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May 7

Most specific term for the misleading sensation I am feeling

I can't quite explain the sensation I am referring to, but loosely-speaking it is "the sensation of being in the specific room that happened to be my bedroom approximately ten years ago".

Yes, I am on drugs, which probably explains why I am feeling said sensation. But I am not on a hugely strong deluriant or anything; indeed I wouldn't have expected to have this sort of unusual sensation. But it's very strong indeed, hence my starting this discussion. Said room was approximately twice the size of this room, had a different shape (was "in the attic" so sloping on two sides) and with windows in different locations. Also I'm in Ballabeg, Isle of Man while said room was in Ely, Cambridgeshire. I can't actually see anything as my light is out and the laptop I'm typing this on, which is on my chest, is saturating my vision. So it's all about sensation.

All quite peculiar and one of the reason I advocate to everyone that they take hallucinogens (not that I have taken any today) as otherwise their only hope of feeling these very peculiar things is random occurrences like this - which I probably wouldn't have even noticed save for my hallucinogenic experience. And btw none of the drugs I have taken "ought" to produce symptoms like this, but they may have made me more receptive to them. I went to the toilet during typing this out and of course was fine when I had visual evidence of what was going on.

So... again - please do describe, as precisely and concisely as possible, what's happening to me

Grazi,

Egg Centric 01:30, 7 May 2012 (UTC)

Sounds like drug-enabled deja vu to me. The memory-based explanations section of the article sounds pertinent to me, if you're asking about why the brain is triggering these odd sensations. Soapbox: Here's the thing about drugs: they are just ways to add chemicals in your brain. Your sense of everything in life — all that is what you call "reality" — is also produced by chemicals in your brain. So you're playing with the balance of chemicals in your brain. The effects of some chemicals are fairly predictable — alcohol in your system will probably react more or less the same way each time, though each time it's in your blood (and thus your brain) it's going to be playing with other variables of your current state (emotions, for example). But other chemicals can have far more complicated interactions. Anyway, the point is, one should not be too impressed with whatever subjective states are created by playing with the brain chemicals — weird sensations, funny colors, amusing or terrifying notions, whatever. They're all just manifestations of the chemicals. That's all. Completely boring and material. That they can plugs into memory centers in funny ways, or plays with your vague sensations, is not that interesting except as a reflection of the ultimately chemical nature of your brain, the organ that interprets sensations. The most impressive thing about hallucinogens, in my experience, is that it takes only milligram levels of certain chemicals to make your reason-box go completely haywire, to start feeding you completely bonkers versions of reality. The subjective states themselves are, to me anyway, less interesting than most dreams. --Mr.98 (talk) 02:14, 7 May 2012 (UTC)

Surely you jest. To block the inhibition of perception reveals tremendous beauty in many ordinary things, and this is a lesson people can learn from. But there are risks... some fairly well established, others beyond the familiar realms of science. Wnt (talk) 06:02, 7 May 2012 (UTC)

I've yet to see too many deep insights come out of the "beauty of ordinary things" approach. These things feel profound when you're on them, but in the morning they all look like "What's nausea but a kind of -usea?" which isn't very impressive. What's impressive to me is that a milligram of the right substance and reality goes out the window — that our grasp on basic cause and effect is so tenuous, so frayed. That drugs can make you feel that like, dude, pants are so arbitrary, and kissing is such a weird idea, seems subversively brilliant at the time but those aren't that deep of insights. --Mr.98 (talk) 11:51, 7 May 2012 (UTC)

Taking halucinogenic drugs is a very bad idea - it is well known they can scramble your brain. A well known example is Timothy Leary - who started out a highly intelligent and articulate academic and ended up, after taking LSD, a clown you could not have a sensible conversation with.

Your experience may be a form of flashback http://en.wikipedia.org/wiki/Flashback_(psychology). It is well known that hallucinogens, from drugs with very mild hallucinogenic effects, like cannabis, thru to strong ones like LSD, cause flashbacks long after the main effects have long worn off. Flashbacks can even occur months or even years later.

Having said that, your experience is not at all unusual, even for people who are dead boring normal and have never taken any sort of drug. It is quite normal to occaisonally get a sensation, when in a very dark room, of being in a much larger room. I myself sometimes have this sensation when laying half awake in bed in the morning, or if I awaken during the night. As soon as I move to get out of bed, or turn on a light, the sensation immediately goes. Some small children require a dim light in their bedroom - they get distressed as they know they are in their bedroom, but they have the sensation that the walls have receded into the distance, and it scares them. There is a medical term for this, but I can't remember it right now. I'll re-post if it comes to me.

Wickwack58.169.254.40 (talk) 02:30, 7 May 2012 (UTC)

According to Lysergic acid diethylamide#Flashbacks and HPPD flashbacks aren't actually a recognized medical syndrome; they can arise from a number of memorable experiences. But there are visual symptoms which can be more disturbing. Of course, this is not what the original question is about. Wnt (talk) 05:54, 7 May 2012 (UTC)

You vastly overstate Timothy Leary's incomprehensibility, even into old age. He was highly-intelligent and articulate until his death. While taking regularly high doses of LSD (as Leary did for decades and decades) may have long-term effects (our article points out that this is not at all well-established by science), I think stating that occasional uses of such chemicals "scramble your brain" is overstating things quite a bit. You may want to reexamine what you have been told, because it is wrong in every respect. --Mr.98 (talk) 11:51, 7 May 2012 (UTC)

Mr. 98, in your post beginning I've yet to see too many deep insights, you were spot on. But you need to think before you write in response to others. You don't read carefully what others have written. You provide links to make your words look good, but the material you linked does not support what you are saying. I checked the Leary YouTube video. Within the first minute, he's said he went to 7 colleges and was expelled from several. That doesn't seem likely (Get expelled from one, and you can go to another. Get expelled from two, you can try another. Get expelled from 3 or more and none will take you on) and does not fit the known facts. And all that stuff about eyes in the later part of the video - its just boring nonsense that has meaning for only Leary and those like him. The interviewer had a conversation with Leary, but it was not a sensible one. Wickwack58.167.228.55 (talk) 01:23, 9 May 2012 (UTC)

That's interesting Wickwack. As the drugs I was on at the time do not usually have hallucinogenic effects I'm wondering if sleep depravation or similar may have cuased it. Do you notice a particular reason behind the times it happened for you? Egg Centric 23:50, 8 May 2012 (UTC)

I can't comment on whether sleep deprivation would do it, except to say it seems possible. I myself have not noticed any particular reason for the experience, and would not expect to. It just happens at infrequent random intervals. Wickwack58.167.228.55 (talk) 01:00, 9 May 2012 (UTC)

If you want the technical label, this is a type of delusional misidentification syndrome. It's not all that uncommon for people with amnesia or certain types of brain damage to show false beliefs about location. Looie496 (talk) 02:51, 7 May 2012 (UTC)

Wrong label. Neither what I was talking about, nor the OP's experience as he described it, is a delusion - he was clearly aware that his experience was in only one sensory mechanism, and he was clearly aware it was a false one. It is a halucination, not a delusion. And as explained, it clearly does not require, and does not indicate, brain damage. Wickwack120.145.56.245 (talk) 03:23, 7 May 2012 (UTC)

Nimur deleted the whole section as "medical advice"; clearly it isn't. We don't provide medical advice here, and some of the talk above about brain damage strays in that direction, but it's not very relevant. Wnt (talk) 05:40, 7 May 2012 (UTC)

Correct. I've removed the medical advice hat-ing cause it is no such thing. Egg Centric 22:13, 8 May 2012 (UTC)

This sounds like a "madeline cake" moment. Personally I get these sort of sensations quite often, sometimes several times a day. There's often an overt sensory cue, like the sunlight being just as it fell when I was in school at age 9, or beech leaves lying against a red-brick wall, but just as often there is no obvious link. One just feels that way, maybe because an emotional state meshes, or a thought, or the juxtaposition of two words. And it's certainly much stronger than a memory, but not hallucination or delusion, just the identity merging between the two life-points for a while. Rich Farmbrough, 02:12, 9 May 2012 (UTC).

For those not in the know, Rich's reference to madeleine cake (he spelt it wrong) refers to involuntary memory triggered by a particular stimulus. The term comes from author Proust http://en.wikipedia.org/wiki/Madeleine_(cake). It seems to me that the stimulus for Egg Centric's madeleine cake experience (if that's what it was) was the halucination of his room expanding that can occur thru sensory deprivation (the dark room). Note that the term "halucination" refres to a sensory experience, of any sort, that is not induced or caused by a real stimulus. It is not necessarily, and most often isn't, a bizare experience as may be caused by drug taking or brain damage. For example, an random itch on your skin, if not triggered by something touching you, is tecnically a halucination. Wickwack60.230.222.4 (talk) 02:54, 9 May 2012 (UTC)

how nuclear radiations caused pancytopenia?

Pnacytopenia is a disese There are many reasons for causing pancytopenia, nuclear raditions also one of the cause but i dont know How nuclear rays cause Pancytopenia?? If anybody know this so please tell me.. — Preceding unsigned comment added by 111.68.108.51 (talk) 07:55, 7 May 2012 (UTC)

Ionizing radiation, such as the radiation produced by certain nuclear reactions, is able to penetrate through a human body and mutate the DNA within cells. High rates of mutation cause a variety of effects in cells, including cell death. These effects are far more dramatic in rapidly dividing cells, such as those found in bone marrow. This results in a gradual reduction in the blood concentrations of all cells produced by bone marrow, leading to pancytopenia. Someguy1221 (talk) 08:25, 7 May 2012 (UTC)

Quantum Mechanics/Heisenberg Uncertainty Principle?

Hi, I'm having trouble understanding the mathematical equations for Heisenberg Uncertainty Principle page from Wikipedia as well as the Wave/Particle duality due to my mathematical understanding limited to Calculus I. What makes the ideas of quantum mechanics so fascinating. And if the given position of a particle is known, then the energy is unknown and vice-versa? Is there an actual value for both at a precise time, but we cannot measure it by the technological means we have today? Also, couldn't the tools used in the experiment alter the electron placement via electromagnetic fields or by some other means?

If anyone can just give the details on this experiment it would be great! — Preceding unsigned comment added by 98.231.19.48 (talk) 09:06, 7 May 2012 (UTC)

Momentum, not energy. Anyway, what the Heisenberg uncertainty principle means, practically speaking, is that any is that no measurements are physically possible, regardless of how awesome your technology is, that will reveal the momentum and position of a particle more precisely than is allowed by the equation. This is a fact, and it is experimentally verified. The meaning of this fact, its implications for the nature of particles/waves, is less clear however. To my knowledge, most physicists take a very literal view of the uncertainty principle, and maintain that until observed a particle/wave has neither a precise position nor a precise momentum, and that accurately measuring one means the other simply does not exist as a precise value (waves can be that way). A minority of physicists take the view that a particle may have a precise position and a precise momentum simultaneously, but that the act of measuring one alters the other to an extent that makes accurate measurement of both impossible (the De Broglie–Bohm theory is an example of such an interpretation). They also hold that this is a fundamental property of measurements, and cannot be circumvented by superior technology. Someguy1221 (talk) 09:45, 7 May 2012 (UTC)

Note that momentum is always the object of quantum effects. Electrons in their orbitals vary in units of the reduced Planck constant (hbar), the precise unit of angular momentum that the photon carries in its direction of motion (though it somehow carries another, not in its direction of motion). And the Heisenberg Uncertainty Principle is that an atom in space can't have its momentum known past hbar/2 - i.e., to the nearest hbar unit...

What I don't myself know for sure is ... is there any way to know that two particles have a linear momentum relative to one another more precisely? And if so... is it quantized in units of hbar? (But I think that's just the same as the electron case - i.e. that it is quantized, but the quantization doesn't predict the outcome beyond that level of resolution) Wnt (talk) 13:55, 8 May 2012 (UTC)

It is impossible to simultaneously measure both the momentum and position. To truly see why is inherently technical. The reason for this is that the eigenstates (or state of the system corresponding to an observed value) of the position operator are not eigenstates of the momentum operator. That means that the less the uncertainity that we measure the particles position, the closer it is to being in a single eigenstate of the position operator. A single eigenstate of the position operator when represented in the momentum picture again requires a linear combination of the momemtum operator eigenstates. There can be no point where it is in a known state in both representations because momentum and position don't commute. It is not a matter of technical limitations on our ability to measure. See Quantum state for more details. IRWolfie- (talk) 22:17, 9 May 2012 (UTC)

Philosophically, the idea that there are objective properties of the particle which you are passively observing (in a God-like omniscient way) is no longer applicable. There is no such thing as action at a distance; to observe something means you have to interfere with it in some way. If not actually poking it with your finger (which of course means bringing the electron orbitals of your finger into the area of the particle until the force between them is measurable), then you are bouncing a photon of some type off it; or you interfere with it using an electromagnetic field, or a gravitional field, or some such. More realistically, you have to drop the concept that you are observing something basic and fundamental about the particle, and fall back to the position that you do an experiment and you get an answer, period, and the answer you get depends on what you ask/do. But doing an experiment itself alters the situation; things which have been experimented upon are not the same afterwards, and subatomic particles are no exception, so you can't do two different experiments right after each other and assume that the answers you get were both true at the same time. To find out the position of a particle, you need to trap it, more or less, which of course will alter the momentum; to find out the momentum, you need to adsorb it onto something which will alter the position. More to the point, since the basic issue is more fundamentally from the wave-like nature of particles; to find out the position of a "wave" you want it to look kind of like a single pulse, the narrower the better. After all, how would you describe the position of a wave which extended uniformly to infinity in either direction? But to do so, Fourier analysis tells us that such a pulse would be the superposition of an infinite number of waves of different wavelengths, the more tightly located the pulse, the wider the spectrum of wavelengths. And since momentum is a linear function of wavelength, that means an infinite selection of momenta (momentums?). Conversely, to get a perfect measure of momentum, you need a single wavelength, and Fourier tells us that that would extend to infinity in either direction; thus no information on position. So it's a trade-off; the more precisely you specify the position the less precise the wavelength gets, and vice versa, in a mathematically well-defined way. Gzuckier (talk) 04:37, 12 May 2012 (UTC)

adding angular momenta in quantum mechanics (QM)

Texts on QM never make it 100% clear when one should use the Clebsch-Gordan coefficients approach to adding angular momenta and when one should use LS(Russell Saunders)/jj coupling. I have searched all the Wiki articles I can find on the subject and am still not clear about it HELP!! Ron Baskin — Preceding unsigned comment added by 109.152.200.254 (talk) 10:31, 7 May 2012 (UTC)

You can do the computations from first principles. Considering that you don't know what method to use, you should forget about using such methods, close your textbook, take blank piece of paper and do the computations by e.g. writing down the trivial equation for the state with the highest l and m in terms of the product state and then repeatedly applying L^(-) = Lx - i Ly on both sides. And then you find the state for the lower l's, by using that they must orthogonal to the subsspace spanned by the higher l states.

Only when you can do this without any difficulties, should you use CG or LS tables. Count Iblis (talk) 16:06, 7 May 2012 (UTC)

Alternatively, you could try both and see which is easier for the particular case. 71.215.84.127 (talk) 06:35, 8 May 2012 (UTC)

Generic lifts

Many smaller lift companies use generic fixtures (produced by supply companies such as Dewhurst, EPCO, and SCHAEFER), because they don't make their own fixtures. My question: Why? --84.61.181.19 (talk) 19:28, 7 May 2012 (UTC)

That would be an economy of scale issue. That is, it would be more expensive to create their own than to buy from others. For an example, think of how expensive it would be for you to make a car from scratch, versus buying one made by others. StuRat (talk) 19:35, 7 May 2012 (UTC)

Are all recent Stannah lifts generic lifts? --84.61.181.19 (talk) 19:38, 7 May 2012 (UTC)

Around 1980, many lift companies in my area (such as FHW, K&S, OSMA, Schmersal, and W&W) used a rectangular button. My question: Why is this button no longer used? --84.61.181.19 (talk) 19:54, 7 May 2012 (UTC)

I can't speak for lift manufacturers, but we wouldn't use that sort of button in a new design for two main reasons - the side elements that hold the button cap in place are very fragile and break off too frequently, and the incandescent bulb uses a lot of power and needs changing too often. But it was the only reasonably-priced illuminated button you could get 20 years ago. Tevildo (talk) 20:39, 7 May 2012 (UTC)

Who has manufactured the aforementioned rectangular button? --84.61.181.19 (talk) 10:53, 8 May 2012 (UTC)

The ones in the photo look very like Omron A3D switches, but that basic design is produced by most switch manufacturers. Tevildo (talk) 16:04, 8 May 2012 (UTC)

New control panel designs have no moving parts to wear out or collect grime. 84.209.89.214 (talk) 23:45, 8 May 2012 (UTC)

The oldest automatic slide doors in lifts in Germany are about 60 years old. --84.61.181.19 (talk) 10:58, 8 May 2012 (UTC)

Why are generic lifts hated by many lift filmers? --84.61.181.19 (talk) 14:09, 9 May 2012 (UTC)

Possibly due to Product placement. CambridgeBayWeather (talk) 06:11, 10 May 2012 (UTC)

Not exactly on topic but this is interesting: "A recent swab study on elevator buttons showed 2,210 colony forming units of bacteria per elevator button…" Bus stop (talk) 12:56, 10 May 2012 (UTC)

I wonder if they could invent a germ-free system. A few ideas:

1) Voice recognition. "FLOOR TWELVE", for example. Buttons would remain for backup use only.

2) Tiny electric eyes for each button. Just wiggle finger between the two extensions to select each floor.

3) UV light to sterilize panel when elevator is empty. StuRat (talk) 22:14, 12 May 2012 (UTC)

May 8

Speed of Light and Black Holes

If the speed of light is constant, then how is it that a black hole has a gravity force so strong that light cannot escape? Before the collapsing star becomes a black hole light will be emitted. At some point, will light that has left slow down, stop, and then reverse back into the hole? If so, then how is the speed of light constant? 209.197.169.54 (talk) 02:31, 8 May 2012 (UTC)

The light doesn't reverse, instead it would be going in the direction of the singularity right from the start. Inside the event horizon, nothing can move in the positive radial direction, it is a bit similar to how everyting in flat space is forced to move in the forward time direction, inside the light cone. Count Iblis (talk) 02:58, 8 May 2012 (UTC)

The speed of light isn't constant either. It has a maximum, but the speed of about 300 million meters per second or whatever it is, is the ideal speed of light in a vacuum. Light's been successfully slowed to the speed of a car. Shadowjams (talk) 03:27, 8 May 2012 (UTC)

That's a little misleading; the speed of light is constant in a vacuum. But ideas of speed, direction, and even time break down past the event horizon. In fact, we really can't say for sure anything about physics inside the event horizon, because it is causally separated from the rest of the universe. -RunningOnBrains^(talk) 03:56, 8 May 2012 (UTC)

It's constant given whatever medium it's in.... it'll always be the same speed given the same medium... but I think the OP's thinking the speed of light is always constant, when in fact it's quite variable depending on what it's passing through (hence mirages and lenses). Shadowjams (talk) 04:13, 8 May 2012 (UTC)

Well there are really two separate concepts here which are the speed that photons move at through a given medium, and the universal constant called "the speed of light". While the former can vary, the latter is hard-coded into the geometry of space-time. Rckrone (talk) 04:21, 8 May 2012 (UTC)

Actually, as I understand it, photons never move at any speed other than c. When light is passing through a refractive medium, if you want to describe it in terms of photons, you have to describe them as being absorbed and re-emitted in random ways. For this to come out with the observed orderly behavior of the wavefront, you have to sum over all possible Feynman diagrams, the so-called Feynman path integral, which is unsatisfying to a philosophical realist because there can be no answer as to which Feyman diagram is the one that "really happened" (but this is true of QM in general; nothing special here).

There is a sort of compromise description which quantizes the particles' interaction with the medium into a particle called a polariton. I don't know much about those.

