Wikipedia:Reference desk/Archives/Science/2008 October 14

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October 14

Plutos' core

Is Pluto's core generally hot or cold? From this image, it said the center is made of alloy, iron-nickel, and the mantle is rock and ice. I thouhgt Pluto's core would not be hotter than the surface of Venus, but may still be warm enough for water to become a steam? Since Pluto's atmosp is only 1/1000 of Earth's fraction, the globe colour would be gray perhaps yellow-tan or orange-yellow tinge add to the gray.--Freeway19 00:50, 14 October 2008 (UTC)

Do we have answer to is Pluto's center hot or cold. Some scientist beieve it is made of ieon nickel with alloys stuff. Will It put pluto's center to at least 100 C. I know it is unlikely to be 500 C or 1000 C. --Freeway19 02:30, 14 October 2008 (UTC)

Probably over 1000 C. Hundreds of kilometers of rock and ice is a very good insulator; it holds in heat. If there is a liquid ocean, people think it starts only ~250 km down. [1] Dragons flight (talk) 03:54, 14 October 2008 (UTC)

Except that everything in the solar system is roughly formed at the same time, so roughly exposed to the same conditions. As Pluto is smaller than the moon, and the moon can demonstratably be shown to have a cold center, Pluto is likely to also have a cold center. --Jayron32.talk.contribs 10:38, 14 October 2008 (UTC)

Well, if the moon formed from a collision with the Earth, then it could lack some of the heavier elements and those are often the radioactive ones. That would mean there would be more radioactivity in Pluto's core than the moon's, but I'm not sure it would be enough. --Tango (talk) 10:46, 14 October 2008 (UTC)

The moon's core may be as high as 1400 C [2]. That's "cold" only from the point of view that iron is not molten (needs 1600 C). Dragons flight (talk) 10:51, 14 October 2008 (UTC)

I'd have to do some research to be sure, but my guess would be that Pluto's core is ice cold. How much heat it could have retained from the formation of the solar system is dependant on size and Pluto is tiny, so it likely has very little retained heat. The sun is obviously too weak at that distance to heat it up. There could be some heat from radioactivity, but that's about it (there won't be any tidal heating since it is tidally locked with its only large moon - I doubt Nix and Hydra are large enough or close enough to do much). Radioactivity could keep it warm, but I would guess not to above freezing. If I get a chance, I'll research it later. --Tango (talk) 10:46, 14 October 2008 (UTC)

I already provided a reference to a scientific paper predicting liquid water on Pluto at only 250 km, i.e. 1/5th of Pluto's radius. Dragons flight (talk) 11:03, 14 October 2008 (UTC)

Here's another one [3]. Pluto goes above the freezing point of water at only 180 to 300 km depth. That leaves another 1000 km of temperature rise to get to the core. Radioactive heating is efficient when you are planetary size and can't easily dissipate heat. Dragons flight (talk) 11:14, 14 October 2008 (UTC)

Light Concentration

What exactly is a Light Concentration diagram? I have failed to find one on Google, or anywhere for that matter. And if someone can answer that, could you tell me where I could find one for Lake Baikal (in Russia), or what one would look like?72.65.101.51 (talk) 00:53, 14 October 2008 (UTC)

Could you mean light intensity? A diagram or graph would show the intensity dropping with depth. Graeme Bartlett (talk) 03:07, 14 October 2008 (UTC)

Some mathematical physics expression

$\displaystyle {D_{x}^{I}\rho _{I}V_{I}T_{I}\ {\overline {B_{xy}^{(I\,II)}}}}$
This is an expression I saw in a picture written on a blackboard behind Niels Bohr. Could someone please tell me what it pertains to and means and what articles would have more information about whatever it is? Thanks in advance, Ζρς ι'β' ^¡hábleme! 02:14, 14 October 2008 (UTC)

I don't think you are going to get a definite answer from just that. It might help to know how old Bohr was in the photos since physics evolved a lot in his lifetime. Off hand, I'd guess some form of quantum mechanics expression, with ρ a density, V a volume, T a temperature, D_x a differential operator in x, and the I and II denoting two kinds of material. If you assume he's dropping constants (as theorists often do) then it looks like a derivative operator in x acting on an energy times some interaction function B. What B is, I haven't a clue. Often "B" denotes a magnetic field, but you'd be unlikely to sub and superscript it that way if that were the case.

Also, I could be totally wrong. Dragons flight (talk) 04:53, 14 October 2008 (UTC)

He was older in the photos, perhaps 60-65. Ζρς ι'β' ^¡hábleme! 23:19, 14 October 2008 (UTC)

Looks like Einstein notation to me, but not sure. EverGreg (talk) 09:06, 16 October 2008 (UTC)

Is Heisenburg's Uncertainty Principle really universal?

Perhaps it's just personal, but I find this Principle to be a fraud. Surely, though, I'm not right and everyone else is wrong. It states that by locating a particle you make its momentum uncertain and vice versa. But a Principle of physics should accurately describe matter and the universe, not our ineptitude as observers. For example, if we were omnipotent gods, and could 'see' these particles, Heisenburg's Principle surely would not make sense. If really small aliens possessing intelligence and observational powers were the same size of these particles, surely THEY could determine the position AND momentum for any given unit of time.

I find it like cave men trying to understand tigers, only the tiger eats them when they come near him. They only way they can study him is to throw spears at him until he's dead. Would these perhaps thoughtful cavemen have a Tiger's Uncertainty Principle, and state "Well a living Tiger is just UNKNOWABLE" because they lack the proper tools to analyze the Tiger?

I feel that Heisenburg's Uncertainty should not be presented as a Principle, a 'rule,' or really any part of Physics other than a statement along the lines of "We suck as observers and can only 'detect' these particles by shooting high energy particles AT it, thereby ruining our original setup."

Why is this not presented in this way, or has noone made these objections? Am I missing something?

Ehryk (talk) 05:41, 14 October 2008 (UTC)Ehryk

No the point, and I agree it is spooky, is that a particle cannot have both a precise position and precise location at the same time. It is not simply that they are unknowable, but rather non-existent, even to God, aliens, or whoever else might claim to be able to see them. The double slit experiments, Bell inequalities and related results demonstrate empirically that our conception of matter having fixed position and momentum simply isn't how the universe works on a small scale.

