email this page". I found some info that I wanted to share with family, and when I saved it to a document file it broke it into numerous files and I was unable to find the text. Help. Anjie

Why not email your friends the Wikipedia page's URL? Alternatively, you can save the webpage and email the .html file (forget about the folder with the same name), if you don't need any pictures.

Another option is to save the webpage, compress the numerous files you were talking about into one file, and then send the one file. To open the webpage, click on the file ending in .html. --Bowlhover 05:40, 2 March 2007 (UTC)

Email them the URL - cut/paste it from the bar at the top of your browser window directly into the email text. That way they have a link to the latest version of the page so if we fix things in the future, they'll see the fixed version. Worse still, links within the article are relative - not absolute - so if you send them the HTML from Wikipedia, links and images won't work for them - if they go directly to the Wikipedia site via the URL, they will. Not only that but you won't be filling their in-box with junk. If you did succeed in actually sending them everything, you'd be sending them a copy of the Wikipedia logo - which is illegal because the logo is copyrighted (although the body of the encyclopedia is free to be copied - the logo isn't) SteveBaker 11:54, 2 March 2007 (UTC)

solar furnaces

i`ve benn reading on solar furnaces and i was wondering and i was wondering how, since they produce such high temperature they are not the proposed way of producing energy oposed to other types of solar gathering divices ?

also i was wondering what is the size of the area requiered to gather so much light ?

Well, I'm not entirely sure what your first question is getting at, but there is actually a lot of solar energy that hits the earth, and that energy can be turned into heat in many ways (okay, not "a lot" in the cosmic sense, but allow me this liberty). The rule of thumb is that roughly 1 kW/m² of solar power is incident on the Earth's surface on a sunny day. Of course, there is no way to convert that to your favored energy form with 100% effiency, but even with conversion (in)efficiency, there's enough there to work with for many purposes (photovoltaics, direct solar heating, etc). -- mattb @ 2007-03-02T07:26Z

i was talking about high flux solar furnaces like this one http://www.nrel.gov/csp/lab_capabilities.html?print

theyr talking about heat high enough to vaporise carbon coming from sunlight alone, isnt that more eficient than plants like the solar one tower ?

It depends on what you want to do with the energy. If you want to focus it all into a small area and make something really hot, it's great, because you're making direct use of sunlight (as opposed to letting it be used in photosynthesis, compressed for millions of years, and then set fire to, wastefully releasing the heat in all directions). Solar power towers actually do work like this, but they collect the heat in another object, where it can be drawn off and used at a later time; but there must surely be additional losses involved. Given that most current solar farms focus on collecting solar energy directly (solar to electrical), rather than these two or three intermediate steps, I'd assume that that's a more efficient process (just as not relying on plants to turn it into coal first is), else we wouldn't be doing it. Solar panels do keep jumping up in efficiency. (And please sign your posts with four tildes, ~~~~) Spiral Wave 17:47, 2 March 2007 (UTC)

Unknown military device?

I don't know is it illegal for me to tell about this. Therefore I am not revealing where this happened. This was not long ago.

While I was camping during my compulsory military service our group saw a ground-colored truck with had tall thing totally covered with "curtain" at its back. Then at night while I had to patrol the area with one other person we saw that thing without curtain. There was like a thick pillar attached at the back of tuck. At the top of it there was like two "horns", resembling gigantic U-letter. It did not rotate like radars but it changed its direction once.

After we went to the tents we heard two times terrible very high pitch noise that made many people to put fingers on their ears. I don't know does it have anything to do with the truck we saw. Could you have any idea what we saw? Radar jammer perhaps? Akrieria 06:52, 2 March 2007 (UTC)

Radar dishes only go round and round when they are sweeping the area looking for something. A targetting system that has found it's target and locked onto it may stay pointed at it tracking small movements. So if it was a targetting system then it might well sweep rapidly then stop when it's locked onto something. Is it possible that those two 'horns' were actually short missiles? That might well be what the radar was aiming. I suppose a high pitched noise could be a missile launch even - but there are other possibilities - it's hard to know without hearing the noise. Was it the sort of exercise where live fire might have taken place? Personally, I would have asked my superior officer - if you were training then learning what these other things are is just a part of the learning process. SteveBaker 12:04, 2 March 2007 (UTC)