As a practical matter, though, if you want to know how light moves through a medium, it's generally best to forget about photons entirely and use the wave formulation in terms of electric and magnetic fields. --Trovatore (talk) 01:09, 9 May 2012 (UTC)

Right, I just had a beef with your wording Shadowjams; you made it sound like the speed of light varied, which it does not. It is just different depending on what it is passing through; and since we're really talking about the speed of light in a vacuum, I wanted to make sure the OP understood that. -RunningOnBrains^(talk) 22:28, 8 May 2012 (UTC)

Every object floating around out there in space has an "escape velocity". For the earth, it's about 25,000 miles per hour. The more massive the object, the greater the escape velocity will be. If a black hole or any other object is sufficiently massive that its escape velocity is greater than the speed of light, then light can't escape from it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:08, 8 May 2012 (UTC)

It's a bad comparison, though. In a low gravity environment, such as Earth, an object launched straight up with insufficient velocity will slow down and then fall back to the surface. Light, however, can't slow down. So the analogy completely fails to say what would happen, for instance, should someone inside the event horizon aim a flashlight away from the singularity and turn it on. The light doesn't slow down and fall back, and I'm not comfortable enough with general relativity to try and explain what actually happens. Someguy1221 (talk) 05:03, 8 May 2012 (UTC)

I think the answer is that you can't be inside the event horizon aiming a flashlight away from the singularity. I'm not an expert on this, but going on Count Iblis's response I think whatever you did in there, everything including the light from the flashlight would always be moving toward the singularity from the start. Addressing the OP's scenario where the light is emitted before the star becomes a black hole, I think the answer is that the event horizon expands no faster than the speed of light, so light emitted by the star directly away from the singularity is never overtaken by the event horizon and will escape. Rckrone (talk) 05:49, 8 May 2012 (UTC)

It's true that everything is always moving toward the singularity, but until you get too close to the singularity everything in the local reference frame behaves normally. In fact, the infalling observer doesn't experience anything peculiar as he crosses the event horizon. Someguy1221 (talk) 05:52, 8 May 2012 (UTC)

The escape velocity of a black hole is higher than the constant speed of light in a vacuum. Since light cannot go faster than its own limit, it can never attain escape velocity of a blackhole. Gravitational isobars travel at the speed of light, thus any light that is travelling ahead of the expanding isobar will escape. Any light trapped within the critical isobar will be trapped and move towards the singularity of the blackhole. Plasmic Physics (talk) 06:05, 8 May 2012 (UTC)

(EC)Spaghettification is not "anything peculiar"? ;) I'm just kidding, i know it's not directly related to the event horizon and depends on the size of the black hole. Vespine (talk) 06:08, 8 May 2012 (UTC)

I don't approve of 'spaghettification'. I think that 'gravitational extenuation' is a more cromulent term. Plasmic Physics (talk) 12:49, 8 May 2012 (UTC)

How about pancakeification or crepeification.165.212.189.187 (talk) 13:00, 8 May 2012 (UTC)

I don't think so. Spaghettification refers to how spaghetti is made - by pulling it into long, thin strands. In the process, all positions along the axis of action are pulled apart, while all positions perpendicular are pulled together. In 'pancakeification', all positions along the axis of action are compressed together, while all positions perpendicular are pushed apart. Do you see? Plasmic Physics (talk) 02:09, 9 May 2012 (UTC)

Yes, that is before the event horizon. I'm talking about after it.68.83.98.40 (talk) 04:54, 9 May 2012 (UTC)

It should still behave under the spaghettification model, until even the quarks are stretched appart into preons. Who knows what happens after that, or even what happens when it finally collides with the singularity. Some even doubt that it can reach the singularity, they suppose that the information gets snapped to the future after the black hole has evaporated. Some also doubt that there is a singularity. This being said, pancakeification would be an applicable term for an object smashing into a neutron star and pooling over the surface, before becoming part of it. Plasmic Physics (talk) 10:52, 9 May 2012 (UTC)

Well i dont think so.165.212.189.187 (talk) 13:55, 9 May 2012 (UTC)

There's something I don't understand here. I thought light isn't matter, so how can it be sucked into the black hole in the first place? Do black holes suck up everything or just matter? I'm confused. Narutolovehinata5 ^tccsdnew 13:20, 8 May 2012 (UTC)

Although photons have no rest mass, they have gravitational mass proportional to their energy. Gravity, including from black holes, affects everything not just stuff with rest mass. This is an important part of mass-energy equivalence. Rckrone (talk) 14:40, 8 May 2012 (UTC)

Gravity affects photons in accordance with gravitational redshift and gravitational lensing. --Modocc (talk) 19:52, 8 May 2012 (UTC)

Indeed, one of the first confirmations of Einstein's work on relativity was the observation during a total solar eclipse that the sun was bending the light from stars, making them appear displaced. See Tests_of_general_relativity#Deflection_of_light_by_the_Sun -RunningOnBrains^(talk) 22:28, 8 May 2012 (UTC)

True, but I've always been intrigued by how wrong conclusions can nevertheless give correct results, sometimes spectacularly so, yet still entail equally wrong conclusions, because models often only need to be self-consistent to be useful predictors. --Modocc (talk) 23:21, 8 May 2012 (UTC)

Light isn't matter, but it exhibits wave-particle duality, ie. it behaves as if it were both a wave and a particle. — The Hand That Feeds You:^Bite 22:52, 8 May 2012 (UTC)

By that reasoning matter also isn't matter, since everything exhibits wave-particle duality. Someguy1221 (talk) 00:01, 9 May 2012 (UTC)

Clarification from original poster: I'm not asking about light from an already existing black hole. I was thinking more of a collapsing star before it becomes a black hole -- moments before -- for at some point it needs to come into existence; and then the moment it becomes one; and then after it is one. Before it is one, light will be emitted since the escape velocity is less than the speed of light. But at the moment the density becomes such that the escape velocity is greater than the speed of light, no more light will escape from the (now) black hole. What happens to the light that has already left? Will any of it slow down and reverse back in as the black hole becomes even more dense? Or is it that once the light has escaped, even with the increase in gravitational pull, it has already made it out and will never return? I understand if the gravitation pull is constant, then the light would not return, but if it is increasing, will it not pull back some of the light that left earlier but had not travelled very far away yet? If it did, then those photons would have to slow to zero before reversing back to the hole?

Thank you to everyone who has contributed to this question.209.195.82.45 (talk) 00:03, 9 May 2012 (UTC)

The idea that "gravity gets stronger" as a black hole forms is actually a common misconception. Look at the equation for Newtonian gravity. You can also look at the significantly more complicated Schwarzschild metric. In either case, the density of the source of gravity is irrelevant. You experience the same force regardless, so long as your distance to it and its mass are the same (and in the case of general relativity, the shape and rotation also matter).

Anyway, what's actually happening when the core of a star collapses into a black hole is that although nothing beyond the core notices a difference, gravitationally, gravity does get stronger inside what used to be the core. Put yourself inside the core. Per the shell theorem, you only feel the gravity of the portion of the star that is closer to the center than yourself. As the core gets denser, that portion gets heavier. So there is a region that used to be inside the core that is now experiencing increased gravitational pull, but everything beyond the core still doesn't see a difference in gravity (at least, not because the core is shrinking. Other drastic things tend to be happening at the same time). The core of the star becomes a black hole the moment it achieves a critical density for its size, but at that moment, the event horizon forms right at the edge of the black-hole-forming mass. It's not like it shrinks down, and then all of a sudden the entire region around it is inside a black hole. So once again, in the initial moments the black hole forms, only the mass that created the black hole is contained by the event horizon. The event horizon thereafter only grows as stuff falls in. Someguy1221 (talk) 00:12, 9 May 2012 (UTC)

I think what you're asking is, can an expanding event horizon outrun the speed of light? Certainly it could outrun light moving perpendicularly to it. But any change in the distribution of mass takes time to propagate (the Earth circles where the Sun was, not where it is "now") so I think that there's no way for the news that you're in an event horizon to outrun the light. Except... if the light is close to a big event horizon and there are masses just a little behind it and off to either side, then maybe they could add up? Hmmmm. I think you need a better answerer. ;) Wnt (talk) 00:17, 9 May 2012 (UTC)

The light emitted just before the black hole forms will be intensely red-shifted, the photons being very low energy. At the critical instant a hypothetical photon would have zero energy. (Disclaimer: I am not a physicist. A real physicist will be along to tell you that's all rubbish in a moment.) Rich Farmbrough, 01:31, 9 May 2012 (UTC).

Perhaps, there is a minimum wavelength for light, based on the fact that energy could be quatisised. A photon with with zero energy is meaningless to me, it is equivalent to no photon. If I'm walking at 0 m/s, then it's safe to say that I'm not walking at all. Plasmic Physics (talk) 02:27, 9 May 2012 (UTC)

"Equivalent to no photon" was exactly what I meant. Rich Farmbrough, 13:42, 9 May 2012 (UTC).

Energy is quantized, but frequency and wavelength are not (so far as we know). You can always red-shift a photon further. The energy gets smaller but does not go to zero.--Srleffler (talk) 16:31, 9 May 2012 (UTC)

How is that possible, I thought that λ = hc / E? Plasmic Physics (talk) 22:29, 9 May 2012 (UTC)

It's the energy of light at a particular wavelength that is quantized. Without altering wavelength, you can only change the energy of a light wave by adding/removing quanta of energy (aka photons). But wavelength itself (and therefore frequency) can vary continuously. Or at the very least, no one has demonstrated that such is not the case. Someguy1221 (talk) 22:39, 9 May 2012 (UTC)

How harmful are the expected failure modes of London subway congestion?

After reading multiple reports that the London Underground subway will almost certainly become congested beyond operational capacity during the 2012 Summer Olympics, and perhaps several times so, I would like to know the extent to which its expected failure modes involve injury. E.g. [1] suggests that even moderate passenger congestion on platforms occasionally leads to people being pushed or falling onto the live tracks. What London agency is responsible for this risk assessment, and where are their reports? Per [2] it appears that measures, which seem almost certain to increase congestion, are being taken against "Terrorism, Serious and organised crime, Domestic extremism, Public disorder, and Major accidents and natural events," but the effects of ordinary congestion are simply not considered. "Public disorder" is taken to mean intentional disruption by individuals, and not the results of crowds. Do stations have the ability to limit their occupancy? If so, is spillover expected to streets or other holding areas? 71.215.84.127 (talk) 07:11, 8 May 2012 (UTC)

There has been a documentary series about the London underground system recently on UK TV and there are indeed mechanisms used to limit the overcrowding on stations. They close the gates to people entering the station. We saw several examples of this happening during regular rush-hours. There was a predictable build up of angry people in the street but they were much easier to deal with than bodies on the line. Richard Avery (talk) 07:26, 8 May 2012 (UTC)

Yes, London's Underground stations have the ability to prevent overcrowding on platforms. All the large Underground stations have CCTV systems and manned control centres, and they close gate lines if platforms become overcrowded - at some stations this happens several times a week. We could raise our umbrellas high and march on City Hall, but as we are British, we tend to stand around and grumble instead. Gandalf61 (talk) 11:01, 8 May 2012 (UTC)

I take it from the Q that those subways have a platform open to the tracks. I've never understood this. For a modest cost, they can build a wall between the platform and the tracks, with doors that slide open only when a train is present. Why don't all subways have this safety feature ? StuRat (talk) 16:05, 8 May 2012 (UTC)

The Jubilee line does. I guess it's more expensive to retrofit than to build in from new. --TammyMoet (talk) 17:01, 8 May 2012 (UTC)

I wouldn't expect it to be. After all, you don't have to remove what's already there, just bolt the new wall to the existing concrete floor, walls, and ceiling (if it goes all the way up). I'm assuming that the dimensions are the same at each station, but, if not, then you'd need to either custom fit each one (at additional expense) or leave a gap. StuRat (talk) 17:15, 8 May 2012 (UTC)

At some stations it would be difficult (although not impossible) due to curved platforms. Even at the straight ones, it would probably be more than a weekend's work and it isn't something you can really do a bit at a time. That means they would have to close stations during the week, which is something they try extremely hard to avoid. Most of the problems they have with renovating and upgrading the underground is that they still have to transport millions of people every day while they're doing it. --Tango (talk) 20:06, 8 May 2012 (UTC)

Why couldn't they do it a bit at a time ? I assume the wall is in sections, so install one at a time. StuRat (talk) 20:14, 8 May 2012 (UTC)

How many people actually die from falling onto the tracks? If it's one drunk dude in 30 years, it makes no sense to spend millions of dollars adding a safety feature to prevent it when that money could be spent improving the system's capacity and coverage. --140.180.5.49 (talk) 22:19, 8 May 2012 (UTC)

According to Suicide on the London Underground and Safety on the London Underground, most fatalities are suicides, of which there seem to be 50-100 a year. AndrewWTaylor (talk) 11:10, 9 May 2012 (UTC)

The Jubilee line didn't have it when it was new. Or even quite some decades after. Rich Farmbrough, 01:34, 9 May 2012 (UTC).

Platform edge doors are a feature of the new Jubilee Line Extension stations from Westminster to Stratford, which were opened in 1999. I don't think they were retrofitted to any of the older stations on the line. Gandalf61 (talk) 06:02, 9 May 2012 (UTC)

That article describes a fatality from those under crowded conditions - I really would expect more of this type, actually, unless the trains have some advanced system of sensors. Wnt (talk) 13:24, 10 May 2012 (UTC)

One of the reasons that these doors couldn't be retro-fitted to older London stations, is that for ventilation, they rely on air being forced through the tunnels by the movement of the trains. If you put a screen up, you lose your ventilation. Many of London's deep "Tube" stations are more than 100 years old and excavating a new ventilation system for them is going to be a difficult and expensive job. As I understand it, most US metro systems are quite close to the surface, so the same problems don't apply. Alansplodge (talk) 23:44, 10 May 2012 (UTC)

Hmmm, if that were the case, couldn't they just make the barriers out of a fine-grained steel mesh? Wnt (talk) 15:42, 11 May 2012 (UTC)

Maybe they could. Another solution could be waist-high barriers. You'll have to ask Transport for London. Alansplodge (talk) 17:08, 11 May 2012 (UTC)

Putrescine

Putrecine is a foul-smelling chemical emitted by putrifying flesh.

1. Which plant genus contains a species with the higher average putrescine content: Medicago or Lathyrus?
2. Is there another organism with a higher content than either one of these?

Plasmic Physics (talk) 10:02, 8 May 2012 (UTC)

Your search might be more fruitful if you use "putrescine". Brammers (talk/c) 11:12, 8 May 2012 (UTC)

Sorry, I meant to spell it that way. (I used the correct spelling when I searched for it.) I have corrected it. Plasmic Physics (talk) 11:38, 8 May 2012 (UTC)

The question is still open. Plasmic Physics (talk) 23:49, 9 May 2012 (UTC)

Real-life applications of Pokéballs

If Pokéballs were actually invented, what would likely be their applications? That would assume that Pokémon don't exist, but the actual balls did. I would imagine that they would probably find great applications in transporting very large cargo and make transportation of cargo much easier, possibly even replacing cargo containers. But would that be the case? Narutolovehinata5 ^tccsdnew 11:20, 8 May 2012 (UTC)

All powers plants would be replaced by Pokéball powered perpetual motion machines since the balls can readily alter mass. Cheap infinitely sustainable energy would pretty much change the world. 173.32.168.59 (talk) 11:37, 8 May 2012 (UTC)

Why do you ask us? anyone is qualified to speculate about the hypothetical applications of a fictional device. Basically, what answers do you want us to feed you? Plasmic Physics (talk) 11:45, 8 May 2012 (UTC)

As in, how the functions of the Pokéballs as seen in the anime can be used in real-life. For example, how the Pokémon is somehow transformed into energy and put into the ball, and that the ball can shrink or expand with a press of a button. Can these technologies, especially the one of energy convertion have real-life applications? Would Pokéballs as cargo containers be feasible or practical? Narutolovehinata5 ^tccsdnew 12:13, 8 May 2012 (UTC)

You tell us. Plasmic Physics (talk) 12:28, 8 May 2012 (UTC)

We don't know the capacity or limitations of these fictional 'technologies', so they can be applied in any way you deem fit. Plasmic Physics (talk) 12:30, 8 May 2012 (UTC)

It's like asking, if I had a genie in a lamp, what could I wish for? Plasmic Physics (talk) 12:33, 8 May 2012 (UTC)

Ammonia is gaseous at STP, but can be a ligand bounded to certain metal ions. --84.61.181.19 (talk) 11:28, 8 May 2012 (UTC)

That is completely unrelated to the question. Plasmic Physics (talk) 11:45, 8 May 2012 (UTC)

As an answer to this nonsensical trollish question it is just as valid and reasonable as any other string of characters. Roger (talk) 12:50, 8 May 2012 (UTC)

This is actually a serious question you know. Being a Pokémon fan since childhood, I'm genuinely interested in the science of Pokéballs and how they can be used in real-life. Yes it is fictional so we can't say for sure exactly how they work, but the actual concept of a Pokéball, a device that converts matter into energy for storing: how would they probably be used in real life? This question means "How can the concept of a Pokéball be used in real-life?" Narutolovehinata5 ^tccsdnew 12:56, 8 May 2012 (UTC)

There is no science behind them. You're not listening, we can't make any scientific predictions about a fictional device that doesn't follow real world physics. Plasmic Physics (talk) 13:06, 8 May 2012 (UTC)

Airliners could use them instead of seats to get alot more people on each flight who wouldnt complain or have to use the lave or ask for peanuts and soda.165.212.189.187 (talk) 13:14, 8 May 2012 (UTC)

I want one that converts energy into steak and beer! Roger (talk) 14:38, 8 May 2012 (UTC)

You could have such a thing in a simulated reality but not in a universe with constant laws of physical reality. And if you had a functional one that would be strong evidence that you were in such a simulated reality – so theres that. SkyMachine ⁽⁺⁺⁾ 15:50, 8 May 2012 (UTC)

It would depend on what the underlying technology was capable of. Can it turn any matter into energy, and back as required? So, could you extract as much energy as you wanted by converting seawater, at the cost of permanently reducing the ocean? A rising sea-level double win, although also likely to backfire. Can you use it to turn energy into any matter, or only the matter it was originally? And you could use it to 'store' ill people in the hopes of finding a cure and returning them to life. And like the techniques in Orson Scott Card's book Capitol, you could use it to effectively elongate your life at the cost of dipping in and out: if you left your pokeball one month per year, you'd live 12 times longer, although miss most of it. Useful for watching investments grow, but bad for social mobility and societal engagement. You could use it to send people to distance planets, without having to spend a lot on ships with the life-support for a long journey, or even having to spend fuel on the full weight of the people. You could use it to go far into the future. You could use it to contain people you wanted out of the way, or people you wanted to take somewhere against their will. You could use them as a weapon, throw them onto the battlefield to capture the enemy. You could use them to 'evacuate' civilians from an area, before bombing it: given that normal pokeballs are most successful on the weak, someone could argue that anyone who wasn't caught was strong enough to have left the area themselves. People could use them to store pets or even children to make them easier and more convenient to care for, as well as maximising the amount of growing-up time you personally get to spend with them, even if it takes them 10 years to reach their first birthday.

Sorry if some of that gets a bit weird: I blame Capitol. 86.140.54.3 (talk) 23:39, 8 May 2012 (UTC)

That's actually very interesting.. If anyone could just hibernate for 10-20 years to capitalize on investment, I imagine our economy would devalue such a scheme to the point of making it not very worth while. Perhaps actually DOING work would become the most valuable activity again, as opposed to the thinky veiled gambling and larceny (otherwise known as the stock market) which underpins our current economy Vespine (talk) 00:51, 9 May 2012 (UTC)

Yes but if such devices were rare only the very wealthy oligarchs could afford them / steal them in the first place. SkyMachine ⁽⁺⁺⁾ 01:26, 9 May 2012 (UTC)

http://xkcd.com/989/ Rich Farmbrough, 01:41, 9 May 2012 (UTC).

Newly discovered pathogen in Roundup Ready crops

This and other sites has a letter pronouncing the discovery of an "electron microscopic pathogen that appears to significantly impact the health of plants, animals, and probably human beings" isolated from Roundup Ready soybeans. It only provides very scant details on this supposed pathogen which makes me slightly suspicous. Can anyone find anything about this is any reliable sources? SmartSE (talk) 13:08, 8 May 2012 (UTC)

"Emeritus" is a word, which, in biology, foretells many wonders... the notion of a fungus the size of a virus is ... interesting. Note that a fungus by definition is a eukaryote. It has mitochondria and a cell nucleus. To make it appear the size of a virus on EM, a lot of structures have to be eliminated or scaled down to teeny weeny little versions of themselves. And he mentions nothing about DNA tests to back up his ideas. That said, he is a scientist who has written about diverse fungal pathogens ( http://books.google.com/books?hl=en&lr=&id=WeR23VTJE64C&oi=fnd&pg=PA169&dq="Don+M.+Huber" ), and ..... nothing is impossible in biology. But a lot is unlikely, I think. Search Google for "livestock" and "spontaneous abortion" and most of the hits come back to this guy. If he were telling the truth about the sudden rise in this, wouldn't we be reading stuff about it from a thousand sources as farmers lose their livelihoods? Wnt (talk) 13:38, 8 May 2012 (UTC)

Yeah, that's kind of what I thought... It just annoys me to see this stuff is used as an example of why "GMO=evil" online, when it seems as if there is zero scientific evidence to back it up. Sigh... SmartSE (talk) 14:18, 8 May 2012 (UTC)

Reminds me of the supposed fossil found in the Mars meteorite. It was also at the wrong scale to be the type of organism supposed. In the end, they decided it was likely just an inorganic formation.

