Wikipedia:Reference desk/Archives/Science/2008 November 6

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November 6

Frames per second

I learned in school that most movies contain twenty four frames per second. This is a two part question:

1. What are the extreme frame rates for human vision--how many are needed in order to detect motion, at what rate does it move two quickly to discern what's happening?
2. What is the "frame rate" of reality? That is to say, is it possible to speak of how quickly my eyes convert what i'm seeing into recognizable images in terms of frame rates?24.147.171.20 (talk) 00:36, 6 November 2008 (UTC)

Our articles frame rate and persistence of vision can hopefully help. The latter talks of a 16fps threshold for film (between flicker and motion image) and that "a critical part of understanding these visual perception phenomena is that the eye is not a camera: there is no 'frame rate' in the eye". Booglamay (talk) - 02:05, 6 November 2008 (UTC)

I recall hearing on the tv show QI that the reason pigeons don't move out of our way (or the way of cars) as quickly is that their 'frame-rate' (or whatever the word is) is much faster than humans, so to them things appear to be moving slower (or something like that) and so the reason they don't get out of the way is that to the thing is 'further' away than it is to us. Could be nonsense but that's what I heard and the show is usually reasonably well researched (being a comedy quiz show about common myths and unusual info). 194.221.133.226 (talk) 09:16, 6 November 2008 (UTC)

The pigeon story sounds like bollocks, IMHO. You are assuming that humans have the "right" frame rate, and species with a lower frame rate will constantly be shocked at how fast everything seems to be moving, and vice versa. Pigeons would be used to their own frame rate. 141.14.217.217 (talk) 11:48, 6 November 2008 (UTC)

Sorry to clarify - it's not that the pigeons are 'shocked', it is that the car is approaching slower so what to us looks like a last-minute get out of the way is to the pigeons plenty of time. I'd try find it on youtube/something as hard to explain, but i'd be surprised if it wasn't based on some truth - the whole role of the show QI is about facts/common mistakes so would be a bit silly. 194.221.133.226 (talk) 14:38, 6 November 2008 (UTC)

That makes no sense - pigeons instinctively know what their frame-rate is so they know how to convert what they see into actual speed, just like we do. The idea that a fast frame-rate corresponds to slow motion only applies if you film at a fast frame-rate and then play it back at a standard one. Either you are remembering incorrectly or QI is talking rubbish (it does happen). --Tango (talk) 15:58, 6 November 2008 (UTC)

To put things a different way, with 194 is proposing, the pigeons are for some reason too 'stupid' to be able to comprehend the speed of a fast moving object. The issue of framerate is an unnecessary distraction and we can never know if it's the cause (I would say it's unlikely, it would just be their brain doesn't compehend fast speeds). For something like a pigeon which AFAIK is resonably intelligent and likely to be preyed upon by a variety of fast moving animals, this would be a major shortcoming and therefore seems unlikely. Nil Einne (talk) 08:51, 8 November 2008 (UTC)

• What are the extreme frame rates for human vision--how many are needed in order to detect motion, at what rate does it move two quickly to discern what's happening?

  The limiting rate that we can distinguish depends on a few things. At the edges of your field of view, you are much more sensitive to flicker than in the center. Secondly, there is a huge variation between individuals. Most (if not all) people can see flicker out of the corners of their eyes at 40Hz. Some are bothered by 50Hz, few at 60Hz - hardly any over 70Hz. But there was one guy I met who (even with the center of his field of view) could see flicker at over 80Hz. His life was miserable because both TV and movies were unwatchable for him. He could use a computer - but only with a very high end video card and a monitor that could be cranked up to refresh at over 100Hz. At the low end, our ability to 'fuse' fast motion into continuous imagery also varies. I hate watching action movies in cinemas because that 24Hz rate doesn't work for me when things are moving fast. Everything becomes very jumbled and essentially unwatchable. But some people can work down to perhaps 15Hz. You can figure out what's happening even as low as 1Hz though. Suppose a lion is rushing towards you through the jungle. You're running and trying to keep an eye on where the thing is. You won't be able to see it all the time - it disappears behind trees - you have to switch back and forth between looking forwards so you don't trip over something - and looking back to see how close the lion is. You can manage to keep a mental 'image' of where the lion currently is between glimpses of it - so long as you get to see it again every few seconds. This ability is what allows you to keep track of what's going on at VERY low frame rates.

• What is the "frame rate" of reality? That is to say, is it possible to speak of how quickly my eyes convert what i'm seeing into recognizable images in terms of frame rates?

  The 'frame rate of reality' is something we discussed in the next question (below) - it's either a meaningless question - or the answer is the planck-time which is around 10^-44 seconds - which is an unimaginably short time. So essentialy, the answer is "there is no such thing". But your eyes don't have "frame rate" - so (as below) the question is moot. SteveBaker (talk) 18:49, 6 November 2008 (UTC)

"Reality,"" or humans' perception of changing visual input, has been modelled as a "continuous flow model" [1] rather than successive frames of movie film or processing steps by a digital computer, so the question may be meaningless. Edison (talk) 05:57, 7 November 2008 (UTC)

Why is there no flicker in real life?

The question above got me thinking: shouldn't there be a flicker from the interference between reality's framerate and my eye's framerate??? Even if reality's is a hundred times higher there should still be barely perceptible flicker, maybe less than once per second depending on how long it takes for the two to get in synch again... —Preceding unsigned comment added by 82.124.214.224 (talk) 02:51, 6 November 2008 (UTC)

See Planck time. The universe's frame rate is at about 5 x 10^-44 seconds. Lets say, for the sake of argument, that your eye can perceive differences in timing of 0.01 seconds. That means that the universe's frame rate at a speed of about 5,000,000,000,000,000,000,000,000,000,000,000,000,000,000 times faster than your eye's frame rate. Good luck finding that "flicker"... --Jayron32.talk.contribs 03:00, 6 November 2008 (UTC)

Neither you, nor the universe, have anything that can really be considered a frame rate. The rods and cones in your retina don't pick up light in synch, which is good, because they don't do it often enough to get a usable frame-rate. The universe becomes less deterministic as you look closer, so talking about anything much smaller than a planck time is pointless, but it's not as if the universe is separated into frames of a planck time each. Also, even if they did have a frame rate, it would just mean that every once in a while the universe would go 5 x 10⁴² + 1 frames instead of 5 x 10⁴². Not really noticeable. — DanielLC 16:47, 6 November 2008 (UTC)

