Wikipedia:Reference desk/Archives/Science/2009 July 25

= July 25 =

Could a gull lift a cat in its beak?
See here. Sounds unlikely to me, taking into account that most housecats are heavier than most gulls and the wing-loading and compensation for nose-heaviness that would be necessary for such a feat of strength (in human terms, it would be a bit like piggybacking a person twice your weight, then trying to sprint at full speed - or possibly something more difficult than that). Considering that this was a rooftop-nesting gull in the UK, it would likely be a Herring Gull or a Lesser Black-backed Gull (with an outside chance of it being a Great Black-backed Gull). I've personally seen a gull grabbing an adult cat by the scruff of the neck and yanking it from a drainpipe as it tried to climb up and I've seen gulls fighting with cats and winning - but neither of these scenarios involve physically lifting the cat into the air. --Kurt Shaped Box (talk) 04:27, 25 July 2009 (UTC)


 * Are you asking for the airspeed of an unladen swallow gull? Seriously... It's not a question of where he grips it! It's a simple question of weight ratios! A five ounce bird could not carry a one pound coconut cat. -- Jayron  32  05:28, 25 July 2009 (UTC)


 * A lot of cats are more hair than flesh, so they're actually pretty light. And some gulls are pretty big, the ones at my adopted home of Vancouver are much bigger than the ones in Ontario (and they scr-r-ream like humans being murdered, early in the morning). Definitely a large gull could have a go at a small cat - but the weight ratio and nose-down problems would come into play, which I think explains the four-foot extent of the abduction attempt. The more interesting question for me is why a gull would decide to target a cat rather than, say, a discarded hot-dog bun. Maybe its eyesight is failing? Anyway, I'm definitely going to stop putting bread on my pets before letting them out! :) Franamax (talk) 06:00, 25 July 2009 (UTC)


 * For the gull to lift a cat it'd have to be dead. Getting the "neck grip" right isn't easy and I doubt a gull's beak is suitable.   I would have thought it would also have to be a small cat, but then I found that those gulls carry off salmon in the 12 lb. range.  So weight wise it might be possible.  I'd agree with Framamax that the big question would be "why" and I'd rate such a necessity presenting itself as rather rare.  71.236.26.74 (talk) 21:46, 25 July 2009 (UTC)


 * If it really happened, it's pretty obvious to me that the gull was planning to kill the cat by flying up and dropping it from a great height. Gulls *really* don't like cats. I've heard of them killing rats and mice for food in that way (they apparently follow the prey down, then strike it beak-first, moments after it hits the ground). I read somewhere (and I *so* wish that I'd seen this myself!) that the gulls will sometimes go into a steep, full-speed dive with the prey in their mouths, then let go of the thing in a similar way to a Stuka dropping a bomb.
 * So, an approx 3-4lb gull can fly with a 12lb salmon? Really? I didn't know that - sounds amazing, if true... --Kurt Shaped Box (talk) 02:23, 26 July 2009 (UTC)
 * Reliable source needed for any bird carrying something weighing several times as much. And a cat dropped from a considerable height could survive. Edison (talk) 03:24, 26 July 2009 (UTC)


 * Indeed, 'extraordinary claims require extraordinary proof' and all that. I know that gulls are strong (if you've ever held one, you'll know how powerful the wings are) but I'd be astounded if they were strong enough to fly with 3x their own bodyweight (at least!) loaded at the front (they can't grip objects with their feet). As for the cat, I don't think it's fair to expect a gull to know that cats always land on their feet... --Kurt Shaped Box (talk) 04:13, 26 July 2009 (UTC)


 * At closer inspection the source that threw me off my common sense objection turned out to be a "fish story" in every respect of the phrase. Some fishermen apparently were trying to get rid of some presumed competition.  A more reliable source says that Great Black-backed Gulls had never been reported to carry off anything heftier than an Eider duck.  If those were anything like the ones described here is still pretty impressive, but less than half the fishy tale.  That would get us back to a rather small cat.  If you'd ever tried to hold on to a cat that didn't want to be held you'd know that they are pretty good at wiggling out of being gripped.  That makes the scenario of a conscious life cat being carried off rather impossible.  It'd at least have to be stunned or unconscious.71.236.26.74 (talk) 07:09, 26 July 2009 (UTC)
 * Landing on the feet is NOT going to save the cat, if it's landing at terminal velocity, which I can't calculate off-hand, but can be 120 mph for skydivers, so it not likely to be very slow.
 * If the bird knows to, or accidentally does, pick up the cat by the scruff of the neck, the cat will dangle in a fairly helpless position, where it can't fight back or wriggle too much.
 * How much weight a bird can fly with would depend more on the size of its wings, less on its body-weight, as it is the wing-span which gives it the lift for flying. Migrating species often carry 50% more than their "normal" weight in pre-migration fat stores, albeit this weight is well distributed on their bodies, not dangling in a very un-aerodynamic manner from their beaks. - KoolerStill (talk) 14:11, 26 July 2009 (UTC)
 * Cat't don't typically land on their feet when falling that far. They land upright, but more spread out in a belly-flop formation to lower their terminal velocity. It sometimes works. However, even when it does work, it looks like about 2/3 of them require immediate veterinary attention. (We can assume that the other third is really sore.) So I think that if I were a seagull I would consider this a suitable revenge against a cat who was being a jerk. APL (talk) 17:32, 26 July 2009 (UTC)
 * I'm having a bit of trouble envisioning how a gull is supposed to hold on to a cat by the scruff and take off. the former would put it's beak at an angle towards the cat's body. Hence it might work for dragging a cat off a pipe as Kurt seems to have observed.  In this position I can't quite see how the gull could take off.  There seem to be a lot more likely scenarios of what it could do, like throwing the cat or bashing it on to the ground to stun it.  Carrying it off while it is still able to struggle and getting the neck grip to work with a beak in close to upright position is just a very unlikely scenario. 71.236.26.74 (talk) 21:08, 26 July 2009 (UTC)
 * Empirical evidence of a sort: Seagull flies off with cat in beak --Tagishsimon (talk) 09:04, 29 July 2009 (UTC)

HIV cure
why is a cure not yet found for HIV??What are the difficulties faced in finding the cure for HIV??whats so special about HIV?? —Preceding unsigned comment added by 117.193.139.242 (talk) 05:07, 25 July 2009 (UTC)


 * Mostly because HIV is a virus, and there are no "cures" for viruses. Antiviral drugs do not actually "cure" us of any viruses, merely slow them down so that our own immune systems can keep them contained.  This is true of all viruses, not just HIV.  Viruses have treatment, but no cures.  Either your own immune system adapts to them, and you get better, or your immune system does not, and you die.  Since HIV actually infects immune system cells directly, this creates a HUGE problem...  -- Jayron  32  05:24, 25 July 2009 (UTC)
 * Me personally, I'd define "get better" as being "cured". Franamax (talk) 06:28, 25 July 2009 (UTC)

I think part of this is that HIV doesn't just destroy white cells, it actually uses the T-cells' CD4 receptor (which is the main receptor that they use to identify the virus in the first place) and / or the antigen-antibody complex to assist with binding to the white cells, then reproduces INSIDE those white cells -- so the body's natural immune response not only don't help at all, it actually just makes the infection that much worse. (Which is why I don't think a vaccine can ever work against the AIDS virus.) It might in principle be possible to cure someone with the AIDS virus by taking all the blood outside the body, radiating it to kill all the white cells, and filtering the blood through a nanofilter before returning it to the body -- followed by a complete bone-marrow transplant -- but the problem is, since you killed all the white cells, the patient will have to be confined to a sterile room for several weeks until his / her immune system creates new, clean white cells, cause if the patient gets even the slightest infection during those several weeks, he / she could easily die. FWiW 98.234.126.251 (talk) 05:29, 25 July 2009 (UTC)