That said, I would expect nature to "fight back" at some point. That is, if the GMO foods are more tolerant of pesticides and thus aren't infected with the usual pests, this will put evolutionary pressure on those beasties to adapt. So, we should expect pesticide resistance to also develop in them. StuRat (talk) 15:58, 8 May 2012 (UTC)

Yep. 71.215.84.127 (talk) 20:43, 8 May 2012 (UTC)

RR crops are normal plants which have had a certain molecule in a particular amino acid pathway slightly modified in shape so that RR molecules cannot attach and inhibit the pathway. A claim that these RR crops are a major threat to humanity due to a never before seen type of organism is extremely suspicious, particularly knowing that there is a community fighting against all GMOs largely with unsubstantiated claims of great peril, similar to this. If the retired prof has actual proof he can easily show it to other scientists. Until there is a significant number of scientists backing the idea I would pay it no mind what so ever. Unique Ubiquitous (talk) 23:14, 8 May 2012 (UTC)

Further inspection of the website shows that it is indeed full of deception. The article Roundup and Birth Defects is sillyness, it rejects RR crops as "glyphosate causes malformations in experimental animals at high doses". That reasoning would mean we would ban vitamin pills because if someone used 100x the appropriate rate it would hurt them. It is also silly as glyphosate's use generally replaces the use of more dangerous pesticides. Continuing to read from such a poor source would only hurt my brain and is not worth anyone's time. Unique Ubiquitous (talk) 23:34, 8 May 2012 (UTC)

These crazy stories are typically rooted in a hatred of "corporate" farming, coupled with astonishing ignorance. There is no glyphosate in RR soybeans. RR soybeans are "glyphosate tolerant", meaning that they won't die when Roundup is sprayed on them. If "super weeds" do eventually come along, Monsanto will invent something else. Or maybe figure out a way to turn those super weeds into sileage. The original article cited by the OP indicates these alleged scientists can't even figure out if it's Roundup or the RR gene that's the "culprit". Maybe they had best get back to the lab and get their story straight. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:21, 9 May 2012 (UTC)

The whole point of them being "glyphosate tolerant" is so they can be sprayed with large quantities of glyphosate. So, RR and glyphosate exposure must be considered together. StuRat (talk) 01:08, 9 May 2012 (UTC)

Roundup is the commercial name of a pesticide containing glyphosate. There is trace levels of glyphosate upon RR produce though the level is of a level to be of no concern even if one's entire diet was of RR produce. Unique Ubiquitous (talk) 01:30, 9 May 2012 (UTC)

And were the studies which concluded that funded by the makers of Roundup ? StuRat (talk) 16:30, 11 May 2012 (UTC)

The levels of glyphosate in the environment and food, after more can be used, are indeed worth asking about. Undeniably some people do suffer glyphosate toxicity, but generally by ingestion (PMID 22077202 ) which is a risk we typically write off when considering consumer products, and doesn't specifically apply to Roundup Ready farm crops. But it can also enter groundwater (but when? How much? how often? PMID PMID 22101424 , PMID 22097024 etc.) The total impact of Roundup Ready crops may be hard to figure out (PMID 21898904 ). I'm not pretending to have the answer to this one - there's a combination of precise and extensive data and philosophical attitude that together produce a person's decision. It would be easier for me to reject such crops if no one ever went hungry, but it is not really a lack of farm production that is to blame for that... Wnt (talk) 21:22, 12 May 2012 (UTC)

Light bulbs

I think I notice that when changing a light bulb, incandescent or fluorescent, the new bulb is brighter than a bulb that has been in use for awhile (identical manufactured product). What would account for this? The outside could be dirty on the older bulb. Or maybe the components inside the bulb don't give off as much light after being in use for a long time? How would this be explained? Bus stop (talk) 16:33, 8 May 2012 (UTC)

I don't know what the mechanism is for fluorescent, but in incandescent bulbs, some of the tungsten from the filament evaporates and is deposited on the inner surface of the glass bulb, where it absorbs some of the light that would otherwise escape from the bulb. Jc3s5h (talk) 16:37, 8 May 2012 (UTC)

And yes, the bulb can be dirty. Specifically, grime seems to accumulate on the top. In the kitchen this can be greasy and in a house with a smoker, it can be yellow tar. Thus, cleaning off the bulb (and any dead bugs from the fixture) can help. StuRat (talk) 16:52, 8 May 2012 (UTC)

From our incandescent light bulb article, I found this section of "The Great Internet Light Bulb Book, Part I", which contains a nice plain-english description of the time-evolution of incandescent bulb filaments. For fluorescent bulbs, there are several long-timescale failure-modes: failure and degradation of the Ballast electronics; diffusion or leakage of the gas mix; deposition of metals and mercury on the bulb glass; and other phenomena discussed in this section of our article. Nimur (talk) 16:54, 8 May 2012 (UTC)

Thanks. This is great information...I just haven't read it yet. Bus stop (talk) 16:57, 9 May 2012 (UTC)

I agree with darkening caused by material from the filament deposited in the inside of the glass globe, as an explanation of why incandescent bulbs get darker at the end of their service life, A secondary explanation might be increased resistance in the filament due to decreased cross section, causing lower current and lower temperature. Certainly and obviously dirt and dust deposits on the bulb would decrease light emittance. Edison (talk) 03:46, 13 May 2012 (UTC)

How long do adult flies live ?

I trapped a fly in my storage room in Detroit. Assuming it was a young adult (because of how active it is), how long will it live at room temperature ? I don't want to open the door again until it's dead. StuRat (talk) 23:18, 8 May 2012 (UTC)

Three weeks. Or a day in Detroit if it can figure out a way to get to the suburbs. 71.215.84.127 (talk) 23:35, 8 May 2012 (UTC)

Unless that storage room is airtight, there's a good chance yon fly has fled. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:13, 9 May 2012 (UTC)

I'm not sure about that - Bugs are pretty stupid. present company excluded. Someguy1221 (talk) 00:17, 9 May 2012 (UTC)

Agreed. They pretty much stay in the window until they die, unless disturbed, in my experience. StuRat (talk) 00:19, 9 May 2012 (UTC)

If it appears to be dead you should poke it with something to see if it leaps over a couple of metres, flies will often play dead when low on energy as a survival behaviour. SkyMachine ⁽⁺⁺⁾ 00:26, 9 May 2012 (UTC)

And that's why you never hear about Schrödinger's fly. Blakk and ekka 12:40, 9 May 2012 (UTC)

Flies are not bugs, and I agree with the IP, about a month at most. Though I must ask, why do you care so much about the fly's possible escape? Unique Ubiquitous (talk) 00:21, 9 May 2012 (UTC)

It can't do much harm in the storage room. But, if it gets into the rest of the house, it can land in my food, fly in my face, wake me up by buzzing in my ear and landing on my face, etc. Best case scenario, I manage to swat it, then I have fly guts to clean up. StuRat (talk) 00:39, 9 May 2012 (UTC)

Did you try flypaper? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:23, 9 May 2012 (UTC)

I tried it once. It was a disaster. The brown glue got all over me and the walls. To me, this is a desperate measure you take if your house is overrun with flies, not what you do if you have one safely locked in a storage room. StuRat (talk) 16:56, 9 May 2012 (UTC)

...I want my time and effort back :P Unique Ubiquitous (talk) 01:33, 9 May 2012 (UTC)

The word bug came before any formal classification system, it is still ok to use bug to refer to insects in general in nonformal contexts. SkyMachine ⁽⁺⁺⁾ 00:30, 9 May 2012 (UTC).

Tell that to my old IPM prof...Unique Ubiquitous (talk) 01:33, 9 May 2012 (UTC)

Probably the same guy that claims dinosaurs are birds. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:23, 9 May 2012 (UTC)

Nearly - birds are dinosaurs. Not all dinosaurs are birds. (That's if you define "dinosaur" to refer to a clade, which scientists and pedants sometimes do, but nobody else does.) --Tango (talk) 19:40, 9 May 2012 (UTC)

Birds are no more dinosaurs than are humans marmosets. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:41, 10 May 2012 (UTC)

StuRat, as you are getting bored, I have a more interesting problem you should investigate in your lab in Detroit: How long would it take to create giant flies by selective breeding in a high oxygen atmosphere? Count Iblis (talk) 15:21, 9 May 2012 (UTC)

Would giant flies be able to fly without major physiological changes? While one may put pressure upon a population to grow simply larger, it would be much harder, and close to impossible due to low genetic diversity, to also bring the physiological changes required as the fly loses its surface area to volume and food source benefits....I suggest high doses of radiation...or at least genetic engineering for the less adventurous. Unique Ubiquitous (talk) 16:51, 9 May 2012 (UTC)

Presumably the high oxygen environment is to allow the fly to continue to get enough oxygen, despite the higher mass-to-surface-area ratio. The next size related problems would probably be an inability to fly, as their wings are designed for small insects, and an inability to stand on walls and ceilings, do to their foot design. Thus, you'd end up with a "fly" which could only crawl on the ground. Then, at some point, the exoskeleton would be insufficient to support it's weight. It's circulatory system might also need to add an extra level (capillaries), which is a major change. With all of these changes, you might get a fly the size of a Goliath beetle. StuRat (talk) 17:04, 9 May 2012 (UTC)

Might as well splice a few of the more interesting fly's genes with one's own to get a really exotic and much larger "fly"... And barring anything that interesting, a fly bottle or two might help spare you another visit from the one you have trapped or any of its vengeful kin. ;) --Modocc (talk) 21:35, 9 May 2012 (UTC)

May 9

"Center for Innovation, Technology and Testing"

Can anybody make any sense out of [3]? The article claims that this Potemkin village in the middle of nowhere is going to be funded for $1 billion - nearly as much as NIAID spends on HIV/AIDS research yearly, for example. We don't even have an article "Center for Innovation, Technology and Testing", nor on "Pegasus Holdings". The news article claims it's so they can test self-flushing toilets and automated washing machines (say what?) True, they also claim to test "self driving cars", but how do you test them meaningfully on a city-wide scale without pedestrians? I've never heard of such an absurdly high-budget low-yield research project. What's the story?

(To be clear, they actually have a web site at [4], but it doesn't make any more sense than anything else. True, they do mention the "homeland security", which is what would be my guess anyway --- I mean, what else are Americans capable of doing innovation on nowadays except ways to spy on and control and punish people? --- but it still doesn't make any sense they need a billion dollar project for that. Any spying project on such a grandiose scale will never stay secret anyway.) Wnt (talk) 06:03, 9 May 2012 (UTC)

Presumably you're including Google, Facebook and Twitter among those spying innovations. So, this thing is privately funded, right? Or it says it is. Although it sounds more like a cooperative effort. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:42, 9 May 2012 (UTC)

"Pegasus is also a U.S. Government authorized prime vendor and manufacturer of defense equipment and technologies." You ever hear of private money funding Homeland Security? Corporations may be stupid, but they don't fund that kind of a boondoggle except when they're being paid. Wnt (talk) 13:36, 9 May 2012 (UTC)

And as far as I'm concerned Twitter and (especially) Facebook exemplify the sort of technology we'd be better off without. But I'm pretty sure that Pegasus/CITT is blameless for that. Wnt (talk) 13:38, 9 May 2012 (UTC)

Just to add to the confusion, there seems to be 2 Pegasus Global Holdings. One of them is 'Pegasus Global Holdings (“Pegasus”)' [5], the one involved in the project. Another one is 'Pegasus-Global Holdings, Inc' [6] who appear unconnected. Nil Einne (talk) 07:43, 9 May 2012 (UTC)

Thanks - that "Global" made me find The Center, New Mexico, which is about this (though it still doesn't make it any clearer to me). Wnt (talk) 13:41, 9 May 2012 (UTC)

I agree that the price versus the possible payoff, as stated, is goofy. I wonder what the government connection really is (other than "the government is expected to pay for this," which is obvious — it's the only way the dollars can add up). --Mr.98 (talk) 15:11, 9 May 2012 (UTC)

Sure seems fishy to me, especially with no university involvement. Although it's early enough in the planning stages that maybe university partnerships will come along later. -RunningOnBrains^(talk) 16:50, 9 May 2012 (UTC)

One possible project which might justify that investment is self-driving trucks that could deliver supplies to combat areas. They could drive across the desert, limiting interaction with people, and could then be driven manually, in a heavily armed convoy, the last bit through the city. StuRat (talk) 17:11, 9 May 2012 (UTC)

I believe that the military is very interested in self-driving vehicles — DARPA doesn't sponsor big contests just for the fun of it — but I still don't see how that would justify a billion-dollar mock-town. The makers must be expecting hundreds of millions of dollars per year to make the investment worthwhile. That seems like an awful lot based on the description. There are certainly ways to test self-driving vehicles that don't involve paying millions of dollars — you could pave your own bare-bones test course for a small fraction of that price. --Mr.98 (talk) 23:16, 9 May 2012 (UTC)

You might miss some potential problems that way. For example, the car might go off the road and follow a building's shadow, but only if there is a large shadow on the test course. StuRat (talk) 23:21, 9 May 2012 (UTC)

I agree there seems to be a lot of unknowns here. As stated by others, the source of funding is unclear. It seems strange some random virtually unknown private company would spend $1 billion of their own money, presuming they even have that much, doing this. (Which highlights another issue, as the OP mentioned, there does seem to be rather limited info on them, they're only 10 years old and as a private company, we have no real idea how much money thay have. They seem to have a fairly low profile up to now, but given their apparent strong involvement with the US federal government particularly the military, perhaps they are a lot better off then the low profile would suggest.) The earlier source only claims they asked for no state funding, it doesn't say anything about federal funding. However [7] as linked by Wnt does claim it will be privately funded. Perhaps the construction is privately financed but they have a contract with the government for using or for developing stuff in the facility.

Beyond the defence/homeland security stuff, it seems clear from [8] they have good relations with the federal government. (Edit: The secondary source I provide later also mentions a several military bodies they worked with.) As Wnt noted the project page mention 'homeland security' and the description mentions 'which will include a secure testing area for first responder technology with the benefit of proximity to the civil and commercial infrastructure'. The pictures are also interesting but it's easily possible the web designer just used them randomly. I thought perhaps they're planning to destroy stuff, plant IEDs and stuff like that (you can stimulate some of this, but perhaps there are advantages to real world testing) to help test their first responder technology, but this earlier source [9] suggests there will be no destructive testing. (I wonder how far that goes though. Does it mean they won't burn buildings to test automated fire engines, for example?)

It also notes a lack of information on what they're planning to do there. Interesting it notes they did earlier seek some state funding for a feasibility study, but it was denied. The amount they plan to spend seems questionable to me. The above source says construction cost is estimated at $400 million. This one says $200 million. (Given this is a private venture apparently trying to win over the government and people in some fashion by emphasing how good it's going to be, I actually trust the lower figure more.)

Either way what's happening with the other $600-800 million they are allegedly going to spend and when are they going to spend it? Is this the amount they estimate they will invest in their own research using the town over its lifespan (which would potentially be decades)? If so, it makes the costs slighly more reasonable. Note that the older source also mentions $1 billion but in a different way 'But with research contracts, user fees, selling surplus utilities, and other methods of generating revenue, CITE's overall value could easily reach $1 billion.'

If we look at their other projects, beyond the commercial space launch thing, they also have [10] and [11]. Are they planning to make self reproducing military robots and want to keep them away from the general population in case things go wrong? ;-)

Nil Einne (talk) 01:23, 10 May 2012 (UTC)

If they bother with maintenance costs the town should be in fine condition when they are done with it. Their plan might involve a substantial portion of their profits coming from the sale of the town. --145.94.77.43 (talk) 03:39, 10 May 2012 (UTC)

Yeah, but who wants to live in a town full of top-secret prototype spy devices? (Yeah, I know, I know ... the point of the research is that by the time the town is up for sale, those devices will be in every town, everywhere in the world) Wnt (talk) 18:01, 10 May 2012 (UTC)

Sounds like the plot of Eureka. StuRat (talk) 15:13, 11 May 2012 (UTC)

Almost makes you wonder where that show got its funding. A substantial portion of entertainment shows is product placement, after all. Wnt (talk) 15:40, 11 May 2012 (UTC)

Crude oil, 'condensate'

What exactly is 'condensate', used in reference to crude oil production, and more specifically to substance or product that can be stolen, as is done in the case of oil 'bunkering' in the Niger Delta? Thanks if you can help. — Preceding unsigned comment added by 83.84.219.135 (talk) 16:18, 9 May 2012 (UTC)

I think this article is going to help. :) 16:40, 9 May 2012 (UTC)

Thanks, that's a start, but it refers specifically to natural gas. Maybe that's the answer I was looking for, but it isn't clear to me that bunkering and 'artisanal refining' processes referred to natural gas. Anybody else? — Preceding unsigned comment added by 83.84.219.135 (talk) 17:07, 9 May 2012 (UTC)

Well, oil will evaporate and recondense, just like water. This occurs at a much slower rate, at STP, than water, however. But, at the high temperatures used in some refinery processes, the amount of condensate may be significant. StuRat (talk) 21:55, 9 May 2012 (UTC)

Possible confusion could be that condensate, which is in gaseous form underground condenses out as it reaches the surface and is then treated as a liquid. Bunkering in this case just means illegally extracting the liquid hydrocarbons, including presumably condensate. 'Artisanal refining', however, would just be on crude oil I think. Mikenorton (talk) 22:26, 9 May 2012 (UTC)

Historical rate of beta decay?

Have the light curves of distant supernova been studied to see if the beta decay rates have remained constant for the last several billion years? Hcobb (talk) 16:45, 9 May 2012 (UTC)

I think not. We can predict the general form of the energy spectrum of the (observable) beta particle, but not the absolute decay rate, from a simple theory proposed by Fermi. 84.209.89.214 (talk) 21:53, 9 May 2012 (UTC)

free space in atoms 2

Recently this was posted: yes, free space is being slowly added everywhere. The reason you don't notice your head slowly expanding is a combination of two things: A) the expansion is very slow, at a couple thousandths the diameter of a proton every second per meter; and B) "Space is expanding" means that things are getting farther apart, but the laws of physics are not changing. The nuclei of atoms and the atoms of molecules are still held together by the same forces as always, and they aren't going to go flying apart because a teeny force has been applied. -Someguy1221

My question is: It also implies that when we look at things extremely far from us they are actually smaller than their present state because we are seeing them so far in the past (when they were smaller). Does that make sense?165.212.189.187 (talk) 17:32, 9 May 2012 (UTC)

Not if the light bringing you the image of those items is spreading apart at the same rate as the original object. StuRat (talk) 17:45, 9 May 2012 (UTC)

No, Stu, photons are point particles.165.212.189.187 (talk) 18:10, 9 May 2012 (UTC)

No, the reason you don't notice the expansion of free space within your head isn't merely because of the rate of expansion. The expansion is only observable between objects which are not otherwise bound to each other by other forces, such as gravity or electromagnetism. The forces holding the atoms and molecules inside of your head together is more than sufficient to overcome the expansion. Even something as diffuse as a galaxy is not subject to the expansion of free space, as gravity is sufficient to hold a galaxy together. See Metric expansion of space which explains some of the details of this oft-misunderstood concept. So no, objects in the past were not smaller than they are today, its just that the space between the really BIG objects (like galactic superclusters was less. Distantly in the past, even galaxies were the same size as they are today, and certainly anything smaller was. --Jayron32 18:00, 9 May 2012 (UTC)

I've not studied cosmology anytime recently (in any case, my memory is fuzzy on what I did study on this), so I need to ask something about this explanation. You say that "...the space between the really BIG objects (like the space between the really BIG objects (like galactic superclusters was lesss was less." Same question as the OP's for these objects. Is there evidence that the more distant galactic superclusters were nearer to each other? Or is it that cosmological inflation conveniently explains away any lack of such evidence for this assertion? Update: Having now taken a glance at the cosmological inflation article, I see that it does answer the OP's (and mine) question! --Modocc (talk) 18:57, 9 May 2012 (UTC)

The superclusters were once closer together. In principle this can be seen directly with telescopes. I don't know whether it can in practice. I think you're mistaken about the inflation article answering your question, though, because the superclusters didn't form until a very long time after the inflationary epoch. -- BenRG (talk) 00:14, 11 May 2012 (UTC)

I see I need to clarify my post, for I was not suggesting that the superclusters are thought to have been nearer due to the hypothesized cosmological inflation. Instead, I've always understood that the lack of direct observation of an expansion has been due to the overall homogeneity created by the initial hypothetical expansion. If it were not for this hypothesis, which the article details, we would be observing an expansion at much smaller scales and, in addition, even with the hypothesis in place, we have, apparently, not yet directly observed the left-over expansion at the largest scales either. --Modocc (talk) 14:13, 11 May 2012 (UTC)

None of this makes any sense to me. Are you talking about expansion during the inflationary epoch or subsequent expansion? Can you point to the part of the cosmic inflation article that you're using as a source? -- BenRG (talk) 17:35, 11 May 2012 (UTC)

"Inflation answers the classic conundrum of the Big Bang cosmology: why does the universe appear flat, homogeneous, and isotropic in accordance with the cosmological principle when one would expect, on the basis of the physics of the Big Bang, a highly curved, heterogeneous universe?" In other words, the universe is essentially a lot larger and appears more homogenous than it would be otherwise. --Modocc (talk) 19:51, 11 May 2012 (UTC)

Inflation does provide the necessary initial conditions to end up with the universe we see now, and it does hide information about the nature of the universe before inflation, but it doesn't hide information about the subsequent expansion. If we didn't know about the expansion then we wouldn't know about the necessary initial conditions that inflation turns out to provide. It's always subjective what counts as direct evidence for something, but traditionally the most important piece of evidence for the expansion of the universe was the distance-dependent redshift of galaxies, and now it's probably the CMBR. In principle, if you plot all the superclusters at a given distance (or lookback time), there will be less empty space between them the larger the distance. I don't know whether the available data is good enough to detect that. -- BenRG (talk) 23:08, 12 May 2012 (UTC)

"The forces holding [you] together [are] more than sufficient to overcome the expansion" is wrong. There is no expansion to overcome. Yes, the matter you're made of used to be uniformly expanding hydrogen gas, but it isn't any more. It doesn't retain any memory of its former expanding state. The superclusters are moving away from each other because of leftover momentum from the big bang, but the matter in your body doesn't have any leftover momentum relative to other matter in your body.

"Free space is being slowly added everywhere" is also wrong. There's no concept in general relativity of space being added somewhere. Space doesn't behave like a substance. The cosmological constant does act to stretch you apart (it behaves as a repulsive force). Likewise, ordinary self-gravitation acts to compress you. You don't change size for the same reason you don't shrink under the influence of air pressure. Even if the gravitational effect was very large, comparable to the effect of air pressure, you presumably wouldn't notice it for the same reason you don't notice air pressure. Being aware of it would not enhance your differential reproductive success. -- BenRG (talk) 00:14, 11 May 2012 (UTC)

What you said seems to contradict the current cosmological theories. I guess I will link to metric expansion of space again. The point is that distant objects aren't moving away from each other at constant relative velocity, they're actually accelerating away from one another. The geometry of space-time apparently has some intrinsic curvature (even in the absence of gravitational fields). You can view this as free space expanding in time. But the effect is only noticeable on a large scale. Rckrone (talk) 00:37, 11 May 2012 (UTC)

When people talk about the expansion of the universe they're talking about the relative velocity of the superclusters. The velocity changes very slowly over time, but that acceleration isn't what people mean by "the expansion of the universe". The relative velocity of the superclusters is just inertia. It's not associated with spacetime curvature. People describe this as "space being added" between the superclusters. I think this is silly. I suppose it's not wrong as such, for the same reason that it's not right: it just has no meaning in any actual experimentally verified physical theory.

