Wikipedia:Reference desk/Archives/Science/2007 October 15

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1 October 15

[edit] October 15

[edit] race

If the distinction between species is so ambiguous how are modern races distinguished, especially with so much inbreeding? Clem 02:19, 15 October 2007 (UTC)

Many scientists feel that race has no scientific basis at all. Dragons flight 02:27, 15 October 2007 (UTC)

The short answer is not easily. There are massive committees dedicated to this sort of thing. For animals it's the International Commission on Zoological Nomenclature (ICZN) which creates the International Code of Zoological Nomenclature, effectively the rules of how to name things when disputes arise. For plants it's the International Code of Botanical Nomenclature. Narrowing the question, for most non-microscopic sexually reproducing animal species the division between species is typically decided based on whether or not the animals frequently interbreed in the wild or not. Mammals may be considered separate species even though they can technically interbreed if they are geographically separated. As a rule of thumb, biological nomenclature for a particular group of organisms is designed so that it can be fairly easy to apply. Dragon flight raised the issue above that labeling a group of organisms a species attempts to impose a black and white concept on the grey world of biology with varying results. While ideally we would like to be able to classify every organism with a consistent definition, we can't at this point. There are tons of cases where it is currently difficult to observe or expensive to exhaustively test whether or not an organism interbreeds with related species or reproduces asexually so the typical criteria don't apply, or whole bunches of other reasons. In these cases, the concept of "species" is based off of observable morphological characteristics which appear to "set apart" a group of organisms from similar organisms. In parts of mycology this method is frequently used; fungal species are determined by differences in spore characteristics, hosts, range, disease symptoms, and whatnot so that populations of very similar organisms are lumped together to form a "species." Sifaka ^talk 02:33, 15 October 2007 (UTC)

Note that human races were considered ill-defined even before the species problem really came to a head. You can find discussions about the lack of human races being real biological distinctions going back into the 19th century at least. In any case there is nobody today who thinks that human races are different species. It has occasionally been a belief floated by various scientists in the 19th century but even then it was considered spurious by many (including Darwin). --24.147.86.187 02:50, 15 October 2007 (UTC)

According to the article subspecies the International Code of Zoological Nomenclature calls human races "infrasubspecific entities." Sifaka ^talk 03:10, 15 October 2007 (UTC)

Next time I want to piss someone off, I'll call them an infrasubspecific entity. Might be interesting to see how they react. :) Or unhealthy. :( DirkvdM 18:10, 15 October 2007 (UTC)

This is really another one of those "what's in a name?" questions that we shouldn't be too concerned about. It's clear that humans inherit their skin colour and hair type and various other physiological features from their parents. In that sense the races 'breed true'. But on the other hand, we can interbreed between races quite freely and successfully too - so you can't describe the various racial types as separate "species". Between one end of the scale and the other - it's just a matter of what name you decide to use - and that's as much a matter of political correctness as it is science. This is equivalent to asking whether Pluto is a planet or not - biologists need to put a stake in the ground and define their terminology (just as the astronomers did) - but it doesn't "mean" anything in any important way. Sadly, people will make just as big a fuss over whatever they decide as they did over Pluto's demotion to "minor planet" status...and it's just as big a waste of breath to discuss it. SteveBaker 14:02, 15 October 2007 (UTC)

Problem is, if others like to waste their breath so much, the ones who know can't stand by and say nothing. After all, why did you answer this question? :) DirkvdM 18:10, 15 October 2007 (UTC)

Note, I suppose you meant interbreeding, not inbreeding. DirkvdM 18:10, 15 October 2007 (UTC)

Would Interbreeding require that race be acknowledged as a Taxon? If not, is inbreeding between races a better fit? Clem 19:29, 15 October 2007 (UTC)

[edit] Breast hormones

Why don't flat-chested women use estrogen to grow larger breasts instead of getting implants? Doesn't estrogen work to grow breasts on males? --124.254.77.148 09:08, 15 October 2007 (UTC)

Well it can cause males to develop breasts but this is different from causing breasts to grow larger. Lanfear's Bane 10:59, 15 October 2007 (UTC)

Hormones are the bio-chemical equivalent of cluster bombs: you can't just apply the œstrogen to one part of the body - it would spread, causing havoc through the rest of the body; it could screw up the menstrual cycle, digestive processes and even induce cancer. Plus, œstrogen can cause the body to burn fat and kill muscle tissue, causing a net reduction in size. Laïka 11:30, 15 October 2007 (UTC)