At a fine scale, quantum mechanics tells us that everthing is smeared out in a fuzzy way. Even a single particle doesn't have one precise position but rather a whole distribution of positions, and with them a whole distribution of momentums. Things at the subatomic scale simply don't exist at only one place and time. The more we try to confine them to only a single position, the more they will necessarily widen their range of momentums. Your view that there should be some hidden and singular true position/momentum visible to God is known as local hidden variable theory and the most obvious forms of that have been shown experimentally to be false. Dragons flight (talk) 06:19, 14 October 2008 (UTC)

Heisenburg isn't talking about our ability to measure - he's talking about the fundamental nature of the particles themselves. It is literally true that if you try to limit the momentum of a particle it literally becomes a fuzzier thing so that its position is an increasingly vague thing. If you try to confine it into a small space to nail it's position more accurately - then it's momentum will become more 'blurry'. So you can take the "Us" and "observers" out of the debate here. Even omnipotent gods and teeny-tiny aliens would see the position of a particle as a statistical 'cloud' and its momentum as an indeterminable thing. Quantum mechanics is something that we humans are not equipped to comprehend because at our 'scale' of existence, the effects are generally negligable - but they are strange and oddly beautiful. But without them, the computer you're sitting at right now wouldn't work. The statistical weirdness of the position and momentum of a particle is what makes 'quantum tunneling' work - and without that, you wouldn't have any flash memory for your BIOS, your MP3 player or your memory sticks. So Heisenburg isn't just a means to describe the limits of our abilities - it's describing how the universe operates at a fundamental level. SteveBaker (talk) 09:41, 14 October 2008 (UTC)

As SteveBaker points out, the UP is not just about our limits as observers. Another way to think about it, a more elegant way than the "we move a particle to detect it", is as a wave function. Every complex wave can be considered a series of waves added together. You could, hypothetically, layer more and more wave functions together and they would cancel each other out leaving one big wave in the middle. Now imagine doing that for a very small particle. You'd layer wave after wave after wave, trying to get one little spike in the center. Well, when you get down to the scales where the UP takes effect, it requires an infinite number of waves to make that final tiny wave. Or something along those lines. This formulation of the UP is identical to the more classical ones—except it has nothing to do with measurement. --98.217.8.46 (talk) 11:31, 14 October 2008 (UTC)

The uncertainty principle is a mathematical theorem that holds for any kind of wave, not just quantum mechanical wave functions. If you force a classical light wave (Maxwell's equations) or a classical water wave through a narrow opening it will spread out in all directions on the other side, because by confining its position you've left its momentum very uncertain. Musical notes are subject to a pitch-time uncertainty relation: a note of brief duration has uncertain pitch. Piano tuners listen for beats between a note made by the piano and a reference tone; as the two pitches approach each other the frequency of the beats approaches zero, so it takes arbitrarily long to tune a piano arbitrarily well. That's the uncertainty principle. Waves of any kind behave more and more like particles as the frequency increases. That's why geometric optics works so well for visible light. Classical physics is (in a mathematically precise sense) the geometric-optics version of quantum physics. It works well at ordinary scales because Planck's constant is small. -- BenRG (talk) 11:57, 14 October 2008 (UTC)

The first thing you must know is that Heisenburg's Uncertainty Principle is a mathematical property and NOT a physical property. By that I mean it occur because of mathematics and not because Physicist discovered it in the real world. Human beings are not designed to think in terms of wave like behavior which is why you have such a hard time understanding it. If you imagine taking a picture with a SLR camera, you can increase the sharpness of the picture by reducing the aperture but doing so you would need to increase the shutter time. So you can say the aperture (size) * the shutter time is a constant. The uncertainty principle is just like that. 122.107.229.49 (talk) 13:09, 14 October 2008 (UTC)

Einstein thought that the randomness of the uncertainty principle is a reflection of mankind's ignorance of some fundamental property of reality, leading to Einstein's famous quote, "God does not play dice with the universe".

I read that the Bell test experiments put to rest Einstein's objections although I cannot see how any test can possibly prove this if this test was conducted by a human. To rule out human ignorance, you would need a higher life form.

Scientists have for decades tried to reconcile quantum mechanics and general relativity in a single unified theory, which implies that one or both theories might be wrong or at least incomplete.

I agree with the original poster that the Heisenberg Uncertainty Principle is flawed. According to quantum mechanics, the Moon does not exist unless there is someone to observe it.

Given that everything else in the universe is deterministic - everything from the boiling point of water to the timing of the next solar eclipse, I find it hard to believe that subatomic particles would behave any differently. I still think it is more likely that our inability to make deterministic quantum predictions is due to a lack of understanding than a lack of determinism.

It should be pointed out that scientific consensus can and does change over time. Ptolemy's model of the universe was the consensus for over a thousand years, until it was supplanted by Copernicus' model, which lasted over 300 years until it too was supplanted. Yes, quantum mechanics is the current scientific consensus. But for how long?

Fortunately, science is a self-correcting process. As long as human intelligence is great enough to figure it out, it's only a matter of time before it's disproved.

It would be nice, however, if in my lifetime, this issue is resolved. 12.10.248.51 (talk) 14:06, 14 October 2008 (UTC)

The issue has already been "resolved" - many times over - and to the utter (eventual) satisfaction of great minds like Einstein. The Uncertainty principle is as real as Newtons laws of motion. It is literally true that the computer you are sitting in front of when you read my words would not function if it were not for the truth of the UP at the physical level. This is not something you should be doubting! SteveBaker (talk) 23:04, 14 October 2008 (UTC)

Actually, the HUP says nothing about observations of macroscopic objects like the moon. Your senses and reason are perfectly adequate to make statements of objective reality about objects like the moon, because the act of observing the moon does not change the moon. This is VERY different for fundemental particles. When you look at the moon, you do not need to change it; you can passively observe it. For something like an negatively charged electron, in order to observe it, you need to set up a detector with some sort of charge of its own, and measure the deflection of your detector. The problem is, and this is a basic "classical" mechanics situation, any deflection on your detector will result in an equal and opposite deflection on the electron. Thus, by the very act of observing the electron, you must change it. The HUP is a generalization of this phenomenon, and it patently does NOT apply to large objects whose observation does not depend on changing them in some fundemental way. The moon really is there if no one looks at it. --Jayron32.talk.contribs 16:42, 14 October 2008 (UTC)