 * I can't find any mention of this in the HIV article - but haven't there been a few tens of people who have completely recovered from HIV infection through means as yet unknown? Or was that all just ill-informed science by press conference stuff? --Kurt Shaped Box (talk) 05:50, 25 July 2009 (UTC)
 * Well, there's the Daily Mail . I wouldn't exactly put that in the article though... However, I'm pretty sure that there are some tens of people who appear to be completely immune in the first place. Prostitutes in Uganda or something, if I recall. Franamax (talk) 06:28, 25 July 2009 (UTC)
 * Yes, the fact that the virus attacks the very immune system cells targeting it certainly makes things difficult. My understanding too is that the genius of this particular virus is the gp120 glycoproteins which "decorate" the proteins which effect entry of the virus into the cell. To "cure" something, or to make a vaccine against something, you need a target. But gp120 is highly variable, so it's difficult to target, and it hides the less variable proteins underneath that do the dirty work of infecting the T-cells. Any one successfully infecting HIV can produce a million new particles with variant gp120's, and only one of them has to work for the infection to continue.
 * And 98.234, your irradiation scheme might work except that HIV can cross the blood-brain barrier, so you'd have to remove and irradiate all the cells in the brain, which might not work so well. ;) And there may also be other undiscovered reservoirs of infection too. Franamax (talk) 06:28, 25 July 2009 (UTC)
 * I didn't know that it crosses the blood-brain barrier like methylmercury or something! (Ain't there so much new stuff to learn on Wikipedia?)  I stand corrected regarding the radiation scheme.  And BTW, Kurt Shaped Box, there haven't been "tens of people who completely recovered from HIV infection through means as yet unknown -- there was one man who completely recovered from the AIDS virus after being given a complete bone-marrow transplant (it's not yet clear if his recovery really is "complete" complete, as in NO viruses OR infected cells remaining in the body), but no other miraculous recoveries so far.  That Daily Mail article is just plain wrong (well, what do you expect, they're just reporters...) 98.234.126.251 (talk) 08:01, 25 July 2009 (UTC)
 * This is only partically true... irradiation works similarly to chemotherapy in that it doesn't target specific tissues but is especially toxic to cells that are dividing quickly; this includes many cancers, but also the cells of the bone marrow, digestive tract and hair follicles. While irradiation would kill off a major HIV reservoir in the bone marrow, one major factor that keeps an irradiation approach from working is that HIV can also infect and replicate with macrophages, which don't divide, and therefore typically aren't killed off by irradiation. In addition, macrophages often migrate to and take up long-term (i.e., years) residence within many tissues, including the brain (where they're called microglia) but also many others (see the macrophage article for a short list). So in that respect HIV can cross the BBB, but only by being ferried across by a previously infected macrophage . HIV, however, can't actually productively infect any of the other cells in the brain though, so it's not the crossing of the BBB that keeps irradiation from working, it's the ability of macrophages to find a nice comfortable home, get a cat and a white picket fence, and live there for a looooong time. Another good thorough review: http://www.ncbi.nlm.nih.gov/pubmed/19486514. Cheers! – ClockworkSoul 19:34, 26 July 2009 (UTC)
 * Okay, fair enough. Thanks. --Kurt Shaped Box (talk) 02:46, 26 July 2009 (UTC)

wavelength distribution


Is there a similar diagram for wavelengths between .000002 and .000006 nanometers? -- Taxa (talk) 14:03, 25 July 2009 (UTC)


 * If my calculations are correct, those wavelengths correspond to temperatures in the region of 100 billion kelvin, which are associated with Type II supernovae. They emit light over pretty much the entire spectrum, so are easily visible from the Earth's surface. Gamma ray photons of those wavelengths have energies of about 0.6 GeV, which I don't think are quite strong enough to trigger showers of secondary particles when they hit the upper atmosphere (which is how really high energy gamma rays are detected), so they would probably be very difficult to detect from the surface (even if they could penetrate the atmosphere there would be so few of them that you would need an extremely large detector to stand a reasonable chance of one hitting it). You may find our article, Gamma-ray astronomy useful. If you explain why you are interested I might be able to give a more useful answer. --Tango (talk) 15:23, 25 July 2009 (UTC)
 * Within this range of wavelengths fits the radius and diameter of the electron. I'm curious how such a distribution of electromagnetic waves would look in this range whether produced in a laboratory or observed above the atmosphere. -- Taxa (talk) 15:58, 25 July 2009 (UTC)
 * Electrons don't really have a diameter, the classical electron radius (which I assume is what you are talking about) is a fairly meaningless concept. There is certainly no connection between electrons and photons of that wavelength. The closest you get to a connection between electrons an a certain wavelength is the de Broglie wavelength, which depends on the electron's speed. I'm not sure what the opacity of the atmosphere has to do distribution of wavelengths - the distribution will depend on what is emitting the radiation (if it is emitted above the atmosphere and detected beneath it then the opacity will be a factor, but it won't be the only factor). --Tango (talk) 16:32, 25 July 2009 (UTC)
 * I don't think you meant to say that the radius of an electron is smaller than .000002 or larger than .000006. Just in case let's change the wavelengths to between .000001 to .00001. nanometers. Also, lets replace the atmosphere with an electron and see whether there is any difference in the intensity for each wavelength between this range. You may be surprised. -- Taxa (talk) 22:06, 25 July 2009 (UTC)
 * I meant precisely what I said - electrons don't really have a diameter. In the standard model they are point particles. I don't know what you mean by replacing the atmosphere with an electron or what you want the intensity of. Your question makes no sense. This is a recurring pattern with your questions. Please learn a little more about the subjects that interest you before asking questions like this - your questions are often based on fundamental misunderstandings of the subject matter so cannot be answered. --Tango (talk) 01:34, 26 July 2009 (UTC)
 * Is this a request for us to perform original research? We don't do that.  This self-published and typo-laden physics paper purports to investigate the earth-atmospheric and extraterrestrial absorption of high energy gamma-rays; maybe it can be a starting point for your investigations.  The trouble is that not much experimental physics has been done with that range of gamma ray, because it's hard to make in the laborator (due to its very high energy).  As such, characterizing the Earth's atmospheric absorption is difficult.  I suspect there will be negligible absorption or attenuation, as such high energy waves don't interact with atomic-scale objects; but it sounds like you are proposing that somehow, they will interact with electrons.  Take a look at scattering.  At present, there are many types of known scattering observed in physics, but as far as I am aware, there is not experimental data for the wavelengths in question. Nimur (talk) 02:03, 26 July 2009 (UTC)
 * You might also be interested in terrestrial gamma-ray flashes, which until recently ( ~1994) were considered "spurious". They are now an active area of atmospheric and space-physics research. Nimur (talk) 02:05, 26 July 2009 (UTC)


 * Any charged primary above a few MeV is likely to interact in the atmosphere via pair production, which is the essential mechanism for a shower. The more energy, the larger the shower.  Dragons flight (talk) 02:34, 26 July 2009 (UTC)

purpose of neutral wire in household supply
what is the purpose of neutral wire in the domestic electric supply? If the neutral one is provided for earthing then why an extra port is provided for earthing in three pins? —Preceding unsigned comment added by 203.197.117.165 (talk) 14:57, 25 July 2009 (UTC)
 * See Ground and neutral. It has a section on combining earth and neutral. --Tango (talk) 15:29, 25 July 2009 (UTC)
 * The neutral must carry the same current, but opposite in phase, to that carried by the hot or "phase" wire. If only one hot wire were connected to a device, and no neutral wire, no current would flow, no power would be drawn, and the device would not light up, heat up, move, or whatever its function is supposed to be. There would be an "open circuit," as surely as if the switch were turned off. The neutral wire is not there for earthing. The ground wire is the safety conductor, so that if a device shorts to the metal case, the current flows to earth on the ground wire and the fuse blows. The earth/ground wire should carry no current in normal operation. The neutral is essential to operation, and the earth/ground is a safety feature.Edison (talk) 03:21, 26 July 2009 (UTC)