Pregnant women grow larger breasts (and it's often a permanent change) - I wonder what hormonal brew does that? But as you say - the number of side-effects would be pretty horrific, so it's not something you'd really want to do. SteveBaker 13:53, 15 October 2007 (UTC)

The worst side-effect of that being a parasitic growth that drops out after nine months and then feeds off you for eighteen years or more. Sometimes. Lanfear's Bane 14:52, 15 October 2007 (UTC)

Worst still, the parasite somehow latches onto the father as well. (And 18 years is a severe under-estimate.) SteveBaker 15:42, 15 October 2007 (UTC)

They do! Many women report that taking birth control pills causes their breasts to get a little bigger. --Sean 15:21, 15 October 2007 (UTC)

As I recall, there are a few published studies of the effect of estrogen supplementation on breast size in women and they do not indicate that estrogen supplements have much effect on breast volume in most normal women. Most women have normal levels of estrogen and adding more estrogen will have little effect to increase breast size. There are probably some doctors who will help normal women try topically applied estrogen for a few months, without promising any results. Rarely, women who have low estrogen (genetically, for example, see aromatase; or otherwise) will have a spectrum of problems and breast size is not likely to be their main concern. During pregnancy there are multiple hormones and growth factors that can influence breast size including progesterone, IGFs, prolactin and poorly-characterized factors that influence weight gain and patterns of adipose tissue growth. Hormone/growth factor levels are not the whole story; there is genetic variation in how tissues respond to these signaling molecules. --JWSchmidt 15:54, 15 October 2007 (UTC)

Oh. Well, maybe when women get on the pill they also start wearing tighter sweaters, which has led to these false reports. :) --Sean 17:16, 15 October 2007 (UTC)

Combined estrogen and progesterone will stimulate mammary gland tissue growth inside the breasts of many women, which is mainly of concern for associate increased risk of breast cancer. Is a possible small increase in breast size worth an increased risk of breast cancer? Orally administered estrogen supplements increase the risk for stroke and other blood clotting problems. I think a doctor who gives women prescriptions for oral estrogen or an orally administered estrogen+progesterone supplement in order to try to increase breast size would be a likely target for legal action. I suspect most doctors feel it is not ethical to give women drugs that have serious side effects while trying to deal with something like small breast size, which is not really a medical problem. --JWSchmidt 17:43, 15 October 2007 (UTC)

As far as medical ethics go, I note that doctors routinely operate on perfectly healthy women for breast enlargement surgery. Both anesthesia and major surgery carry the risk of serious complications, but are still widely available. --Sean 19:29, 15 October 2007 (UTC)

Medical uses of breast implants, estrogen and progesterone are all regulated by the FDA. Breast implants are approved for breast size augmentation. To my knowledge, estrogen and progesterone supplements have not been approved by the FDA for use in attempts to increase breast size, but I might have missed it. --JWSchmidt 20:14, 15 October 2007 (UTC)

I didn't mean to imply that they were. I was just noting that doctors are not ethically above doing other potentially risky procedures for something that is, as you say, not really a medical problem. --Sean 21:03, 15 October 2007 (UTC)

I probably should not have left it at "not really a medical problem". In our society there can be psychological problems arising from breast size (even in the normal range), so it has been possible do document psychological benefits for some women from breast size augmentation. In terms of medical ethics, there should be some balance of the benefits against the risks. If there is an FDA-approved medical procedure and a doctor makes sure that the patient knows the available risk/benefit information then they are on fairly safe ground. --JWSchmidt 22:28, 15 October 2007 (UTC)

(outdent) As I understand it, once a medication is approved by the FDA for one purpose, doctors are (as a general rule) free to prescribe it for any purpose. (Do we have an article on off-label prescriptions?) I do seem to recall hearing recently of an exception to this general rule; I don't recall what it was.