Personally, I do believe that the moon exists when no one is looking at it, but that's not what David Mermin, Professor of Theoretical Physics of Cornell University claims:

"Pauli and Einstein were both wrong. The questions with which Einstein attacked the quantum theory do have answers; but they are not the answers Einstein expected them to have. We now know that the moon is demonstrably not there when nobody looks."

http://www.jstor.org/pss/2026482 —Preceding unsigned comment added by 12.10.248.51 (talk) 17:20, 14 October 2008 (UTC)

That's SO bogus. "Looking" is not the same as "observing". Even if the moon were subject to quantum effects (which - for all practical purposes - it's not). What "demonstration" can be done to show that the moon isn't there when you're not "looking"? I can be on the other side of the planet from the moon - and notice that the tide is going in and out. Which is indirect proof that the moon is still there. To have any hope of proving such a patently false hypothesis - you'd have to exclude all kinds of observation. So you'd have to say that the moon isn't there when nobody is looking at it AND nobody is noticing the tides AND nobody is noticing it's effect on the progress of the earth's orbit around the sun AND...so on. Since every atom from here to the next star over is feeling SOME gravitational tug from the moon - how can there ever be a situation when it's not be observed in some sense. This SO bogus. I have two pieces of advice here: (1) Philosophers are a waste of space...unless they are actually IN SPACE - then they're a waste of perfectly useful vacuum. Not one thing they've ever come up with has been worth the effort of reading. (2) If you attempt to learn about quantum theory and what the likes of Einstein and Pauli were REALLY talking about - "The Journal of Philosophy" should not be your first (or last) stop! SteveBaker (talk) 23:04, 14 October 2008 (UTC)

(edit conflict) Err, you really do have to read the whole article to make sense of what he means. He's not talking about the literal moon. He's talking about the EPR paradox and how the Bell tests appear to have resolved it. In a very very simplistic version of the EPR argument: if you know UP means you can't know position/momentum at the same time, what if you do some sort of process which theoretically spits out two identical particles at the identical velocities in exactly opposite directions. Couldn't you measure the momentum of one, jot that down, and at the same time measure the position of the other? Wouldn't that tell you two impossible-to-know things about the particle which you measured the position of? That's basically the EPR argument (except that spin and something else was the entangled property, if I recall)—that UP would limit you physically from measuring things but didn't limit the possibility of measurement of entangled properties. Einstein said, "you can know everything despite UP," Bohr said, "well really you're just wrong", and Pauli said it was just a philosophical debate—like asking about the moon. But decades later a smart dude named Bell came along and actually came up with an experimental setup that could distinguish between the two points of view. That's what the Bell tests are about. They are not that easy to explain (the Mermin article does a pretty good job of it but I was still pretty baffled) but the gist of it is if you do a bunch of statistical tests you'll find that when you "look" at the properties you see different things than if you hadn't looked. Very weird stuff but experimentally it seems to work out. --140.247.11.9 (talk) 23:09, 14 October 2008 (UTC)

You people are talking about Werner Heisenberg, right? I wouldn't trust that Heisenburg guy for a second. Franamax (talk) 08:32, 15 October 2008 (UTC)

If Mermin meant that as a metaphor, then it's not quite that bad, but still wrong. Not being able to measure an electron's position and velocity at the same time is not the same thing as saying that the electron has no position or velocity until it is measured. 67.184.14.87 (talk) 14:49, 15 October 2008 (UTC)

hmm. i'm not satisfied with anybody's answer thus far, so i have to throw in my $.000000002 worth. the uncertainty principle is based on the principle that all particles are actually waves. as such, fooling around with fourier analysis or just a little insight will tell you that a wave of a specific frequency extends infinitely; in order to put boundaries on it, you have to smear the frequencies out a little so that they are finally out of phase where you want the wave to end. in the ultimate opposite case from having a defined frequency with infinite dimensions, you have a pulse with a single defined position; but this requires a mix of an infinite number of frequencies. that's absolutely true for waves, nobody has any disagreements or doubts. well, if all particles are actually waves, then it must be absolutely true for them as well; the more defined they are in "location space", the less defined they are in "frequency space" and vice versa. how it works out in reality, and perception, etc. are all just derived from that basic property. Gzuckier (talk) 15:11, 15 October 2008 (UTC)

Why did bacteria evolved?

What is the need for more complex forms of life above bacteria? Aren't bacteria not fit enough everywhere on Earth? Mr.K. (talk) 09:48, 14 October 2008 (UTC)

Because multi-cellular life didn't die out. One can speculate about what advantages multicellular life might have had (greater mobility, greater ability to regulate intracellular conditions, greater longevity, intelligence, dashing good looks, etc.) but ultimately the only real "reason" behind complex life is that life tried it out and didn't die. Evolution doesn't have some overarching plan or some predesigned number of niches to fill, it is simply the persistent accumulation of whatever genes happened to have worked. Dragons flight (talk) 10:00, 14 October 2008 (UTC)

(Repeating Dragons Flight because this cannot be repeated enough...) Evolution is not intelligent and, therefore, doesn't decide when to evolve and not to evolve. Evolution is a term for a process in which DNA slowly changes over long periods of time. So, you cannot ask "Why did bacteria evolve?" You can ask "How did bacteria evolve?" It evolved by a slow process of DNA mutation, survival of the fittest, and replication of rare qualities until they became common qualities. -- kainaw™ 13:29, 14 October 2008 (UTC)

Of course you can ask why a living organism evolved. The answer would be that some living organisms were not fit for their new environment. That makes specific mutations become stable in a population. The problem with bacteria is that they seem to be the fittest form in any environment on Earth and apparently even outside it. Mr.K. (talk) 15:53, 14 October 2008 (UTC)

Hardly. Archaea are much fitter. --Ayacop (talk) 16:03, 14 October 2008 (UTC)

Well, there's a tautology here, and a valid one, that we are ignoring. When you judge fitness on a set of arbitrary conditions, like "hey, this stuff grows in lots of weird places, so it must be the best form of life EVER", well, that isn't really a measure of fitness. The true measure of fitness is survival. Many organisms are quite fit in their own ways, and if they were somehow less fit than others, the others would have crowded them out by now. --Jayron32.talk.contribs 16:33, 14 October 2008 (UTC)