Your eye doesn't have a "framerate" in the way that a TV camera does. Vision is a continuous phenomenon. The "interface" between your eye and your brain isn't a set of 'pixels' being updated at some fixed rate - it's more like "there is a vertical edge moving at 27 degrees per second from left to right across the visual field"...although even that is an over-simplification. There simply isn't enough bandwidth along the optic nerve to pass whole images. Since this isn't a discrete set of events, the idea of "interference" is meaningless. Hence the update rate of your TV (50Hz or 60Hz depending on where you live) doesn't cause 'beat frequency' problems with your visual system as it does when you point a cheap video camera at your TV. The idea of a "frame rate" for reality is even more disturbing. Again, there is no such thing - although I guess if you're forced to come up with something - Jayron32's explanation of the plank time is reasonable. But that's only the smallest measurable interval - because light cannot cross one planck length in less time than that and space is quantized in planck-lengths. I don't think it's the case that everything in the universe progresses one step at a time in perfect sychronism every 5x10^-44 seconds...although it starts to become a meaningless question. SteveBaker (talk) 16:40, 6 November 2008 (UTC)

I'm not sure it's entirely accurate to say "the universe is quantised in planck lengths". We simply don't know what happens on smaller scales, that doesn't mean that nothing happens. --Tango (talk) 18:03, 6 November 2008 (UTC)

Yes - that's true too...which makes it even less accurate to say that time ticks along at the planck time. SteveBaker (talk) 19:13, 6 November 2008 (UTC)

Well, at least it does, in that case, bear some parallels to the motion-picture-camera concept of framerate. When we view a motion picture, we don't know what is going on "between the frames". It could be nothing at all (ala stop-motion animation) or it could be something which is just cannot be recorded as happening (when the camera flicks off, the world doesn't flick off). Likewise, with Planck Time, its not that we can know for a fact that nothing happens in a time interval smaller than this, its just that we can't know what happens in that smaller interval; it is an imperfect analogy to "frame rate", but it works reasonably well, especially in answering the OP's question, and in demonstrating the false assumptions it makes. --Jayron32.talk.contribs 21:18, 6 November 2008 (UTC)

Yeah, the analogy almost works. The main flaw if that frames are set instances equally spaced and you see whatever is happening at that time. That means that an event taking 1/2 the time between frames could either be captured by a frame or fall inbetween two frames. With Planck time, there is no set beginning and end to each interval, so there is no concept of whether a short event happens between frames or not. --Tango (talk) 21:45, 6 November 2008 (UTC)

Indeed. A real film camera will have an adjustable shutter time - so you can either capture short "instants" of time spaced at some interval - or you can leave the shutter open for longer then very rapidly shut it, move the film on and get the shutter open again. This captures all of the action over an extended period - so almost none of the action is "missed" - but the frame is the average of all of the incoming light. Motion blur is the consequence of that. I'm not sure precisely what happens with planck time - but it's possible that it's more analogous to a long shutter time than an infinitely short one. The action would be a smeared statistical mush...which seems intuitively more like we'd expect with quantum theory kinds of events that are always somewhat fuzzy.

The singularity-less black hole

I had a brainwave one day while walking down the street for school that a black hole does not need to have a singularity! My idea was like this: in general relativity, time slows with an increasing gravitational field. Then, in a collapsing star, its mass will never be squeezed into zero volume because the collapse will also be slowed down infinitely when the mass is squeezed into the Schwarzschild radius! Maybe this is why general relativity breaks down in singularities, in the singularity, time goes to the infinites and complex numbers and the universe did not exist at that time! So, perhaps we have to change our definition of black holes into an object with density equal or larger to a certain density(precisely c^6/6G^3M^2 after calculation)! But i didn't use General Relativity. So can anyone who knows General Relativity calculate and tell me is it true or not, please? The Successor of Physics 07:58, 6 November 2008 (UTC)—Preceding unsigned comment added by Superwj5 (talk • contribs) 03:15, 6 November 2008 (UTC)

All objects inside the event horizon collapse to the singularity in finite proper time. The notion of things taking infinite time is an artifact of how things appear to an outside observer trying to use photons to watch someone fall into a black hole. See also black hole and gravitational singularity. Dragons flight (talk) 03:37, 6 November 2008 (UTC)

And to observe things, the best you can do is to use photons, and even gravity travels at c so it makes no difference between what you observe and the slowing of time. Check "http://www.geocities.com/angelto.geo/bhole/blackho.htm"(has changed) "http://www.relatividad.org/bhole/blackho.htm"out and you will know that you are wrong.The Successor of Physics 08:00, 6 November 2008 (UTC)

Somehow I doubt that geocities is the arbiter of all things astrophysics. — Lomn 14:07, 6 November 2008 (UTC)

On that density definition: An event horizon does not form if the mass inside the dense region is moving outward fast enough. That is by the way the trick to escape a black hole, even if you are already in. Blow it up! —Preceding unsigned comment added by 84.187.64.186 (talk) 16:20, 6 November 2008 (UTC)

Of course, the matter making up the black hole is under the same rules as you are, so if the black hole already exists you can't blow it up (other than waiting for Hawking radiation to do the job). You would have to impart the outwards velocity before the event horizon initially formed, which would simply stop the collapse. --Tango (talk) 17:41, 6 November 2008 (UTC)

A black hole is an area of a metric from which no timelike curve leaves. Blowing all matter apart *changes* the metric. There might be some principal obstacles to do this, but the preexisting event horizon is none. —Preceding unsigned comment added by 84.187.77.58 (talk) 08:32, 8 November 2008 (UTC)

Endocannabinoids and autism spectrum

Have endocannabinoids or their absence been implicated or ruled out as part of the mechanism of autism spectrum disorders? NeonMerlin 05:12, 6 November 2008 (UTC)

I don't think that research has been done (know anyone who has been doing their own research/self-medicating? ;) ). Mirror neurons, on the other hand, may play a role in autism. Check out Causes of autism. --Shaggorama (talk) 06:41, 6 November 2008 (UTC)

an imaginary history of time

I recently read A Brief History of Time and was underwhelmed, but curious about one chapter that seems to say: if time is real it has a singularity at the Big Bang, but if time is imaginary we can think of space-time as a smooth hypersphere – or was it the other way round? – and choosing one or the other is a matter of taste. Eh? As a layman not afraid of the occasional bit of math, is there something I can read that makes more sense of this? —Tamfang (talk) 05:42, 6 November 2008 (UTC)

You might enjoy Introducing Time if you're just looking for a quick, accessible read. --Shaggorama (talk) 06:38, 6 November 2008 (UTC)

This is probably heresy of the first degree, but I still haven't read ABHOT. However, what Steven's talking about is basically the choice of basis for your metric of spacetime. If you choose your time variable, t, to be defined in a "conventional" way, then that gives you one expression of the metric - in Minkowski space, you get $ds^{2}=dx^{2}+dy^{2}+dz^{2}-dt^{2}$ - which is just a flat, plain old Riemannian manifold. However, there's nothing stopping you from defining a new time variable, $\tau =it$, and it's fairly easy to show that the metric becomes $ds^{2}=dx^{2}+dy^{2}+dz^{2}+d\tau ^{2}$. Since tau is i times your original t, you can, if you want to, call tau "imaginary time". And other metrics will have similar transformations under such a change of variables. Confusing Manifestation(Say hi!) 22:23, 6 November 2008 (UTC)

what is the temperature of heat (not mainstream).