The acceleration is associated with spacetime curvature, whether it's attractive (ordinary gravitation) or repulsive (the dark energy). Spacetime curvature is not the same as adding or removing space either. Again, this concept just doesn't exist in general relativity.

You can't say that spacetime has intrinsic curvature in the absence of a gravitational field, because the gravitational field is spacetime. You probably mean in the absence of matter. But we don't know if empty space is "really empty" or filled with a dark energy field of some sort. -- BenRG (talk) 17:35, 11 May 2012 (UTC)

The intrinsic curvature of space-time is what this thread is about, and that's also what the term "metric expansion" refers to. The original question is why this curvature of space-time doesn't cause a person's head to expand. You wrote a post saying that such an effect doesn't exist and that the universe is only expanding because of inertia. That's incorrect (at least according to current theories). Metric expansion would cause the particles in your body to accelerate away from each other, but as others already explained this is easily overcome by the usual forces that hold your body together. Actually I'm sort of confused by your answer since you later acknowledge that the cosmological constant acts as a repulsive force.

As for whether "space is being added," that obviously doesn't mean anything precise. There are various ways to intuitively understand the idea of metric expansion, and that one seems fine to me. Rckrone (talk) 18:34, 11 May 2012 (UTC)

Whenever I talk about this I feel obliged to mention the cosmological constant because otherwise someone will follow up with "but what about...". What I was trying to make clear is that the cosmological constant doesn't deserve special mention because it's not fundamentally different from the attractive force of gravity. In the static (non-expanding) Einstein universe you could perfectly well ask "why don't I continually shrink under my own self-gravitation?" and the answer would be the same as in an expanding universe. Likewise you could ask why you don't continually expand under the influence of the positive cosmological constant (since the Einstein universe has that too, despite being static), and the answer would be the same as in an expanding universe.

The other thing I always say is that the expansion of the universe is velocity (inertia), not acceleration (force). A few times in the past I've mentioned the Milne universe, which is an exact solution to the Friedmann equations with Ω=0 (versus Ω≈1 in the real world). It is an eternally expanding universe (there being nothing to slow it down) with a scale factor that goes as a(t) ~ t. It's infinite in size and spatially hyperbolic. It follows Hubble's law, including the part where it says that sufficiently distant objects have a recession velocity larger than c. Despite all this, the spacetime curvature is zero everywhere, and in fact the spacetime is simply Minkowski spacetime. It's a nice counterexample to a lot of misconceptions in cosmology, including the idea that expansion is tied to curved spacetime.

Here are some previous threads where I talked about the Milne universe: Shape of the Universe, Light from just after the Big Bang, Infinite amount of mass in the universe?. -- BenRG (talk) 23:08, 12 May 2012 (UTC)

Big rip. 84.209.89.214 (talk) 21:46, 9 May 2012 (UTC)

I don't think that's relevant... -- BenRG (talk) 00:14, 11 May 2012 (UTC)

Maltose vs Lactose

Is there a simple test other than "Osazone test" to differentiate between Maltose and Lactose ? — Preceding unsigned comment added by 196.202.92.186 (talk) 18:59, 9 May 2012 (UTC)

If you are capable of purifying out the sugar, you could just test for its solubility in water or its melting point. Both are noticeably different between maltose and lactose. For a more hilarious test, you could feed large quantities to a lactose intolerant and see if they develop explosive diarrhea. Someguy1221 (talk) 19:47, 9 May 2012 (UTC)

lol this isn't a simple test ! Is there something easier than finding a lactose intolerant or testing the melting points ? I mean the osazone test sounds easier — Preceding unsigned comment added by 196.202.92.74 (talk) 19:55, 9 May 2012 (UTC)

OK, even easier, taste them. Maltose and lactose have distinctly different flavors. You'll have to consume a known quantity of each first so you know how to tell them apart. Someguy1221 (talk) 20:45, 9 May 2012 (UTC)

Okay, Thanks — Preceding unsigned comment added by 196.202.92.242 (talk) 21:03, 9 May 2012 (UTC)

They have quite different optical rotations. Use a polarimeter. Rmhermen (talk) 01:15, 10 May 2012 (UTC)

In so-called "99% ethanol", is this 99% by concentration or mass? --150.203.114.37 (talk) 23:47, 9 May 2012 (UTC)

It typically means 99% by volume. But you should be aware that "concentration" is a vague term. It could mean by volume, mass, moles, or even heterogenous measures, like mass per volume. Someguy1221 (talk) 23:51, 9 May 2012 (UTC)

With that many significant figures it is not going to make any difference, as the contaminant is probably water with a density not too far from ethanol. Graeme Bartlett (talk) 12:46, 10 May 2012 (UTC)

99% is a very strange concentration. 96% or 100% would be more normal. Perhaps this means around 99% alcohol plus 1% denaturing agent. Rmhermen (talk) 14:16, 10 May 2012 (UTC)

I am aware of so-called 99% alcohol liquors, 198-proof. The one reliable source I found was for illegal moonshine concentrated to an absurd degree, possibly with non-distilling drying methods as well as traditional distillation. HominidMachinae (talk) 19:11, 12 May 2012 (UTC)

Alcohol, whether for consumption, medical or other purposes, usually has a percentage indicated by volume (v/v, ABV, etc). FiggyBee (talk) 05:50, 11 May 2012 (UTC)

May 10

Why are salad shrimps so cheap?

Jumbo shrimps cost $5 a pound usually even on sale (have seen $4 once), but cooked salad shrimps cost $3 regular price and $2 this week at my favorite supermarket. Why the price difference? 66.108.223.179 (talk) 00:56, 10 May 2012 (UTC)

Supply and demand. As with any other seafood, it takes longer for a critter to grow to larger size. Older shrimp are rarer, because there's more time for them to be eaten by predators. Thus, it is relatively easy to catch lots of little tiny shrimp, or in the case of Shrimp farming, it takes a lot of resources to grow shrimp to larger sizes. In either case (wild caught or farmed), it is going to be more expensive per pound to bring larger shrimp to market than smaller, because of the numbers of shrimp or the resources needed to get them that large. --Jayron32 01:01, 10 May 2012 (UTC)

Jayron, would you know by chance the cost differential between growing a pound of jumbo shrimp and a pound of baby shrimp? I totally believe you, but it strikes me as counter-intuitive that growing the same amount of meat but on a larger number of animals is actually the more efficient way to go. Someguy1221 (talk) 01:13, 10 May 2012 (UTC)

How about this: Economic Update on Gulf Shrimp Fisheries, a recent report from the South East Regional Office of the NOAA Fisheries Service. This report details an economic and ecological model for different-sized shrimps, and the economics of catching them using differently-sized shrimping boats. "The magnitude of the price decline has varied by shrimp size category, with the under 15 count (“jumbo”) and 68 and over count (“small”) size categories seeing the smallest declines (approximately 23%) and the 31-40 and 41-50 count (“large” and “medium”) size categories seeing the largest declines (approximately 35%). Due to inflation, these price declines are even larger in real terms. ... According to Haby, et al. (2003), increases in shrimp imports have been the primary cause of the recent decline in U.S. shrimp prices. A complete discussion of the factors contributing to the increase in imports can be found in Haby, et al. (2003)." You can't get much better an answer than that! "...Relatively lower wage rates have allowed major shrimp exporters (e.g. Thailand) to increase production of more convenient and higher value product forms, such as hand-peeled raw and cooked shrimp. With respect to the second factor, changes in farming technology and species have allowed production of foreign product to shift towards larger, more valuable sizes. As a result of these factors, imports are more directly competing with the product traditionally harvested by the domestic industry, thereby reducing the latter’s historical comparative advantage with respect to these product forms and sizes."

(I found this page via the main page links at the Southwest Fisheries Science center, which I regularly read; I navigated to the "Resource Fisheries" section and went straight for the South East region, including Gulf of Mexico, where much commercial shrimping takes place in the United States; though much shrimp in your grocery store comes from the Pacific Northwest or from Mexico, or overseas imports). Nimur (talk) 01:38, 10 May 2012 (UTC)

Here is a simple way to think about it. Suppose you have 2 small shrimp and one eats the other. If it was 100% efficient at converting the shrimp it ate into it's own body, then the total mass would be the same before and after the cannibalism. However, digestion is nowhere near 100% efficient. So, your cannibal shrimp ends up maybe 10% larger than it was. Thus, you went from a weight of 2x for both shrimp to 1.1x for one shrimp. Even if the shrimp aren't cannibals, similar ratios apply, whatever they eat. StuRat (talk) 05:22, 10 May 2012 (UTC)

The problem with you scenario is you appear to have started with 2 magic small shrimp. If these shrimp aren't magic, how did you get them in the first place? If the shrimp needed to eat 10x it's final body weight to reach its final bodyweight, it doesn't matter whether you have 2 shrimp weighing 5g, or 1 shrimp weighing 10g, you still needed to feed 100g. Don't get me wrong, there are plenty of reasons why raising 1 large shrimp may be less efficient then raising 2 small shrimp (e.g. possibly lower food conversion efficiency) but your explaination doesn't really help. You're explaining why it's usually better/more efficient to eat something lower down in the food chain, rather then why eating something smaller is better. Nil Einne (talk) 08:20, 10 May 2012 (UTC)

It's not only the amount of food the shrimps eat to grow to mass X, you also need to factor in the time. If we assume shrimp growth is a linear process it takes 1n shrimp time t to grow to mass x while 2n shrimp would only take t/2 to grow to mass x. Thus the output of the shrimp farm would double if they harvest them at "half size". Roger (talk) 08:48, 10 May 2012 (UTC)

Jayron said it all: supply and demand. It doesn't actually matter how much it costs to produce something, the margin might be bigger for some product than for other, but manufacturers are not passing the cost to you, they only charge as much as possible, and incidentally, consumers are willing to pay more for bigger shrimps, which is not amazing, since for the same weight, you would get more eatable meat. 95.20.183.251 (talk) 13:26, 10 May 2012 (UTC)

1) Why is the ratio of eatable meat higher in a larger shrimp ?

2) Cost is not solely a question of how much people are willing to pay for an item, the cost to produce it must also be considered. Indeed, when competition works, the price should be pushed down until only slightly above the production cost.

3) An advantage I've found with larger shrimp is that they are easier and quicker to clean, since you have fewer shrimp to clean. StuRat (talk) 15:22, 10 May 2012 (UTC)

Measuring human tasked energy consumption with calorimetry

How might you extend the concept of the calorimeter to measure the energy consumption of a person doing a particular task, such as riding a bicycle? --Accountness (talk) 01:18, 10 May 2012 (UTC)

I put your huge title into the body and gave it a short title. StuRat (talk) 05:16, 10 May 2012 (UTC)

Stu, that one word title makes it just about useless if someone later on tries searching for it in archived questions. May I suggest a new title "Measuring human tasked energy consumption with calorimetry"? Wickwack60.230.217.112 (talk) 05:47, 10 May 2012 (UTC)

OK, changed it. However, there aren't going to be all that many calorimeter questions, and we can search through the contents, as well as the title, to narrow it down further. StuRat (talk) 05:53, 10 May 2012 (UTC)

AFAIK human energy consumption in such situations is usually determined by measuring respiration - oxygen intake versus carbon dioxide output. One could put the subject inside a very well insulated room and measure the rise in air temperature but it's much easier just to measure the respiration rate. Roger (talk) 08:38, 10 May 2012 (UTC)

Easier except for the subject. Doing a VO2 max with a mask on is pretty unpleasant, from my experience. --BozMo talk 20:04, 10 May 2012 (UTC)

This sounds like a another homework assignment question. It would help if you (the original questioner) expanded a little on what you want.

The energy consumed over a period of time by a human under sustainable conditions may be approximately considered as:-

....E_TOTCON = E_FOOD + E_BODYMASS + E_THERM

where E_TOTCON is the total energy consumed;

..........E_FOOD is the energy contained chemically within the food and drink eaten;

..........E_BODYMASS is the energy consumed (or replaced) by the body consuming its' own mass (as in fat stores being converted back to energy, and muscle mass being converted back to energy)

and ...E_THERM is the energy contained as heat in the food and drink consumed by virtue of these being at a certain temperature.

Therefore, to properly understand and measure the energy consumed by a human, whether at some task or not, you must understand and measure each of these sources.

E_FOOD can be measured by burning samples of the food in a Bomb Calorimeter (see http://en.wikipedia.org/wiki/Bomb_calorimeter#Bomb_calorimeters). The term bomb here does not meaning blowing anything up, it means that the combustion is contained wholely within a measurement container. There is a considerable volume of literature giving the energy content (in kJ or calories) of almost all types of food and drink. Energy content is normally given on food packaging, at least in Australia and the USA, but the accuracy is not stated. So, if you want to measure it for yourself, you need a bomb calorimeter. NOTE: the energy value obtained for any given food type does vary significantly depending on the actual measurement technique used. Bomb calorimetry is not by any means an exact science, particularly with food. There is a definitional issue as well: Food is a fuel - as with any fuel, you can consider the chemical energy as a Low Heat Value or as a High Heat Value. When fuel is chemically consumed, the products ultimately are CO₂ and H₂0 and perhaps "ash" (residual stuff that cannot be burnt). If the H₂O is emitted/excreted as vapor (as it is in sweating) it still contains heat of vaporisation ( http://en.wikipedia.org/wiki/Heat_of_vaporization ), so the energy extracted is the Low Heat Value, otherwise it is the High Heat Value.

The energy E_THERM supplied in food and drink may be calculated with sufficient accuracy (given everything else to do with human energy is not at all accurate) by weighing the food, measuring its temperature, and taking the heat contained (in kJ) as though it is water (~4 kJ kg^-1 K^-1)

The energy E_BODYMASS contained in any body mass consumed or replaced could be estimated by weighing the human before and after the task, correcting for sweat and any urine excreted. The best way would be to rehearse the test so you get the human to maintain his/her weight the same throughout the test, and make the test long enough in duration (at least several hours a day for a week or more) so a small change can be detected.

To make any useful sense of energy consumed, you also need to measure energy expended (ie in mechanical work, sweating, etc), and compare energy consumed and energy expended. The total consumed will of course be equal to that expended. Mechanical work done will range from zero to about 25% of E_TOTCON depending on the task, the human, and how comfortable you keep him/her. As previous poster Roger has said, you can use oxygen consumption and/or CO₂ expiration to measure energy chemical conversion, but humans are not terribly efficient not consistent in converting chemical energy as measured this way into mechanical work. You can also use an instrumented room as Roger said - this is the use of a Calvet Calorimeter. However, this on its own is very inaccurate for this purpose and has serious limitations re comfort of the human. I may make a second post on accurately measuring energy expended later.

Ratbone58.164.236.109 (talk) 03:59, 11 May 2012 (UTC)

Nutrients for human brain tissue culture

What nutrients are required or beneficial for cultures of human brain tissue in vitro? NeonMerlin 05:10, 10 May 2012 (UTC)

Is this some sort of medical school homework question? I should think that if you are in a position to legally obtain human brain tissue, you would have the qualifications or team backup to already know the answer to this question. Ref Desk policy is not to give homework/assignment help unless you provide evidence you've worked on it and got stuck. Wickwack60.230.217.112 (talk) 05:53, 10 May 2012 (UTC)

Whole point of Wikipedia is, people have a right to know things. The model that knowledge is something to be doled out only to Authorized Personnel according to occupation, assignment, need to know and security clearance ... not our model. And this is not written like "homework", just legitimate curiosity. Wnt (talk) 12:55, 10 May 2012 (UTC)

Yes, people do have a right to know. Not only that, spreading the knowlege around enables creativity and benefits mankind. In no way was I seeking to restrict knowledge to those authorisied. Rather, logic tells me that this is not likely to be a genuine need (as a person in actually thinking of doing this would already have the answer, in order to satisfy authorisation requirements), therefore it may be a homework or assignment question. The OP's talk page shows he IS a student. Pure curiosity is perfectly fine, and we love to help with that. But the OP should still have made his own research effort before expecting others to do so. If the OP confirms it is not homework, and/or he indicates he has given it some thought, he is likley to get good answers. He hasn't done so yet. Wickwack124.178.180.170 (talk) 00:31, 11 May 2012 (UTC)

I don't follow your distinctions and have little interest in your restrictions. It isn't obviously a homework question to me; that's enough (indeed, if that rule is going to get questioners this kind of reaction we'd be better off without it). Wnt (talk) 12:40, 11 May 2012 (UTC)

Maybe so. But I didn't suggest or impose any restrictions on answering. I merely pointed out that if the OP provided some evidence that he's made some effort himself, he may get more and better quality answers. But you've answered, you probably enjoyed doing so, and that's fine. Wickwack124.178.33.132 (talk) 01:20, 12 May 2012 (UTC)

It apparently depends a lot on what kind of brain tissue you are growing. Someguy1221 (talk) 06:14, 10 May 2012 (UTC)

Well, fish is alleged to be "brain food". That could be worth a try. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:35, 10 May 2012 (UTC)

• To clarify, are you asking solely about the actual nutrients like glucose, or also about regulatory signals meant to mimic the body environment such as nerve growth factor or the ubiquitous (but extremely uncontrolled) fetal bovine serum Wnt (talk) 12:57, 10 May 2012 (UTC)

Anyway, to answer the question, see [12] for some general nerve growth protocols; [13] is a rather disturbing description of short-term maintenance; [14] (not readily accessible) describes culture of neurospheres; [15] (not readily accessible) describes organotypic culture of slices. But this one is perhaps closest to what you're looking for. There are many more I could cite - it depends on your desired cell type, length/extent of replication wanted, form of culture, etc. Wnt (talk) 12:40, 11 May 2012 (UTC)

Two diagonal rings, one touching the other at just one point and spinning

Is there a name to that? Is that possible, maybe with magnetic rings? I saw that in a science fiction film, but want to know if there's something like that. It would be a kind of toy like the Newton's cradle. — Preceding unsigned comment added by 95.20.183.251 (talk) 13:09, 10 May 2012 (UTC)

If you mean this [16] from Superman II, it was simply two metal rings welded together and attached to a turntable. The centre part of the turntable was stationary, so the actors could stand and have the rings appear to spin around them.--TrogWoolley (talk) 14:02, 10 May 2012 (UTC)

Yes, I meant that, but what if you put the two rings into a transparent tube? Would a construction with two independent rings be possible? OsmanRF34 (talk) 17:33, 10 May 2012 (UTC)

Intriguing. There's no doubt that a ring or coin can, for a short time, spin around in a narrow circle, perhaps even in place?, supported by only one spot on the edge at any given time. And if a second ring/coin could be positioned precisely, so that it spun exactly the right way, then the top one would never know it was on anything but a flat surface. Doing that, of course, makes the usual acrobat and a tower of chairs seem like child's play, and we start to think of cheating with glass tubes or magnets or superconductors or gyroscopes. But what if we cheated with some kind of computerized mechanism, that applied only small corrections? That would seem closer to achieving the feat virtuously. Wnt (talk) 17:58, 10 May 2012 (UTC)

Master of Public Health

What are the different jobs that a Master of Public Health prepares one for? I don't have a previous medical background. Thanks. Rodney Boyd (talk) 21:39, 10 May 2012 (UTC)

This page provides some suggestions. --Mr.98 (talk) 22:03, 10 May 2012 (UTC)

Thanks. I saw that page. I was hoping for something more detailed. For example, what jobs would be included under International Health? Rodney Boyd (talk) 00:27, 11 May 2012 (UTC)

Working at NGOs, mainly. Some government agencies and think tanks, too. See International health. --Mr.98 (talk) 01:12, 11 May 2012 (UTC)

Lava tornado

What would happen if a tornado passed over a lava field would it create a lava tornado, cause it to lose strength and die out would it strengthen. — Preceding unsigned comment added by 86.41.95.141 (talk) 22:33, 10 May 2012 (UTC)

Yes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:11, 11 May 2012 (UTC)

Lava is very sticky and dense, the strongest tornado wouldn't be able to lift much if any of it. Lava is just liquid rock, after all, and tornadoes don't pick up boulders; they pick up things that catch the wind well. Occasionally you will find in the most violent tornadoes that some of the ground, or even pavement, has been stripped, but that is more from debris scouring than anything else. The stuff you see lofted high by tornadoes are lighter objects like dust, paper, insulation, etc., or heavier debris that has a large cross-sectional area to catch the wind, like large trucks and roofs of houses.

As to whether it would intensify, it's tough to say. Tornadoes run mostly off low-level instability, caused by warmer, lighter air below cooler, denser air, so in theory a bunch of added heat at the surface would intensify the tornado. But tornadoes also need moisture, so increasing temperatures without adding any water vapor would actually lower the humidity, which is not good. Then there is the consideration of what a lava field might do to the overall structure of the parent supercell; I think more than likely, it would disrupt the storm.