To Kainaw: Yes, DNA is a big part of the picture, but there's also evolution of the epigenome and siRNA's that are not strictly heritable only through DNA, they seem to be a meta-system inherited with the DNA. In other words, DNA comes with the pre-formed elements that shape the use of the DNA. Just my impression, but it's all quite fascinating. Franamax (talk) 08:24, 15 October 2008 (UTC)

bottom line; there were some environments which bacteria hadn't thoroughly exploited successfully, so there were niches for other organisms to evolve into. (the inside of a refrigerator, for one example....) bear in mind, though, that for billions of years bacteria and their cousins blue green algae were the only critters on earth, so they did a pretty good job. on the other hand, as soon as eukaryotic cells evolved, there has been this burst of complexity in a relatively short time, so that was apparently the area prokaryotes couldn't evolve into. Gzuckier (talk) 15:28, 15 October 2008 (UTC)

A) Blue green algae are bacteria. B) Bacteria shared the early Earth with archaea. C) Prokaryotes did evolve into those niches... by way of becoming eukaryotes. D) Single-celled eukaryotes arose at least 500 million years before they evolved into large complex forms, and perhaps more than 1.5 billion years (i.e. no rush to complexity). Dragons flight (talk) 17:32, 15 October 2008 (UTC)

I see that my knowledge of the evolutionary dates of eukaryotes is sadly out of date. Gzuckier (talk) 21:24, 15 October 2008 (UTC)

Medical condition relating to films

I once heared about a medical condition where the sufferer could not follow films (or tv shows) because if a different camera angle was used in a scene they could not comprehend that it was the same scene. Does anybody know what this condition is? Thanks Mark Model (talk) 11:17, 14 October 2008 (UTC)

This doesn't sound like it's necessarily a medical condition: our capacity to understand the narrative shown to us in filmic media is a trained skill. One common convention we take for granted is the match on action: shot 1 john points to his left, shot 2 we see a car accident. If it we hadn't seen so many movies and TV already, we wouldn't necessarily make the connection that john was pointing at the car accident. I remember hearing that when motion pictures were still young, there was a film that showed a train coming towards the viewer (maybe man with a movie camera?). The audience fled in terror. You may find culture-bound syndrome interesting. If what you describe is a real 'condition,' it may be an agnosia. --Shaggorama (talk) 16:35, 15 October 2008 (UTC)

Some people on 4chan say that their parents get dizzy or sick while watching them play 3d video games. What's this about?Avnas Ishtaroth _{drop me a line} 01:31, 16 October 2008 (UTC)

pwnitis, perhaps. --Shaggorama (talk) 07:33, 16 October 2008 (UTC)

This is the same phenomena as Sim-sickness.

I certainly get dizzy/sick when watching other people play some kinds of 3D game - and (very rarely) a movie will cause it (the one that comes to mind is Cloverfield). (Which - since my job is writing software for computer games - can be a pain to deal with!) For what it's worth, I can generally pin the problem down to poorly written camera motion software - especially if the field-of-view is set out unrealistically wide (which is almost always the case with 1st person games). When the virtual camera ("eyepoint") is moving at high speeds but not leaning into the corners or being thrown out sideways realistically - then I get sick. The effect is much worse when the frame rate is poor and it's worse when someone else is playing than when I'm playing (but it's still there when I play alone for a large amount of time) - and it's much MUCH worse on large TV's or projection systems. The error between physical reality and what the computer does can be fairly subtle. My "gut feel" (in an all-to-literal-sense!) for bad camera motion has become legendary in some places I've worked. My belief is that when you play the game yourself, your control over the camera gives you some kind of feedback for why it's doing what it's doing. The large screen TV issue is because the more of your visual field is filled by the bad camera action - the more your brain starts to think you're "in the game" rather than "outside the game". The sensation itself is identical to sea-sickness - and drugs like dramamine do help. In the flight simulation world, this is called "Sim-sickness" and an amazing amount of government dollars have been put into fighting it for military flight simulation. SteveBaker (talk) 13:30, 16 October 2008 (UTC)

Cola as a spermicide?

Is this true? Why do so many people still drink it then? Which amounts are they talking about for it to work? --217.227.77.18 (talk) 11:20, 14 October 2008 (UTC)

They mean if you directly immerse your sperm in cola they might swell up and die (2008 Ignobel Prize). This is not generally claimed to be an effective contraceptive under any normal circumstances, and merely drinking lots of cola is not claimed to have any effect at all. Dragons flight (talk) 11:29, 14 October 2008 (UTC)

Yes, although it is probably a weak spermicide. "The Spermicidal Potency of Coca-Cola and Pepsi-Cola," C.Y. Hong, C.C. Shieh, P. Wu, and B.N. Chiang, Human Toxicology, vol. 6, no. 5, September 1987, pp. 395-6. Pubmed. Ingesting a liquid is entirely different than applying the liquid to your sperm. Your digestive system breaks down liquids before they are circulated through the body so it isn't as though pure coke is being pumped into your testes.--droptone (talk) 16:05, 14 October 2008 (UTC)

Just to be absolutely clear, Droptone is not suggesting anyone inject cola into their testes as a contraceptive! ;) My guess is that it would be very effective and very permanent... --Tango (talk) 12:21, 14 October 2008 (UTC)

That sounds like an excellent recipe for a Darwin Award. Dragons flight (talk) 13:21, 14 October 2008 (UTC)

No - it's DEFINITELY not true. The Mythbusters busted this theory. Also Snopes says "No" - and they cite a half dozen impressive scientific studies in reputable journals. SteveBaker (talk) 22:42, 14 October 2008 (UTC)

Actually... the exploration of the "Effect of 'Coke' on sperm motility" (in the NEJM, no less) that showed it was effective, and the followup that refuted the claims were joint winners of a 2008 Ig Nobel Prize! :) — Scientizzle 22:53, 14 October 2008 (UTC)

Wow... with highly scientific and well studied sources who aren't just selecting a few Scientific claims without consideration of Scientific Bias or strict methodology, like those, who needs actual science or to read published papers for themselves? We should just stick to basing our Science on Mythbusters and our Politics on Penn and Teller... then we don't need to think, compare studies or evaluate the experiment's merits in determining whether their conclusions are valid. Seriously though, don't just take everything the TV, or indeed any paper says, on face value, don't question everything for the sake of it either, but come on, you just sound a bit sheep like. - Jimmi Hugh (talk) 23:49, 17 October 2008 (UTC)