What is the temperature of pure heat (not mainstream science which says heat cannot exist in pure form). also, is it possible to extract pure heat in solid or gas form, or only liquid? (also not mainstream science persp). thank you! —Preceding unsigned comment added by 82.124.214.224 (talk) 07:17, 6 November 2008 (UTC)

Mu. Your question is nonsensical, since even you seem to grasp that "pure heat" isn't a thing. Heat refers to a type of energy. It is not an object and has no temperature. Dragons flight (talk) 07:40, 6 November 2008 (UTC)

Whats liquid heat look like?124.169.66.245 (talk) 08:40, 6 November 2008 (UTC)

Like this. DMacks (talk) 08:51, 6 November 2008 (UTC)

To pinpoint the first answer, let's see what heat is. Heat is kinetic energy, basically. Atoms in materials oscillate about their equilibrium. The rate of their oscillations is a measure of their temperature, and the overall amount of these microscopic kinetic energies in a piece of material is its heat. There is no kinetic energy other than the energy related to moving bodies. Heat isn't unique in that sense. It's the same issue. Second, there is no mainstream or any other streams from the point of view of physics, and there is no meaning to heat outside the realm of physics. This issue was debated centuries ago, when the notion of flogiston came up, but this possibilty is already over by now. Analogically, there is no meaning to sound outside the context of material as well, since sound waves too, are vibrations in air, liquid or solid. BentzyCo (talk) 09:56, 6 November 2008 (UTC)

I don't understand you guys, I clearly said I wasn't looking for the mainstream scientific perspective! I said it in the title. I said it in my first sentence. I said it in my second sentence. I guess I should have said it after "thank you" as well. As for the answers you guys gave me, I acknowledged them already in the question, saying "mainstream science [...] says heat cannot exist in pure form". So after I've already acknowledged your perspective, and explicitly asked for a different one, why bother to write all that? It's all in the heat article, or in the history of heat under 18th, 19th, and 20th centuries. Why spend time retyping an article?

To reiterarte, I asked a simple question, what is the TEMPEREATURE of pure heat, in liquid form, not from the point of view of scientists who say pure heat is not possible at all. Further, can pure heat be extracted in solid or gas form, or only liquid form -- again, NOT from the point of view of scientists who say pure heat is not possible. Answering hint: you might say 'there is no point of view in the world, held by a single scientist, pseudoscientist, crank, crackpot, or layman, according to which pure heat is possible', though in this case you'd better have a reference for this bold assertion. But if this point of view exists, then that's what I'm asking for -- so if you give an answer that is consistent with the idea that pure heat is not possible, you're NOT answering my question, but only retyping a wikipedia article. (Maybe you could better spend you time adding your thoughts to the heat article in that case?) —Preceding unsigned comment added by 82.124.214.224 (talk) 14:51, 6 November 2008 (UTC)

Temperature is a scientific measurement which relies upon a certain verifiable, falsifiable, universally accepted understanding of material physics. It is incompatible with this nonsense concept of "pure heat". Plasticup ^T/C 15:24, 6 November 2008 (UTC)

Your question cannot be answered because what you are calling "pure heat" is nothing more than nonsense that you made up. It is impossible for anyone to answer what the temperature of something in your imagination would be. Your should consider your insult about "Maybe you could better spend you time..." and realize that you could better spend your time asking questions that can be answered instead of nonsense about stuff you've just made up. -- kainaw™ 15:35, 6 November 2008 (UTC)

Put another way: you're proposing that such a things exists that we as mainstream-science people don't follow. So just what is "pure energy in liquid form"? DMacks (talk) 15:40, 6 November 2008 (UTC)

Red Bull? --LarryMac | Talk 15:58, 6 November 2008 (UTC)

If you ask a question on a SCIENCE desk - and demand non-scientific answers - you are going to get laughed at and soundly denounced as a person of very little brain (which is what is happening right now). The definition of the the word "temperature" and the word "heat" are such that you simply cannot have "pure heat" that's like a physical thing. That's an idea that came in with Phlogiston theory in the 1600's and was proven to be false (and subsequently abandoned) in about the year 1750. You ask for a reference for that - and I suggest you read our article about Mikhail Lomonosov and check the references at the bottom of that article. Even so - if you believed in phlogiston - I don't think your question made sense because even phlogiston didn't have a "temperature". Anyway - if you want an answer from a non-scientist then I suggest you call the Psychic Friends Network - because we can't answer such a nonsensical thing here.

Two and a half centuries of careful experiment has lead to the conclusion that heat is a property of the motion of atoms. The energy we attribute to heat is the kinetic energy of all of those particles bouncing around - and temperature is a measure of that. So when you look carefully at a sufficiently small scale, there is no such thing as heat or temperature - there is just motion. The concepts of heat and temperature are just handy shorthands for this. But that's the scientific answer (and also "The Truth") - evidently you'd prefer to be lied to...so I'll say that the answer is 147.23 degrees centigrade and you'll be just as happy - right?

SteveBaker (talk) 16:29, 6 November 2008 (UTC)

How can heat be a liquid? 216.239.234.196 (talk) 16:31, 6 November 2008 (UTC)

Maybe liquid heat is where liquid smoke comes from. -- kainaw™ 17:37, 6 November 2008 (UTC)

What would be our speed if none of us were here?

Your question is nonsensical and you even insulted people trying to correct you! If you want to ask a nonsensical question then don't ask it on the Wikipedia Science Desk! Please don't insult people trying to help you. You are certainly a person of a tiny brain.----The Successor of Physics 11:11, 7 November 2008 (UTC)

If I understand right, you're asking what (in a hypothetical world) absolute hotness might look like. Now, I could be silly and say [insert sexy movie star name here] embodies absolute hotness, but let's try to answer the question instead.

Initially, it seems like you're asking for the impossible, yes. You're asking for something which is measurable, like "speed" or "distance" or "gallons per second through a pipe", then are asking "what would absolute speed be like?", "what would absolute distance be like?", "what would absolute water flow rate be like?".

Normally, absolutes are the domain of religions. God is allegedly completely good, all-knowing, all-seeing, everywhere, every when, he is the absolute of heat but also of cold, blah blah blah... nonsense words that sound impressive.

But let's try absolute temperature. I think I remember from highschool that heat is from atoms jiggling. The faster they jiggle, the more heat there is. The more atoms you have with the jidggling, the more heat there is. That gif of the rattling things is a good description of heat. The more atoms you have per unit volume, jiggling faster, the more energy you have in heat form. So it's a function of speed and density.

So. Speed. Beyond a certain point, the atoms in a solid get so energetic, they can't keep structure, and they turn to liquid: the solid melts. And then, beyond even that, they fly apart, becoming a gas: the solid boils. Finally, even the gas breaks, as the atoms fall apart, and you get a plasma.