However, brief tornado-like circulations can be caused by fires (as seen in this video). Indeed, the only fatal "tornado" ever recorded in California was from an enormous fire caused when lightning struck an oil storage facility. These firewhirls have different formative mechanisms than classical tornadoes, however, and die quickly if they move away from the source of heat. -RunningOnBrains^(talk) 01:00, 11 May 2012 (UTC)

(edit conflict)That would be a rather unusual situation! Lava could not be picked up at the base of the twister unless the twister was very strong and/or the lava was splashing, if, however, it was picked up, it would not stay as lava long; it would soon turn into lava bombs and eventually rocks, so no lava tornado, just a tornado carrying some lava. As for the last part, I don't think it would effect the tornado much. Lava would mean heat (obviously), meaning rising air, which is what gets storms started in the first place. So it might strengthen the storm as a hole, and indirectly the tornado, but by a very small factor. --T H F S W (T · C · E) 01:05, 11 May 2012 (UTC)

It would quickly die if lifting something so heavy. Even waterspouts, which lift water, quickly lose their strength. StuRat (talk) 04:51, 11 May 2012 (UTC)

There's no time limit on waterspouts, they can last as long as sufficient instability exists. It's not that they're lifting too much water, it's that evolution of the storm creates cool downdrafts which cut off the warm, unstable inflow. And as I stated above, I don't think a tornado would lift the lava at all, but it could feed off the heat produced. -RunningOnBrains^(talk) 05:03, 11 May 2012 (UTC)

May 11

before penicillin

Penicillin was not widely used before the 1940s but what did they use before then to treat illnesses such as inner ear infections strep throat and pneumonia? — Preceding unsigned comment added by Wrk678 (talk • contribs) 00:42, 11 May 2012 (UTC)

See Antibacterial#History, antibiotics are not as necessary to treat infectinos as much as we have come to rely upon them. For an ear infection for example, avoiding dairy/sugary products and keeping the ear dry can help while your body fights off the infection itself. Unique Ubiquitous (talk) 01:06, 11 May 2012 (UTC)

Basically these are infections which would have killed many people who acquired them: if the initial infection didn't see you off, then a secondary infection or complication may have. They still have the potential to kill people without good immune systems, such as elderly, children or people on immunosuppressant drugs. --TammyMoet (talk) 09:16, 11 May 2012 (UTC)

Well, that Polygonum I mentioned a few days back was also used for ear infections by Dioscorides [17] (see Panicudine, which I started then) - also Stipa of some sort, Psyllium; also an elxine, Parietaria or Helxine of which this translation's author seems uncertain of the identity, but which sounds like some seriously good stuff. I mean, remember, Dioscorides didn't know that purulent ears, inflamed tonsils, erysipelas (cellulitis), chronic cough, and "all types of inflammation" would be treated by antibiotic - yet he ascribes all those activities to this plant, and not to a different larger form of "helxine" for which he has a separate entry. I'm pretty convinced the ancients knew their stuff, even if they did occasionally add in some white lead in hair-raising concotions. We could learn a lot from them. N.B. there is absolutely zero information about antibacterial properties of the plants suggested as elxine in PubMed, despite that remarkable paragraph by Dioscorides. Wnt (talk) 12:06, 11 May 2012 (UTC) Note: Nicholas Culpeper, writing on Pellitory of the Wall, gives a description more like a painkiller. [18] Nonetheless, I'm not at all sure this is what Dioscorides was writing about. Wnt (talk) 14:42, 11 May 2012 (UTC)

I'm also surprised that the antibacterial properties of Honey aren't separately mentioned in the article quoted by Unique above. They've been well known about for some time, before being rediscovered by medicine in the last few decades. --TammyMoet (talk) 13:51, 11 May 2012 (UTC)

Inner ear infection is mostly caused by a virus, so no real treatment exists; Pneumonia was a killer disease before antibiotics; can't find a lot on treatments for these, it's as if before the 20th century everyone was busy trying to cure syphillis. Toxic metal compounds were used a lot, arsenic in the form of Fowler's solution, arsphenamine, or arsenic trioxide; thallium salts, various forms of mercury, like mercury(II) chloride. See also medical uses of silver. Ssscienccce (talk) 14:15, 11 May 2012 (UTC)

Actually, it is not impossible that an herb could be an immune modulator after the fashion of imiquimod; the right modulator might persuade the body to put on a different and possibly more useful immune response toward an infection. Wnt (talk) 14:42, 11 May 2012 (UTC)

The short answer is that prior to the development of antibiotics, a lot of people who developed serious bacterial infections died because there just weren't any effective alternatives. My grandmother's sister died in her late teens from an infection caused by a troublesome wisdom tooth. Without proper antibiotics, you're left with plain old supportive care: keeping the patient comfortable, supplying IV fluids as needed, and hoping for a good outcome. TenOfAllTrades(talk) 14:28, 11 May 2012 (UTC)

My doctor always told me that without antibiotics a inner ear infection will cause the eardrum to burst, not to mention the fact that an inner ear infection is extremely painful. Although some ear aches are caused by viruses most ear infections that last more than a day or two are caused by bacteria. — Preceding unsigned comment added by Wrk678 (talk • contribs) 01:41, 12 May 2012 (UTC)

Not sure if it was used for the three specific infections mentioned by the OP, but Sulfonamide (medicine) was used before penicillin. The Prontosil form of sulfa was introduced in 1935., and was effective against streptococci. Actual sulfa was an old drug (1906) and out of patent. It was very helpful in WW2and the article says it saved tens of thousands of wounded soldiers from death. Before sulfa came into use there was [[Arsphenamine}Salvarsan]], used starting around 1910 to treat syphilis. Before these, physicians used a variety of chemotherapeutic agents with limited success, such as carbolic acid, alcohol, iodine, and iodoform in the peritoneal cavity or elsewhere. These agents might kill pathogens, but tissue damage was also likely. Quinine was effectively used to treat malaria. A typical recommendation from 1904 was to treat infections by "absolute rest of both the patient and the part involved, drainage and evacuation of septic foci, soothing and cleansing applications to the parts, promotion of elimination and support of the patient." This is not so different from what a homeopathic doctor would have done at the time, except the "regular" or allopathic physician might open, irrigate and drain] the infected area. Not sure what the doctor of the pre-antibiotic era would do to treat an inner ear or throat infection, but a mastoid infection would be surgically drained, and antiseptics might be instilled in infected areas such as sinuses or the abdomen or genitals. By [19], war surgeons found it effective to use diluted bleach with other chemicals (Dakin's solution) to treat wound infections. Back in the 19th century, a physician would have likely treated an infection by administering a highly poisonous mercury compound called Calomel, by purging the patient with laxatives, and by bleeding the patient, which were rarely beneficial and all of generally increased mortality and had severe side effects. But even back in the US Civil War, some surgeons treated abdominal infections by irrigating with boiled (and cooled) water, before they had a clear germ theory of disease. Edison (talk) 04:17, 12 May 2012 (UTC)

For a project with strict rules against giving medical advice, I reckon this thread is dangerously packed with misinformation and quackery. We really shouldn't be describing non-professional "cures" here. HiLo48 (talk) 04:35, 12 May 2012 (UTC)

Do you have a beef with referenced historical information which answers the OP's question about how infections were treated before penicillin? Any accurate answer to a question about how things were done in an earlier era will describe ways which are no longer considered optimal, whether it is farming, fighting a war or fighting infection. Edison (talk) 04:39, 12 May 2012 (UTC)

Not at all, but a lot of the "advice" above is not "referenced historical information". HiLo48 (talk) 04:45, 12 May 2012 (UTC)

If you see misinformation above, or advice, by all means, point it out. Wnt (talk) 21:12, 12 May 2012 (UTC)

I see some ill-founded intuitive suggestions, based on original research, by guess, and by gosh, as well as my response which is based on a search of books from the pre-penicillin 20th century. Before penicillin there was sulfa, before that there was supportive therapy, giving the body a chance to heal itself and the immune system a chance to defeat the infection, along with operations to drain abcesses, boils, and other foci of infection, and the questionable use of chemical antiseptics which killed pathogens but also harmed body tissues, This is distinct from earlier medical quackery with calomel, bleeding and purging. Edison (talk) 03:40, 13 May 2012 (UTC)

Minimizing the effects of aging on skin

How a person can minimize the effects of aging on skin? Is life extension technologies or hormone replacement therapies developed enough to make someone look younger at their old age? What is the possibility of research progress in the next 30 years? Should Resveratrol supplement from a much younger age help someone to prevent aging-related changes in skin? What measures should be taken by someone who is 19 years old to delay aging? --NGC 2736 (talk) 03:58, 11 May 2012 (UTC)

While there is not a great deal of publicly available good scientific research on the subject of preventing skin ageing, beauty therapists are trained to advise on this. I'll give you some advice here, which any beauty therapist would be able to give you: drink plenty of water, use a good moisturiser day and night, cleanse your skin thoroughly before you go to bed and when you wake up, eat a balanced diet, don't smoke - and choose your grandparents well. Whether you should supplement with anything is medical advice which we can't give here. --TammyMoet (talk) 09:10, 11 May 2012 (UTC)

And don't, under any circumstances, lie around half-naked in the sun! FiggyBee (talk) 09:28, 11 May 2012 (UTC)

Calorie restriction, avoid over-cooked food, alcohol, fermented meat & donuts. Eat lots of salad and fruit. SkyMachine ⁽⁺⁺⁾ 09:52, 11 May 2012 (UTC)

What is the most accepted theory of aging? --NGC 2736 (talk) 10:17, 11 May 2012 (UTC)

See senescence for the general theory. As for skin, of those listed above, avoiding UV exposure is, by far, the most important. This can be done be staying inside, covering up when outside, using sunblock, etc. And absolutely never use a tanning bed. StuRat (talk) 15:03, 11 May 2012 (UTC)

See Photoaging for the specific theory relating UV-light and aging. OsmanRF34 (talk) 21:43, 12 May 2012 (UTC)

I think it goes well beyond theory at this point, it's an established fact. StuRat (talk) 22:18, 12 May 2012 (UTC)

It is a theory. But the proper meaning of 'theory' is not 'hypothesis', it is 'an explanation backed by facts.' Anyway,, I don't think there are any doubts in the connexion between UV rays and skin aging. ~~ — Preceding unsigned comment added by OsmanRF34 (talk • contribs) 11:59, 13 May 2012 (UTC)

Is Element Zero In Mass Effect Possible

In the Mass Effect series theres an element that effects the mass around it when charged with electricity. Its usually found near pulsars and neutron stars. Would this kinda thing be possible cause you can control gravity with this stuff. — Preceding unsigned comment added by Lightylight (talk • contribs) 04:23, 11 May 2012 (UTC)

Whether the stuff can control gravity or not doesn't matter. In either case, the stuff isn't possible. Plasmic Physics (talk) 08:21, 11 May 2012 (UTC)

See antigravity. The ideas are just as speculative but you'll get more respect from the crowd if you describe them in those terms. Wnt (talk) 11:45, 11 May 2012 (UTC)

Atoms are made of electrons, protons and neutrons. Elements are numbered according to the number of protons (which is the same as the number of electrons) that they have. An "element zero" would presumably have none of either - so it could only consist of neutrons. We actually have an article about this: Neutronium. An "atom" consisting of just one neutron would not generally be described as an "atom" - so we don't normally place it on the periodic table at number zero - but we could - and several people have actually done that. Sadly, a neutron left on it's own decays with a half-life of around 15 minutes - so there wouldn't be much of this stuff around for very long unless something was continuously replenishing it. You can also have groups of more than one neutron (which, technically, would be isotopes of neutronium) - and groups of two neutrons (Dineutron) have definitely been observed in nature. Tetraneutron (a group of four neutrons) is hypothesized to be possible - and there is some evidence that it actually exists, although this is controversial.

However, I doubt we'll find that we can control gravity or do anything else particularly exotic with neutronium. Sometimes science fiction is just fiction. 216.136.51.242 (talk) 15:07, 11 May 2012 (UTC)

Now that we're talking about actual neutronium, what is its theorised state in a neutron star - liquid or solid, or super-solid? Can it even exist in the liquid phase, or does it sublime under all conditions? Plasmic Physics (talk) 06:29, 12 May 2012 (UTC)

I should note that "Element Zero" is the nickname, not its place in the periodic table. That said I don't see a potential way any chemical, elemental or compound, could change its mass when subjected to an electric field. Mass is a function of gravity attraction, which, according to the most commonly accepted theory, is a function of the curvature of spacetime caused by an object "resting" on it (in a fashion somewhat similar to a giant rubber sheet). This is a massively gross oversimplification but it explains the problem well. The conservation of matter states that you cannot create matter, which is the only thing that has mass, or destroy it. For an "element zero" to be possible it would have to destroy in a reversible way mass when a current was applied so that its "dent" in the sheet would become greater or lesser. In general it would require the relativity model of gravity to be wrong and Gravitons to exist, and somehow the element to generate a field that interacts with gravitons. The theories that posit Gravitons have serious problems (as the article points out). And beyond that, even if Graviton theories were true it is probably not possible to interact with gravitons in a meaningful way because they would be massless particles that have a very low probability of any sort of interaction with other forces. HominidMachinae (talk) 19:26, 12 May 2012 (UTC)

is the file autorun.inf executable by itself?

I have an autorun.inf file in my USB and it looks like some kind of messy code in notepad, but I cannot find any other application linked to this file. I wonder if it is some kind of malware that is executable by itself?--Noname67097 (talk) 05:24, 11 May 2012 (UTC)

autorun.inf is a file checked for by Windows when you insert a CD or other volume device, and contains instructions about what to do when that volume is inserted into the computer. It is not an executable in itself, but can cause Windows to launch some other executable. FiggyBee (talk) 05:43, 11 May 2012 (UTC)

Thinking out loud, what if you rename a *.exe file to autorun.inf. Will windows execute the code? Zzubnik (talk) 11:24, 11 May 2012 (UTC)

Well, the article says it's a text file, so no sane computer should try to run it. Then again, this being Windows, who knows? Wnt (talk) 11:43, 11 May 2012 (UTC)

For the future, note you're probably better off with questions like this at the Computing Reference Desk. -RunningOnBrains^(talk) 19:41, 12 May 2012 (UTC)

What's the term for one way only traffic lane design?

Hi,

I remember years ago reading about a traffic plan system that avoided making intersections, and used only one way roads that fed into each other using over passes and under passes kind of thing. I'm trying to find the term that describes this type of roadway.

It would be like the artery / vein system in the body, where the blood flow is practically one way only.

Thanks

--InverseSubstance (talk) 06:49, 11 May 2012 (UTC)

Controlled-access highway?--Shantavira|^{feed me} 07:21, 11 May 2012 (UTC)

Sounds impractical. In addition to the high cost of all those bridges, you'd need a cloverleaf interchange to replace every intersection. Those use up a huge amount of land, concrete, and money. StuRat (talk) 14:54, 11 May 2012 (UTC)

Well it's the way every motorway junction is designed in the UK! TammyMoet (talk) 20:34, 11 May 2012 (UTC)

Not Junction 3 on the M50! Tevildo (talk) 11:25, 12 May 2012 (UTC)

You need to help me with what a "motorway" is in the UK. Obviously, not every road or driveway intersection has a cloverleaf, so are you talking about controlled-access highways only ? If so, that's the same as in the US. StuRat (talk) 02:32, 12 May 2012 (UTC)

It's not hard to imagine a system of streets that has forks but no crossings. I've seen plenty of districts, typically in city centres, in which all streets are one-way. It's somewhat harder to imagine combining these two features. But intersections and overpasses can both be avoided with roundabouts. —Tamfang (talk) 06:45, 12 May 2012 (UTC)

Roundabouts don't avoid intersections, they are just another type, with the same problems of having to be extra careful, slow down, and even stop in heavy traffic, with the risk of being T-boned. This can all be avoided with a well-designed cloverleaf. StuRat (talk) 16:00, 12 May 2012 (UTC)

But what do you do if you live in a Cul-de-sac? SkyMachine ⁽⁺⁺⁾ 08:28, 12 May 2012 (UTC)

Of course we have articles on everything: Motorway. This is what a typical motorway junction looks like from the air. This is what a typical motorway junction looks like if you're travelling down it. Note that if you want to leave the motorway you do so from the left-hand lane. --TammyMoet (talk) 09:13, 12 May 2012 (UTC)

If you're restricting the plans to one-way streets, you only need two slip-ramps (for going from road A to road B and for going from road B to road A, with A and B themselves continuing in their straight directions crossing over/under each other), not the usual of the usual set of eight ramps of a full cloverleaf (between A and B with two directions of travel on each, there are 8 permutations of directional connections between A and B). An alternative is to have A and B merge to form a single one-direction road for some distance and then diverge again. That seems to require more (or at least more specifically shaped) land. But it also might make more driver annoyance overall (*everyone* merges) unless there are lots of outside-edge lanes that do not require merging. Depending on whether A and B diverge from the same side (set of lanes) from which they merged or opposite, there could be an easier flow for drivers switching to "the other" road than for those keeping on "the same" one from which they came (and more weaving for the other set of drivers). A normal ramp configuration is easy to be unimpeded for drivers remaining on the same road but substantial deceleration and then acceleration and merging for those switching from one to the other. DMacks (talk) 18:54, 12 May 2012 (UTC)

With a properly constructed ramp, you don't have to slow down at all, and there's plenty of time to merge, or sometimes no need to merge, if the ramp becomes a new lane (which then becomes the exit ramp at the next cloverleaf). It's only when they try to skimp that you get tight turns without a slope, requiring you to brake. StuRat (talk) 23:59, 12 May 2012 (UTC)

WTC

This may have been answered before, but here are a few questions about the collapse:

1. Why did they collapse at such a high rate, if it was supposedly by a progressive process?
2. Why were contents of the office floors completely pulverised as if by explosive force? As noted by a firefighter, the largest recognisable component of any of the many desk phones that are bound to found at the site, was half a key pad. He also noted that the debris of the structure itself was basically turned to dust, instead of the rubble he usualy finds at a scene of a collapsed building.
3. What was the cause of the explosions in the vicinity of the 8 floor?
4. Allow me to speculate, is it possible for the towers to have been constructed with built-in demolision explosives?

Plasmic Physics (talk) 12:19, 11 May 2012 (UTC)

Probably:

1. Gravity & height. Things tend to get faster the further they have to fall.
2. What do you expect things to look like when crushed under tonnes of concrete which has fallen from hundreds of feet? How many collapsed tallest ever tower blocks has the fire fighter experience of?
3. Pass
4. Possible, yes. Most extremely unlikely. --Tagishsimon (talk) 12:37, 11 May 2012 (UTC)

You can find discussions of all that and more! starting with our 9/11 conspiracy theories article. --LarryMac | Talk 12:45, 11 May 2012 (UTC)

Plasmic, you seem like a clever person - how can you be at all attracted to ideas that a second cause is needed after someone flies a jet airliner into a building? I fairly strongly believe that the "9/11 conspiracy theories" are deliberate disinformation, disseminated to push the national discussion away from more realistic conspiracy theories, such as that the Bush administration or intelligence establishment or private companies or somebody paid bin Laden to fly those planes into the towers in order to justify creating a security state with massive spending on unproductive programs. In this way it would resemble the second-shooter theories of the Kennedy assassination, which divert discussion away from whether the Russians or American intelligence arranged with Oswald for the crime. Wnt (talk) 14:34, 11 May 2012 (UTC)

A conspiracy to create a conspiracy theory - would that be a meta-conspiracy ? Gandalf61 (talk) 14:38, 11 May 2012 (UTC)

That's a bit silly. Presumably the reason behind that conspiracy theory would be to make money for Halliburton, etc. However, considering that Bush and Cheney were already rich and powerful, it seems absurd to risk losing everything, and gamble on life imprisonment and humiliation, in order to increase their wealth a bit more. StuRat (talk) 14:44, 11 May 2012 (UTC)

Who said anything about imprisonment? Remember Arms-for-no-hostages? Remember Pat Robertson's support for Charles Taylor (Liberian politician)? This is the kind of stuff these people do, and even if they're caught they get away with it; it's not even an embarrassment except in the sense that they couldn't keep their unmentionables unmentioned. They'd muddy the waters a little, make it unclear whether they were paying to cause the attack or prevent it, the press would call it a scandal for a day or two, and people would move on. Wnt (talk) 16:20, 11 May 2012 (UTC)

You fail to understand the difference between killing foreigners and Americans. Politicians can get away with the former, but not with killing 3000 Americans, especially the rich ones working in the WTC. StuRat (talk) 16:24, 11 May 2012 (UTC)

Bear in mind we're talking about over $1 trillion dollars in spending generated by the attacks. That's a lot of money even for the richest people on the planet. So far as I know, there are no trillionaires ... yet. Wnt (talk) 16:32, 11 May 2012 (UTC)

But very little of that went to the decision makers in your conspiracy theory (Bush and Cheney). And the difference between being a powerful millionaire and imprisoned is a lot more than the diff between being a powerful millionaire and a slightly richer one. StuRat (talk) 16:37, 11 May 2012 (UTC)

If Dubya made any decisions for himself I'd be amazed. Wnt (talk) 16:55, 11 May 2012 (UTC)

I'm not a conspiracy theorist, but if you are interested where that money went — and a lot of it did go to people in the intelligence agencies — Dana Priest and William Arkin's Top Secret America book is pretty fascinating. George Tenet, for example, has made quite a tidy amount of money for himself as a "intelligence consultant" to the government in the post-9/11 world, to point out one guy in particular. The revolving door between intelligence/security professionals and high-paid security consultants has been spinning like a dervish since 2001. --Mr.98 (talk) 17:37, 12 May 2012 (UTC)

Backtracking a moment, I should point out that the existence of a disinformation campaign doesn't require that the allegation being suppressed is true. It is possible that a conspiratorial involvement by U.S. agencies or even by Russia or some other foreign country would become the object of such a campaign simply because it is seen as troublesome. For example, intelligence agencies after JFK's shooting might have wanted to downplay any possible role for Russia simply out of fear that minor politicians would start going on TV and calling for the nuking of Russia and ratchet up tensions to the point where a real nuclear exchange became more likely. Wnt (talk) 17:00, 11 May 2012 (UTC)

4) Considering that the WTC was built in the early 1970's, why would explosives have been built in back then ? This was long before al-Qaeda existed. StuRat (talk) 14:48, 11 May 2012 (UTC)

When George Bush designed the buildings in late 1960s, his plan was to be president in 2001. Sandboxer (talk) 15:18, 11 May 2012 (UTC)

 :-) StuRat (talk) 17:04, 11 May 2012 (UTC)

Once a couple of floors have let go, the dynamic impact loading so far exceeds the designed static loading capacity of the structure that there is no delay as the mass impacts the next floor. The kinetic energy released is ample to destroy just about everything. How many collapsed 100 (or even 10) story buildings has this firefighter seen?