Name of Phobia

Is there a name for a phobia of seeing a swarm of the same thing? For instance, I panic and run if I see a swarm of ants. It skeeves me out. But if I see one ant walking around, its fine. Same for worms, bees, ladybugs, etc. And one time, I saw a cartoon of a swarm of catepillars (with happy faces) in a coloring book. I couldn't even look at it without feeling like I was gonna dry heave. Is there a name for this phobia? --Emyn ned (talk) 13:32, 14 October 2008 (UTC)

It may simply be a mild insect/worm/creepy crawly phobia. One is not too much for you to handle, but several at once is too many.CalamusFortis 15:28, 14 October 2008 (UTC)

(ec) Most person-specific phobias aren't medically recognized and named. You could call it swarmophobia if you'd like. -- MacAddct1984 ^{(talk • contribs)} 15:34, 14 October 2008 (UTC)

err..says who? The APA has made a point of classifying every human neurosis and eccentricity imaginable! In fact, I'm of the opinion that they've gone somewhat overboard and are blurring the lines between personality trait and condition in a growing number of instances. --Shaggorama (talk) 17:33, 14 October 2008 (UTC)

See specific phobia (DSM-IV 300.29). The only phobia I can find specifically mentioned is agoraphobia (300.21, 300.22). -- MacAddct1984 ^{(talk • contribs)} 17:47, 14 October 2008 (UTC)

Since it's up for speculation, let's try plethoraphobia because it seems to be a fear of an excess of something, or more precisely, aggregatophobia from aggregare for "herded together" or "a flock". Julia Rossi (talk) 09:46, 15 October 2008 (UTC)

Computer program to visualise biomolecular pathways/interactions

The network of interactions occurring between different proteins in different cellular contexts is terribly confusing. Is there are computer program that aims to help process and visualise the interactions and their effects, using the many databases that exist on the Internet? I'm thinking along the lines of those complicated posters of signalling pathways except that using a computer program, the display could be more simple (not displaying necessary information), dynamic (adding or removing complexity while one studies) and always up-to-date. Does such a program exist?

Such data is manually gathered and presented at http://www.reactome.org

You can't automatize this. Even UniProt has an automatized partition (TrEMBL) and an edited part. --Ayacop (talk) 15:58, 14 October 2008 (UTC)

That website is pretty cool, thanks for sharing! --Shaggorama (talk) 17:22, 14 October 2008 (UTC)

McCain's arm

I have observed that McCain's arm is somehow too stiff. Does he has any known medical condition?Mr.K. (talk) 15:55, 14 October 2008 (UTC)

Yes. Due to injuries sustained while a POW, McCain cannot fully raise his arms. Likely this extends to general stiffness. — Lomn 16:06, 14 October 2008 (UTC)

He's also a septegenarian. Most people to reach his age have some form of arthritis, or stiffening of the joints. Its a general symptom of being old. --Jayron32.talk.contribs 16:28, 14 October 2008 (UTC)

That makes a difference. Is his conditions degenerative? Should we vote for Obama? Mr.K. (talk) 16:37, 14 October 2008 (UTC)

It shouldn't make any difference, we have had very successful presidents who have had crippling mobility issues far worse than McCain has. McCain's arthritis and former injuries should not be a reason to make a decision over his ability to lead. His fitness to lead should be judged on his past actions and on his plans for the country. On those facts alone, we should judge him entirely unfit to lead, but not on any perceived health issues. --Jayron32.talk.contribs 16:46, 14 October 2008 (UTC)

It's worth noting, however, that FDR did die in office. According to our article, his medical condition affected his (and his party's) choice of running mate in the 1944 election—serious consideration was given to the issue of who his successor would be as President if he were to be elected and die. Honestly, John McCain is getting on in years, and it would be foolish to pretend that he isn't. Asking if his running mate capable of running the country in the event of his death is not an unreasonable question.

To be fair, it's a question that should be asked regarding all Presidential tickets. According to our list of United States Presidents who died in office, eight of the United States' 43 Presidents have died on the job (four by assassination), and we've lost at least one other to resignation. Historically, there's a better than one in five chance that the guy elected in November isn't going to make it all the way through his Presidency. TenOfAllTrades(talk) 22:02, 14 October 2008 (UTC)

If not for the incumbent advantage, the relevant question would be how likely he is to get through one term. That would make the odds look better. —Tamfang (talk) 03:26, 15 October 2008 (UTC)

True, but we'd be breaking new statistical ground with McCain. Only three past Presidents first took office after age 65, and none after age 70. (McCain is now 72.) For white males in their mid-seventies in the United States, the average mortality (all causes) is about 3.5% per year—roughly a one in seven shot that McCain wouldn't survive his first four-year term. That doesn't account for the appreciably-better-than-average medical care a President is likely to get, nor does it include the extra stress the Presidency would apply relative to the average 72-year-old's lifestyle. It also doesn't include the risk of an elderly President suffering a non-fatal but incapacitating medical event (most likely a heart attack or stroke) that renders him temporarily or permanently unable to carry out his duties. (Figure the odds of a serious but non-fatal cardiovascular event are going to be another 1% or so per year.)

In the interest of completeness, it should be noted that all of these risks apply to Obama as well, but at age 47 the probabilities are about an order of magnitude smaller. There's also nothing to preclude him being the victim of an assassination attempt, a car accident, or just a bad fall down the stairs. While it is much more likely that McCain's health will fail him in office, voters will certainly want to evaluate both candidates' running mates. TenOfAllTrades(talk) 05:51, 16 October 2008 (UTC)

and none after age 70. Lamentably no longer true. —Tamfang (talk) 04:40, 25 August 2023 (UTC)

@Jayron32 - re: "His fitness to lead should be judged on his past actions and on his plans for the country. On those facts alone, we should judge him entirely unfit to lead, but not on any perceived health issues" - this isn't the place to be advocating for or against any candidate on political questions. It's the Science reference desk. -- JackofOz (talk) 04:04, 15 October 2008 (UTC)