Man With 'Two Brains'
I just watched a fascinating documentary about a man who had the two halves of his brain disconnected from each other and this answered some parts of an almost lifelong question I have had. Here is a hypothetical scenario: a person is laid on a track and a circular saw comes along and cuts him exactly in half from head to groin. Besides the obvious pain this person would be in (let's give him some strong painkillers first), what exactly would the two halves be feeling in the few minutes that it would take for the brains to shut down through lack of oxygen? I have thought about this ever since I heard that cutting a worm in half makes two separate worms. OK, it's more complicated with a person, because the two halves of the brain operate differently. Not only that, what would happen to consciousness? Would the person's brain favour the consciousness of one half or the other? Or both? --KageTora - (영호 (影虎)) (talk) 15:45, 25 July 2009 (UTC)
 * The brain has a tendency not to react well but to react fast to such shock. When people say a loved one died instantly in a crash what they really mean is that the brain shut down instantly. You are unconscious and in the case you have described unlikely to regain consciousness be fore your enter the next world. -- Taxa (talk) 16:07, 25 July 2009 (UTC)
 * Firstly, you don't get two worms, you get a dead worm in two halves. Occasionally the head end may survive, but what people usually see is just random muscle spasms for a short time after death. With a human being cut in half they would lose conciousness due to pain and blood loss extremely quickly (seconds, not minutes). There wouldn't be time for the two halves of the brain to have independent thought. When someone undergoes a corpus callosotomy it is done very carefully and cleanly. A circular saw would rip the head and brain to shreds. --Tango (talk) 16:08, 25 July 2009 (UTC)
 * Right, but what if a brain was separated into two halves and kept alive, although operating completely independantly from each other? My real question is where the consciousness would be - of course, it would be in both. But, how would that seem to a brain that originally had the two halves connected and now has two separated? --KageTora - (영호 (影虎)) (talk) 17:04, 25 July 2009 (UTC)
 * I think the only way you could keep it alive was if you separated them surgically with a corpus callosotomy. The resulting condition is called split-brain, that article will probably answer some of your questions. --Tango (talk) 17:18, 25 July 2009 (UTC)


 * There is not a clear scientific consensus on the presence or physical manifestation of consciousness in the brain. The OP's queries about "where" the consciousness would be provide an interesting thought-experiment (although the actual method proposed would result in near-instantaneous unconsciousness and death).  We have a large number of articles related to consciousness.  Some of the better ones, like neural correlates of consciousness, attempt to summarize current scientific understanding about the physiology of consciousness (e.g. where in the brain does it take place).  Unfortunately, (as you will discover if you read through these articles), there is not much agreement on basic principles such as the definition (or even the existence) of consciousness, so it is hard to say in which parts of the brain it is residing.  For a less biological and more philosophical overview, read mind-body dichotomy.  Unfortunately a review of the results at Google Scholar shows a lot of philosophy and preciously little biology.  This is a tough research area for real science.  Nimur (talk) 02:11, 26 July 2009 (UTC)
 * Douglas Hofstadter's books discuss this stuff in an entertaining way. He likes he concept - the metaphor - of an anthill having consciousness as the result of the interactions of its individually mindless ants. 213.122.53.30 (talk) 17:16, 27 July 2009 (UTC)

Some of my questions are answered, but I still have one remaining one. What if (by some new method) we were able to keep the two halves alive? What would the person feel, now being two 'people'? This is really the crux of my question. --KageTora - (영호 (影虎)) (talk) 06:41, 26 July 2009 (UTC)
 * That experiment has never been done, so there are no suitable references to point you toward. The reference desk is not supposed to be the place for wild speculation about hypothetical stuff.  Nimur (talk) 16:11, 26 July 2009 (UTC)
 * Well, the study has been partially done, in the split-brain patients studied by Sperry and others. The general outcome is that only one of the halves is capable of using language, and the language-using half is not aware that it only controls half of the body.  The non-language-using half can often express itself to some degree by controlling behaviors such as hand movements, but can't understand or answer questions.  (It should be noted though that these brains are not fully split -- there are subcortical connections that remain intact, and allow whole-body behaviors such as walking to be performed.)  There have also been patients with massive strokes who to a large degree are left with only half a brain. Looie496 (talk) 17:33, 26 July 2009 (UTC)


 * You may be interested in a series of papers by Prof Donald Mackay of Keele about dialogue between the right and left half of almost split human brains (try google scholar). Also there is a very funny long poem written about this in 1910 by "APBS": The Amputee: A Forecast Circ AD 1970. There is a long medical history of a car/plane/tram crash then in the middle it goes "Now amputations Hitherto had left it fairly clear, and to causal observers it must obvious appear That it's easy to distinguish which is A the patient and, Which is B the part removed from him, an arm or leg or hand; But a singular dilemma now confronted Dr. P, He was really not quite certain which was A and which was B, For B or what he thought was B had horrified Perowne By indulging in a totally inexplicable groan..." The poem concludes "Some say A was first to die and some say it was B".


 * See the novel Peace on Earth by Stanislaw Lem. Mikmd (talk) —Preceding undated comment added 18:33, 29 July 2009 (UTC).

Viruses - what's the point?
What's the point of viruses? What's the point of inhabiting a body, killing it, and then dying when it dies? Why not be friendly with it and be a symbiotic bacteria or something? --KageTora - (영호 (影虎)) (talk) 15:49, 25 July 2009 (UTC)


 * Even in our own DNA are programs which cause death. For instance, the webbing between fingers and other extraneous materials and constructions which benefit us when they are gone. -- Taxa (talk) 16:02, 25 July 2009 (UTC)
 * True but irrelevant. --Tango (talk) 16:13, 25 July 2009 (UTC)
 * Most viruses don't kill their host. Take the common cold, for example - it's very mild and the only symptoms are ones that aid it in spreading (coughing and sneezing). Often when a virus is deadly it is because it has crossed over from a different species. It wouldn't kill members of that species, but does kill humans. It won't generally spread for long in humans before killing all its hosts and dying out. Consider Simian immunodeficiency virus, the version of HIV found in other primates. It doesn't do any harm to them, but when it crossed over into humans and became HIV it became deadly. HIV takes a long time to kill you, though, which is why it can spread so effectively. --Tango (talk) 16:13, 25 July 2009 (UTC)
 * No point. They just are.  APL (talk) 16:17, 25 July 2009 (UTC)


 * Viruses don't have a motivation, or plan a strategy. What's important to think about is what mechanisms have led the virus to continuing to exist and spread.  Viruses that fail in that disappear, and viruses that are successful continue on.  The way that viruses reproduce is inherently destructive: they trick host cells into producing more viruses at the expense of the cells' normal functions.  If that leads the host to eventually die, it's not necessarily a set back for the continuation of the virus if it has a means of spreading to other hosts in the mean time.  However deadly viruses don't kill people out of malice, it's just a side-effect of the mechanism they use to effectively stay alive and reproduce. Rckrone (talk) 16:33, 25 July 2009 (UTC)
 * Exactly, but staying alive and reproducing are two different things. I'd love to be alive in a hundred years' time and with a bunch of kids to look after, but if having kids (through a host - not a nice way of putting it, but this is an analogy, remember) is going to kill me in a few weeks or months, I really wouldn't mind just getting along with the host and looking after each other. I think you see my point. --KageTora - (영호 (影虎)) (talk) 17:10, 25 July 2009 (UTC)
 * Your survival instinct is because you need to be alive to reproduce again or to look after your children. That doesn't really apply to a virus. Viruses reproduce exponentially, so the original virus still being alive is pretty much irrelevant to the rate the virus can continue to reproduce. --Tango (talk) 17:21, 25 July 2009 (UTC)


 * As others have mentioned, the virus doesn't care what happens to the host, as long as it's able to reproduce. Certain strategies diseases use to spread (diarrhea for rotavirus, uncontrolled bleeding for ebola, etc.) have very disastrous consequences for the host, but by the time the host dies, the virus has a new host. Your general inclinations are correct, though, that if the infection is too severe the virus may kill the host before it can spread, or reduce the host population to the point where spread is not sustainable. There is usually a tendency for diseases to moderate their lethality toward their native host over time - those viruses which can maintain themselves in a host without killing tend to produce more offspring over the long term than those which move quickly from host to host, leaving dead bodies in their wake. -- 128.104.112.87 (talk) 17:54, 25 July 2009 (UTC)


 * To add to what Tango said look through the article on Zoonosis, diseases which humans get from animals. Most of the diseases listed there kill us amazingly fast but their vectors are animals, not us. Killing humans really fast doesn't affect its ability to spread itself. They include Anthrax, Cholera (really infectious among us as well though), Hantavirus, Ebola, Marburg Virus, Plague.