Yes, I imagine doctors who do this would be taking risks from a malpractice standpoint. They'd probably want the patient to sign an informed consent form at the very least. --Trovatore 22:34, 15 October 2007 (UTC)

Off-label use would be what you are looking for. Rockpocket 22:55, 15 October 2007 (UTC)

I know some doctors are very comfortable with topically applied estrogen and the breasts are one body location that is sometimes recommended for application of estrogen-containing creams. I'm not aware of FDA approval of estrogen for breast enlargement, but I think some doctors would be comfortable with letting their patients try it for a short time: this would probably qualify as an example of off-label use. --JWSchmidt 23:17, 15 October 2007 (UTC)

This study of topical estrogen therapy for labial fusion had a patient who demonstrated breast enlargement as a side effect (but that was only one out of a cohort of twenty). Rockpocket 23:37, 15 October 2007 (UTC)

Besides all the other points made, not all women want large breasts, nor do all men find them attractive. -- Kesh —Preceding comment was added at 23:38, 16 October 2007 (UTC)

[edit] Kinetic energy, part 2

The previous questions about kinetic energy and absolute zero touched on a topic that wasn't specifically answered. If you have an electron - just a plain electron - how much energy can you add to it without changing it? It must remain an electron - just a high energy electron. Is there any limit? If you converted all the mass in the entire universe to energy and applied it to the electron, would it still be an electron? I believe this is what the original kinetic energy question was getting at, but was not answered. -- kainaw ™ 12:34, 15 October 2007 (UTC)

Yes as far as I know you can keep adding kinetic energy to an electron - under non-relatavistic thinking as well as under relatavity theories..87.102.47.243 13:12, 15 October 2007 (UTC) The difference between the theories is that as an electron gets approaching infinite energy in relativistic theories it has approaching the c as a velocity (ie 3x10^8m/s), whereas in non relativistic theories it has approachin infinite velocity.

Again as far as I know (and I'm sure someone will take this up) - no electron has ever been found to simply disintegrate due to instrinsic high energys87.102.47.243 13:15, 15 October 2007 (UTC)

Certainly the electron cannot disintegrate due to too much kinetic energy because kinetic energy is a relative thing. Relativity allows us to consider things from the point of view of the electron - and from it's point of view it's dead stationary - why would it spontaneously disintegrate? From our point of view, yes, we can keep pumping energy into it and it will go faster and faster - but even with the entire energy of the universe pumped into that one solitary remaining electron, it'll still only be going 99.99...9% of the speed of light (there would be quite a lot of '9's in that '...' bit - I can't be bothered to work out how many!). This experiment has been done to quite high fractions of 'c' in various high energy physics labs - I don't think any of them have claimed any spontaneous disintegrations in the process - if they did, it would surely be big news. SteveBaker 13:51, 15 October 2007 (UTC)

oops I walked into that one (fun!) - I'm going to pretend that I meant no electron has ever been found to disintergrate due to a high energy collision - actually I'd like to know if this is true? anyone?83.100.252.179 18:20, 15 October 2007 (UTC)

The electron, by my quick calculation, would be moving at $c(1-4.6\times10^{-166})$ , so about 160 9s in your ellipsis (and then a 5 after your last 9). --Tardis 23:16, 15 October 2007 (UTC)

Sorry, I should have mentioned that I rounded to 159 places of decimals. I predict we will be using the results of your calculations in future ref desk answers! Thanks! SteveBaker 02:26, 16 October 2007 (UTC)

Thank you for the all the responses, even though i've only had undergrad physics i still found it fascinating! 24.88.103.234Tim

[edit] Possibly to make a hybrid/tribrid car that captures wind energy?

Is it possible to make a car with air intakes, that capture wind energy while the car moves? Like the air flow spins a fan inside the intake, which converts that into electricity which is stored in a battery. 64.236.121.129 13:36, 15 October 2007 (UTC)

No - that's definitely not a good idea. The energy you'd extract from the wind would merely show up as increased drag on the car. So the energy your little wind turbines would extract would be dwarfed by the extra drag they'd impose. There is no such thing as a free lunch! If your idea worked then you could build a perpetual motion machine by fixing a windmill onto a cart, and using the windmill (through some gear wheels or something) to drive the wheels of the cart - give it a little push and it would run forever. Since perpetual motion is not allowed (the first law of thermodynamics is a harsh mistress) - we know this can't work. Some older aircraft used little turbine blades out on the wing somewhere to generate electricity - but this was so that they still had a source of electricity if the engine died - they were a net energy loss though, eating kinetic energy (by slowing the aircraft down) at a considerably higher rate than the electrical energy they'd generate. SteveBaker 13:42, 15 October 2007 (UTC)