He released his medical records to try and convince people that he was healthy enough for the job and there was nothing in there that suggested it would be a real problem. Of course, at his age new problems can develop quickly. If you think McCain would be a better president that Obama but are worried about his health, you need to decide how bad it would be if did fall ill (based on you opinion of Palin, among other things) and how likely that is to happen and compare that to how bad you think it would be to have Obama as president and vote accordingly. --Tango (talk) 16:59, 14 October 2008 (UTC)

He didn't "release" them, he let a bunch of reporters look through the ~1200 (I've heard 1173) pages for three hours, without taking any copies or such. Among the findings seem to have been four bouts of melanoma, several precancerous colon polyps and a bunch of other worrying things. -- Aeluwas (talk) 17:15, 14 October 2008 (UTC)

And, you must consider the health of Obama, who has not released his medical records. He could easily have extreme hypertension and hypercholesterolemia without showing any outward signs of illness. Then, after a couple stressful months in office, he could have a heart attack. If you are basing your vote on something as silly as possible health risks, why not go for the silliest? If you are simply trying to validate your vote on some silly factor, why not base it on something sillier, such as refusing to vote for anyone who has ever been a pilot? -- kainaw™ 17:19, 14 October 2008 (UTC)

Obama did release a partial medical history that claimed he was in "excellent health".[4] Although the article states that his blood pressure was 90 over 60, which is a bit low for a systolic pressure... -- MacAddct1984 ^{(talk • contribs)} 17:31, 14 October 2008 (UTC)

People never seem to worry about low blood pressure... I'm not sure why not since, as far as I know, it can be just as dangerous as high blood pressure. --Tango (talk) 18:19, 14 October 2008 (UTC)

That depends on how you define "high" and "low" blood pressure. High blood pressure is a modifiable risk factor for cardiovascular disease, and it's more common than low blood pressure. See "Blood pressure". Axl ¤ [Talk] 18:37, 14 October 2008 (UTC)

Oh my! If we are speculating about future ailments, we can toss in a possibility of Addison's disease with a blood pressure as low as 90/60. Can we trust a man with the faint possibility of Addison's to make reliable decisions? -- kainaw™ 18:51, 14 October 2008 (UTC)

You mean like JFK? ;) -- Aeluwas (talk) 18:59, 14 October 2008 (UTC)

Even worse! Now there is historical evidence that electing a President with Addison's leads to an assassination! How many more idiotic reasons can we find to back a superficial preference for one candidate over the other? -- kainaw™ 20:28, 14 October 2008 (UTC)

7812819, give or take 42. --Stephan Schulz (talk) 22:50, 14 October 2008 (UTC)

I plan on voting for whoever is taller. APL (talk) 23:21, 14 October 2008 (UTC)

Au contraire, your the one who is being idiotic. Are you seriously suggesting that it's not valid to consider the health of a candidate or that age and known existing or previous medical conditions are a factor in considering the health of a person; in an election where you are electing that person for a fixed term? Personally, I would say McCains health, while of concern, is probably not enough to warrant people not voting for him solely for that reason. But his health is clearly of far greater concern then it is for Obama. And while if I were an American I would never vote for him anyway, if I was in the position of deciding between the two I would definitely factor his health into the equation and the possibility of Sarah Palin taking over as President I would consider far more likely then Biden. Nil Einne (talk) 08:43, 15 October 2008 (UTC)

I disagree with your premise. Given the nature of the US electoral system, you're basically stuck with the vice-president until 2012 if something were to happen to the president to make him or her unfit for office (including death). Therefore, it's perfectly resonable to consider whether ill-health is likely to make this happen. While obviously this applies to all candidates there is intriscly significantly greater reason to have concern when the candidate is 72 years old with some relatively serious health concerns then there is when the candidate is 47 years olf with no known health concerns. Obviously you can't predict precisely what will happen but this doesn't mean you shouldn't make a decision based on the evidence at hand. After all, for all we know McCain or Obama might go nuts and decide to nuke China and Russia one day because they're bored. In both cases I would say the evidence suggests this is unlikely but clearly if one of the candidates did have a tendency to do reckless things which seriously endanger others when they were bored, d it's perfectly resonable for a person to consider it more likely that this candidate would do something to endanger the security of the US and to let this affect their vote. In other words, just because it's theoretically possible that all candidates would do the same thing or worse doesn't mean it's ludicrious to consider the likelihood of something happening based on the evidence at hand. Nil Einne (talk) 08:31, 15 October 2008 (UTC)

The story now seems to be that his arms were injured when he was tortured as a prisoner of war, but in January 1968 interview with a French reporter [5], he said his arms and a thigh were broken when he ejected from his plane. In the propaganda tape he recorded under duress for the North Vietnamese which was broadcast by Radio Hanoi to U.S. forces in South Vietnam on June 2, 1969, McCain said "“I was a U.S. airman engaged in the crimes against the Vietnamese country and people. I had bombed their cities, towns, and villages and caused more injury even death for the people of Vietnam. After I was captured I was taken from a hospital in (?Da Nang) where I received very good medical treatment. I was given an operation on my leg, which allowed me to walk again, and a cast for my right arm which was badly broken in three rpt three places. The doctors were very good and they knew a great deal about the practice of medicine. I remained in the hospital for some time, I regained much of my health and strength.” In a propaganda interview with a Cuban official 14 days after being shot down, McCain said that when he bailed out he collided with the remains of his plane and fractured both arms, one in three places, and his right leg at the knee. See also [6] which has reports of the McCain interviews while he was a POW and [7]. Edison (talk) 05:01, 15 October 2008 (UTC)

@Jack – so it is! (the science desk). In that case I find Jayron32's comment observational and objective. And personally am enjoying the role of Mccain's arm as punctum.;) Julia Rossi (talk) 09:36, 15 October 2008 (UTC)

Clearly he might have sustained additional injuries "while a POW," as Lomn stated, but his injuries while ejecting from his plane 'before' he was a POW are sufficient to explain his present limited range of motion in his arms. Edison (talk) 14:52, 15 October 2008 (UTC)

what is this plant?