Computeridiot34 (talk) 18:05, 25 July 2009 (UTC)
 * It's of note that cholera is not really that infectious from person-to-person, unless contaminated water supplies are shared. --98.217.14.211 (talk) 18:15, 25 July 2009 (UTC)
 * And anthrax is not contagious from person to person at all. 98.234.126.251 (talk) 01:07, 26 July 2009 (UTC)
 * Can we also point out that its not even clear if viruses are technically "alive" or not (see Life, subsection on viruses). They aren't acting consciously. They're sort of ideal replicators — they are about one step up from raw DNA. It's like a bug in computer code that happens to perpetuate itself onward. --98.217.14.211 (talk) 18:13, 25 July 2009 (UTC)
 * That is purely a technicality. How we define life really doesn't make any difference to anything. --Tango (talk) 19:12, 25 July 2009 (UTC)
 * Except in that giving the virus itself too much autonomy in making its decisions is clearly wrong. --98.217.14.211 (talk) 02:52, 26 July 2009 (UTC)


 * KageTora also appears to be making a presupposition about self-preservation as an implicit goal for the virus. Self-preservation is present in most species because it has evolved and continues to enhance the capability to proliferate.  As an intelligent creature, you can think about survival strategy and choose particular courses of action.  However, most "lower forms" of life (and viruses, which are borderline "life") do not strategize.  They simply "do".  Viruses continue to exist on earth because their method of existence is conducive to reproduction and propagation.  Though in some cases this results in catastrophic self-destruction, that is not something which precludes the virus from pursuing its natural course of action.  In fact, the virus lacks the physical or biological capability to even be aware that its actions cause any environmental changes that might harm its future survival chances.  You might find the articles about symbiosis, parasitism, and predation useful; many organisms participate in such biological coexistence relationships without any awareness that they are part of a multi-organism system.  In some cases, this results in the eventual destruction of one or both organisms.  Long-term sustainability is less relevant than the prior history here (as Rckrone mentioned).  Nimur (talk) 02:21, 26 July 2009 (UTC)
 * Exactly my point. Viruses seem to have no stimulus whatsoever for self-preservation, but rather a goal for replication regardless of itself. That goes against everything that Darwin said. --KageTora - (영호 (影虎)) (talk) 02:45, 26 July 2009 (UTC)
 * Except it doesn't actually play out that way. In fact, they're a beautiful example of Darwinism at the extreme, to the point where you can represent their survival very precisely in an abstract way (which is a lot harder to do with, say, lions and tigers). On the one hand, if they killed everything they touched, they wouldn't survive to reproduce another generation. If they tip the "fatal" side too much that way, then they're definitely not going to be that prevalent. If they can get it just right, they thrive and thrive. Consider the common cold, most influenza, and other viruses we are rather familiar with because they don't actually kill most people who get them (any more). They come and go, spreading themselves through the population just fine. As for whether they kill the host organism, it's inadvertent in probably most cases (there are probably some viruses that benefit from death practices in being spread and wouldn't spread if the human was alive), in the same way that human biology starts to rapidly break down once we are past the age in which our health is vital to our reproductive success. --98.217.14.211 (talk) 02:52, 26 July 2009 (UTC)


 * The point of a virus is that it kills an unhealthy creature. Sickly creatures tend to go around making things unpleasant for more robust individuals, so for a virus to remove them from the ecosystem isn't a wholly bad outcome. Being that viruses are not strictly considered 'life', they don't need to have any higher goal. They just kill. They could perhaps be better considered to be an emergent, temporary aspect of a higher but very ill being, like vomit. What's the point of vomit? There's no point, it's just a disgusting product of a sickly animal. Vranak (talk) 17:27, 26 July 2009 (UTC)


 * I'm sorry, but that's unhelpful and incorrect. Viruses do more than simply kill; see mitochondrion and Endosymbiotic theory for some interesting theories regarding how other viruses play the game. More generally, viruses are designed simply to reproduce; killing the host organism is only a problem if the virus has been unable to spread past the corpse. It's no different than people consuming corn or chickens - killing the organism during harvest is not the specific intent, but simply a result and a result we don't care about if we can move on to the next corn plant before we starve.
 * KageTora, you seem to be looking for purpose in nature. There isn't one. Our article on teleological argument is slated toward the religious aspect, but may still be helpful. Viruses don't get to chose their strategy and the one they have now seems to work just fine for them anyway. Matt Deres (talk) 16:21, 27 July 2009 (UTC)


 * What's the point of "life"? Richard Dawkins would say that it's to propagate DNA. Axl  ¤  [Talk]  19:42, 30 July 2009 (UTC)

David Merrell's mouse experiments
where is our article on David Merrell's mouse experiments please? thx 82.234.207.120 (talk) 16:05, 25 July 2009 (UTC)
 * Try Hopping mouse. -- Taxa (talk) 16:15, 25 July 2009 (UTC)
 * What does that have to do with the question? --Tango (talk) 16:21, 25 July 2009 (UTC)
 * We don't seem to have an article. I've found this page via Google, though. I'm not sure it is notable enough to have a Wikipedia article - it is an experiment done by a high school student for a science fair. It got several awards, but I haven't found much independent news coverage or anything else that would make it notable. --Tango (talk) 16:21, 25 July 2009 (UTC)
 * Are you kidding? It sent shock waves through the UNIVERSE, no tto mention receiving acolade from the Navy and even CIA.  It is the most notable thing I've read about in the past 3 weeks. 82.234.207.120 (talk) 16:28, 25 July 2009 (UTC)

thanks for that nice article. —Preceding unsigned comment added by 117.193.129.196 (talk) 19:20, 28 July 2009 (UTC)


 * If you can find several independent reliable sources about it, then by all means write an article. --Tango (talk) 16:35, 25 July 2009 (UTC)
 * If you are interested, there are a few articles here on Google News. It seems it did get some coverage, but I don't know if it was really enough to warrant an article. --Tango (talk) 16:40, 25 July 2009 (UTC)
 * Click "random article" on the bar at the left 20 times. Still feel that way?  82.234.207.120 (talk) 17:14, 25 July 2009 (UTC)
 * The ref desk isn't here to debate notability. I gave you some advice based on my extensive experience of Wikipedia, if you don't want to take it then write the article and see what happens. --Tango (talk) 17:23, 25 July 2009 (UTC)


 * I suspect the interest in the story is mostly about a 16 year old coming up with something interesting at a science fair. Would like to see proof of the CIA and Navy accolades. The story is more human interest than hard science (and it sounds like he left the music on while they navigated the mazes, which introduces a lot of question into the findings, in my opinion... I suspect that thumping hard rock music is going to disrupt a mouse's internal navigation a lot more than anything else). It also doesn't in any way actually show that hard rock is negative in humans (mouse models are not exact, especially cognitive models!!). Anyway... I don't see shock waves in the universe, personally. --98.217.14.211 (talk) 18:19, 25 July 2009 (UTC)


 * "Navy and CIA accolades" could mean that the recruiter who was present at the Science Fair commended the student. (Or it could mean national recognition and a scholarship).  The article does not say.  Usually, events that are notable enough to merit articles appear in several online and offline sources.  If this research was worthy of followup work, eventually a paper would be published somewhere.  That might constitute a reliable source, depending on who published it, whether it was peer-reviewed, etc. Nimur (talk) 02:27, 26 July 2009 (UTC)

rabbits and Hopping mouse
Are rabbits related to the Hopping mouse? -- Taxa (talk) 16:19, 25 July 2009 (UTC)
 * The mice are rodents, which are similar to rabbits (rabbits were once classed as rodents, but not now).83.100.250.79 (talk) 16:23, 25 July 2009 (UTC)
 * Not closely, no. Hopping mice are rodents, rabbits are lagomorphs. According to that article: "Though these mammals can resemble rodents (order Rodentia), and were classified as a superfamily in that order until the early twentieth century, they have since been considered a separate order. For a time it was common to consider the lagomorphs only distant relatives of the rodents, to whom they merely bore a superficial resemblance." --Tango (talk) 16:24, 25 July 2009 (UTC)

Muad'Dib, the hopping mouse! SGGH ping! 20:01, 25 July 2009 (UTC)