So, "absolute heat" will involve the elements moving at light speed, so it'll be be a plasma, I think. Even atoms couldn't exist in it. However, the denser something is, the more heat it can store, so, it'd have to be as dense as it can possibly be. A black hole. A singularity.

I think, then, "absolute heat" would give you a singularity with the bits inside it moving around at light speed. You couldn't get denser and you couldn't get faster. Except that there's nowhere in the singularity for the bits to move TO. So they'd have to move in synch, the whole singularity vibrating together.

That's the best I can do, anyway. Hope that helps you with your NaNoWriMo god of heat (am I right?) DewiMorgan (talk) 21:29, 8 November 2008 (UTC)

Heat is electromagnetic radiation that is within a certain range of frequencies. If the radiation falls on a solid physical object, it makes the atoms at the surface of the object quiver faster (assuming the body was relatively cool). The increased quivering is passed on to atoms deeper in the body (heat conduction). In the case of a gas or liquid, the atoms are free to move, so they move faster and quiver faster (convection currents can also occur). Thus when an object is hot its atoms quiver or move rapidly. But heat itself is electromagnetic radiation. One more point is that quivering atoms radiate electromagnetic heat, and an object becomes warmer or cooler depending on the net income-outgo of radiant heat.

BLASTing lots of short sequences

Hi,

I want to blast ca. 40,000 70bp (approx) sequences against a particular genome to see which of them are present in the genome. Does anyone know how I could go about this?

Many thanks

141.14.245.167 (talk) 09:16, 6 November 2008 (UTC)

Use an itty-bitty machine gun? --67.185.190.46 (talk) 22:51, 6 November 2008 (UTC)

(To 67.185): The original poster is referring to BLAST, an algorithm for aligning DNA or protein sequences. --NorwegianBlue ^talk 00:50, 7 November 2008 (UTC)

• I would do it the other way around and blast the genome against a large set of peptides. Or you could write a perl script to blast the different sequences... - Mgm|^(talk) 08:06, 7 November 2008 (UTC)

Textile Finishing

What is trubenising? —Preceding unsigned comment added by 203.153.35.130 (talk) 12:22, 6 November 2008 (UTC)

That word give only 90 Google hits. Are you sure that you have spelled it correctly? Plasticup ^T/C 15:33, 6 November 2008 (UTC)

Spelling with a "z" gets 210 ghits. Zain Ebrahim (talk) 16:19, 6 November 2008 (UTC)

Lamictal

One of the effects of a Lamictal overdose is seizures. Can someone please explain to me, in terms of like biology and pharmacology, how an anti-seizure medication can cause seizures? Thanks. —Preceding unsigned comment added by Jamlessness (talk • contribs) 14:12, 6 November 2008 (UTC)

One proposed mechanism (as far as I know there is no conclusive mechanism that is agreed by pharmacists) is that Lamictal stabilises neuronal membranes by inhibiting voltage-sensitive sodium channels and modulates presynaptic transmitter release of excitatory amino acids. My guess would be that an overdose of Lamictal destabilises the voltage-sensitive sodium channels once again and increases the quantity of seizures. —Cyclonenim (talk · contribs · email) 16:50, 6 November 2008 (UTC)

There are several potentially implicated mechanisms. Here is one article that discusses this. Axl ¤ [Talk] 11:01, 8 November 2008 (UTC)

let's try this again.

In a science-fiction alternate universe in which heat was a liquid of some kind that flowed from thing to thing, making it hot, was produced in exothermic reactions, etc, what would be the most plausible temperature for the liquid? If you insist, you can move this question to the humanity section. —Preceding unsigned comment added by 82.124.214.224 (talk) 16:27, 6 November 2008 (UTC)

Since you're talking about some imaginary universe you invented, you can make up whatever rules you like. Asking what's "plausible" doesn't make any sense. Friday (talk) 16:31, 6 November 2008 (UTC)

Are you asking because you're writing some kind of science fiction story? 216.239.234.196 (talk) 16:34, 6 November 2008 (UTC)

If this is for a science fiction story that you're writing, say it's temperature is infinite or that it's so high, it cannot be measured. 216.239.234.196 (talk) 16:41, 6 November 2008 (UTC)

Or, you could say it has negative temperature - I've always thought that sounds like something from sci fi. --Tango (talk) 17:48, 6 November 2008 (UTC)

Wow, you just blew my mind. 216.239.234.196 (talk) 20:51, 6 November 2008 (UTC)

Friday makes a good point, you cannot create an imaginary universe with different rules and then ask us to try and apply real universal laws to it. Why not just pick any temperature if you're writing a story? —Cyclonenim (talk · contribs · email) 16:42, 6 November 2008 (UTC)

I'm fairly certain your question as stated is incoherent. If this imaginary liquid is heat, how can it have a temperature? That's like asking what color is color. Heat is a property of matter, and I think the attempt to try to imagine a property of matter as a form of matter is confusing you. If heat were transfered in this way, the liquid itself wouldn't have a temperature because it imparts temperature. Any attempt to measure its temperature would just cause the thermometer to keep rising with continued exposure. But again, its your imaginary universe, so you can do what you want. If you like, you could just say "heat is only transfered by the exchange of a liquid of 1,000,000K" or something like that, but then you might have a hard time coming up with a reason why this liquid is the only way heat could be exchanged. --Shaggorama (talk) 16:45, 6 November 2008 (UTC)

See Caloric theory. This is not as wacky idea as it may sound, this was once the prevailing scientific theory of heat. You will likely receive some good insight by reading that article... --Jayron32.talk.contribs 17:52, 6 November 2008 (UTC)

Indeed, but I don't think that theory ever tried to give a temperature of the caloric. --Tango (talk) 17:56, 6 November 2008 (UTC)

In part because, as noted, the idea is incoherent. Caloric doesn't have a temperature. It is temperature. --98.217.8.46 (talk) 01:27, 7 November 2008 (UTC)

If you are inventing some 'thing' (a liquid in this case) to which you choose to arbitarily attach the label "heat" - what is the effect (in your imaginary universe) of molecules moving around very quickly? Is that also heat? If so - then it must be a different kind of heat than the kind that appears as a liquid. In such a situation, you'd be well advised to give the properties of your weird liquid a different name - because it's a different kind of thing than heat "really" is. If you claim that it's the SAME thing as the usual meaning - then your liquid has molecules that are moving - and it's not "pure heat" anymore. "Heat" is a word with a meaning. When you give it another meaning, you've just blown the relationship between "heat" and "temperature" because "temperature" relates to the ordinary (atoms moving around quickly) meaning of "heat". So now you're asking us how much of one thing relates to some other thing - when both 'things' are stuff that you've just made up in your head.

