Wikipedia:Reference desk/Archives/Science/2007 March 1

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[edit] March 1

[edit] 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--VectorPotentialTalk 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)

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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...--HoneymaneHeghlu 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)

[edit] 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:

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:

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)

[edit] 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)

[edit] 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).

[edit] 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.

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)

[edit] 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)

[edit] 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)
Yes, there are a few experts on theoretical physics here. Both string theory and supersymmetry are essentially unfalsifiable experimentally, since the string scale can be made arbitrarily small, and the superpartner masses from symmetry breaking can be made arbitrarily high. Most people in high energy theory certainly hold out hope that the LHC will find some evidence for the two, but I've heard many who think this will be unlikely. Some only hope for finding the LSP.
In my opinion, the largest problems with high energy theories today is that most were created because of mathematical beauty or mathematical and conceptual problems with currently accepted theories. In all of my studies of high energy theory, not a single person was able to give any actual reason why the theories should be correct besides being mathematically beautiful and solving some conceptual problems. But there isn't really anything else to go on right now. We know that the currently accepted theories (SM+massive neutrinos and GR) won't work in certain situations, but we can't reproduce those situations. So as a result, the experimentalists build ever-larger experiments to try to move closer to those areas, but what are the fundamental theorists to do in the meantime? There is nothing to base a new theory on right now besides mathematical pursuits, and that is but a shaky basis that has often resulted in failure (Einstein's late research is a well known example). This is, in fact, why I am no longer in high energy theory. —Constantine Evans 09:08, 3 March 2007 (UTC)

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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)

Does this question not depend on your gender. the new scientist recently ran an article saying that to lose weight, men could increase their exercise and they're intake proportionally and lose the same amount of weight as women who increased their exercise without increasing their calorie intake. its something to do with how we've evolved (men to wresltle tigers, women to have babies) and helps explain why non-fat women (atheletes and models) usually dont menstruate. Certainly i was a fat kid until i discovered the joys of an active lifestyle but still consume my fair share of bad food.87.194.21.177 15:42, 3 March 2007 (UTC)

[edit] 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)

[edit] 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)

[edit] 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)

Less deaths from better medicene, but still a lot of births, especially in china and africa. See the demograthic transition model

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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)
It might also be worth considering that the sort of smooth, flat ground with no reachable vegetation around, which is where a beetle will have the most problem getting upright, is not particularly common in nature. --TotoBaggins 01:53, 3 March 2007 (UTC)

[edit] 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.