Maximum sustainable population
What is the best estimate of the maximum world population that would be environmentally sustainable? Neon Merlin  18:21, 25 July 2009 (UTC)
 * I don't think there are any particularly good estimates. Improvements in technology can increase agricultural yields and political issues can result in food not getting to where it is needed (or even not being grown in the first place). See Malthusian catastrophe for a discussion of the issue. --Tango (talk) 18:52, 25 July 2009 (UTC)
 * Considering what was done to people in the movie the Matrix people could be packed together to a degree that I care not to imagine considering the state of all the major cities today. -- Taxa (talk) 18:55, 25 July 2009 (UTC)
 * The Matrix is a load of nonsense. Humans don't generate energy, they use it. You can't pack people together like that without some kind of food source. --Tango (talk) 19:02, 25 July 2009 (UTC)
 * You need to define your terms, and you need to decide whether or not to permit technology that has not yet been invented. If we define "sustainable" as using only renewable resources, and you define "renewable" as coming from the sun, then we can compute an upper bound. The earths' diameter is 12,000KM, then the earth has a capture cross section of about 3/4 x 144 million Km^2, or very roughly 100 million million square meters. Each square meter is good for about one KW, and a resting human uses about 125W, so we have energy for 8 humans per square meter of capture cross section, or 800 million million humans. Now pick a technology "discount" based on your own assumptions: let's assume that an acceptable technoligy can practically operate at only one part in 800 "efficiency" in an environmentally sustainable manner. Then, we get one million million humans as an upper bound. Of course, by the time we have this level of technology, we will not need to remain on earth. -Arch dude (talk) 02:35, 26 July 2009 (UTC)
 * Does this take into account the costs of recycling air and waste products? Neon  Merlin  04:28, 28 July 2009 (UTC)
 * I think so, yes. The energy required to photosynthesis CO2 and water into glucose and oxygen is the same (give or take some inefficiencies) are the energy released by respiring glucose and oxygen into CO2 and water. Ditto for all the other reactions going on in the human body. All you need to do is replace the energy lost as heat, and that is the 125W mentioned. There may be a little more lost by the plants, etc., but plants aren't warm blooded, so there isn't much. --Tango (talk) 20:25, 28 July 2009 (UTC)

Substance Dependence
What mechanism defines the "normal" amount of a particular neurotransmitter? Can this value be altered?—What prevents us from eliminating opiate tolerance, for example, and therefore allowing for an infinite amount of pleasure?

Alfonse Stompanato (talk) 18:55, 25 July 2009 (UTC)


 * "An infinite amount of pleasure" is an ill-defined concept. Increasing the dose of opiate will have adverse effects, though.  Hypersensitivity and pleasure-response are not the only physical responses to opiates.  Take a look at the adverse effects in our article.  Respiratory depression can occur, which can lead to death, if doses are sufficiently high.  Nimur (talk) 02:34, 26 July 2009 (UTC)


 * The mechanism is homeostasis. The amount of neurotransmitter could theoretically be extremely different in two people but the neurophysiology is near identical, because other factors are involved (number of receptors, receptor modification, enzyme number, et al). The problem at the moment is that agonists at the opioid receptor trigger signalling pathways associated with analgesia/euphoria/etc but also trigger signalling pathways associated with desensitization and tolerance. It may however be possible to trigger only the positive signalling pathways, but it's a relatively new discovery so don't expect any non-tolerant opioids on the market for at least 15 years. I strongly recommend reading these papers (in order):
 * Galandrin S, Oligny-Longpré G, Bouvier M. (2007). The evasive nature of drug efficacy: implications for drug discovery. Trends in Pharmacological Science. 28(8): 423–430.
 * Whistler JL, Chuang HH, Chu P, Jan LY, von Zastrow M. (1999). Functional dissociation of mu opioid receptor signaling and endocytosis: implications for the biology of opiate tolerance and addiction. Neuron. 23(4): 737–746.
 * Bosier B, Hermans E. (2007). Versatility of GPCR recognition by drugs: from biological implications to therapeutic relevance. Trends in Pharmacological Sciences. 28(8): 438-446.


 * The original question is the topic of a great deal of ongoing research, and the answers are still very unclear. The nature of pleasure in the brain is also still unclear in many respects.  As Nimur says, eliminating opiate tolerance certainly wouldn't allow infinite pleasure -- opiates are mainly sedative and only secondarily rewarding.  Eliminating dopamine tolerance in certain brain areas would be more effective, but there is probably more to the story. Looie496 (talk) 17:25, 26 July 2009 (UTC)


 * Thanks! I figured that this question might not have an answer yet—but I didn't necessarily know the reasons for this. —Preceding unsigned comment added by Alfonse Stompanato (talk • contribs) 18:14, 26 July 2009 (UTC)

Mysterious carpark bumps
Please help me identify the function of these mysterious objects found in the carpark of my local Tesco supermarket - context, closeup. Here is all I know about them: there is one in every parking bay, located on the midline of the bay about 1 metre from the end - roughly where the engine-block of a car would be if you were parking nose-in; the bumps have no identifying marks (no manufacturer, no patent number, no serial number, no "property-of" tag); the bumps are attached to the ground, but can be wiggled around - it's probably straightforward to prise them up with a couple of crowbars; there is no evidence of wires running to them; the bumps are made from a dense black plastic (not rubber) - it feels like they're just a shell over something; the carpark in question does not suffer from drainage issues; the bumps are approximately 100mm in diameter and are about 15mm high, with a tapered edge - they are too small to be effective as traffic calming measures; the carpark in question is close to the shopping area of town (and is used by non-tesco shoppers) so Tesco employs a man with a clipboard on Saturdays to police overstayers; the bumps are very robust (they can withstand frequently being driven over) and there is no indication that they have any mechanical aspect (I don't think they're mechanical switches of any kind); I've never seen a store employee or contractor cleaning, touching, or servicing them, and there is no signage suggestive of their purpose; I don't think they're caps for holes one would use to put in parking-prevention bollards - they're at the wrong end of the bays for that.

My guess is that they are related to parking control: that they house a magnetic car sensor and keep track of how long the car above them has been in that bay (resetting when a car leaves). If that's true, they must be battery powered and presumably have a short-range RF capability, so the clipboard-weilding parking man can interrogate them individually with some kind of handheld wand. If this is correct, I'm impressed that they can run a small computer, a magnetic sensor, and a two-way RF connection all off a battery, presumably for weeks or months on a charge. I doubt that having several hundred of such fancy devices would be cost effective in a carpark that is free.

I've asked several employees, but they didn't know (or have been sworn to secrecy by the carpark bump conspiracy). Does anyone have any idea what these might be, and who makes them? -- Finlay McWalter Talk 19:55, 25 July 2009 (UTC)
 * Perhaps parking related as you suggest? If not to time the car in and out then at least to tell when the car park is full. SGGH ping! 20:00, 25 July 2009 (UTC)


 * I should point out that there is no "car park full" sign, and no "spaces free" counter sign either, so I don't know what Tesco would do, in practice, with information about how full the lot was (other than internal statistics, which I'd doubt would justify the cost of sensors. And there is no barrier or ticket-machine at the carpark's entrance. -- Finlay McWalter Talk 20:05, 25 July 2009 (UTC)


 * There's plenty of material on parking space sensors from google, including a paper which shows the internals of one - much the same size as yours. However, per your narrative, it remains a mystery what tesco is doing with the information collected, if anything. Nice shoe, btw ;). --Tagishsimon (talk) 20:06, 25 July 2009 (UTC)


 * It seems apparent that Tesco has too much money for their own good. Vranak (talk) 20:08, 25 July 2009 (UTC)


 * I did also consider the possibility that they were passive reflectors, which could be used by a remote-camera system to count and time cars (if the reflector is obscured then there must be a car in the bay) - given the few cctv cameras around, this would have to be done by sensors atop lampstandards - but I don't think there are enough lampstandards for this, and these dull opaque bumps are the very opposite of reflective (I guess they're less reflective than cars, so maybe that's it). -- Finlay McWalter Talk 20:10, 25 July 2009 (UTC)
 * Meanwhile in SF, "The device, called a “bump,” is battery operated and intended to last for five and 10 years without service." - . --Tagishsimon (talk) 20:22, 25 July 2009 (UTC)
 * If a camera/reflector system were being used, they would have to install quite a number of cameras or have them very high up since the car in the next space over could block more than a single bump. Dismas |(talk) 20:27, 25 July 2009 (UTC)