Simply forcing something to be true by defining it as true in an imaginary universe means that all connection with fact, logic and reason just got blown away. Without those connections, we can't connect the redefined meaning of "heat" in the context of your imaginary universe with the imaginary definition of "temperature" (which could easily mean "number of migrating swallows per cubic parsec" for all we know!). If you could define the meaning of your word "temperature" in the context of your re-definition of the word "heat" - then perhaps some self-consistent answer might emerge - but it's not the "real" answer because there isn't one.

SteveBaker (talk) 19:10, 6 November 2008 (UTC)

One of the problems with these sorts of "what if just this one thing were different" questions is that it's very easy to get inconsistencies. Scientific theory is constructed to be self-consistent, and changing one rule may make others absurd (in fact proving that a theory leads to contradictions is a major way in which both math and science work). You have to specify what sort of situations you want the new fictional theory to hold, and which you can safely ignore, in order for there to be some semblance of consistency. (And even then, someone will likely find a hole related to something you ignored.) - With that in mind, lets look at heat and temperature. If you take 1L of water, and add a given amount of heat, you raise the temperature. If you take half a liter, you only need half the heat. So it's not the total amount of heat that determines the temperature, it's the "density." If you could "distill" pure liquid heat, the temperature would likely depend on how concentrated you could get it. How much more caloric does 100 L of boiling water have than 100 L of water at freezing? 1 L? 1 mL? 1 nL? The temperature-as-heat-density could vary by orders of magnitudes. You'd have to take into consideration heat capacity as well, though. A given amount of heat applied to 1 L of water doesn't raise the temperature to the same amount as it does when applied to the same amount, either by mass or by volume, of air, metal, or even oil. You'd also need to think about heat of vaporization and heat of fusion. You have to add a lot of heat to ice at 0 C to get it to melt, and once it's melted, the temperature is still at 0 C. One potential dodge is to claim temperature as being the density of "free" caloric, and claim that a certain amount of heat binds to or reacts with the material when it melts/freezes. This can also explain away the heat capacity issue, if you claim that a portion of the caloric doesn't go to increasing the temperature, but binds/reacts with the substance. The temperature of your "pure" caloric would then be related to the hypothesized density, as well and the fraction which gets bound up. (You could even postulate that pure heat has a temperature of near absolute zero, if in your fictional world you say that in pure form caloric "binds to" itself, thus resulting in no "free" caloric, and thus a low "free" caloric density (temperature).) - As mentioned above, once you remove yourself from reality, you can make practically any answer "correct". -- 128.104.112.72 (talk) 19:19, 6 November 2008 (UTC)

In your imaginary universe the "temperature" of a thing might be defined as ([Amount of Liquid Heat] / [Mass of Object]) * [A Constant] = Temperature. If that's how the imaginary scientists in your imaginary world measure "temperature". Then the temperature of pure liquid heat would tend towards positive infinity because of the divide by zero.

Of course, this is all completely meaningless. If your imagination is different than mine, then your imaginary scientists may come up with a completely different formula. APL (talk) 20:08, 6 November 2008 (UTC)

About 42 degrees Q. CBHA (talk) 21:09, 6 November 2008 (UTC)

Why confine yourself to liquid? That's so mundane! Friction wears away the fabric of space letting the heat leak in from another dimension.  :-) Saintrain (talk) 21:36, 6 November 2008 (UTC)

Another dimension? Nonsense! The real answer is much more grim. Friction heat comes from the future. You see, in the far future they stave off the heat death of the universe by sending pockets of heat back in time to what we know as the present day, thus creating an energy gradient in their own time. APL (talk) 13:47, 7 November 2008 (UTC)

That would imply that the heat somehow 'wears out' or otherwise 'goes away' - if it doesn't then they just get it back again from the past and the problem is much worse. I'm also bothered by the fact that if heat is a liquid - we know it can flow through almost anything - that's why the outside of a hot kettle is...hot. So you can't contain it in anything...that would suggest that either this liquid is massless - in which case it should all just float off into space - or it has mass and it would all sink through the earth and sit at the center (which I'm guessing the proponent of this theory will say explains why the earth's core is so hot...although, sadly not why the moon doesn't also have a hot, molten core). There are just too many inconsistencies in a theory like this. It doesn't hold together at all. That's why the Phlogiston theory of heat (which is essentially what this is) was abandoned 250 years ago. SteveBaker (talk) 18:10, 7 November 2008 (UTC)

I HIGHLY recommend you guys search for all of the posts made by the OP's IP address across all the ref. desk boards. The combination of bullheadedness and misunderstanding, spliced with occasional genuine curiosity, is either genius or madness. NByz (talk) 03:56, 8 November 2008 (UTC)

I answered this in your above post, but I'll have another bash at it. The most plausible to me would be that it would have no easily-measurable heat: heat would be an effect of it, not an attribute of it. However, the liquid could get "used up", converted into energy by being absorbed into the thing it was heating, as fast as it could absorb it. Insulators would be things that were very bad at absorbing the heat, which is what you'd have to use to hold the stuff in. If you dipped a thermometer into it, the thermometer would just max out, until the "heat" was all used up. If the thermometer could not absorb all the heat, it would melt, and even boil (both "state changes" involve releases of energy, so would absorb some of the heat liquid). Kinda like why, in the real world, temperature readings are taken "in the shade" - if you take a temperature reading in the sun, you will only measure your thermometer's ability to absorb heat. If you had a bottle of heat-liquid, you'd measure how much you had not in degrees, but in degree-litres or somesuch - the amount you could heat a litre of water with it. Another reasonable thing to measure it in would be watts: people would quite easily say "I've a bottle with 50 kilowatts of heat in". Dilute heat might raise a thermometer to less than the max, maybe, though I don't know what you could dilute heat with... unless you also have a "cold" liquid.

Guess I was wrong about the NaNo God then :) DewiMorgan (talk) 21:42, 8 November 2008 (UTC)

Iron content in apple juice

Not for medical advice or anything but I've been juicing 3 more or less mid sized apples and consuming the juice everyday for the last week or so. Is this amount large enough to induce iron toxicity related disorders? Leif edling (talk) 17:38, 6 November 2008 (UTC)

According to our apple article, 100g of an apple (not juice) has about .12mg or 1% of your suggested daily intake. So it's very very doubtful. -- MacAddct1984 ^{(talk • contribs)} 17:48, 6 November 2008 (UTC)

According to nutrition data, a single large apple has 0.3mg of iron. The recommended dietary allowance is 8mg. So, 3 apples is less than 1mg. Over a week, it is less than 8mg. So, over a week, you are getting less than the RDA for iron. -- kainaw™ 17:45, 6 November 2008 (UTC)

Just saying it isn't a request for medical advice doesn't make it so. "Is this activity I'm doing likely to cause a medical problem?" is a request for medical advice. Our article on apples has the nutritional information including the percentage of recommended daily consumption of iron, see Apple#Health benefits. If you want more than that, ask a doctor. (And you should probably verify the source of the nutritional information as well.) --Tango (talk) 17:47, 6 November 2008 (UTC)