A vertically mounted turbine (rotate about the vertical) - could capture side winds - but the benefits would be minor - and the downsides (low bridges etc) major..87.102.47.243 13:48, 15 October 2007 (UTC) I don't believe such things can be very efficient easily anyway.87.102.47.243 13:52, 15 October 2007 (UTC)

Sure, you can make a wind-powered vehicle - it's called a 'yacht'! Notice how few yachts use windmills rather than sails! There is a reason for that! However, I have seen things like this A fuel-saving system for ships relies on kites and Giant Sails that could power ships - but they aren't extracting energy from the slipstream air caused by the motion of the vehicle (as our OP suggests) - because that's not possible. SteveBaker 15:31, 15 October 2007 (UTC)

A supercharger pumps cold air into the engine to extract chemical energy by optimizing the fuel-air ratio. This is not usually considered wind energy. It probably adds extra drag, but the energy boost outweighs the drag. Nimur 14:43, 15 October 2007 (UTC)

That's completely the opposite thing! Our OP is talking about extracting energy from the wind using a turbine - you are talking about something that consumes energy to create an air flow (more like a jet engine than a windmill). Superchargers are driven by a belt off the main drive shaft - and turbochargers extract energy from the cars exhaust flow to pump air into the engine. Also, it's not so much that they optimise the air/fuel ratio - a decently designed carburettor can do that without supercharging or turbocharging - the point of a super/turbocharger is that with increased airflow you can inject more fuel and keep the SAME optimum ratio - and thereby either get more power from the same engine - or the same power from a smaller engine. Neither superchargers nor turbochargers directly affect drag - although it is common to add a hood scoop to feed air directly into these beasts, because the pump is sucking air into the duct, it actually creates a small amount of negative drag (but it's pretty negligable!). In the case of a turbocharger, you are actually taking some of the energy out of the exhaust flow to drive the thing - so I suppose you reduce the tiny amount of extra thrust that you car gets from the 'jet' of exhaust fumes being pushed out the back...but again, it's totally negligable compared to the extra power it enables the engine to deliver. As usual though, there is no such thing as a free lunch and these gadgets almost always make the fuel consumption of the car worse, not better. SteveBaker 15:31, 15 October 2007 (UTC)

Commercial aircraft have an emergency generator of this type that deploys if all of the engines fail. It increases the drag, but it provides enough power for the essential flight systems. These units deployed in at least two situations when an airliner flew through a volcanic cloud and lost all engines. -Arch dude 15:41, 15 October 2007 (UTC)

Your comment reminds me of the Gimli Glider story. -- JSBillings 15:55, 15 October 2007 (UTC)

Yes, that plane did use its ram air turbine. --Anonymous, 21:55 UTC, October 15.

Hmmm, I wanted to make a lame joke about how we could interbrid different technologies, but it turns out tribrid is an existing word. (Note how I sneaked in the joke anyway. :) ) Anyway, with a strong sidewind, it might still help if the car had sort of a sail or wing shape. However, given the usual speed of a car, it would have to be a pretty strong side-wind to have a noticeable effect. And if the wind comes from the other side, the car would have to shapeshift. Not a good idea, it seems. DirkvdM 18:21, 15 October 2007 (UTC)

[edit] what is the LD50 of...

vicoden?
percocet?
zoloft?

--MKnight9989 14:25, 15 October 2007 (UTC)

Hydrocodone: 227 mg/kg (rat, oral)[1]
Sertraline: 419 mg/kg (mouse, female, oral)[2]

Icek 17:16, 15 October 2007 (UTC)

[edit] pulse and bleeding

–15:00, 15 October 2007 (UTC)15:00, 15 October 2007 (UTC)~~ca person falls on the ground in front of me,i check his ABC (airway, breething, circulation) and find out that he has no pulse nor breething, hence i start doing CPR trying to revive him. now while i do this can the person start bleeding. basically my question is , can there be bleeding without pulse on?82.148.96.68 15:04, 15 October 2007 (UTC)cuby

If the person still has a decent blood pressure - yes. However, if their blood pressure has fallen too far - then the only blood that'll flow out is under gravity - so maybe yes, maybe no, depending on where the wound is. SteveBaker 15:11, 15 October 2007 (UTC)

Also you are compressing their chest and forcing air into their lungs, pressure may force blood out from any wounds. Lanfear's Bane 15:15, 15 October 2007 (UTC)

[edit] Possible to make a Freeze Gun?