As to the absurd idea of placing explosives in a building by design, I can assure you that architects and engineers spend their time more productively to assure that buildings protect their occupants (the relevant standard is called the "Life Safety Code"), and that nobody would countenance (or be insured for) such a measure. I'm pretty sure my professional liability insurance doesn't cover demolition explosives, nor did Minoru Yamasaki's. That of course ignores the general absurdity of the "controlled demolition" conspiracy theories, which unquestioningly assume that total demolition of WTC 1, 2, and as an afterthought WTC 7 were an obviously essential outcome, and not trusting that a couple of fueled 767s at high sonic speeds would create a satisfactory commotion, and ignoring that the Pentagon and Capitol weren't similarly leveled, and assuming that this conspiracy extends over decades and reaches into the highest levels. Acroterion (talk) 17:07, 11 May 2012 (UTC)

I have this theory that it was all caused by a bunch of religious nutters flying planes into buildings. HiLo48 (talk) 22:27, 11 May 2012 (UTC)

Nah. Too obvious. Remember the conspiracy theorists credo: The obvious explanation must always be discarded. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:51, 12 May 2012 (UTC)

I would have expected a debris field around the building, with a great many objects tossed some distance from the building, as things collide and columns buckle. and not all ground to powder under the main footprint of the building. Edison (talk) 04:01, 12 May 2012 (UTC)

I wouldn't. We had no reason to know what to expect. It was a one-off experiment, one we're not likely to reproduce any time soon. It hadn't been done before, and now we know what happens when a bunch of religious nutters fly planes into buildings like that. HiLo48 (talk) 04:16, 12 May 2012 (UTC)

The towers came straight down, piling on each other, and there were plenty of nearby buildings (at least one of which also collapsed later in the day) to kind of "contain" the debris, so the stuff that was scattered tended to be dusty (and a fair amount of it toxic - asbestos, maybe?) ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:43, 12 May 2012 (UTC)

Many times a tornado will destroy a house and countless small objects go missing, never to be seen again. And that's without millions of tons falling on them. If nothing else, the WTC attacks confirmed that they way they built it, which seemed so nifty at the time, with the exterior being the primary support, was a possibly fatal design decision. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:39, 12 May 2012 (UTC)

Hmmm, we don't have much to compare it with. For all we know, if it had one major support beam in the middle the terrorists would have taken it down with the van bomb. Or if were a visibly tougher building, maybe they'd have crashed the plane into the Empire State building instead and taken it down immediately with many more fatalities. We're so far out into anecdotal data here, no real experiments possible, it's impossible to say what would or wouldn't have been best to do at the engineering level. Wnt (talk) 23:47, 12 May 2012 (UTC)

WTC 1 and WTC 2 did not fall straight down in a neat pile. They collapsed on top of a dozen neighboring buildings. One building was an immediate total loss, and several others were damaged beyond repair. The towers did not turn into dust; trucks carried steel and concrete from the site for months. 88.114.124.228 (talk) 15:45, 12 May 2012 (UTC)

Yes, the surrounding buildings took much of the hit of the collapse (including the building across the street that collapsed later in the day). The dust cloud funneled through the surrounding streets. One thing to keep in mind is that in the cubic volume of any office, typically there's going to be a fair amount of "air". Obviously, when a 100-story building pancakes down, a lot of that air is going to be pushed out, leaving just the solid rubble. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:34, 12 May 2012 (UTC)

A significant amount (by mass, if not by volume) is also liquid (water in the plumbing, etc.). That would either drain away or evaporate, in short order, after the collapse. StuRat (talk) 23:53, 12 May 2012 (UTC)

Regarding 3, the explosion on the 8th floor: an emergency responder (firefighter or whatever) reported that he heard two explosions around this floor, so it's very plausible that indeed some explosions happened. The building had emergency power systems, powered by diesel fuel, and that were on separate floors, including the 8th. In the 8th floor there was one 275 gallon tank power generator.

Regarding 4: I'd rather say that lots of people would know it if it were true. There is not only the build-in during the constructing, but you'll have to take care that no one find the explosives during a renovation. OsmanRF34 (talk) 22:08, 12 May 2012 (UTC)

These conspiracy theories all seem to center around the way the buildings pancaked and crumbled. They assume that the buildings were properly constructed in the first place. My experience tells me that properly mixed concrete does not begin to deteriorate for something like a hundred years. properly mixed concrete tends ,when demolished, to break into large pieces held together with rebar. substandard concrete tends to pulverise when impacted and has little flexural strength. I have not reseached who the building contractors were and I'm guessing it was government funded. It is not unknown for contractors to pocket large sums of money on the back of substandard fraudulent construction. Amongst all the hype,furor and investigation, has there been one word investigating the construction. A scenario like that would certainly warrent some smoke screen from influential freinds.190.56.115.245 (talk) 00:47, 13 May 2012 (UTC)

The building was designed to 'pancake.' What would you prefer, it falling to any side in a highly populated area? And it wasn't converted into dust (as the conspiracy theorist say). And the issue was not the quality of the construction of the building. It could withstand a small ṕlane crashing, but a full-loaded jetliner is too much to any building. OsmanRF34 (talk) —Preceding undated comment added 12:09, 13 May 2012 (UTC).

How about this: the experts have said that the steel columns at the core of the building should have halted the collapse, and directed the force outward. Since the building was stronger in the core than toward the edges, the edges would have been falling faster. This should cause the collapse to lose momentum by redirecting falling debris outward instead of mostly downward. In the least, the floors should have pancaked around the columns, the violent vibrations of the bare columns should have twisted the collapsing building off the vertical and dragged it over, instead of it falling perfectly downward. The collision also caused assymmetric damage crosswise, even a small lag in failure would translate into an amplified effect visible further down the collapse. Plasmic Physics (talk) 01:39, 14 May 2012 (UTC)

Why is it that a demolision takes months to so carefully plan to ensure that a building falls as perfect as possible downward, when in this case it just happens naturally? Plasmic Physics (talk) 01:44, 14 May 2012 (UTC)

Well, a demolition doesn't want a building to probably fall perfectly downward! 9/11 shows that they managed to fall straight down on their own twice, but nobody knows what would happen on a third try. More to the point, the collapse of a very tall building will tend to be qualitatively different, because the downward force and moment of inertia is so much greater. Maybe if the fire burned away one whole edge things would have been different, but with everything failing more or less at once as whole floors were on fire ... it probably tends to be pretty symmetrical. Wnt (talk) 03:58, 14 May 2012 (UTC)

A controlled demolition would need to be a lot cleaner than that, or they would all be sued for the damages to the nearby buildings. Note that the same design features which keep buildings from falling over sideways while intact also work (somewhat), when the building is no longer intact, to keep the debris from falling over sideways. StuRat (talk) 04:11, 14 May 2012 (UTC)

If it was a covert demolition, then it would be kept out of the books and no one could be sued; there needs to be a balance between minimising collateral damage and maximising believability. I don't quite understand your second statement. Plasmic Physics (talk) 04:26, 14 May 2012 (UTC)

It's a question of stability. Let's consider an unstable design, like an inverted pyramid. That might very well fall over sideways, either while intact or when demolished. StuRat (talk) 05:26, 14 May 2012 (UTC)

Transitional relativity ?

Hello,

does someone know if "transitional relativity" exists outside of Star Trek ? If so, what is it anyway?

Thank you. 194.199.79.181 (talk) 13:30, 11 May 2012 (UTC)

I can find no reference to 'transitional relativity' in science that does not relate to that single throwaway Star Trek gag, save for one book review that appeared in Nature in 1969: [20]. In that instance, the term is not being used to describe a particular branch of relativity, but simply to describe the type of textbook. That is, it is a textbook about the theory of relativity that attempts to bridge the transition between the way the subject is taught in (secondary, or high) schools and the way that it is presented in universities; it is the textbook that is transitional, not the relativity.

Additionally, there are a few references to 'transitional relativity' in contract law. TenOfAllTrades(talk) 15:15, 11 May 2012 (UTC)

Digging to Vesta's iron core

I just read that Vesta has an iron core with radius 107 to 113 km [21]; the protoplanet has overall dimensions of "572.6×557.2×446.4 km" as our article summarizes this (I can't access the original report at the moment, despite how much the taxpayers paid for this probe...). So depending on circumstances it is possible that a 100-150 km hole down into Vesta might get you to the very boundary of a frozen iron core. Vesta has about 0.022 g gravity (somewhere...) so the pressure at that depth would be something like a 2 km hole on Earth, which is to say, survivable. Whether there's a hope for some Krubera Cave with a correspondingly greater depth, going all the way down to the core boundary, well... in sci fi there may be. ;) And admittedly boring a 100 km hole, no matter how low the gravity, would be awfully ambitious for the human presence in space.

Nonetheless, suppose we could get down to this frozen core boundary. What would we find? Would there be big chunks of exotic mineral ores that are lighter than iron but heavier than all normal rock? Fields of diamonds like something out of Clarke's Jupiter? Maybe even liquid water and life, pressurized by the vast downward distance and heated by residual radioactivity? Wnt (talk) 18:39, 11 May 2012 (UTC)

Just as a note, Science (the journal) is a private company, that's why you can't access it, but you should be able to arrange a copy through your local public library, or if not any local university probably has access. Also all data collected by government-funded missions like NASA is in the public domain, so if you wrote them asking for data you could get it (although it might be a bit overwhelming if you didn't know what you were looking for). If you want to complain about access to scientific data, try dealing with the Europeans...they're heartless bastards who keep their science under lock and key. America is pretty much the only country in the world where scientific data is freely shared. -RunningOnBrains^(talk) 19:50, 12 May 2012 (UTC)

Even if it was packed with diamonds the cost of returning them to Earth would be far more than they are worth. This is especially true since we can create diamond in labs these days. StuRat (talk) 21:29, 11 May 2012 (UTC)

Oh, I know - especially diamonds, which are overvalued - but it could be a pretty visual image. I'm wondering what is down there, whether it's anything special. But Actually, based on how diamonds form, I suppose it's very very improbable, since the pressure needed is actually greater than Vesta could manage, I think! Unless they formed during some past collision and sank when it was molten or something, but then, I suppose they'd be microscopic, and they wouldn't sink anyway. Wnt (talk) 02:10, 12 May 2012 (UTC)

Cobra Mist

Have there ever been plausible suggestions for the cause of the Dopler-shifted noise that hampered and ultimately led to the shutting down of the Cobra Mist over-the-horizon radar system in 1973? And did this system cause the same interference as the Russian Woodpecker (and if not, why not)? The transcript of the report "The Enigma of the AN/FPS-95 OTH Radar (U)" can be found here, second half of the page. (It's a UFO site, but the transcripts seem genuine, the source in the Cobra Mist article only has the odd numbered pages). Ssscienccce (talk) 20:11, 11 May 2012 (UTC)

Not specifically about that radar, but noise is a common problem with all radar. In particular, things like water vapor droplets or flocks of birds close to the radar show up as much as large objects far from the radar. This problem is usually solved by attenuating the signal returned from nearby objects, so they once again are in proportion to returns from object far from the radar. I don't know if this was done with the Cobra Mist system. StuRat (talk) 21:27, 11 May 2012 (UTC)

Using pulsed wave signals, reflections from nearby objects would be filtered out on a timer basis. The main problem was the amount of ground backscatter, given the long distance the signal traveled (1000 to 3000km), it would receive the ground reflection of an area of maybe 1000 km², while a typical target would present a surface area of only 30 m². The pulse Doppler radar signal processor was required to suppress the ground backscatter by 85 to 90 dB relative to aircraft returns; for that, the transmitter and receiver were designed to have a very large linear dynamic range. Basically they depended on accurate doppler shift filtering to remove the ground backscatter, but for some reason the received signal contained a lot of noise in all the doppler shift ranges. It was as if they received signals from thousands of targets all traveling at different speeds. I found this document suggesting the noise could be due to range-discrete meteor echoes or to range-dispersive auroral scatterers. They conclude: The spectral behavior of the meteor-nose echo agrees very well with that of the FPS-95 noise. Theoretical tenets as well as experimental evidence force the conclusion that the FPS-95 noise is produced in part by meteor-nose echoes. However, it doesn't explain why the phenomenon was seen only over land, not over water, and the writers of the "Enigma" paper do not accept this conclusion. Ssscienccce (talk) 14:06, 12 May 2012 (UTC)

What is it that is constantly moving in large volumes over land, and never over sea? Why, road traffic of course! A single truck could be large enough to produce a detectable echo. On freeways and highways, you get clumps of vehicles moving together, and together they could be a large enough target. As traffic cops using radar know, when you have two directions on a road, you can get echos aparently indicating speeds that are multiples of the true traffic speed, as the bean refects from one vehicle to another, adding the speed of each. Please tell me that folks who spent vast sums of money knew this, and dealt with it somehow. Or have I missed something? Keit120.145.7.207 (talk) 12:51, 13 May 2012 (UTC)

That's a sensible answer! We can't have those! Space aliens are far more likely! Tevildo (talk) 16:45, 13 May 2012 (UTC)

Good point, they don't mention that in the report. Maybe the timing of the noise or the calculated speed wasn't consistent with ground targets, I don't know. Looking at the graphs in the report, the noise levels peak before and after the ground backscatter, maybe that's why they think it must occur when the waves reflect against the ionosphere. I must say their initial expectations were a bit high, there was talk about maybe later, if all went well, increasing the range with a second bounce of the ionosphere. Not sure if they meant ionosphere-ionosphere-target or ionosphere-ground-ionosphere-target ... Ssscienccce (talk) 21:17, 13 May 2012 (UTC)

Eating pearls

Are there any health benefits or risks involved in swallowing pearls? For example, if one is embedded in an oyster and swallowed by accident.

Also, how hard is a pearl? Would biting on one be more likely to break the pearl or a tooth?

(I tried to search for a reference desk item that is relevant to the health question. Got some about Pearl Harbor and "pearls before swine" but nothing relevant.)

Thanks, Wanderer57 (talk) 21:01, 11 May 2012 (UTC)

You could choke on a large pearl. If you manage to swallow it I'd expect it to be dissolved by stomach acid. I'd also expect it to break before your teeth, possible leaving sharp bits that could cut you. StuRat (talk) 21:19, 11 May 2012 (UTC)

If you drink a goblet of wine in which a pearl has been dissolved, make sure you know the motives of the person who dissolved it. --Trovatore (talk) 21:46, 11 May 2012 (UTC)

Pearl is 2.5 - 4.5 on Moh's scale of hardness, which is pretty soft. Made almost entirely of calcium carbonate and thus readily dissolvable in the digestive system as stated above. If you have swallowed it then the risk of choking is virtually zero. I can't agree that there are any health benefits or dangers. Richard Avery (talk) 08:09, 12 May 2012 (UTC)

Well, the record seems to show that it is very hazardous, if the provider of the pearl killed your father, his brother the king, and took over your father's throne and queen. Although in that situation you also need to watch out for poisoned rapiers. --Trovatore (talk) 21:54, 12 May 2012 (UTC)

Drinking pearls dissolved in wine or vinegar seems to have been a well-known (if rarely done) act of ostentation. Cleopatra performed the trick to impress Anthony.[22] Caligula was another pearl drinker, and Sir Thomas Gresham is said to have ground up and drunk a pearl worth £15,000 to impress the Spanish Ambassador according to this source or in drinking the health of Queen Elizabeth I when she visited his new Royal Exchange according to Brewers. Alansplodge (talk) 09:01, 12 May 2012 (UTC)

Typically, a pearl is wrapped around a bit of sand from the bottom of the ocean. If that's something you want to consume, knock yourself out! ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:46, 12 May 2012 (UTC)

It could perhaps help digestion as a stomach stone. Count Iblis (talk) 02:18, 13 May 2012 (UTC)

May 12

Rate data for dissociation & recombination reactions

For chemical reactions of the form A + A + M → A₂ + M and the reverse A₂ + M → A + A + M, there is a range of published rate parameters (ie values to insert into arrhenious and modified arrhenious reactions) for all sorts of elements A. But the published data is restricted to only a few element/molecules M (the bath gas in lab tests) Almost entirely, M in published data seems restricted to N₂ and the noble gasses Ar, He, and Xe (Noble gasses are not of course terribly useful). Sometimes, but not always, you see M set to A or A₂, which is most useful. Sometimes you see CO₂. Is there a usable way to predict approximate rate constants where M is A, A2 or even useful things like O, O₂, N, and N₂, given rate constants for published values of M? Ratbone121.215.159.87 (talk) 15:00, 12 May 2012 (UTC)

Have you tried http://kinetics.nist.gov/kinetics/ ? Ssscienccce (talk) 16:03, 12 May 2012 (UTC)

Yes, of course. I've used it enough to know that it has many inconsistencies, traps for young players, and some errors. It's main value is that for any reaction in the database, it gives a list of references to look up. It is no help whatsoever with the question I asked. Ratbone121.215.147.93 (talk) 03:17, 13 May 2012 (UTC)

You probably won't find data for M = O (oxygen atom), except for A = O, because the O will have a greater affinity for A than another A. In other words the rate for A + A + O → A₂ + O will be very much lower than the rate for A + A + O → A + AO, and the reaction A + O + O → A + O₂, making product from the first reaction insignificant and thereby difficult to measure before all the O is used up. Keit120.145.7.207 (talk) 12:37, 13 May 2012 (UTC)

Lift controls

What happens if you press the button for the floor, on which the lift is parked with closed doors? --84.61.181.19 (talk) 16:33, 12 May 2012 (UTC)

What happens if you press the button for the floor, on which the lift closes its doors? --84.61.181.19 (talk) 16:36, 12 May 2012 (UTC)

What is the difference between pressing the door open button, and pressing the button for the floor you are currently on? --84.61.181.19 (talk) 16:39, 12 May 2012 (UTC)

I would guess that the answers depend on the control software for that particular lift, and on whether you are inside or outside. Why not experiment on real lifts and report your findings here? Dbfirs 16:41, 12 May 2012 (UTC)

What is the difference between old and new lifts in respect of my questions? --84.61.181.19 (talk) 16:42, 12 May 2012 (UTC)

In really old lifts, you open the door yourself, pushing the current floor won't do anything since the door stays unlocked until you select another floor, or someone on another floor calls the lift. Ssscienccce (talk) 17:26, 12 May 2012 (UTC)

It certainly depends on the elevator, but in my experience, if you're on a floor and you push the button for that floor, nothing happens, the elevator just sits there. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:30, 12 May 2012 (UTC)

FYI, the OP here has been elevated to the block house. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:42, 13 May 2012 (UTC)

What do these presumably space related acronyms mean?

Take a look at File:Mission_control_center.jpg and specifically the map of the earth; there are a bunch of regions on it - I've worked out that SAA is the south atlantic anomaly, and am pretty sure that the biggest ovals are going to be to do with daylight/darkness, but am not sure what the other things are. Google doesn't seem to be of help. The acronyms from West to East, so far as I can make them out (although I encourage you to look at the image) are:

• T???SW
• HTSS
• SAA (identified as South Atlantic Anomaly
• ShLK
• ????
• RDE
• KiPA
• ULDA
• USKA
• PPKA

Egg Centric 19:07, 12 May 2012 (UTC)

I'll admit, I'm stumped. At first I thought they looked to be the orbits of various quasi-geostationary satellites relative to the ground. Yes, geostationary satellites aren't perfectly geostationary, they typically wobble([23]) though these seem a lot more extreme than the typical wobble. But I agree with your assessment of SAA being South-Atlantic Anomaly, which makes my theory less plausible. I can speculate that maybe HTSS is some Hawaiian high-altitude observing station, as would be the various circles over Russia. Unfortunately I can't find many references to the above acronyms that seem relevant. -RunningOnBrains^(talk) 20:28, 12 May 2012 (UTC)

The Kaena Point Satellite Tracking Station is the site of the Hawaii Tracking Station or HTS, but that doesn't explain the extra "S". -- ToE 20:58, 12 May 2012 (UTC)

I agree that the large oval-like light and dark regions are daylight. The shape and size looks like File:Daylight.png (the lede image at Daylight). Even the specific part that is daytime makes sense: the Mission Control clock ("GMT" display top just to the left-of-center) is "063:15:00:44+" (3pm in England), in keeping with the "becomes dark" line about 30° east of England (about 2 hours of daytime left). DMacks (talk) 21:50, 12 May 2012 (UTC)

Searching [24] sniffs out a link at NASA, but I don't know what kind of file it is. (I dunno... lot of random noise when viewed as text... I might be Helen Keller reading the stucco wall here) Wnt (talk) 23:36, 12 May 2012 (UTC)

Searching for things related to the "PPKA" site, two interesting similars are "PKA" (acronym for the Russian Federal Space Agency) and Petropavlovsk-Kamchatsky, which is definitely in the correct location for that label. But this is definitely my WP:OR here. DMacks (talk) 03:22, 13 May 2012 (UTC)

Alright, found some more concrete information. ISS Ground Stations and Capabilities lists a bunch of Russian space-tracking installations, including things with identifiers "ULD", "PPK" (agrees with the lead I found by an unrelated search method), and "KLD". Soviet/Russian OKIK Ground Station Sites lists more sites with less information about them. DMacks (talk) 07:20, 13 May 2012 (UTC)

I suppose it goes without saying that "ShLK" is a Russian acronym of some sort (Sh is a single letter in Russian, Ш). --Mr.98 (talk) 15:13, 13 May 2012 (UTC)

Herschel and life on the Moon, etc

Mormon cosmology says "Such beliefs were common in the nineteenth century and were even considered to be "scientific fact" by many at the time. For example, William Herschel, the discoverer of the planet Uranus, argued "[w]ho can say that it is not extremely probable, nay beyond doubt, that there must be inhabitants on the Moon of some kind or another?" Furthermore, "he thought it possible that there was a region below the Sun's fiery surface where men might live, and he regarded the existence of life on the Moon as 'an absolute certainty.'"