Vox pop here, but a tv nutritionist dumbed it down this way, that it takes five apples today to get you the iron that an apple a day in the 50s gave you. Make of it what you will, Julia Rossi (talk) 21:34, 6 November 2008 (UTC)

Some apples these days are so anemic, they're not even red. —Tamfang (talk) 03:03, 7 November 2008 (UTC)

Apple juice has 0.1 mg of iron per 100 ml according to my nutritional values book. Graeme Bartlett (talk) 21:38, 7 November 2008 (UTC)

It might also be worth pointing out that apples have a little bit of vitamin C, which enhances iron absorption. On that count, though, you might want to be more concerned about oranges. Not that apples and oranges are comparable in any way. SDY (talk) 21:45, 7 November 2008 (UTC)

Too late for a word, I guess, but, referring to Tango 's objections, the words i opened my question with were meant as a sort of a disclaimer to say that if i took the opinion by people replying to my question and it harmed me , i would have none to blame but my foolish self. I don't understand (dont know, rather) why medical advice with proper disclaimers is not allowed on Wikipedia.Leif edling (talk) 16:53, 12 November 2008 (UTC)

Proton Proton Chain

In proton proton chain, gamma ray is gradually released. But is there any fixed energy limit of this ray (i.e range of frequence) or is it same as the common gamma ray?117.201.97.211 (talk) 17:38, 6 November 2008 (UTC)

There is no "common gamma ray" energy. The energy is certainly fixed by conservation of energy. Unfortunately the standard equations for showing fusion and fission reactions don't really show you how the energy is apportioned up in the constituent products. For example, in the standard DT reaction, we see it as this:

D + T = 4He + n + 17.6 MeV

But really the "energy" side of the equation is not just some magical spark (as it is usually depicted, and as it is displayed in the awful illustration at the top of the nuclear fusion page), but in the energy of the products (the neutron flies off with a force of 14.1 MeV, the alpha particle flies off with a kinetic energy of 3.5 MeV). --140.247.243.184 (talk) 18:31, 6 November 2008 (UTC)

Colour of the sky

Two questions:
1. Why is shorter wavelength (i.e. bluer) light subject to more scattering in air than longer wavelengths?
2. Regarding why the sky is bluer overhead than at the horizon, I had a look at this but I still don't understand why the increased scattering of light coming from the horizon makes it lighter.
Thanks, Zain Ebrahim (talk) 17:58, 6 November 2008 (UTC)

Have you seen Rayleigh scattering and diffuse sky radiation? Dragons flight (talk) 18:21, 6 November 2008 (UTC)

Thanks. The external links in those articles helped answer my questions. Zain Ebrahim (talk) 18:11, 9 November 2008 (UTC)

Capsaicin fatality

No, I'm not asking for medical advice. ;) This is just curiosity. There seems to be a large contradiction between the Hot sauce article, in which it's stated that the "heat" caused by Capsaicin is a harmless chemical reaction, and the Capsaicin Toxicity, it's now claimed to be potentially fatal. Is Capsaicin fatal in large amounts because of the body's reaction to it? --Sarcasticninja (talk) 18:44, 6 November 2008 (UTC)

Pretty much everything is toxic in large enough quantities. --Tango (talk) 19:54, 6 November 2008 (UTC)

Indeed, you can even be poisoned by pure water. Capsaicin is harmless in any quantity you are likely to consume in the course of normal eating, even from the dreaded habanero. That doesn't mean that, in large enough quantities, it cannot get toxic. --Jayron32.talk.contribs 21:11, 6 November 2008 (UTC)

My back of the envelope calculations: The world record Naga Jolokia pepperhas about 620 mg of capsaicinoids while a jalapeno of the same weight has about 1.5-5 mg. The lethal dose in mice 47.2 mg/kg, that's about 3300 mg in a 70 kg human. So 5 Naga Jolokia's or 2200 jalepenos could be lethal (extremely rough numbers). The heat is caused by a harmless reaction between your pain receptors in your tongue and the capsaicin, but it has many other effects on your body which taken to extremes could be harmful. -- Mad031683 (talk) 22:33, 6 November 2008 (UTC)

Asuming, of course, that mice toxicity is translatable to human toxicity. There is likely no reason to believe it should be... There are many things toxic in small amounts to one species which are relatively harmless to others (i.e. theobromine toxicity in dogs; humans are not nearly as effected by this chemical.) There is probably little correlation between the LD50 for mice and the LD50 for humans for any given compound... --Jayron32.talk.contribs 23:12, 6 November 2008 (UTC)

While LD50 is hard to measure in humans (the inbred ones don't live in my state :-) ), here is an example of pretty good correlation between human model (in vitro culture) tox data and mouse data:[2]. Admittedly, this is outside my area of expertise, but it seems as though you might be stating the case against animal models for drug toxicity a little too strongly. Any data? --Scray (talk) 00:39, 7 November 2008 (UTC)

Look at this data, culled from our article on Theobromine poisoning:

Animal	Oral toxicity (mg/kg)
	TDLo	LD50
Cat		200
Dog	16	300
Mouse		837
Rat		1265

Assuming that you DON'T have LD50 data for humans, which one of these would you use for a human analog? There's a 6 fold difference in this random sampling of mammals; there is no reason to assume that humans are a closer fit, metabolically, to any one of these mammals. Theobromine is an alkaloid like capsaicin is, I don't expect the toxicity data for that to be any more reliable that theobromine vis a vis animal vs. humans... --Jayron32.talk.contribs 01:31, 7 November 2008 (UTC)

Variation of 6-fold is not that bad. As pointed out earlier in this exchange, the variation in capsaicin levels per pepper are probably comparable, and for many drugs the therapeutic index is much larger than that. These tox data could provide a fair start for dose-finding studies in human trials of a drug (certainly much better than wondering whether the human LD50 is likely to be closer to 0.001, 0.1, 10, or 1000 mg/kg). --Scray (talk) 03:54, 7 November 2008 (UTC)

Cat Scan of Serial Killer's Brain

What would a cat scan of a serial killer's brain look like? Meaning besides those who are not serial killers? --Emyn ned (talk) 21:30, 6 November 2008 (UTC)

Computer tomography of a serial killer's brain would be the same as a normal person's brain. The difference is psychological, not physical. —Cyclonenim (talk · contribs · email) 22:26, 6 November 2008 (UTC)

Usually psychological. I'm not sure about serial killers, but I know some mass murderers (such as Charles Whitman) where later discovered to have brain tumors and similar physical ailments affecting their mental stability. Dragons flight (talk) 22:48, 6 November 2008 (UTC)

• See post hoc ergo prompter hoc. Charles Whitman was discovered to have a brain tumor, and he was also mentally unstable. Not necessarily causitive in his case... --Jayron32.talk.contribs 23:08, 6 November 2008 (UTC)

Actually - we can do one better - and you can see! The Visible Human Project took a corpse, encased it in gelatin - froze it solid and sliced it a fraction of a millimeter at a time - taking photographs at each stage - then reassembling thousands of photos into a 3D computer model. This is better than a CAT scan - you can see exactly what every part of the body looked like without having to be able to interpret the peculiar appearance of CAT scan data. As it happens, the body they used was Joseph Paul Jernigan who was a murderer (OK, only ONE murder - but a pretty brutal one). The project did this to two corpses - one male and the other female. The woman had died of a heart attack - and (as far as we know) lead a more or less blameless life. Comparing the two reveals only the expected differences between men and women.