Like the gun Mr. Freeze uses? If so, how would it work? 64.236.121.129 15:27, 15 October 2007 (UTC)

Well, the problem with Mr Freeze's gun is where all that water comes from. I suppose you could make a mixture of water and something that would evaporate very quickly when released into the air that would pull the energy out of the water and freeze it. But you'd have to carry a gigantic tank of water around with you - and I can't imagine any way around that. If he were just freezing the water that was already there - then there is no mystery because a CO₂ fire extinguisher or a can of freezer spray can really do that (albeit on a small scale). But he seems to be able to create ice anywhere - even when there is no water around - and there is much more water created than would fit into that tiny gun+backpack. I think the myth is that he's freezing the water vapour in the air - but there isn't anywhere near enough of that to do the job. So basically, "No". SteveBaker 15:39, 15 October 2007 (UTC)

Also see Frozone. Lanfear's Bane 15:48, 15 October 2007 (UTC)

Yep - same problem. It's all very well being able to freeze things - but if there isn't anything there to freeze, you're out of luck! I suppose he might be freezing the air itself - but that's an altogether more difficult proposition! SteveBaker 16:10, 15 October 2007 (UTC)

.129, I hope these answers haven't left you "COLD"! --Sean 17:25, 15 October 2007 (UTC)

Sometimes you just gotta take the heat. 64.236.121.129 17:37, 15 October 2007 (UTC)

Cool puns, guys. risk 19:28, 15 October 2007 (UTC)

Maybe use hydrogen to power a refrigerator and use the resultant water as the water supply? But then you have to carry hydrogen tanks instead. --antilived^{T | C | G} 05:01, 16 October 2007 (UTC)

That's funny. But seriously, if you haven't seen the movie Frozone claims to use the moisture in the air, which is why his powers didn't work in that building fire. Besides, what about liquid nitrogen? It worked on the Termintator...and my friend's wart. XD --JDitto 18:56, 17 October 2007 (UTC)

[edit] Hydrogen Alpha Images of the Sun

I am a student trying to find hydrogen alpha pictures of the sun. I need to access archives and find one every day for the past week at roughly the same time. I tried the soho website, but their archive section is very confusing. Any help would be greatly appreciated. —Preceding unsigned comment added by 128.255.107.249 (talk) 17:35, 15 October 2007 (UTC)

The Sun in H-alpha light

Why don't you use Google's Image search? Google for "hydrogen alpha sun" and you'll get plenty of nice pics. There is also one here is to the right. 85.127.181.53 21:50, 15 October 2007 (UTC)

This is what you need: Culgoora Observatory H alpha images Graeme Bartlett 01:25, 16 October 2007 (UTC)

[edit] Galactic Angling

Out of curiosity only, what's the angle of the Earth's orbit in relation to the galactic plane? GeeJo ^(t)⁄_(c) • 17:39, 15 October 2007 (UTC)

Galactic coordinate system; a diagram. There seems to be confusion between various internet sources, some say: "The plane of our Galaxy is titled about 66 degrees relative to the plane of the Earth's orbit around the Sun, which is called the ecliptic". --JWSchmidt 17:53, 15 October 2007 (UTC)

That looks about right according to the two lines in my Atlas of the Heavens. --Milkbreath 18:57, 15 October 2007 (UTC)

According to the formulae found in Ecliptic coordinate system article, and using the position of the North Galactic Pole (NGP) from Galactic coordinate system article (ie. 12h51m26.282s +27°07′42.01″ (J2000)), the position of the NGP is: 179.9768° ecliptic longitude, 29.8115° ecliptic latitude. The galactic plane is perpendicular to the direction to the NGP, at an angle of 90°-29.8115° to the ecliptic. Therefore, to answer the OP's question, the Earth's orbit is tilted at an angle of 60.1885° to the galactic plane. Astronaut 00:10, 21 October 2007 (UTC)

[edit] Radio Transmissions

If I had a remote control car, would there be a way to extend the radio transmissions to go very far and for the signal to not have so many interuptions, i.e it could go into a sewer or a cave and still receive my signals from a distance? Could it work off of a satellite or is there a way to strengthen the radio signals? —Preceding unsigned comment added by 63.110.180.29 (talk) 21:08, 15 October 2007 (UTC)

I guess you could hook the radio controller up to a more powerful transmitter with a larger aerial? You'd need one that could transmit the same frequencies, and you'd probably violate several laws doing so. Radio waves don't penetrate solid objects very well, so it's unlikely you could get it to work underground. It's probably conceivable to transmit a signal to a satellite and have it beamed down again, but you'd end up with noticable lag in the cars' response. Exxolon 23:03, 15 October 2007 (UTC)

To get radio signals in tunnels special leaky coax antennas are used to carry the signal into the underground space and make it available all through. You too could use this technology in your sewer or cave, but in fact you may be better off with a roll of optic fibre or wire that unrolls as the car goes forward, and you can drive by wire.