I thought that one of the fundamental rules of being a soldier was "don't ask, don't tell"? ;) --Kurt Shaped Box 17:09, 2 March 2007 (UTC)

its fun to know what the military is up to though wouldnt you agree kurt? Maverick423 17:11, 2 March 2007 (UTC)

If I asked, they wouldn't tell me. --Kurt Shaped Box 17:28, 2 March 2007 (UTC)

Sounds like a tuning fork but in a large size. i acctually heard that the military was wanting to use sound weapons to suppress resistance and minimize casulaltys. i dont see the point to this though since if your in a war with someone else you should kill them not give them mercy. NO MERCY GET BACK TO WORK SOLDIER AND KILL!! =P JK or am i?? Maverick423 17:06, 2 March 2007 (UTC)

I think you're right about it being an experimental non-lethal sonic weapon. There are many cases where non-lethal weapons are needed. Take the case of the "students" who overran the Iranian US embassy in 1979. Mowing them down with machine guns would have resulted in war between the US and Iran, but a piercing noise could have driven the "students" away before they captured the entire embassy staff leading to the Iranian Hostage Crisis. There are many current cases of "protests" in Iraq and elsewhere that aren't yet violent, but need to be dispersed before they become violent. StuRat 17:33, 2 March 2007 (UTC)

Great idea Maverick, it seems like an excellent candidate! [Mαc Δαvιs] X (How's my driving?) ❖ 18:17, 2 March 2007 (UTC)

File:Active Denial System Humvee.jpg

Active Denial System

It probably wasn't this, since these non-lethal microwave weapons haven't been deployed yet. Nimur 19:34, 2 March 2007 (UTC)

Coloured fire preparing safety

I am planning to make logs that burns with green coloured fire. Internet pages tells that I should do it by putting logs in water with copper sulfate until they are completely wet, and then dry them until they are completely dry. But can I do this at home? Is it safe to breath inside if I do it? Or should I do it outside? The problem is that I live in high house and have no own yard. I will burn the logs while I go to forest 193.167.45.242 09:04, 2 March 2007 (UTC)

Copper sulfate is not very good for you at all. It's poisonous. That being said, I've never come across copper sulfate fumes, despite handling copper sulfate solution a number of times, so you might be safe. I'm not entirely sure how healthy burning logs coated in copper sulfate would be for people around the fire, either. Maybe someone a little less rusty with chemistry can chime in :) Capubadger 09:38, 2 March 2007 (UTC)

Borate is the better choice. (For indoor use borate or boric acid are mixed with alcohol and a drop of sulfuric acid and this mixture burns than with a green flame.) Soaking a log with boric acid or borate dissolved in water should work, but a test with a pice of paper would help. --Stone 10:09, 2 March 2007 (UTC)

I have to try that. Why is sulfuric acid needed to be mixed there? Alchemal 11:56, 2 March 2007 (UTC)

The triethylboric ester does not form spontanious, it needs acid catalysis. The methylester forms without acid catalysis, but methylalcohol is very toxic. --Stone 15:57, 2 March 2007 (UTC)

Electrically Charging a liquid

My question is that is it possible to electrically charge a liquid or even a drop of liquid ... ??

Yes, see Oil-drop experiment for a famous example. In fact, drops of liquid we encounter in everyday life are usually charged to some degree: by interaction with the nozzle, by air friction, or by some other mechanism. The excess charge, by the way, is practically always found on the droplet surface. Cheers, Dr_Dima

A glass or plastic container partially filled with water becomes a Leyden jar and electric charge was stored in it (probably in the surface lining the container) with the experimenter's hand outside as the other conductor comprising the capacitor. Note that a dangerous electrical shock can be the result of charging such a capacitor to high voltage, so don't try this without proper supervision and knowledge of and observance of all safety precautions.Edison 16:09, 2 March 2007 (UTC)

Early inkjet printers used electrostatic deflection of ink droplets.