If you have a strong stomach - you can view the results on many web sites, this one, for example. (Don't say I didn't warn you!) SteveBaker (talk) 23:05, 6 November 2008 (UTC)

I would not be at all surprised to find some structural differences between people whose behavior is normal and those whose behavior is grossly abnormal, like serial killers. WE know that brain damage can cause aberrant behavior, like those with bullet wounds to the brain or those who were the victims of psychosurgery. Similarly brain trauma from alcohol or the effects of Altzheimers, strokes, or abnormal intracranial pressure cause abnormal behavior. Edison (talk) 00:41, 7 November 2008 (UTC)

Unfortunately, such descriptive data does not always work in reverse. Merely because trauma can cause abnormal behavior does NOT mean that abnormal behavior is always caused by trauma. Some people make horendously bad choices, and there isn't always a "cause" for it... --Jayron32.talk.contribs 01:35, 7 November 2008 (UTC)

I would say that people who behave bizarrely are a mixture of those with detectable brain trauma or abnormalities and those without presently detectable brain abnormalities (bad life experiences, chemical imbalances). Edison (talk) 03:41, 7 November 2008 (UTC)

Or sometimes, they are just assholes. When somebody acts in ways that we find incomprehensible, we seek ways to excuse the behavior as beyond their control. See the idea of locus of control. Some people understand that all of their actions are the result of their own consious choosing, others wish to blame every choice they make on factors out of their control. --Jayron32.talk.contribs 04:50, 7 November 2008 (UTC)

The difference is "psychological, not physical"? Well, physical differences in gross structure can manifest as psychological differences. Steve Pinker writes in The Blank Slate, "convicted murderers and other violent, antisocial people are likely to have a smaller and less active prefrontal cortex, the part of the brain that governs decision making and inhibits impulses." --VectorField (talk) 07:40, 13 November 2008 (UTC)

Why don't birds on the power lines get electrocuted

I know I read about this in wikipedia but for the life of me could not figure out how to search for the question or the answer in order to locate that page again. —Preceding unsigned comment added by 12.34.246.35 (talk) 22:08, 6 November 2008 (UTC)

By searching 'bird power line site:wikipedia.org' (Google's "site:" filter is great!), I quickly found this discussion from last June. — Lomn 22:12, 6 November 2008 (UTC)

Because the birds do not complete an electric circuit. In order for electricty to flow, electrons need a complete path either to the source from whence they came, or to the ground. If this condition isn't met, there is no electricity. --Jayron32.talk.contribs 22:15, 6 November 2008 (UTC)

Which is why large birds (eagles, condors, and the like) can get electrocuted: they're big enough that when one lands on a telephone pole, they're likely to touch more than one wire. --Carnildo (talk) 22:56, 6 November 2008 (UTC)

The electricity has a choice - it can either travel a couple of centimeters up one leg of the bird - across it's body and a couple of centimeters back down - or it can take the "short cut" across 1cm of copper. Since electricity flows more easily through copper than through bird - it goes the quick, easy way...and essentially none of the electricity flows through the bird. If the wire midway between the bird's legs were to suddenly snap - the bird would be fried in very short order! If the bird were in contact with the ground and with the wire (a bird with L-O-N-G legs!) then the electricity would find it easier to go through the bird to get to the ground than to go all the way to the far end of the wire, do all the work to drive your PC (or whatever) - then go through your house wiring down to the ground. SteveBaker (talk) 22:54, 6 November 2008 (UTC)

Good answers, but this video is really great for showing what's going on: [3]. --Sean 00:26, 7 November 2008 (UTC)

A bird would get a nasty shock if it landed on a line at a very high voltage, like 345kv or 765 kv, since there would be capacitive current flow with perhaps a big spark when it got close to the wire. The current flow would not be nearly as large as if the bird completed a circuit to ground or to another conductor, so the bird should not get burned up. But I only see birds perched on lower voltage lines. like 12 kv or 4 kv. Not sure about 34 kv. Edison (talk) 00:36, 7 November 2008 (UTC)

Bird on a wire [4]--GreenSpigot (talk) 08:36, 7 November 2008 (UTC)

Ringnecked Parakeet and Alexandrine Parrot

Can these breed together to produce healthy offspring? —Preceding unsigned comment added by 84.71.86.42 (talk) 23:03, 6 November 2008 (UTC)

The answer seems to be yes. [5]

A more extensive search will probably give you some more reliable sources. As we discussed in a previous post [6] hybrids are generally frowned upon by conservation experts and most breeders. Since the Alexandrine Parakeet/Parrot seems to be declining in numbers in the wild, breeding with another Alexandrine would probably be preferable. Lisa4edit (talk) 06:09, 7 November 2008 (UTC)

Negative calorie food

Is there any scientific reason why negative calorie foods can't be artificially produced? Or even just negative calorie additives — e.g. a flavorless substance that would burn calories, that could be, say, added to a cheeseburger to make the net calorie gain only a handful or so? Could one describe what characteristics such a substance would have on a chemical or structural level? It seems to me that such a product could have a variety of medical benefits for the very obese, especially those who are obese to the point that the possibility of an exercise regimen is severely diminished. This would not be the same thing as a substance that was simply zero calories, of course (which seems comparatively straightforward—anything that can't be digested, among other things!). --98.217.8.46 (talk) 23:36, 6 November 2008 (UTC)

TANSTAAFL... likely many of these additives could have undesireable side effects... --Jayron32.talk.contribs 01:21, 7 November 2008 (UTC)

Well you can say that about all additives, even just calorie-free sweetners. Doesn't mean that the positive effects can't outweigh the negative ones. --98.217.8.46 (talk) 13:52, 7 November 2008 (UTC)

There's always Olestra! A little indigestion can't hurt, right? Orlistat is also sort of along the same lines. Both target fats, which are the densest calories, though simple carbohydrates (e.g. sugar) are probably a bigger demon when it comes to empty calories. Chemically or structurally, these substances don't "remove the calorie value", they impair the body's ability to digest the food and turn it into energy (calories). Most normal "negative calorie" foods don't lack calories, they just have calories in a form (e.g. cellulose) that humans can't digest. They're negative only in the net negative sense that you use more energy digesting them than they provide in nutrition. Truly negative calories would mean negative mass: it's not... likely. SDY (talk) 06:41, 7 November 2008 (UTC)