To extend over satellite you will need a fancy antenna on the car, and there is no way to make this work in a cave. Graeme Bartlett —Preceding comment was added at 00:39, 16 October 2007 (UTC)

It's just a matter of power - as a 'thought experiment' - it you really had to, you could equip a satellite with enough power to send a signal that a toy car could pick up 5 feet underground. Soil attenuates radio waves but it's not a sudden cut-off. It would probably have to be a VERY large satellite with one heck of a big transmitter though. But for more sane applications, you can certainly boost the range. When you want to double the effective range of a radio transmitter, you have to quadruple the transmitter power. So let's suppose your car's standard transmitter worked out to maybe a kilometer - to run your car (out in the open) from geostationary orbit (35,786 km) your satellite would have to have a transmitter maybe 35786*35786 times more powerful than the one you have now. That's about 1.3 billion times more powerful! To get through a few feet of dirt afterwards would push the power requirements to truly ridiculous levels. However, that's assuming that (like your regular transmitter) it sends radio waves out in all directions equally. If it only had to send a narrow beam down towards the toy car - it would need a lot less. NASA have used 'ground penetrating radar' systems in satellites that can see down through several meters of martian soil - and in that case they have not only send a radio signal that far - but detect the return 'bounce' too. Those probably don't run on the frequency that your car uses - and that probably makes a difference too. So it's "possible" - but definitely not "easy".

In terms of a practical answer to running your car at longer distances, it's certainly possible to boost the power - but there is a reason they don't do that. Because they sell lots of toy cars (and boats and who-knows-what-else) that use the same range of frequencies, if the signals at the transmitter are too strong, then someone driving one of these things two streets away would interfere with your car - and that would make matters worse, not better. For this reason, radio control transmitters operate at power levels that are strictly limited by law. The best way to get good range from your transmitter is to ensure that the antenna is always fully extended - and if the car has one of those 'dangly wire' antennas - thread it through a drinking straw and hot-glue that onto your car to make that antenna stick up vertically as far as it will go. Don't coil it up! Holding your transmitter antenna vertically will then get you the best possible range. SteveBaker 02:15, 16 October 2007 (UTC)

At some point, the power levels you're using to get the signal through the ground leave the realm of "radio signals" and enter the realm of "directed-energy weapon". The energy in the radio waves doesn't just magically vanish as the signal is attenuated by the ground -- some of it gets reflected, while more of it gets absorbed. --Carnildo 21:34, 16 October 2007 (UTC)

[edit] Growing a mushroom on the skin

Don't laugh.

Dermatophytes are fungi, and they are terrible. Amanita muscaria is also a fungus, but it is pretty. Would it be possible to cultivate a fly amanita on one's skin? Would it be safe to do so? HYENASTE 21:59, 15 October 2007 (UTC)

It is not possible, the diet of the fungi is too different. Perhaps you could live off a diet of human skin, but I think you would not survive long on a diet of mulch and tree roots. These different fungi have the same issue. Graeme Bartlett 00:35, 16 October 2007 (UTC)

What's the name of that ancestor of Panoramix in Asterix and Obelix vs Caesar? DirkvdM 08:09, 16 October 2007 (UTC)

There is no way to grow a saprophytic Amanita muscaria on one's living skin because it is not adapted to deal with the human body's defenses. You couldn't even grow it on a decomposed flesh either because Amanitas are adapted towards decaying plant matter. So definitely not. Any fungus growing on your skin is going to be decomposing it, ushering in all manner of infection and putridity, so it wouldn't be safe or the least bit attractive either. Lastly, sorry I did laugh. The mental image of mushroom people I conjured up was way too surreal for me not to. 71.226.56.79 15:43, 16 October 2007 (UTC) (This is User:Sifaka who is unable to sign in)