Atlant 18:02, 2 March 2007 (UTC)

bluetooth

sir i want to know that can bluetooth be used in tv . by the help of microcontrller. if it is yes then tell me what kind of microcontrller i w'd have to design ? thanks

A complicated one. You can buy commercial microcontrollers that already support Bluetooth. Here]'s an evaluation board from Analog Devices; you can use Google or search major manufacturers' web sites. Nimur 19:37, 2 March 2007 (UTC)

Holding Your Breath

Why is it that I find it must easier to hold my breath for an extended period of time under warmer water compared to that of cold water? For example, I can stay under in a hot tub longer than a cold swimming pool. --Russoc4 16:43, 2 March 2007 (UTC)

not exactly sure about this as i too have that same prob heh. i think it has to do with the lungs contracting more in cold water then in warm water.Maverick423 17:09, 2 March 2007 (UTC)

How about it taking more energy to keep you warm, energy which comes from "burning" calories with oxygen from the air ? StuRat 17:24, 2 March 2007 (UTC)

This is probably a psychological effect more than physiological. Cold water should slow your metabolism, hypothetically enabling you to stay submerged longer. When training for SCUBA, we were always instructed to begin our dive by taking our diving mask down, allowing cold water to hit our face for up to 60 seconds. This was supposed to relax us, equalize our temperature perception (preventing panic if we should get cold water on our face later), and slow our breathing. Nimur 19:54, 2 March 2007 (UTC)

Warning i am Bored

Ok guys i am bored. im thinking about removing the lid of a microwave and using it like a gun or something. what am i getting into if i do this? Maverick423 17:22, 2 March 2007 (UTC)

Do not do this. Hipocrite - «Talk» 18:02, 2 March 2007 (UTC)

This is called a microwave gun. Rather unstandard and always improvised. They are occasionally made for a portable controlled source of microwaves, and are rarely used. I've seen scientists trying to reproduce "higher electromagnetic field strengths" around crop circles with this. Because there needs to be a nozzle mechanism on it, they attempted to make one and there ended up being holes in it, and areas of space with massive heat energy, and one of them got burned. Powerlabs gives as good a disclaimer as any: WARNING: Attempting to operate a magnetron outside its designed cavity is VERY dangerous and will not only decrease its useful life, but will also pose a serious threat to the operator of the device. Microwaves can cause cataracts and deep thermal burns. Any electronic equipment within range of the magnetron will be instantly destroyed. Please do not tamper with your microwave oven. [Mαc Δαvιs] X (How's my driving?) ❖ 18:14, 2 March 2007 (UTC)

File:Active Denial System Humvee.jpg

Active Denial System

It probably won't be as powerful as this, since these microwave weapons operate at 95 GHz and are ... very ... large. Perhaps if you are seriously interested in microwaves, you should study Electrical Engineering (instead of harming yourself and others by taking apart an oven). This solves your boredom problem, too! You will find that microwaves have huge utility outside of the realm of weaponry. Did you know your cell phone operates at microwave frequencies? (*depending on type, carrier, geography, etc). Did you know that your computer's wireless network uses microwave? So do missile-trackers, point-to-point communication systems, weather satellite and deep-space-probe communications systems, and plenty of other neat stuff. Nimur 19:41, 2 March 2007 (UTC)

Or, get a job working with radars. Basically the same theory as what you want to do: Throw a lot of electromagnetic radiation into the air and see what comes back. They make great microwave ovens - just toss your dinner in front of one while it fires. Make sure you don't try to catch it on the way down. Also, make sure you aren't standing on something that melts (like an iced over lake). I lost a lunch that way. --Kainaw ^(talk) 19:54, 2 March 2007 (UTC)

I am trying to interpret your statement about the lunch. A few possible interpretations: 1) The lunch was sitting on the ice, which melted, and then fell into the lake. 2) You were standing on ice, which melted, and then you vomited. 3) You bet your friend that you would stand on a block of ice in front of a powerful RADAR without dying; you lost the bet and had to pay for his lunch. Are any of these close? Nimur 19:58, 2 March 2007 (UTC)

To make it clearer: To use a radar as a quick food heating unit, hold your meal in front of you. Stand in front of the radar unit (they are normally safe to stand around up to 15 feet in the air). Moving your arm in a quick upward motion, release the meal and let it fight against gravity to a height of 20-30 feet. As the radar fires, it will irradiate the meal, filling with a lot of energy. Most food will radiate the absorbed energy as heat (I know that rice cakes do not). When the food returns to your elevation above the ground, it will be very hot. Do not attempt to catch it. Let it hit the ground and it will cool rather quickly as it releases the energy it was just forced to absorb. If, however, you are standing on an iced over lake as you do this, the heat released by the food will quickly melt the ice. Then, your meal will go through the ice and into the lake below. --Kainaw ^(talk) 20:08, 2 March 2007 (UTC)

How can you lose a bet about standing in front of a active radar transmitter without dying and still pay off?! Clarityfiend 20:46, 2 March 2007 (UTC)