 * The SF bumps are associated with revenue (I'd guess they'll cost at least $100 each, so they'd have to pay for themselves) whereas my Tesco bumps are in a free lot (and Tescos got to be as wealthy as Vranak says by not wasting money). And the SF bumps look pretty well grouted in - they'd have to be, to stop someone prising them up and making off with them (Berkeley had a vigilante problem a while ago, with someone cutting down dozens of meters to protest parking fees); Tesco's bumps don't seem that secure.  Maybe I've misled everyone by suggesting the parking-management idea (which really doesn't seem cost-effective), and they're something much more passive and mundane. -- Finlay McWalter Talk 20:36, 25 July 2009 (UTC)
 * In the US at least, many shopping centers have free parking lots that are intended for the use of the shoppers, but are not supposed to be use by daily commuters. If a car is parked inthe early morning and is still there five hours later. The owne ofth lot can have it towed away. The bumps could monitor this.-Arch dude (talk) 21:12, 25 July 2009 (UTC)
 * They have a 2 hour maximum, and they can impose a civil fee (recoverable by court action) in England. But in general shops and shopping centres are rather reluctant to impose these fines (I think they do it for all-dayers, but not for people who stay just an hour longer) as it's a great way to annoy someone and lose their business forever. -- Finlay McWalter Talk 21:18, 25 July 2009 (UTC)
 * Google rulez! Looie496 (talk) 23:51, 25 July 2009 (UTC)
 * Awesome google-fu, Looie --Tagishsimon (talk) 23:55, 25 July 2009 (UTC)
 * Were you referring to Kidderminster, Finlay McWalter? -- Rixxin (talk) 15:04, 26 July 2009 (UTC)
 * Good job on the Google-fu. As an aside in response to concerns about cost, I'll note that the scheme would work very nearly as well if only (say) 1 in 3 'bumps' were genuine and the rest indistinguishable dummies.  The purpose is to discourage long-term or full-day parking that isn't related to visits to Tesco.  If word got around that a) the bumps are tracking parking, and b) Tesco is issuing tickets or towing vehicles, then the fact that only a fraction of the bumps actually work is irrelevant.  (Indeed, from Tesco's perspective the fractional coverage might actually be better &mdash; it would convey the message that tickets were being issued and parking rules enforced, while reducing somewhat the number of people who actually get mad about receiving a ticket personally.  A similar effect could be achieved by issuing warning notices on first offences and by capping the number of tickets issued per day.) TenOfAllTrades(talk) 16:05, 26 July 2009 (UTC)

What happened to the US space VLBI program?
Looks like the Japanese did Space VLBI back in 1997: http://www.vsop.isas.jaxa.jp. If Moore's law was being followed, which in signal processing (as opposed to consumer goods) I believe it generally has been, we might have had a way to see the ozone spectrum characteristics of Earth-sized habitable exoplanets at 34 THz and below (9-10 micrometers) by now.

However: http://web.archive.org/*/us-space-vlbi.jpl.nasa.gov/

Where did the US lose track and how can we get back on track? I don't want to know who was responsible (although I believe they should be held responsible if they can be identified) nearly as much as I want to know who can bring the thing out of mothballs.

Related research: 99.60.2.113 (talk) 19:59, 25 July 2009 (UTC)
 * Schneider, J. (2009) "Pathway Toward a Mid-Infrared Interferometer for the Direct Characterization of Exoplanets"
 * Schneider et al (2009) "Search for Life on Exoplanets: Toward an International Institutional Coordination"
 * Mugnier et al (2009) "Optimal method for exoplanet detection by angular differential imaging"


 * I know a girl who's doing work with Cluster that one might call "VLBI"-like. That is an ESA satellite constellation, but the research is funded by the NSF (I think).  I think there is also a new replacement small-satellite system (either IMAGE or THEMIS, both NASA missions; these have sensors which can also be used for VLBI-like work.  The work that I am aware of is mostly using synthetic-aperture for terrestrial observation, though.  I don't know if these satellites have useful science data for studying exoplanets.  As far as the US "losing track", I agree that we're underfunding our space research; but you might want to look at this article.  Space research is always lower-priority for government spending; and these days it is even lower priority than usual.  Nimur (talk) 02:48, 26 July 2009 (UTC)


 * Also, I don't think any reliable economist or researcher has ever suggested that Moore's law even remotely applies to space research. An engineering professor explained Moore's law best during an ASIC class a while back.  The "law" is only preserved because of an economic feedback loop, where profit is fed back into the engineering investment to double the performance.  This produces more profitable products, so more profit can be fed back into the research.  And as all engineers know, positive-feedback leads to exponential growth.  Space research has no such profit-return path (or at least, not on the 18-month time-scales).  Moore's law does not hold.  Nimur (talk) 03:28, 26 July 2009 (UTC)


 * The necessary profit motive exists in, e.g., fiber optic communications bandwidth markets, which have been improving along with the continuing miniaturization of integrated circuit photolithography.
 * Why can't we use any two existing infrared space telescopes for VLBI? HowDoIUseUnifiedLogin? (talk) 06:58, 26 July 2009 (UTC)


 * We can, provided their data is sufficiently synchronous; but remember, our best timing accuracy is usually GPS time (depending on your circuitry, this can be anywhere from millisecond-accuracy to maybe nanoseconds with some phase locked loop filling in the subsampled time intervals. For interferometry, you need timing accuracy on the order of the wave period for the frequencies you are looking at; that makes VLBI very hard unless the equipment has been specifically designed to measure coherently.  At lower frequencies, such as those EM waves suitable for electromagnetic surveys of the terrestrial and near-earth environment, VLBI is much easier.  Optical surveying of exoplanets, though, is a whole different animal.  Nimur (talk) 16:15, 26 July 2009 (UTC)


 * In fact, after searching yesterday and today, I could not find any real VLBI observations of exoplanets at optical wavelengths. Simulations abound - but this is because in MATLAB, any arbitrary timing coherence is possible.  An actual satellite cluster must have synchronized clocks (or other wave coherency system) that is as accurate as the frequency of observation.  This is not a "small detail", it is a major engineering obstacle that (at infrared wavelengths) pushes several orders of magnitude beyond the state of the art in clock coherency and accuracy.  Nimur (talk) 16:18, 26 July 2009 (UTC)


 * Assuming that the timing and therefore the position information is poor, which I am not sure is a reasonable assumption given modern chip-scale atomic clocks, is there any reason that a brute force search for the matching phases isn't possible? It would seem that the features of the image including the spherical Bracewell-nulled star, possibly the elliptical interplanetary dust cloud emitting blackbody IR, and certainly the planets in question would all provide sufficiently discernible features for pattern recognition which would be distorted in a way that should be obvious to an algorithm when the phases aren't correctly matched. If brute force phase matching is possible, how about a binary search? 99.35.130.129 (talk) 17:26, 26 July 2009 (UTC)


 * It's not a matter of precision, it's a matter of accuracy. As you point out, we can make clocks that are precise to amazingly small time-intervals - but those clocks need to by synchronous across satellites which are tens of thousands of kilometers apart.  That part has not made recent advances - as I said, GPS is our best bet, and it's about 1 ms accurate.  It works great if you are doing low-frequency research.  To be honest, I have no idea what "Bracewell nulling" is, this paper seems to mention it.
 * Bracewell, R.N, and MacPhie, R.H.. Icarus, vol 38, 1979: available here Nimur (talk) 18:05, 26 July 2009 (UTC)


 * Bracewell wrote in 1979, "... it is not clear whether technology or astrophysics will be limiting. It is conceivable that bulk motions of the stellar envelope ... could foil attempts to exhibit ...periodicity."  This is the crux of the issue.  Even in 2009 (thirty years later), we still have neither the technology nor the astrophysical understanding to be sure we are isolating the exoplanet via angular resolution; the interferometric approach suffers similar problems.  Clearly this is an area that can benefit from further basic science research as well as technology improvement; the 1979 paper gives a great overview of the challenges and also has provides some formulae and some example numbers you can crunch for yourself, to determine the necessary engineering constraints for a given exoplanet size.  In summary, "we aren't there yet."
 * Also, you seem to think that phase error "should be obvious to an algorithm when the phases aren't correctly matched" - but that is unfortunately not the case - phase noise. If you can think of such an algorithm which eliminates phase noise, and it actually works, then you'll have made a really solid contribution to interferometry, and signal processing in general! Nimur (talk) 18:29, 26 July 2009 (UTC)