William Herschel says "Despite his numerous important scientific discoveries, Herschel was not averse to wild speculation. In particular, he believed every planet was inhabited,[16] even the Sun..."

So the first says that it was considered scientific fact by many. The second says that it was a wild speculation. Which is more accurate? And will someone correct one of the articles? Bubba73 ^{You talkin' to me?} 19:12, 12 May 2012 (UTC)

Those can both be true. Consider that today, the Earth having been created a few thousand years ago is "considered scientific fact by many". They are completely wrong, of course, and this belief has nothing whatsoever to do with science. StuRat (talk) 22:08, 12 May 2012 (UTC)

Did many scientists consider it a scientific fact that there was life on the Moon, etc? That seems to be what it is implying. Bubba73 ^{You talkin' to me?} 23:25, 12 May 2012 (UTC)

Note that the phrase "scientific fact" was in quotation marks. Anonymous.translator (talk) 01:44, 13 May 2012 (UTC)

I suspect "scientific fact" is too strong a phrase, quotation marks or none. It would have likely been considered speculation. Perhaps not "wild" speculation. It would have been considered likely that other worlds had life — as it is considered likely today, though we now know that the parameters for life on a planet are considerably more specific than they would have known in the 19th century. But even as late as the mid-20th century, the idea that Mars might be populated with plants (if not intelligent life) was considered not an impossible prospect. (Today, of course, the possibilities of life on Mars are reduced to looking for bacteria-like organisms.) Anyway, both the scare-quoted "scientific fact" and the "wild" seem like things worth demanding a reference for. "Wild" is not neutral in any case; and I would want to see someone asserting the "fact" that there was life on the Moon. --Mr.98 (talk) 15:01, 13 May 2012 (UTC)

I agree with you. Bubba73 ^{You talkin' to me?} 18:46, 13 May 2012 (UTC)

The Herschel quote technically belongs to the 18th Century - it was made in a letter to the Astronomer Royal Nevil Maskelyne according to this. However the idea of Cosmic pluralism wasn't a fringe idea in the 19th Century. Not that his writings quite live up to scientific rigour perhaps, but one writer that does spring to mind in the 19th Century is Thomas Dick, who I came across in the Great Moon Hoax article. His 1826 book The Christian Philosopher, or the Connexion of Science and Philosophy with Religion suggesting life on the Moon was widely known, in both Britain and the United States; whether it had any influence on Joseph Smith, I don't know. In another book published in 1837, Celestial scenery: or, The wonders of the planetary system displayed; illustrating the perfections of the deity and a plurality of world, basing his estimates on the population density of Britain and scaling accordingly, he estimated the population of the Moon to be 4,200,000,000, the population of Saturn's rings to be 8 trillion and the population of the Solar System as a whole to be 21 billion (give or take). (These figures taken from this book). FlowerpotmaN·(t) 23:17, 13 May 2012 (UTC)

While I know that it's a myth that you can stop a moving car...

...by shooting a .44 Magnum round though the engine block (did that belief come from a line in the film Taxi Driver, or was it one of the Dirty Harry movies - that people just picked up on?), is there any handgun cartridge at all that can actually do this? --95.150.167.241 (talk) 00:16, 13 May 2012 (UTC)

Technically, a .44 Magnum round could stop a car according to the law of conservation of momentum. However, a 1000 kg vehicle could only be going .0051 meters per second if the bullet was fired from exactly the opposite direction. Similar calculations could be done with other cartridges. Reaper Eternal (talk) 00:23, 13 May 2012 (UTC)

I guess it all depends on what you mean by "stop a car". If you mean stop it's forward movement immediately, it would be have to be going very slow, as noted above. If you mean to stop the engine, I don't think you're likely to cause much damage to the engine block. You could take out any number of critical components by chance, however. The fuel line, distributor, ECM, any number of wires, etc., could stop the engine almost immediately. However, this requires a lucky shot. If you are content to stop the car eventually, putting a hole in the radiator gives you a much bigger target. StuRat (talk) 02:17, 13 May 2012 (UTC)

Stopping a car with any speed would require a serious amount of force, enough to interrupt oil flow probably, or as mentioned above a very lucky shot. Puncturing the radiator, as mentioned, will lead to the engine eventually seizing, but will not be any sort of rapid stop. the largest production handgun in the world is the .500 S&W, which produces a stunning 2600 or more foot-pounds of force. This is nearly 700 Ft-lbs more than the puissant .454 Casull. If you were to assume that the round is similar to the indenter used in a Brinell scale test, then against a typical grey cast iron engine block, it would make an indent defined by: Brinell hardness = (2*force in Kgf) / ((pi * diameter) * (Diameter - Sqrt(Diameter^2 -Indentation^2))) in this case that would be 260 = (2 * 35946.2) / ((Pi * 12.7)(12.7- Sqrt(12.7 - D))). This simplifies to: 260 = 71892.4 / 39.8 * (12.7 - Sqrt(12.7 -d)). The simple answer is 12.55mm which is almost exactly 1/2 in. (one half inch is 12.7mm as seen above). Since the engine block is greater than .5 in. thick, it's unlikely the handgun bullet would penetrate. Since cast iron is fairly ductile it is unlikely to shatter, and it's unlikely to deform greatly from that impact. Keep in mind this is a best-case scenario with a full-caliber tungsten penetrator, like a military AP round.Ssscienccce (talk) 10:24, 13 May 2012 (UTC)

Don't count on a cast iron engine block (leaving aside that most are aluminium alloy these day) not shattering. I've seen more than one engine block with a dirty great hole in the side caused by a thrown conrod (caused by either incorrectly installed bigend bolts, or the conrod itself breaking). However, engines can continue to run under such conditions, if the driver can stand the horrible noise. And if you are shooting at him, he will. Keit120.145.7.207 (talk) 12:29, 13 May 2012 (UTC)

HominidMachinae (talk) 06:42, 13 May 2012 (UTC)

Your best bet would be having the engine destroy itself, since a turning engine has a lot more kinetic power than a bullet. Breaking the timing belt or a valve (if a bullet can reach there) would do serious damage. A bullet at the right spot can initiate catastrophic failure, I suspect.  ::I would think that hitting the gearbox might well (though not always) cause immediate locking of the damaged gears and hence transmission, but you'd probably need quite advanced automotive experience to know where it was on your particular target, and whether or not it was effectively shielded from your position. {The poster formerly known as 87.81.230.195} 90.197.66.211 (talk) 11:31, 13 May 2012 (UTC)

Two words: smart bullet. Of course, when a bullet has the plans of every car coded inside it and decides where to hit in a few microseconds, the days of allowing the pathetic human behind it to have a say when it is fired will soon come to an end. Wnt (talk) 15:16, 13 May 2012 (UTC)

Mythbusters kinda hit on this one a while back. They were doing a myth about phonebooks making a car bulletproof... until Carrie put a .50 caliber round through the engine block(episode). So, I'd say no, a handgun won't be able to pull it off. — The Hand That Feeds You:^Bite 21:15, 13 May 2012 (UTC)

Like I said above, no handgun round could do it, even with military ammo. However a .50 BMG round from a rifle was BUILT to take out light armor would do it handily. Vehicles are tougher than a lot of people give them credit for. Anything capable of taking out a vehicle will be military-grade and probably a squad-level weapon (IE a Boys AT rifle is about the smallest they get, and that thing is 70 pounds). HominidMachinae (talk) 23:10, 13 May 2012 (UTC)

Rusting after burning

Why is it that metal seems to rust much quicker after it's been burned in a fire? Or is this just confirmation bias on my part? Dismas|^(talk) 01:27, 13 May 2012 (UTC)

How is that you've observed the rusting of scorched metal often enough that you observed patterns in it?? If it is because you live in a city that was recently a battlefield, I sincerely feel for you, but otherwise, that is kind of strange. ike9898 (talk) 01:46, 13 May 2012 (UTC)

Upon reading the question I immediately thought of the old campers' dictum (now strongly discouraged) in my country, Australia, of what to do with empty cans - Burn, bash and bury. As Tin can tells us, "Tin cans are made of tinplate (tin-coated steel)", and the burning removed the thin protective tin coating, thus allowing the steel to rust more quickly. If this response has nothing to do with the question, just ignore me. HiLo48 (talk) 01:56, 13 May 2012 (UTC)

That seems like the proper explanation, although I doubt if the tin melts entirely. More likely there are just holes created in it. The plastic lining on the inside may burn away entirely, however, exposing the inside to the elements. Another factor to consider is that cans, once burnt, might be left in a fire pit, where they are far more exposed to the elements (water, changing temps, etc.), than the intact can was whilst in a cupboard. StuRat (talk) 02:06, 13 May 2012 (UTC)

My guess would be that it would have rusted before being exposed to high temperatures had there not been some coating on its surface preventing its exposure to oxygen and water. Paint serves this purpose but perhaps other clear substances, the presence of which one may not be aware of, could have been present before heating but removed or damaged by heat. Bus stop (talk) 02:29, 13 May 2012 (UTC)

No, I don't live in a war zone. And it occurred to me to ask after seeing the rubble from a house down the road that had recently burned down. Someone had made a pile of all the appliances and other large metal objects that were taken from the home. Every bit of it was rusted. Off the top of my head, I remember seeing a sink, a water heater, what appeared to be a washer or dryer, a stove, a few mattress springs, and what appeared to be possibly a table saw. Since the fire, it's been rather dry here with the exception being a couple days this past week and, of course more localized, the spray from the fire hoses. The items were all covered in rust. Dismas|^(talk) 03:34, 13 May 2012 (UTC)

Protective coatings burning off (like paint, oil on tools..) or damaged by impact, moisture for days, chemicals in the water, galvanic corrosion if touching other metals. Ssscienccce (talk) 10:51, 13 May 2012 (UTC)

Autism

Autism is described as being on a spectrum. Presumably 'profound autism' is one end of that spectrum. What is the other end of the spectrum? 'Extrely Nuerotypical'? ike9898 (talk) 01:42, 13 May 2012 (UTC)

People who have abnormally good social skills. Count Iblis (talk) 02:08, 13 May 2012 (UTC)

Asperger's syndrome is a mild form of autism, and then there is PDD-NOS and high-functioning autism. StuRat (talk) 02:26, 13 May 2012 (UTC)

Stu is onto it. A basic definition of autism is the reduced ability to see another's point of view. But the range of Autism is not on a line - it is multidimensional. As with most mental/pschological "problems", a highly intelligent individual can overcome the "problem" by consciously thinking about it and correcting his behaviour. In doing so, the individual may make his autism seem different. I've put the word "problem" in quotes because to a high functioning autistic, it is a matter of opinion whether it is a problem. There are fields of employment where autism actually helps. Wickwack121.221.89.38 (talk) 03:08, 13 May 2012 (UTC)

'Stu is onto it' == 'Stu is on the autistic spectrum'? ~~ — Preceding unsigned comment added by OsmanRF34 (talk • contribs) 12:13, 13 May 2012 (UTC)

I'm sitting on a spectrum ? I can't feel it down there. I'd love to discuss this further, but it's 5:19, which means it's time for me to rip up pieces of paper for no apparent reason. :-) StuRat (talk) 05:19, 14 May 2012 (UTC)

Well, I wouldn't know, but as his posts are friendly, and he never attacks other posters, I doubt it. Note that I said "onto it", NOT "on it". The meaning is quite different. Wickwack58.164.226.214 (talk) 14:35, 13 May 2012 (UTC)

There is a hypothesis floating around by a Bernard J. Crespi that autism and schizophrenia are at opposite ends of a neurological spectrum. He's been going on about this since at least 2008. You can find lots and lots of papers [25][26][27][28][29] etc. about genes that affect both autism and schizophrenia. The problem is, it's hard to really categorize the effect as "same" or "different"; often one or the other is more what you'd call "altered". So some people paint it as two disorders based on the same mechanism, this fellow says they are opposite - in biology, there is little real distinction between synonyms and antonyms!

The most intriguing way to settle the issue would be to put some autistic kids on low-dose LSD - not enough to have obvious trippy effects, but maybe enough to revert autism to normality, if LSD is "psychotomimetic", and if that is some effect opposite to autism. But naturally many things could go wrong in such an experiment and some may question its ethics. ;) Wnt (talk) 04:38, 13 May 2012 (UTC)

You must be joking. Autism, neither the effects, not the cause, is well understood, but it is clear that it is caused by a lack of something - possibly a full set of functioning mirror neurons http://en.wikipedia.org/wiki/Mirror_neuron, maybe that and/or something else. You won't correct that with any sort of drug, any more than you could correct blindness, due say to genetically damaged retinas, with drugs. With enough LSD, you could maybe get the subject to think he has vision though... If you give LSD to autistic people, what you can only get is two problems instead of one - socially inept people who can't think straight, and if enough, socially inept people who halucinate and suffere from delusions. Hardly an improvement. Scientific American had a couple of good articles on autism, the mainstream professional view of it, and the role of mirror neurons, in the last year or so. Wickwack124.178.183.79 (talk) 11:07, 13 May 2012 (UTC)

I don't see the evidence that something is missing - while there are indeed large-scale and permanent variations in autistic brain (the location in the cortex where processing is done, the disruption of the inferior olive, AFAIR), it is often the case in biology that very visible alterations to an organ are less important than small and reversible regulatory changes. I'm not entirely serious in the sense that the low-dose LSD experiment I proposed probably wouldn't work and would very likely be regarded as unethical; nonetheless, I think there's a chance it would be beneficial. Wnt (talk) 15:11, 13 May 2012 (UTC)

In 2002 Simon Baron-Cohen put forward a theory that autism is an extreme form of the male brain, and there is a more recent article here about it. So one answer to the question could be "maleness" (or, depending on whether you see gender as a continuum, "femaleness").--TammyMoet (talk) 09:46, 13 May 2012 (UTC)

In the medical field generally, and the psycology field especially, you can always, if you look, find some wizzo professor who has very different and even bizare views about something. Here in Australia, we had a, otherwise quite well respected, medical professor who kept claiming that smoking had no role in lung cancer. He got in the news from time to time until he got lung cancer and died. However, TammyMoet's link is interesting. Wickwack124.178.183.79 (talk) 11:07, 13 May 2012 (UTC)

[OP] So, would it be safe to say that a spectrum is a bad analogy for the range of autism and related conditions?ike9898 (talk) 13:02, 13 May 2012 (UTC)

Not at all. "Spectrum" is a good word for it. Just as we talk about light having a spectrum, meaning a range of colours, autism is a spectrum, because it encompasses a range of conditions. Not only because you can be mildly, moderately, or severely autistic, but because not all autistic people, even if they are of the same severity, will display the same limitations or advantages. It is multidimensional in impact, as I said. (Not forgeting that autism can be a disadvantage or an advantage depending on the circumstances the autistic finds himself in). Wickwack58.164.226.214 (talk) 14:29, 13 May 2012 (UTC)

1 year.

Earth 2 forms a ring centered on the Sun, located on the circle* of old Earth's orbit. Earth 2 is stabilized by its rotational motion at old Earth's orbital speed. Your job is to find a way of having seasons on the ring. The idea for producing seasons is to allow Earth 2 to oscillate in the direction of its axis, perpendicular to the plane of its ring. Assume that a line from the Sun to Earth 2 oscillates through 46° of angle, with the mid-plane of the oscillation containing the Sun. What is period of the oscillations, in units of years?

If the Sun is a perpendicular distance $x$ from the ring, I worked out the magnitude of force acting on the ring to be ${\frac {Gm_{sun}m_{E2}x}{(r^{2}+x^{2})^{\frac {3}{2}}}}$ which is approximately ${\frac {Gm_{sun}m_{E2}x}{r^{3}}}$ since $r$ is surely much bigger than $x$. It follows that the "spring constant" is ${\frac {Gm_{sun}m_{E2}}{r^{3}}}$ and the period of oscillation is therefore ${\frac {2\pi }{\sqrt {\frac {Gm_{sun}}{r^{3}}}}}$. I look up the numbers and substitute and get a result of a single year. Since the result needs to be given in years, I am suspicious of this result and may have made a mistake. Does anyone agree/disagree with what I have done? --Widener (talk) 01:52, 13 May 2012 (UTC)

*By the way, I am aware that it is actually an ellipse.

Would not the "spring constant" be negative (which will not sustain oscillation)? Wickwack121.221.89.38 (talk) 02:41, 13 May 2012 (UTC)

That would be under the interpretation that $F=kx$ rather than $F=-kx$. Widener (talk) 03:06, 13 May 2012 (UTC)

If I'm understanding the question correctly, is it not obvious that it will be a year? I don't see why you need to use any maths. Egg Centric 02:43, 13 May 2012 (UTC)

Assuming I've understood his text etc correctly, he's visualising a donut/toriod shaped earth that supposedly oscillates up and down its rotation axis. The real earth has seasons because its rotation axis is at an angle away from perpendicular to its' orbital plane, forcing the seasons to be the same period as the orbital period. Such a thing is inapplicable to a donut surrounding the sun. So he needs to calculate the period of this "new" mode of oscillation, which is not locked to the orbital period. It will not actually oscillate though. Wickwack121.221.89.38 (talk) 02:50, 13 May 2012 (UTC)

I was going to say that the oscillation could be made any arbitary period (and therefore presumably a year) by altering the amplitude but then noticed the 46 degree thing... I see the problem Egg Centric 16:13, 13 May 2012 (UTC)

(So presumably you don't want to model it as a ring, just model it as a point mass with a centre of gravity which happens to pass through the sun during the oscillation, which means the equations will be very simple. Although it's a decade since I've done any mechanics, as this thought probably demonstrates) Egg Centric 16:15, 13 May 2012 (UTC)

The statement that r is much bigger than x is not valid. It's bigger, but not enough bigger to make the approximation valid. The max value of x/r is tangent(23 degrees), which is about 0.42. Looie496 (talk) 03:07, 13 May 2012 (UTC)

I don't think this will actually work - the varying distance from the ring to the Sun means the idea of stabilising it by having it revolve at orbital speed doesn't work. The centripetal force from the Sun's gravity won't balance the centrifugal force from the revolution, since the revolution is constant and the relevant component of the Sun's gravity isn't. That means you're going to get internal forces within the ring, which will rip it apart (unless it is made of some hypothetical super-strong material). --Tango (talk) 19:32, 13 May 2012 (UTC)

I don't know what "stabilized" means here; rotation doesn't affect the tendency of a Ringworld to drift into the sun. —Tamfang (talk) 03:20, 14 May 2012 (UTC)

By the way, this sounds like a homework question to me, presumably for calculus class. Ah well, too late now. ;) Indeed, the Ringworld is unstable, but only small attitude jets are said to be necessary. The oscillation along the axis would be unrelated to its instability from side to side.

As for the question, the Ringworld is simply a vertical wall to hold its bits in place. Mass cancels out and is irrelevant. A particle of the ring is accelerated toward the sun at G m_sun/sqrt(x²+r_earth²), but toward the midline at that multiplied by x/sqrt(x²+r_earth²). So you have to integrate dx/dt for G m_sun x/(x²+r_earth²), I think... And I don't think that you can assume x is much smaller than r_earth, or else you wouldn't get seasons from it. Besides, knowing/looking up/figuring out this integral is presumably the point of the assignment. ;) Wnt (talk) 04:30, 14 May 2012 (UTC)

Its not likely to be homework, becasue as such it would be a trick question - its not solvable because it is not oscillatory. In any case, its ok, because this OP showed us he had a go at working it out. Wickwack124.178.138.77 (talk) 06:02, 14 May 2012 (UTC)

Why is CO not the anhydride of formic acid?

The acid's article does not describe why formic acid behaves differently from carbonic acid, which I viewed as simply a higher oxyacid of carbon.--Jasper Deng (talk) 03:30, 13 May 2012 (UTC)

I think you might be mis-reading how carbonic acid behaves when it dehydates: its reaction is O=C(OH)₂→O=C=O, which is a standard gem-diol dehydration to form a carbonyl (lose an H from the OH, O remains attached). Formic acid doesn't have a gem-diol, and forming CO from it would involve loss of H from the C itself. It's pretty difficult to envision losing H and OH from the same position and getting anything close to a stable structure in general: dehydrohalogenation from a single atom (R₂C(H)(X)→R₂C analogous to your O=C(H)(OH) proposal) gives a carbene, which is generally extremely unstable unless there is something special about the R groups.