Alcohol

Hey guys, i understand that alcohol is considered a drug, but is it a stimulant or depressant? I cant seem to find it anywhere and it intrigues me because it has different affects on different people. Any other advice/info/links on alcohol for a teenager would be appreciated, thanks alot Dave 17:47, 2 March 2007 (UTC)

Alcohol is a depressant. It slows reaction time, metabolic activities, etc. Nimur 19:42, 2 March 2007 (UTC)

Advice. Don't drink and drive. Whatever else you do, understand and be prepared for the consequences. In some places, it is illegal to purchase or consume alcohol if you are under certain age. Realize that even small amounts of liquid can contain lots of concentrated alcohol and may affect you seriously. If you're bored, consider studying Electrical Engineering instead of drinking alcohol. Nimur 19:50, 2 March 2007 (UTC)

Surely our article on alcohol contains this information. Better idea, Ethanol metabolism. Oh nevermind, both articles seem to be written at the near graduate level, so I'll just answer it here, it's a depressant. No, wait, here's one: Try Effects of alcohol on the body--VectorPotential^Talk 17:48, 2 March 2007 (UTC)

Advice for a teenager? White cider is bad - very, very bad. No not drink it, even though it is very, very cheap. It causes the worst hangovers imaginable and makes you chunder very quickly. --Kurt Shaped Box 17:52, 2 March 2007 (UTC)

Raw Eggs

How does the nutrition of a raw egg compare to a cooked one, if i put a whole raw egg (white and yolk) into a milkshake? would it be any different than a hard boiled egg or an egg scrambled with no margarine/butter in a non-stick pan? is there any harm in consuming to many raw eggs? i dont mean in terms of fat/cholestrol or other concerns, i mean just in comparison to cooked eggs. e.g., if its healthy for an active person to eat X number of eggs a day, would it be ok to eat them all raw?

Salmonella is the first concern that comes to mind. But it's a statistical thing. Some eggs are perfectly free of salmonella and are safe to eat raw; some are not, and must be cooked to be safe. There is no easy way to know whether a particular egg is safe or not, so it should be cooked (ensuring that all salmonella is destroyed). The symptoms of Salmonellosis are vomiting, diarrhea, and other illness, so you probably want to err on the side of caution. Nimur 20:58, 2 March 2007 (UTC)

Microwaved Egg

Does the nutrition of a scramble microwaved egg (no margarine/butter) differ at all from one thats scrambled in a non-stick pan on the stove (also no margarine/butter)?

Probably not in any significant way. There might be stretch-cases where the pan leeches metal ions into the egg, but I doubt it's significant. Nimur 20:55, 2 March 2007 (UTC)

Microwaved Egg--part 2

is it possible to cook an egg by putting it it alone in the in the microwave without breaking its shell, such that it would turn out just like if it was boiled? it seems to me that should be possible because it contains plenty of water to absorb the waves and heat up. but how long would i have to microwave it?

if not, can u do the same but actually boil it in a microwavble dish

and once again, would the nutrition content vary between a microwaved one (either of the two methotds explained above) or a stove boiled egg?

The egg may burst, since the insides would be heating up very rapidly (as compared to boiling), and there would not be time for vapors to permeate through the shell. I haven't tested this hypothesis. Other than that effect, I don't see why you couldn't. Try it, put the egg in a bowl or on a plate to catch any mess if it does break. Nimur 20:57, 2 March 2007 (UTC)

science and technology dvd player

what is the difference between a 5.1 channel dvd player and a 4.1 channel dvd player —The preceding unsigned comment was added by 216.239.52.136 (talk) 21:13, 2 March 2007 (UTC).

Health and safety when casting steel

Hi! Does anyone know anything about the production of steel? I need to research what health and safety methods need to be put into place in the standard steel factory. So far, the risks I've come up with are:

1. Extreme heat from molten metal
2. Hot gases
3. Fumes from melting process
4. Danger of spillage from molten metal - apparently when molten metal comes into contact with water there's a big explosion or something, a bit like pouring water onto a chip pan fire.

To counteract these:

1. The workers should wear thick leather overalls and gloves as well as boots and masks.
2. Possible ventilation systems?
3. Same as 2.
4. Dry dirt or sand floor with no moisture

Can anyone think of other risks and how to counteract them? I've probably missed some really obvious ones! Thanks, Bioarchie1234 21:28, 2 March 2007 (UTC)