I've been given this plant as a gift, however it has no provided information about species/care instructions etc. I'm fairly sure it's quite a commonly owned house plant but I have no idea what it might be. Here is an image of it: [8] —Preceding unsigned comment added by 86.135.81.194 (talk) 17:53, 14 October 2008 (UTC)

I don't remember what it is called either, but I owned a very similar, if not the same species, of plant. I am fairly certain it is a variety of succulent, but I can't remember anything more specific than that. --Jayron32.talk.contribs 17:57, 14 October 2008 (UTC)

It's either Holiday cactus or some closely related species.CalamusFortis 18:04, 14 October 2008 (UTC)

Thanks, that looks about right :) --86.135.81.194 (talk) 18:09, 14 October 2008 (UTC)

Yes, it is. I've got one. Axl ¤ [Talk] 18:41, 14 October 2008 (UTC)

i have heard the term "Clopathia" applied to similar plants. Edison (talk) 05:37, 15 October 2008 (UTC)

Getting contact lenses in

Hehe, I'm extremely impatient and I can't get the hang of it. Is there any quick tip or something? A putter-inner from eBay for 9.99? --217.227.103.178 (talk) 19:35, 14 October 2008 (UTC)

The first time i got contacts, it took me an hour to get them in by myself. I have now worn contacts for 18+ years. Give it time and practice. Like anything else, you are training your body something new, and it just takes practice. Your body has a natural reflex to prevent bad stuff from getting into your eye. You simply have to retrain your body against this reflex. It's well worth it, I find that my vision is much better with my contacts than with the same prescription of glasses, and once you get used to it, you don't even notice it. --Jayron32.talk.contribs 19:47, 14 October 2008 (UTC)

I'm rather new at it myself. When I have trouble getting them in, I set up a mirror; it helps my aim and also, by giving me something to look at beyond my finger, helps me resist the reflex. —Tamfang (talk) 03:21, 15 October 2008 (UTC)

Frequency guard bands in OFDM

Can anybody explain why the lower and higher frequency subcarriers are left unused in OFDM systems? For example, 802.16 uses a 256-point FFT, however, the 28 lowest subcarriers and the 27 highest are not used. This is also true for the DC subcarrier. What's the reason of this? 85.243.50.175 (talk) 20:42, 14 October 2008 (UTC)

The transmission and reception has to pass through a band pass filter to stop spurious transmission and remove adjacent interference. At the high and low frequency ends there is a roll off in the passband, that will reduce sensitivity and result in noise if signal was used. There is also phase shift in these parts of the passband, so it is best not to use it. The frequency allocations are already overlapped in these sort of systems, so there is no wastage of spectrum. Graeme Bartlett (talk) 21:04, 14 October 2008 (UTC)

Thanks a lot! It has to do with filtering, just as I thought. The frequencies are overlapped indeed, but leaving some slots unused will still make the system sub-optimal. However, that could only be solved by an ideal filter. 85.243.50.175 (talk) 21:37, 14 October 2008 (UTC)

Identify this tree

An unidentified tree, presumably taken near Agumbe.

Same image, retouched to look less foggy.

I recently spotted this image on IfD. I think it could be worth keeping, but it's not very useful if we don't know what it shows. So, can anyone identify the tree with red flowers in this photo? Based on the name and the description page, the picture was presumably taken somewhere near Agumbe, Karnataka, India. In case it helps, I've also uploaded a version I tweaked to make it look somewhat less foggy. Thanks in advance for any help. —Ilmari Karonen (talk) 21:37, 14 October 2008 (UTC)

Royal poinciana or Delonix regia is found in India, or it may be another kind of flame tree. The Indian coral tree is known as Erythrina variegata found throughout southern Asia. Both are suited to tropical areas. Julia Rossi (talk) 09:24, 15 October 2008 (UTC)

Hmm... it does look remarkably like some of our pictures of E. variegata, particularly this image. The timing is a bit suspicious, since all the sources I've found suggest that E. variegata should flower around March, while the Agumbe photo has an Exif timestamp in July, but I suspect the timestamp may simply be bogus — not everyone sets their camera clock correctly. Anyway, thanks! —Ilmari Karonen (talk) 10:36, 15 October 2008 (UTC)

You're welcome, Julia Rossi (talk) 22:20, 15 October 2008 (UTC)

Ethidium Bromide

I was doing PCR analysis today, and touched the ethidium bromide stained agarose gel with my hands when i - instinctively, and without thinking - took it when someone handed it to me. Later i touched the gel again with gloves and then when removing the gloves touched my hand with the glove that i had just used to move the gel. I guess i'm probably not going to die, and after googling i'm almost content in the knowledge that i wont likely be getting cancer any time soon either, but one of my fellow students told me that - if i was concidering it - it would be a bad idea to get pregnant, and that that was a general safety precuation. So for how long should i not be getting pregnant? The next week? Year? Does this mean that my future children will have genetic defects or am i just being paranoid? Thank you 87.60.70.3 (talk) 22:01, 14 October 2008 (UTC)

The Wikipedia Reference Desk is not allowed to give personal medical advice. You are welcome to read Ethidium Bromide (which doesn't really answer your question either), but for concrete advice you should speak to a doctor or poison control specialist. Dragons flight (talk) 22:38, 14 October 2008 (UTC)

(Trying to tiptoe around possibly medical question) I have never personally worked with the stuff, however some background information. MSDS's (JTBaker and Fisher, as well as my LCSS list it only as "possible" teratogen, with more study being needed. I guess it depends on the half-life of it in your system, as teratogens normally only act on a developing fetus. It also depends on how much you came into contact with.

All that said, I'm guessing you are doing this research at a university or school. If you are at all worried, contact your Environmental, Health, and Safety department (or something similar), even to just put your mind at ease. They will possibly have more information, and you are able to give them more information on medical history and under what circumstances it happened, as well as how much and if you followed safety precautions (throughly rinse for 15 minutes or so with water?). It is also likely very confidential. In other words, get information from professionals, not other students.