 * The solution is independent of the time scale limiting initial phase matching accuracy. The interferometric image combination does not discard information, therefore it is a convolution. Expected star, background, and planetary images can be similarly convoluted to derive patterns, comparisons against which a search through the possible timing differences can be guided by to finish in O(log(N)) time.  These convolved but information-rich patterns can be combined for comparison templates allowing an even faster phase match search.
 * There may be an even simpler algorithm. Please consider the phase vocoder used for pitch ("autotune") and time shifting. The total magnitude (or energy?) of changes it needs to make to match phases for resynthesis is proportional to how well the waveforms are matched. A calibration system at that level of sophistication could be tuned on a variety of wavelengths even if starting at 34 THz would be much harder. 99.35.130.129 (talk) 20:58, 26 July 2009 (UTC)

More related research: 99.35.130.129 (talk) 21:44, 26 July 2009 (UTC)
 * Pallé et al (11 June 2009) "Earth's transmission spectrum from lunar eclipse observations" Nature 459: 814-16
 * Le Coroller et al (2004) "Tests with a Carlina-type hypertelescope prototype" Astronomy and Astrophysics 426: 721-8
 * http://collab.digitaluniverse.net/wiki/Interferometry_from_Space - currently omits heteroscopic space VLBI
 * Closure phase - a method of calibrating two VLBI telescopes with a third

Why do buildings have foundations?
What is the reason for having foundations for buildings? Surely it does not make any difference if the weight of a building such as a house is supported on the surface of the ground or a few feet below? 89.243.185.143 (talk) 20:35, 25 July 2009 (UTC)


 * There are a number of reasons for considering sunken foundations, such as development of lateral capacity (i.e. preventing movement), penetration of soft near-surface layers, and penetration through near-surface layers likely to change volume due to frost heave or shrink-swell - see Shallow foundation. But there are above-ground foundation systems, such as concrete on grade, which are suitable for more temperate climates. See also Foundation (engineering) and Deep foundation. --Tagishsimon (talk) 20:53, 25 July 2009 (UTC)

Look at Foundation (engineering), Shallow foundation, Consolidation (soil) and Bearing capacity. Oh and read the Parable(?) of the man that built his house on sand, http://www.thisischurch.com/sermon/wiseman.htm ny156uk (talk)
 * Around here, the Frost line can be as much as 4 feet deep. So when the ground heaves (see frost heave), anything above it will move up.  You don't want this happening under just part of your structure.  Dismas |(talk) 21:05, 25 July 2009 (UTC)

The simple answer is: buildings are expensive. While a house could be built for tens of thousands of dollars, many academic buildings are vastly more complex, and expensive the same way. At the same time, these buildings LAST. Many famous University buildings have been built more than a hundred years ago. So, when a foundation pays for a building, it is one of the longest-lasting charitable actions they can do, while at the same time there is a big financial need for support in building the buildings, which explains both the foundations' and the universities' / other bodies' eagerness to take on these kinds of projects. It's just basic economics, really. 82.234.207.120 (talk) 21:43, 25 July 2009 (UTC)
 * ↑ cute.--70.107.76.121 (talk) 22:39, 25 July 2009 (UTC)
 * Does it help if the foundation rests on a solid rock..efeller? Nimur (talk) 18:50, 26 July 2009 (UTC)
 * The surface of the ground has several problems. In most places it consists of topsoil, full of organic matter that can decay or change. In areas prone to freezing the ground can expand and contract as it freezes, moving up and down. Even in areas where that isn't an issue, the ground will expand and contract according to its moisture content. You always want the material under a building to be essentially unchanging. Furthermore, the soil near the surface has almost always been disturbed by human activity, either building or agriculture and may not be consistent in nature, or may be insufficiently compacted. It is actually worse to have inconsistent bearing under a building than to have poor, but consistently poor bearing, as then different parts of the building will move in different directions, always a bad thing. With rain, freezing, topsoil and disturbance, even light foundations should be at least 18"/1/2 meter below grade, or have the soil cut out to that depth and replaced with a material of predictable characteristics.  The better the bearing capacity of the material, the smaller the foundation may be.
 * It's worth noting that the skyline of Manhattan roughly parallels the availability of Manhattan schist at a depth convenient for the placement of skyscraper foundations. Where it's deeper, like in Greenwich Village, buildings are shorter in stature, as it's hard to spread the load of a tall building over a wide enough area in soil without resorting to pilings. Also, for a tall building, the foundation must resist the wind load or overturning moment, and even in a small building you don't want it tossed by the wind (think about trailers vs. tornadoes).   Acroterion  (talk)  00:04, 26 July 2009 (UTC)
 * If a church is built on the rock it will stand, even when steeples are falling . Edison (talk) 03:14, 26 July 2009 (UTC)


 * Surely it does not make any difference if the weight of a building such as a house is supported on the surface of the ground or a few feet below – actually, it makes a big difference. Try building something with sticks. You'll find that when they're stuck in the ground you can actually build a stable structure. Otherwise, things tend to fall over. Vranak (talk) 17:17, 26 July 2009 (UTC)


 * That's mostly an unrelated phenomenon. Sticks shoved in the dirt are stable due to the soil surrounding them holding them in place, that is mostly not the case for buildings. While having dirt around it sure doesn't hurt, the purpose of digging is simply to reach a stable level. Matt Deres (talk) 16:08, 28 July 2009 (UTC)

example of easy irrational problem?
I am looking for an example of an easy irrational problem or task, that is impossible for the deductive, rational left-brain (or a rigorous computer program etc) to solve or answer, but is so easy that EVERYONE who has both brain hemispheres can solve it, even the most rational, Asperger's-suffering mathematician on Earth. But where the solution MUST be done by their right brain.

Any ideas for what such a problem or task might be? (It's actually okay for me if a percentage of the rational people above mentioned fail at the task -- I am really looking for something almost all of them can do [but which is irrational, can't be done by the left brain].) Thanks! —Preceding unsigned comment added by 82.234.207.120 (talk) 21:49, 25 July 2009 (UTC)


 * Well, assuming the Church-Turing Thesis is true, and the brain is just a meat computer, there is no such problem. There are many problems that are very hard for computers using our current techniques, but which humans are very good at. Recognizing faces from minimal cues is one. Noisy image recognition is a related one. I would suspect music appreciation is similar - if a computer can recognize the Eroica as truly great music, I'd be surprised. --Stephan Schulz (talk) 22:24, 25 July 2009 (UTC)


 * Some experienced mathematicians are unable to complete the following series which is often solved easily by children:
 * 3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, ?
 * Cuddlyable3 (talk) 23:18, 25 July 2009 (UTC)
 * However, a computer with access to Google or the OEIS can also solve that easily, so it doesn't seem to be what the OP is after. Algebraist 23:22, 25 July 2009 (UTC)
 * Your conditions are so stringent that they probably make the problem impossible. For one thing, the standard left brain/right brain distinctions don't apply to everybody -- many left-handers have different lateralization.  If you restrict yourself to people with the standard lateralization (i.e., ordinary right-handers), probably the most basic function that is highly right-hemisphere-dependent and not solvable by logic is recognizing people's faces.  However, people with autism or Aspergers, and some other hyper-rational people (Isaac Asimov for example), are often impaired at this. Looie496 (talk) 23:36, 25 July 2009 (UTC)
 * Ho ho ho it looks like the problem I posed separated the left-brainers from the right-brainers. (Once you see it, it is a no-brainer.) To Algebraist I think we must distinguish between solving a problem and looking for someone else's solution. The GIGO principle suggests there is no irrational act that a computer might not do. Cuddlyable3 (talk) 23:42, 26 July 2009 (UTC)
 * For those of us really bad at spelling it does not become a "no-brainer" even after it's explained. It's not so much a puzzle as much as an exercise. It tests whether or not you've ever seen a puzzle of this sort before, and whether you have the patience to grind through common series until you find it. For me, I can't do these without writing down the words and counting the letters (Even so, how do you spell "eight"? I can never remember.), so I stopped after checking only two series.
 * It may have successfully identified me as a math centric person, but I'm not confident it worked the way you expected. I did at least correctly identify it as potentially being a count-the-letters puzzle.
 * (Incidentally, I was going to guess '6' because of the pairs of repeats in the series, So at the very least you're going to want to end the series on a different element.) APL (talk) 15:10, 27 July 2009 (UTC)