On the other hand, carbon monoxide is an anhydride of formic acid (see our formic anhydride article for details about CO formation in this sense). The carbene-like structure for O=C: in particular is just a resonance form of carbon monoxide, and the lone-pair on the "carbonyl oxygen" is exactly special to fix the octet instability of this carbene. DMacks (talk) 03:48, 13 May 2012 (UTC)

My conclusion stemmed from the fact that CO itself does not seem to hydrolyze in a reaction like CO(g) + H₂O(l)→ H₂CO₂ analogous to carbonic acid.--Jasper Deng (talk) 03:56, 13 May 2012 (UTC)

Carbon monoxide does react with water, just not in the way your intuition thinks it does. See Water gas shift reaction. --Jayron32 04:11, 13 May 2012 (UTC)

I knew about that particular one... I guess that there's little reason for my previous predicted reaction? -Jasper Deng (talk) 04:13, 13 May 2012 (UTC)

(edit conflict) Formic acid is the first of a homologous series known as the carboxylic acids, and those form dimeric anhydrides. If you look at formic acid like acetic acid and propionic acid, you'll see the pattern. The oxidation state of carbon in all three of those is the same, whereas in the carbonate ion, the electronics are quite different. Another way to think of formic acid as quite different than carbonic acid: formic acid has one of its hydrogens bonded directly to carbon, whereas all of the hydrogens in carbonic acid are oxygen bound. Any of these ways of thinking of it will lead you to the more correct conclusions than you reached. --Jayron32 03:50, 13 May 2012 (UTC)

Sorta the same reason that phosphorous acid is diprotic while phosphoric acid is triprotic, I guess...--Jasper Deng (talk) 03:56, 13 May 2012 (UTC)

Have you looked at carbonous acid and methanediol? Plasmic Physics (talk) 07:03, 13 May 2012 (UTC)

Formic acid was once made at a large scale by dissolving CO in hot NaOH solution under pressure. So you could consider it to have some anhydride properties (stoichiometrically) Staticd (talk) 12:17, 13 May 2012 (UTC)

Are there any traits (genetic traits) that are only inherited from one parent?(mom or dad)

Like the mitochondrial DNA that is inherited only from mothers?--2.147.67.209 (talk) 06:43, 13 May 2012 (UTC)

Anything on the Y chromosome is inherited from the father. Boys only, of course. — kwami (talk) 07:53, 13 May 2012 (UTC)

Colour-blindness in boys comes via the mothers. There are others, but I can't remember them right now. HiLo48 (talk) 08:29, 13 May 2012 (UTC)

Yes, the mitochondrial DNA is only inherited from the mother. Since virtually everything inside that DNA is directly related to the function of mitochondria, you don't really see anything but diseases being passed in it (i.e. when it works, you don't notice, except that you're not sick/dead). See Mitochondrial disease for a list of potentially inherited traits. As mentioned above, the Y chromosome is only inherited from the father. Explaining what HiLo said, boys inherit their X chromosome only from their mother. Sex linkage lists a variety of diseases that are linked to the X chromosome. There is also the case of genomic imprinting, in which case you inherit the DNA from both parents, but the DNA from only one parent is active and determines the phenotype. There are maybe 90 such genes, spread out across the chromosomes. Someguy1221 (talk) 08:46, 13 May 2012 (UTC)

Greenland as three islands

There's been a problem with an unref'd or poorly ref'd assertion at Greenland for several years now. The common understanding is that Greenland is really three islands connected by ice. A look at a topographic map shows that's not true: the center is below sea level, but the rim is unbroken. However, AFAIK that's not where the story came from. If the ice sheet were to melt completely, the sea level would rise 6–7 m, and then Greenland would be three islands; conversely, it's thought that glaciation united what had been three islands (at a higher sea level than now). I can't find a decent ref, though. Does anyone know of one, or am I remembering it wrong? (I can find lots of maps of what Florida would look like if the Greenland icecap were to melt, just not what Greenland would look like.) — kwami (talk) 07:52, 13 May 2012 (UTC)

Another theory is that as the icecaps melt, the weight removed would allow the land to rise, so none of Greenland without icecap may be below sea level. HiLo48 (talk) 08:27, 13 May 2012 (UTC)

Not a "theory" but a well-known phenomenon. It's pretty slow, though. Short Brigade Harvester Boris (talk) 21:24, 13 May 2012 (UTC)

I traced the assertion back to 1951 - see the reference I added to the article. However, the original discoverers said nothing about sea level rise so I deleted that bit. --Heron (talk) 09:56, 13 May 2012 (UTC)

check out greenland geology map186.151.67.249 (talk) 11:18, 13 May 2012 (UTC)

OK, you write the article and then we'll check it out. -- ♬ Jack of Oz ♬ ^{[your turn]} 21:39, 13 May 2012 (UTC)

Canada & the northern US are still rebounding from the retreat of the glaciers 11 ka, so I think it might be a while before the same happens to Greenland.

Without a rise in sea level, it looks as though Greenland would be a single island with a giant lake in the middle. But that's not realistic: all that water has to go somewhere. The 1951 claim may not have addressed that, but it's been done since. — kwami (talk) 03:01, 14 May 2012 (UTC)

And to further complicate matters, consider that the warmer conditions needed to melt the Greenland ice cap would also melt the ice shelves off Antarctica, some mainland Antarctic glaciers, and some other smaller glaciers. So, should that extra sea level rise also be taken into account ? If so, perhaps Greenland would be fully submerged. StuRat (talk) 04:51, 14 May 2012 (UTC)

The Nature of Jupiter's Metallic Hydrogen Interior

The wikipedia article of Jupiter says that most of the interior is Metallic hydrogen a kind of degenerate matter. What I'm not clear on is how solid this state of matter would be. Does the metallic hydrogen act more like a liquid or a solid or a gas? Ignoring the gravitational effects, could a spaceship fly through it? I've always been under the impression that Jupiter was mostly a cloud of gas and now need to revise my incorrect ideas. Thanks for any help. --CGPGrey (talk) 10:15, 13 May 2012 (UTC)

It says that in the Jupiter article that there is liquid metallic hydrogen; a spaceship cannot fly through the centre of Jupiter; it is not simply a cloud of gas. Plasmic Physics (talk) 10:31, 13 May 2012 (UTC)

It is a planet with a ferrosilicate core, with a mantle of liquid metallic hydrogen, overlaid with a deep ocean of super-critical molecular hydrogen, topped off with a thick atmosphere of various gasses. Plasmic Physics (talk) 10:45, 13 May 2012 (UTC)

To get hydrogen solid, it would need to be below the triple point temperature, which is only 13.84 K. Not very likely within a large planet. Keit120.145.7.207 (talk) 12:21, 13 May 2012 (UTC)

But as the pressure on the hydrogen increases, so does its melting point. Conceivably, the pressure inside Jupiter could be high enough for solid metallic hydrogen to exist near the core. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 12:40, 13 May 2012 (UTC)

The triple point is where all three phases can exist. Maybe you mean the critical point. But that's thepoint where there's no more difference betweengas and liquid. Higher pressure may still make it a solid. Ssscienccce (talk) 12:55, 13 May 2012 (UTC)

I meant the triple point. Whoop whoop could be correct if the melt line, which begins at the triple point, "leans" significantly towards higher temperatures at higher pressures. From memory, there's not a lot of lean in the hydrogen melt line, but I don't have a phase diagram for hydrogen to hand. Keit120.145.7.207 (talk) 14:21, 13 May 2012 (UTC)

There are some conflicting statements in the metalic hydrogen article imo:

• The initial prediction about the amount of pressure needed was eventually proven to be too low.
• Because previous predictions of the nature of those interiors had taken for granted metallization at a higher pressure than the one at which we now know it to happen, those predictions must now be adjusted.
• at 345 GPa, hydrogen is still not a true alkali metal
• at 140 GPa ... the hydrogen might be considered metallic.
• The lead mentions solid metallic hydrogen but the rest of the article seems to talk about liquid only. It's a bit confusing Ssscienccce (talk) 12:55, 13 May 2012 (UTC)

Even if it's a gas, that doesn't mean a spaceship could fly through it. The density would be enormous, which means the resistance would be enormous too. It would take lots of energy to move the spaceship and all that energy would go into generating heat, so the spaceship would either not move or it would burn up. --Tango (talk) 20:03, 13 May 2012 (UTC)

There is a possibility that metallic hydrogen could be metastable at low pressures. Then if a giant Jupiter like planet is destroyed in a collison, there could be small fragments containing metastable metallic hydrogen, which could give rise to strange meteorites, see here. Count Iblis (talk) 20:54, 13 May 2012 (UTC)

Interesting idea, what would happen if such a meteorite, composed of solid metallic hydrogen, entered Earth's atmosphere? Could it perhaps be a candidate for the Tunguska event? Plasmic Physics (talk) 00:43, 14 May 2012 (UTC)

Maybe a reson why it could descend so far into the atmosphere, could be that the hydrogen centre was thermally insulated by another frozen gas such carbon dioxide (not likely). Plasmic Physics (talk) 00:48, 14 May 2012 (UTC)

Stronger superacids than fluoroantimonic acid

Since gold pentafluoride and bismuth pentafluoride are both stronger fluoride-ion acceptors than antimony pentafluoride, shouldn't hexafluoroauric acid, HAuF₆, and hexafluorobismuthic acid, HBiF₆, be even stronger superacids than fluoroantimonic acid? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 12:15, 13 May 2012 (UTC)

I think these superacids are in the Brønsted–Lowry sense, so acidity is "how strongly does the metal–F complex hold the H" not "how strongly does the metal hold the F?". AuF₅ might be the strongest Lewis acid, since that deals with electron-acceptor modes of the metal center. But adding HF to AuF₅ causes the whole thing to decompose--due to that acidity--and liberate fluorine and gold(III) fluoride (see [[doi:10.1002/1521-3773(20011001)40:19<3690::AID-ANIE3690>3.0.CO;2-5]]) rather than forming a [AuF₆]^– cluster. I know this exact question has been asked on WP before but I can't find it right now. DMacks (talk) 15:47, 13 May 2012 (UTC)

Heh...was my talk-page. See User talk:DMacks/Archive 13#Need help from the smarter where I had found some refs and related ideas. DMacks (talk) 20:40, 13 May 2012 (UTC)

Steel laptop and electroshock

How do they isolate the steel of those new laptops so you don't get a shock? OsmanRF34 (talk) 12:51, 13 May 2012 (UTC)

I don't think there are any steel laptops, although some are made from aluminium or titanium alloys. They are isolated in the same way as any other electricity-using equipment with metal part (washing machines, cars, stereos, toasters...), namely by making sure that there is no electrical contact from power carrying circuits to the frame of the device. If you want more details, iFixit has an article on disassembling a unibody MacBook Pro with pictures showing how the components are mounted on plastic circuit boards mounted inside the metal unibody enclosure. --Stephan Schulz (talk) 13:42, 13 May 2012 (UTC)

In countries following European standards, and countries that have their own standards more or less in harmony with European standards, laptops and any other appliance mus conform to one or two choices. With Choice 1, any and all exposed meatl work must be electrically earthed. The 'third pin' (the one that is different to the other two, or is aligned different to the other two) on the power plug carries the earth connection. Should any fault occur which would otherwise make the exposed metal live, the current is carried away via the earth connection, so you can't get a shock. With Choice 2, the laptop or appliance must conform to the standard commonly known as "double insulated", and must display the double insulated symbol (two squares, one inside the other). In double insulated equipment, it is designed in such a way that no concievable fault can, on is own, cause the exposed metal work to become live. This may be achieved by simply providing two insulating barriers, or by other technically acceptable methods. Choice 1 is the most common choice for personal computers & laptops. As a general rule, countries that have only 2-pin wall outlets (eg Japan) historically had lower electrical standards. However, these days, as manufacturing is for world markets, equipment is made to conform to European standards. Keit120.145.7.207 (talk) 14:12, 13 May 2012 (UTC)

Further to the above valid replies, all the laptops that I have ever seen run from a low voltage (usually 19v) fed from a "power brick" (Switched-mode power supply) which conforms to the EU double-insulation standards in isolating the whole of the laptop from any high voltages. Dbfirs 15:08, 13 May 2012 (UTC)

I think Dbfirs' answer is actually the most relevant one here. It is the power adapter that will have to comply to the mains standard, not the laptop, the laptop runs on relatively low voltage DC. The metal on the laptop does not need to be earthed externally as it is not a shock hazard. Vespine (talk) 22:53, 13 May 2012 (UTC)

Not all laptops have external power units. All the laptops (Toshibas mostly) they issued us with at work had internal power supplies. Wickwack121.215.40.247 (talk) 00:42, 14 May 2012 (UTC)

Promiscuity and inbreeding

Would a fully promiscuous mating system reduce the minimum starting population needed to avoid problems related to inbreeding? Assuming equal gender ratios in the starting population. Horselover Frost (talk · edits) 16:31, 13 May 2012 (UTC)

As compared to a monogamous mating system, I mean. Horselover Frost (talk · edits) 16:32, 13 May 2012 (UTC)

A fully promiscuous mating system would make the problem worse, not better, since it would imply some level of mating between close relatives. But if you didn't really mean that, then I think the answer is that it would not make any difference, since every child has precisely two parents regardless of how promiscuous the mating is. Looie496 (talk) 18:21, 13 May 2012 (UTC)

a system of non-random mate choice for dissimilar individuals would be the best defence against inbreeding in a small population. (rats can smell out close relatives and some plants reject closely related pollen from fertilizing their eggs). Here are my calculations for a random mate choice system -

• monogamy with random partner: If an individual has 'n' offspring, probability of all n being inbred = probability of picking a close relative (p)
• promiscous mating with random partners: probability of all n being inbred = probability of picking a close relative n times = pⁿ < p for n > 1.

So yes, by my rough calculations for a toy model promiscuity is better than monogamy for inbreeding.Staticd (talk) 19:09, 13 May 2012 (UTC)

What do you mean by "problems related to inbreeding", or "fully promiscuous"? There are many separate issues at play in inbreeding, and not all of them are necessarily detrimental to the population. In the meantime, you may be interested in founder effects, and assortative mating. SemanticMantis (talk) 19:51, 13 May 2012 (UTC)

Lead poisoning and weight gain

Could children's bodies react to lead poisoning with weight gain--to sequester the harmful lead in fat tissue?Rich (talk) 19:54, 13 May 2012 (UTC)

I doubt it, since the article mentions as classic signs and symptoms in children: loss of appetite, abdominal pain, vomiting, weight loss. Ssscienccce (talk) 21:35, 13 May 2012 (UTC)

What you're talking about is an evolutionary response. Those only occur to problems which remain a serious threat to the species for thousands of generations. Thus, we have evolved a starvation response to keep us alive during famines. However, toxic lead exposure is rare today, and almost unheard of throughout most of human history. That's just not enough of a threat to the species to cause such an evolutionary response. StuRat (talk) 04:57, 14 May 2012 (UTC)

Stu, if by "toxic lead exposure", you mean exposure high enough to produce obvious symptoms, then its true that such exposure isn't common. However, lead is toxic, meaning degradation in rational behavior and measurable degradation in intelligence, down to very low levels. In response to another question, somebody posted a link to a study that showed that blood levels in US children had dropped in recent years. However, in western countries generally, lead is ubiquitous in the environment, resulting in blood levels around 0.3 to 1.0 ug/L. The USA has set an arbitary limit of 1.0 ug/L as safe, but that is not universally accepted - some experts think that is too high. Even so, a significant fraction of childen are above the US limit. It only takes a few industrial incidents or lead-using industry not complying with requirments, or some developer turning old industrial estates into residential, and you get children way over 1.0 ug/L. Here in Australia, lead poisoning of children gets reported in the media from time to time. See example report http://www.esperanceport.com.au/downloads/inquiry/Leadissueupdate2.pdf Wickwack124.178.138.77 (talk) 05:55, 14 May 2012 (UTC)

thd

what total harmonic analyzer measures? — Preceding unsigned comment added by Vivekmishra1988 (talk • contribs) 20:05, 13 May 2012 (UTC)

Total harmonic distortion. Tevildo (talk) 20:12, 13 May 2012 (UTC)

And THD analyzer. Red Act (talk) 20:17, 13 May 2012 (UTC)

How does myopia work?

I'm wondering how shortsightedness can work: apparently it is usually due to the eyeball being too long, but the point as I see it is that the lens focuses the image so that it will land on the retina. I can't see why we treat it as a focal-length mismatch between the eye and the lens, when the lens is adjustable. It does not have a fixed focal length, so what is the problem? Why can't it just compensate?

Another question: why do people's eyes so frequently get worse? Why don't they spontaneously get better? Assuming the eye is fixed in size and shape from one's early years, what is actually changing to make shortsightedness worsen, and why does it not improve? Thanks in advance, IBE (talk) 20:24, 13 May 2012 (UTC)

It does compensate, which is why they can still see things that are nearby. There is a limit to the range of focal lengths the lens can produce, though. Normally, that limit allows objects at distances from a few centimetres to infinity to be in focus. For shortsighted people, the range doesn't go all the way to infinity. For longsighted people, it starts further away. Some people (particularly the elderly) have both, so end up with a very short range - this can be corrected with bifocals. --Tango (talk) 20:45, 13 May 2012 (UTC)

The lens and the cornea, in combination, focus the light to a particular point. If you have normal vision, the image lands in the right place on the retina. If the eyeball is slightly misshapen, the focused image does not land in the right place. As Tango says, your eyes can adjust, but only so much - and their ability to adjust decreases with age. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:10, 13 May 2012 (UTC)

I think the reason why eyes get worse with age is that our ability to change the focus decreases, as a normal part of aging. There is sometimes an improvement in vision, such as in middle age, when people tend to go from having myopia to presbyopia. This can result in a short window when vision is improved. Eye exercises might also improve vision, at least temporarily. StuRat (talk) 05:04, 14 May 2012 (UTC)

what is cally disease

got it off of a mate and has same symtoms — Preceding unsigned comment added by Errrrrrcally (talk • contribs) 20:54, 13 May 2012 (UTC)

See a doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:04, 13 May 2012 (UTC)

Cally disease is a disease from the planet Auron, in the TV fiction Blake's 7. Has someone pulled your leg or are you pulling ours? Wickwack121.215.40.247 (talk) 00:37, 14 May 2012 (UTC)

Why is KCN basic but not KNO3?

KCN is basic because $CN^{-}+H_{2}O\leftrightharpoons HCN+OH^{-}$. Why doesn't this happen for KNO3? $NO_{3}^{-}+H_{2}O\leftrightharpoons HNO_{3}+OH^{-}$ ? --130.56.90.101 (talk) 01:06, 14 May 2012 (UTC)

Because HNO₃ is a strong acid, which means that the NO₃^- ion will not take an H⁺ from water. HCN is a weak acid, which by definitions means that CN^- will take H⁺ from water. The reasoning is the strength of the relative bonds. In this case, the H-O bond in HNO₃ is much weaker than the H-O bond in water, so there is no impetus for the H⁺ to leave water and join with the NO₃^- ion. With the cyanide ion, the H-C bond in HCN is considerably stronger than the H-O bond in water, so the transfer is exothermic, and the water readily gives up its hydrogen to the cyanide. --Jayron32 01:16, 14 May 2012 (UTC)

Are the injuries sustained by Tony Stark at all possible?

I'm re-watching Iron Man (2008 film), and shortly after the start Tony Stark is injured during a fire-fight and discovers when he wakes up that there are pieces of shrapnel stuck in his chest which are impossible to remove but which if unchecked will penetrate his heart killing him. It is mentioned by another character that this injury is not uncommon in 'his village', and hence he knows the solution is to rig an electromagnet onto Stark's chest to stop the shrapnel moving any further. Now the final part sounds to me like clear fantasy, and I doubt anyone could actually ever be saved from any known injury by sticking a large magnet on their chest. How about the rest though? Have people ever sustained chest injuries from shrapnel that haven't been killed immediately but have died later from the shrapnel finally reaching vital organs? And if not, is it a reasonably plausible injury to occur in the right circumstances? Or is the entire thing just a story to explain the premise, and has no basis in fact at all? Thanks in advance. 130.88.172.34 (talk) 02:01, 14 May 2012 (UTC)

Yes, people have been killed by delayed effects of shrapnel, but absolutely the last thing you would ever do with somebody with dangerous shrapnel inside them is to bring them into the vicinity of a strong magnet. Looie496 (talk) 02:12, 14 May 2012 (UTC)

I seem to recall a story of a US Civil War soldier, wounded near the heart. The doctors concluded that the shrapnel/bullet (I forget which) was best left in, as trying to remove it would likely be fatal. The soldier then lived out his life, and died, in old age. The autopsy showed that his aorta (or maybe vena cava), now weakened with old age, had been torn by the metal fragments. So, he was, in a sense, the last Civil War victim. StuRat (talk) 05:10, 14 May 2012 (UTC)

Weight loss question

According to Weight_loss#Intentional_weight_loss, "Weight loss occurs when an individual is in a state of negative thermodynamic flux: when the body is exerting more energy (i.e. in work and metabolism) than it is consuming (i.e. from food or other nutritional supplements), it will use stored reserves from fat or muscle, gradually leading to weight loss." The article does not make it clear exactly what stored reserve is used: fat or muscle? So in a state of negative thermodynamic flux, will a person loose fat or muscle? --NGC 2736 (talk) 04:07, 14 May 2012 (UTC)

Both. The object is to lose more fat than muscle, of course, and exercise helps with that. Also, that weight loss summary seems to neglect the possibility of retaining water. In that case, losing weight merely means losing water, which has nothing to do with "thermodynamic flux". StuRat (talk) 05:12, 14 May 2012 (UTC)

Thanks. I was searching the Wikipedia articles on this topic and just found Dieting#Fat_loss_versus_muscle_loss. It has an uncited claim "If the diet plan includes a daily caloric intake greater than the basal metabolic rate (BMR), the person will most likely lose fat. In contrast, if the person follows a diet that includes a lower caloric intake than the BMR, this person will lose fat but also a higher percentage of muscle." Although there is a citation tag there, just wondering whether it is true? --NGC 2736 (talk) 05:28, 14 May 2012 (UTC)

I think the logic there is that fat can only be converted to energy so fast, and if that doesn't provide enough energy, muscle will also be burnt. I don't see how the BMR rate is a magic dividing line, though. I would expect it to be more of a continuum, with muscle loss increasing as the rate of weight loss increases. Something else that can happen, of course, is that virtually all of the fat can be gone, say in starvation victims, in which case only muscle remains to burn.

Another factor is that, as you lose weight, less muscle is required to do normal activities. Less leg muscle mass is required to walk, less heart mass to pump less blood a shorter distance, etc. So, unless you increase your exercise rate to compensate, your body will naturally lose muscle mass, as we are designed to use the minimum amount of energy required, and excess muscles "waste energy". StuRat (talk) 05:34, 14 May 2012 (UTC)