[edit] The moon and stars

In what ways are the stars and moon similar? —Preceding unsigned comment added by 24.126.168.23 (talk) 21:59, 15 October 2007 (UTC)

Um, they appear in the night sky? Have you tried looking at our articles on moon and star? I suspect you'll find more that's different than in common, but if you can ask a more specific question we might be able to help better. Confusing Manifestation 22:32, 15 October 2007 (UTC)

They can be used to tell the time of the year, or in lunar calendars the date in the month. Graeme Bartlett 00:34, 16 October 2007 (UTC)

There is really very little that the stars and the moon have UNIQUELY in common - I mean, they are both made out of atoms (well, except for neutron stars) - they are both kinda-sorta more or less round (but so are golf balls and we don't ask about what makes a golf ball similar to a star). Both stars and moon can be seen in the daylight sky (if you have the right equipment) - and technically, there is one star in particular (the one that we call "the sun") that isn't ever visible at night. The moon isn't even always visible at night - about half the time it's only visible in daylight. And what's wrong with planets, asteroids, comets and dust clouds? Those are a lot more similar to the moon than stars are - why aren't they participating in this arbitary listing of objects? It's really hard to come up with any property that's similar between stars and moon that are not also common with almost everything else in the known universe! "star" and "moon" both have four letters? SteveBaker 01:53, 16 October 2007 (UTC)

They're both christmassy!87.102.12.235 17:33, 16 October 2007 (UTC)

Well, think about it this way, stars are formed from nebula dust. A moon is formed when, a large clump forms in the nebula dust surrounding the new star, and as the clump forms, more nebula dust gathers and rotates and around that clump, and you've got a moon. However, The Earth's moon is believed to have formed when a planetoid struck the Earth, ejecting materiel both from it and the Earth, gathering into a ball. Well, I guess you could say they're both made from nebula dust. Well that's our present theory anyway, but it may have a few bugs. For example, if stars are formed from nebula dust, there wouldn't be that much nebula in the galaxy at any one time, so perhaps some of it was made from galactic dust. Well, I con't really give much of an exact answer here. Hope this helps. ~A H 1^(TCU) 20:40, 17 October 2007 (UTC)

See also hearts and clovers. —Tamfang 00:38, 21 October 2007 (UTC)

[edit] Pulling wire and the 4th dimension

In a house, if you connect 2 electrical boxes together, you can't hang the wire through the air, but you have to pull through the walls. So if I have 2 boxes that are 10m away, I could be dealing with 1, 2, or 3 dimensions.

Image I made, for reference.

A: I have 1 wall and 1 dimension. I have to make perpendicular turns in 0 nonparallel planes. I use a maximum of sqrt1*10m = 10m of wire.

B: I have 2 walls and 2 dimensions. I have to make perpendicular turns in 1 (nonparallel) plane. I use a maximum of sqrt2*10m = 14.1m of wire.

C: I have 3 planes and 3 dimensions. I have to make perpendicular turns in 2 nonparallel planes. I use a maximum of sqrt3*10m = 17.1m of wire.

E: I have 4 planes and 4 dimensions. I have to make perpendicular turns in 3 nonparallel planes. I use a maximum of sqrt4*10m= 20m of wire.

But in 4 dimensions, it appears I can end up exactly where I started, although I have to take the time to whip through the 3 planes. Is this correct; does it show that the 4th dimension is time? HYENASTE 23:31, 15 October 2007 (UTC)

In 4 dimensions you are right, you could run the cable there and back. I don't think this has anything to do with time though! just that sqrt(4) = 2.

Graeme Bartlett 23:51, 15 October 2007 (UTC)

This certainly doesn't prove anything special about 4 dimensions. It's just a numerical coincidence. Do the same thought experiment while thinking about the amount of 2D wallpaper you need to cover all of the walls and ceilings - you'll get a completely different set of coincidences. SteveBaker 01:36, 16 October 2007 (UTC)

Sadly, I am very confused by the question. Edison 04:57, 16 October 2007 (UTC)

Simply put - in four dimensions you don't end up were you started - if you start at (0,0,0,0) you end up at (10,10,10,10) - because dimensions are orthogonal ie at right angles (the fourth dimension the same) - you don't end up doubling back on yourself..87.102.12.235 13:15, 16 October 2007 (UTC)