And being slightly paranoid is good when it comes to your health. This is the only body you get (probably) :) --Bennybp (talk) 22:53, 14 October 2008 (UTC)

[Edit conflict] I don't think that a doctor or poisons service could give you any more helpful information. I searched Pubmed and didn't find any relevant articles. I'll try to look at ToxBase later. From our Wikipedia article, I didn't know that ethidium bromide is used to trypanosomiasis in cattle. Axl ¤ [Talk] 23:01, 14 October 2008 (UTC)

Here is an interesting article, although I can't vouch for the reliability/accuracy of the website. Axl ¤ [Talk] 23:30, 14 October 2008 (UTC)

Also [9] Nil Einne (talk) 07:31, 15 October 2008 (UTC)

That is a SPECTACULAR article Nil. Good find, thanks for sharing. --Shaggorama (talk) 07:45, 15 October 2008 (UTC)

Ironically, it was originally in the Ethidium bromide article until I removed it (it appears to be well written but as the personal blog of an unknown scientist I don't think it can be classified as a reliable source), although I didn't find it from there (I found it from Google). Nil Einne (talk) 09:35, 15 October 2008 (UTC)

It is directly linked from the "bitesizebio" article. Axl ¤ [Talk] 10:27, 15 October 2008 (UTC)

Doesn't help for your question, but I recall talking to a researcher who was complaining about other people who were completely paranoid about any exposure to EtBr, but cavalierly stared into the UV lightbox unprotected. (Ignoring the possibility of getting cataracts or skin cancer from the UV exposure.) My experience has been that most labs have a "bogeyman" which everyone gets irrationally paranoid about, while completely ignoring the 20 other items around them which are as bad or worse. Of course, the MSDS's which recommend full protective gear for water, and labels which claim "this product has not been completely investigated" for compounds which are FDA approved drugs doesn't help things. (Both examples have been seen personally.) Back on point, don't trust medical advise from Wikipedia, but also don't trust medical advise from paranoid labmates. -- 128.104.112.147 (talk) 21:41, 15 October 2008 (UTC)

Tropospheric gas giants

After the tropophere have those gas giants have a surface prior to the fliud interior or not. I know Jupiter and Saturn's sky starts at the upper level to be blue, then at lower level is it the tropos it's sky is like orange, brown, yellow (gold or tan). For Uranus and Neptune the sky must start to be blue as a gatorade, then at lower level it's paler blue. Anyways what part of atmosp layers is tropos on gas giants? And what's beenath the troposhper? Normal people say Jupiter, Saturn Uranus and Neptune contains no surface.--Freeway19 23:06, 14 October 2008 (UTC)

As far as I know, your assertions as to the color of the sky from within whatever planet's atmosphere remain entirely unsourced. I'm not sure why you keep repeating them. Anyway, there's not generally an expectation of a solid surface prior to liquified gases around the core. Per atmosphere of Jupiter, the troposphere's lower boundary is the liquid interior. — Lomn 23:49, 14 October 2008 (UTC)

Image:Structure of Jovian atmosphere.png This image is tough to understand. Jupiter's sky will not be black becasue it have an atmosp perhaps the upper level is blue or blue-purple. About Jupiter's center I know it's 5 to 6 times hotter than surface of sun, is the interior bright and hot or black and hot. Thi s is what the book said, I guess the interior is white-hot.--Freeway19 00:00, 15 October 2008 (UTC)

[10][11] [12] [13] This is the source. The trace above the globe glows tinge of blue on Saturn and Uranus. For Jupiter when Galileo pass t's atmos, I belive is thermo, it's tropo must be orange or orange-scarlet, hoever at upper layer jupiter's sky appears blue or indigo. Lomn, you said no source how you explin those.--Freeway19 01:41, 15 October 2008 (UTC)

I don't mean to be insulting, but you do realize that none of those images are real, right? They're just artwork. APL (talk) 03:54, 15 October 2008 (UTC)

Additionally, the first link (the only one that could be used as an actual reference) doesn't appear to be discussing color. I see no reason to assume that the colors present are anything but a visual aid. — Lomn 13:09, 15 October 2008 (UTC)

Artist interpretations generally make use of artistic license. Plasticup ^T/C 15:54, 15 October 2008 (UTC)

• On those planets I saw the diagram. They don't have a solid surface between. Hydrogen or methane haze will possibly make those sky on stratos blue, but at tropos, is the place of varying cloud layers. At that level the sky may be brown or orange, that's for Jupiter and Saturn, however because of the methan haze of Uranus and Npetune, their sky must start to be deeper blue at top layer, and at lower layer, the sky must be lighter blue. After tropos, it will be liquid interior bound. I wonder will it be light / dark at liquid interior. --Freeway8 22:22, 15 October 2008 (UTC)

  I wouldn't expect any sunlight to penetrate the atmosphere of a gas giant (I haven't researched it, though). It could be hot enough to be radiating in visible light itself, though. I don't know where you're getting all this stuff about colours, it sounds like guess work to me... --Tango (talk) 22:30, 15 October 2008 (UTC)

• Titan's also get very little or no sunlight. it's light is only 1/3000 to Earth, but it's sky appears to be light orange or tangerine colour because of it's haze, Cassini have been able to land on Titan.--Freeway8 00:10, 16 October 2008 (UTC)

• Some source says jupiter, Saturn and Uranus have hazes. hazes is judge to be blue.--Freeway8 01:12, 16 October 2008 (UTC)

  It's pretty dark on Titan due to the distance and thick atmosphere, but yes, there is sunlight on the surface. However, it doesn't have anything like as thick an atmosphere as a gas giant - the thicker the atmosphere the less light can penetrate to the surface. The gas giants certainly have hazes and clouds and their atmospheres will scatter different wavelengths of sunlight differently, so as long as you're not far enough down that sunlight is blocked the sky will have a colour, but I don't know where you are getting these ideas about what that colour would be. Who judges hazes to be blue? --Tango (talk) 15:34, 16 October 2008 (UTC)

• I thouht Uranus is mostly coverwith haze, this is why the sky is blue all the time. Those gas giant's sky stay the same all the time, same as Neptune and Saturn. Saturn is much cover with haze too is thicker than Jupiter and neptune's.For uranus and neptune the sky color should be darker blue on top and get lighter on bottom. At the lowest layer must be light blue. Saturn is also much a blue planet I thouhgt, so it's sky much start out blue on haze, but at lower layer must vary to yellow, brown, and orange. Jupiter's have haze, but the disc is rainbow or opal-like color, so the sky on top is specualte to be blue, but not define. At the tropo level juptier may vary white, orange, brown. For Venus, the sky stay the same much all the time I thought. At the cloud levels, it appears to be yellow, but beenath the cloud could be orange mix, becasue of the terrible greenhouse effect, Venus' sky may look scarlet seen from surface. I am not certain what's the color above the top clouds of Venus, becasue it is on the bound to outer space, so I guess it's black.--Freeway8 20:01, 16 October 2008 (UTC)