 * So ... what's the solution to the series? APL (talk) 19:32, 26 July 2009 (UTC)


 * Well, I have pretty serious Asperger's and I got it in about 10 seconds. The clue that made it easy was that the questioner didn't think I'd be able to solve it - which told me I shouldn't be looking at a numerical solution.  However, smart people can think laterally too - so let me give you a clue: ONE,TWO,THREE,FOUR,FIVE,SIX,SEVEN,EIGHT,NINE,TEN,ELEVEN,...got it now?  How about A,B,C,D,E,H,I,K,M,O...what's next?  If you need to give me a problem I can't solve, have me talk about small British cars from the 1960's to an average person at a party.  Challenge me to stop talking when the other person gets bored.  I have no clue how to do that.  Fortunately, people who know me well know that I'm also not in the slightest bit offended when I'm told that I've explained that enough already! SteveBaker (talk) 22:32, 26 July 2009 (UTC)
 * You probably wouldn't be far off if you just didn't start! --Tango (talk) 00:43, 27 July 2009 (UTC)
 * Ah. One of those. I tried the days of the week and the months of the year, couldn't make it fit so I tried a different tack. Are non-logical people (Esp, children) really so good at these? If so I must be pretty non-typical. Forget common series; I can't remember how many characters are in my name without seeing it written or counting on my fingers.
 * Not to make light of Asperger's at all, but I have to ask, for your party question, from the point of view of designing an algorithm, couldn't you get a rather close approximation by judging the interval between intelligent questions? APL (talk) 04:44, 27 July 2009 (UTC)


 * This series depends heavily on how you choose to visualize numbers. If you see the word "three" in your head upon seeing "3", the solution is easy to get.  If you see 3 apples, 3 spheres, or the Arabic numeral "3" and have never visualized numbers any other way, it might take a while.  --Bowlhover (talk) 06:16, 27 July 2009 (UTC)

no, the recognizing faces thing is totally a great example! It's "irrational". A mathematician would have nothing to say about what he's calculating or reasoning while he's doing that: literally nothing. You put them in front of a computer and tell them to write down their algorithm in pseudocode, they would say they're not following an algorithm, it's a nonsensical request. But you ask them to code approximately how they do their grocery shopping, they can lay down pseudocode before you've finished your sentence!!! So I like the example a lot. It's something "irrational" and yet all mathematicians can recognize SOMEONE. Can you give me more examples of this, of something "irrational" that all people, even mathematicians do? Also, the brain laterization thing isn't the crux of the request, but the "irrational" problem solving is!! Thanks. 82.234.207.120 (talk) 00:20, 26 July 2009 (UTC)
 * One simple problem of this type is to decide whether or not a sentence is funny. -Arch dude (talk) 02:12, 26 July 2009 (UTC)
 * Facial recognition can be performed algorithmically. See Facial recognition system.  Maybe some mathematicians do not think about it in an algorithmic way, but clearly the problem can be set up, defined, and solved algorithmically.  The accuracy is becoming very high, and in some professional-grade systems, beats human face-recognition error according to some metrics: "Computers outperform humans at recognizing faces in recent tests".  Nimur (talk) 03:10, 26 July 2009 (UTC)
 * I'm not sure that a human being could consciously eyeball the measurements needed for a facial recognition algorithm. APL (talk) 04:44, 27 July 2009 (UTC)
 * How about just having a normal conversation? AI's still don't pass the Turing test.  Robots with AI are also apparently very bad at soccer.  Then of course there are those images of a word that you're supposed to type.  Some of them have been broken, but in general it's a very hard problem.  Check out the Artificial Intelligence page for for a more thorough description of the types of problems computers are comparatively very bad at.  The original question wasn't really about computers per se, but I'm not sure how to tell if a problem is impossible with only the "left brain." Rckrone (talk) 06:06, 26 July 2009 (UTC)
 * Rckrone may be referring to CAPCHA . Cuddlyable3 (talk) 23:54, 26 July 2009 (UTC)
 * Oh yeah, I forgot that had a name. Also I did a really horrendous job of describing it. Rckrone (talk) 02:40, 27 July 2009 (UTC)


 * Certainly there are problems you can set up that a computer can't solve - but you'd be hard-pressed to find a human-solvable problem that a computer will never be able to solve (presuming it's given the same data and life-long learning that the human gets). Remember - people said that a computer would never be able to beat a grand master at chess - or that it would never be able to drive a car.  It's dangerous to make these claims.  But that's not what the questioner is asking.  We're supposed to be finding problems that a highly logical brain can't solve - that more 'normal' people don't find difficult. SteveBaker (talk) 22:32, 26 July 2009 (UTC)


 * Well in that case I think Stephan Schulz has it right. There's no reason a sophisticated enough computer couldn't perfectly emulate a human brain. Rckrone (talk) 02:40, 27 July 2009 (UTC)
 * Hey! I may not always have it (I'm not Steve Baker), but if I have it, I always1 have it right! --Stephan Schulz (talk) 11:29, 27 July 2009 (UTC)
 * 1 ...for sufficiently small values of always!
 * That isn't quite correctly stated. There is no conceivable computer that could perfectly emulate a grain of sand.  A better way to put it is that there is no valid reason to think that the brain performs any useful function that couldn't be emulated by a computer. Looie496 (talk) 02:52, 27 July 2009 (UTC)


 * CAPTCHAs are designed to exploit the current gap between what humans can solve and what computers can solve. Ironically, they've been quite effective at driving research in these areas, research that continually proves each new CAPTCHA vulnerable to sophisticated machine learning methods. There will probably for a long time to come be tasks that humans perform better at than computers, but the gap continues to close. Dcoetzee 21:37, 27 July 2009 (UTC)

Which cow breed is this Swiss cow?
Hi, I took this photo of a cow in Switzerland a short while ago. I would like to know which breed it is such that I can update the file page description and categorize it properly. I guess it must be some breed of Bos taurus, but I am at a loss which one. Thanks in advance. --Slaunger (talk) 22:12, 25 July 2009 (UTC)


 * Montbeliarde Cattle? I'm not sure, I'm not an expert in that field :) . And it is Swiss, not Swizz. Actually, more like French ;). --Dr Dima (talk) 22:38, 25 July 2009 (UTC)
 * Sorry about the terrible spelling (which I've corrected now). I am not a native speaker nor speller... OK. I do not feel too sure when seeing the photos of that breed, and I think I would like a second opinion, but thanks of for your time. --Slaunger (talk) 22:52, 25 July 2009 (UTC)
 * I asked my wife, who works in the dairy industry, what breed it is and she doesn't know. She was able to definitively say that it's a beef breed though, as opposed to a dairy breed.  Dismas |(talk) 01:38, 26 July 2009 (UTC)
 * The English Wikipedia distinguishes between Simmental Cattle and Fleckvieh cattle which are treated as the synonyms by the German Wikipedia de:Fleckvieh. The Swiss are trying to establish "Swiss Fleckvieh" as a separate breed and are limiting the Red Holstein influence for that purpose.  It's a dual purpose breed (beef and milk) like lots of the "older" breeds.  Here's a picture for comparison, looks pretty much like yours. 71.236.26.74 (talk) 03:34, 26 July 2009 (UTC)
 * Thanks for that thorough answer. I did have a look at the Simmentaler before asking but the photos does did not look quite right to me. --Slaunger (talk) 10:14, 26 July 2009 (UTC)
 * I don't think there is enough information in one photograph of a semi-recumbent animal to accurately identify the breed. Richard Avery (talk) 19:46, 26 July 2009 (UTC)
 * I understand your concern. I think I will conclude from this that "It is most likely a Swiss Flechvieh, could also be a Flechvieh, a Simmentaler or another dual purpose breed (beef and milk)." Finally, one of the Wikipedia articles points to a dedicated German Flechvieh site, which i have seen has a forum, where one can ask questions. I think I will also ask the question there, as they should know if any if it is a Flechvieh or not. Last, but not least, thanks for the help and feedback here. It is very much appreciated. --Slaunger (talk) 21:04, 26 July 2009 (UTC)