See, what I'm interested in is not thing that can't be digested (which I already indicated above). And I'm not indicating negative mass. What I'm indicating is something that would actually, through the process of digestion, burn a significant amount of calories per mass of food eaten. --98.217.8.46 (talk) 13:52, 7 November 2008 (UTC)

Cestoda is an all-natural calorie-burner. Taken orally, it consumes many of the calories the person ingests. It's widely available in some parts of the world, but with some side-effects, including vitamin deficiency and tissue damage. EverGreg (talk) 12:01, 7 November 2008 (UTC)

Yeah, well... I didn't mean parasites. --98.217.8.46 (talk) 13:52, 7 November 2008 (UTC)

I think to answer this question, we'd need to know what the processes are that use up the most calories in the digestive process. If it's just moving stuff through your gut, then a small rock is a good slimming aid. If it's chewing it, then chewing gum. If it's some chemical reaction, then is there anything that can instigate that chemical reaction without providing calories? Would swallowing lumps of pure cellulose help? Sawdust? Hard to tell without understanding the mechanism. DewiMorgan (talk) 21:53, 8 November 2008 (UTC)

I recall reading a humourous short article (found it: link) about ice which pointed out that it takes more energy to melt and heat ice up to body temperature than you get from consuming it (since it contains no calories). As a result of this, the article claimed, you could totally nullify the calories in a can of Coke just by adding 148 ice cubes to it. Maelin (Talk | Contribs) 15:56, 14 November 2008 (UTC)

Muscle density

Related to a question asked before about chimp strength. They are much smaller than humans, but much stronger. Is this due to the density of their muscles? Are our muscles just bulky, but not very dense? I also read that humans have greater endurance than most other apes. Do animals with dense muscles have less endurance or is endurance due to other factors like lungs, blood flow, etc? 98.221.85.188 (talk) 23:39, 6 November 2008 (UTC)

Don't forget the knuckles. You might enjoy this thread[7] where quotes The Straight Dope[8] gives: In tests at the Bronx Zoo in 1924, a dynamometer--a scale that measures the mechanical force of a pull on a spring--was erected in the monkey house. A 165-pound male chimpanzee named "Boma" registered a pull of 847 pounds, using only his right hand (although he did have his feet braced against the wall, being somewhat hip ... to the principles of leverage). A 165-pound man, by comparison, could manage a one-handed pull of about 210 pounds. Even more frightening, a female chimp, weighing a mere 135 pounds and going by the name of Suzette, checked in with a one-handed pull of 1,260 pounds. ... In dead lifts, chimps have been known to manage weights of 600 pounds without even breaking into a sweat. A male gorilla could probably heft an 1,800-pound weight and not think twice about it.

So, at least knuckles, muscle mass and density, and swinging through the trees all day long possibly. Don't be fooled by that low slung posture when on the ground... Julia Rossi (talk) 05:05, 7 November 2008 (UTC)

What's the trade-off? Evolution would not have stripped us of that strength without giving us something in return. Plasticup ^T/C 06:19, 7 November 2008 (UTC)

Well, you can use food to build muscles, or you can use food to build brains. SDY (talk) 06:43, 7 November 2008 (UTC)

The trade-off? Humans can organize and strategy and develop novel solutions to problems, and coordinate their actions as a group, and build and utilize tools, and improve upon prior advances in ways that no other animal has been shown to do. I'd take a good human brain over the ability to dead-lift 600 lbs any day. After all, why use your own muscles when you can devise a simple lever or pulley to allow you to lift that weight easily... --Jayron32.talk.contribs 17:52, 7 November 2008 (UTC)

These are not related to our muscles. Plasticup ^T/C 06:13, 8 November 2008 (UTC)

First, we didn't get "stripped" of strength. We evolved from frail, little, monkey women. We, and our chimps and gorilla cousins, grew strong later. They grew stronger than we did. Mmmmm. Monkey women.

Second, and with respect, and not to draw too fine a point, but No! No! No! No! No! There are no trade-offs. Evolution is not a process, it doesn't happen in real time and it's not planned. Evolution is what we call the result of individuals reproducing or not. Very few two-foot men 'cause they can't reach the gas peddle; very few nine-foot men 'cause they can't fit behind the wheel. So men tend to be around five-six foot 'cause cars get the girls. That's it. Saintrain (talk) 19:50, 8 November 2008 (UTC)

Endurance, speed, and the ability to walk upright for long periods, among other things. --Carnildo (talk) 21:48, 7 November 2008 (UTC)

Can you be more specific? Are we talking about a different type of muscle? A different configuration? Where can I find more information on this? Plasticup ^T/C 06:13, 8 November 2008 (UTC)

Yes, humans have more endurance, in terms of running, than all other primates (citation Bramble, D.M., Lieberman, D.E. 2004. Endurance running and the evolution of Homo. Nature, Vol 432, November 18, 345-352).--droptone (talk) 12:35, 7 November 2008 (UTC)

The strength of limbs can change radically with the attachment point to the bone. It is a simple lever effect, which gives the usual tradeoff between speed and force. I don't know if that is really the reason, but it fits the data and does not need any biological miracles. A large variation in the structure of muscles between two closely realted species of ape sounds rather improbable. —Preceding unsigned comment added by 84.187.77.58 (talk) 08:49, 8 November 2008 (UTC)

Uranus and neptune surface temp

Which blue planet is colder is it Uranus and Neptune. Those two planets is identical, by blue colors, 4 times bigger than Earth, so would they have the same surface temp, average for both is -210 C or -350 F. Some say Uranus is colder, some say neptune is colder becasue uranus is hazier.--FRWY 23:54, 6 November 2008 (UTC)

Planets are not subject to the same blackbody radiation calculations that stars are; their color is not a product of their surface tempurature. The color is likely solely a result of their atmospheric composition. Their surface temperature is likely subject to a number of factors, including distance from the sun, local greenhouse effect, peculiarities of atmospheric chemistry, internal radioactivity in the planetary core, etc. etc. --Jayron32.talk.contribs 01:19, 7 November 2008 (UTC)

See Uranus (−224 °C) and Neptune (−218 °C). By reading the introductions of both articles, filtering for the right information and then engaging my enormous reasoning capabilities I can tell you that Uranus is colder than Neptune. The planets' colors are irrelevant. Plasticup ^T/C 06:23, 7 November 2008 (UTC)

What's the margin of error for those numbers? 6 degrees isn't a big difference. The variation between different times and places on each planet will be more than that. I think it's probably more accurate to just say they are about the same temperature. --Tango (talk) 10:22, 7 November 2008 (UTC)