Wikipedia:Reference desk/Archives/Science/2010 April 11

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April 11

Torque due to gravity

http://web.mit.edu/juang/OldFiles/Public/Classes/8.012/exams/final-F02sol.pdf. For question six, the solution uses the conservation of angular momentum. But doesn't gravity exert a torque on the block? If we define our origin as the top of the cone, then r x mg isn't zero because the two aren't parallel. Thanks. 173.179.59.66 (talk) 01:33, 11 April 2010 (UTC)

The generated torque is perpendicular to the axis of rotation. Since the axis of rotation is fixed by assumption, such a torque can not change the angular momentum about that axis. Dragons flight (talk) 02:44, 11 April 2010 (UTC)

Thanks. 173.179.59.66 (talk) 05:09, 11 April 2010 (UTC)

Quantum Entanglement

Quantum entanglement can't be used to transfer information because this would violate relatvity (the data travel, if possible, would be instantanious, which would be faster than the speed of light), that part I understand. Now consider this, imagine two friends, Alice and Bob, each have a box with a particle in it. Those two particles are entangled to one amother and are in a superpositon of being the color red or blue. As soon as one of the two of them looks at their particle, decoherence will occur and the particle will be either red or blue, not both. Not only that but because the two particles are entangled, the other friends particle will become the opposite color. If Alice looks and finds hers to be red, Bobs, even though he hasn't looked yet will be blue. A soon as Bob looks he will find his to be blue and he will know that Alices must have been red. Isn't this a transfer of information? I know that Alice or Bob can't use this to transfer their own information, like one telling the other their favorite kind of pie, because the color that the particles ultimatly become when viewed is random and unpredictable. But still, isn't information still being transfer, when one looks at the color of their particle they immediatly know the color of their partners too. Wouldn't this violate relativity? Could some one please explain to me how that would be possible, am I mssing something?

The way I'd look at it is that they each already had the info on the other, they just hadn't looked at it yet. So, the info didn't travel between the two remote people at all, it was already right there in the box. StuRat (talk) 03:32, 11 April 2010 (UTC)

I agree...who needs all that funky quantum stuff? Take a matchstick, break it in half and toss each half into a box...give one box to Bob and the other to Alice (at random). Whoever opens their box and sees that they have the head of the match knows that the other person has no head on their half of the matchstick - and vice-versa. That isn't what's happening with the quantum entanglement thing (well, depending on your interpretation of quantum theory) - but the information/communication situation is indistinguishable and no laws are broken in the process. SteveBaker (talk) 03:49, 11 April 2010 (UTC)

Yeah, in this particular experiment there's nothing going on that's very interesting or problematic. Bell's theorem is that there are ways to measure the entangled particles that can't be reproduced with match sticks, but even then there's no information communicated. The test for that is, can Alice make an arbitrary yes/no decision after she and Bob part company, and then somehow let Bob figure out what her decision is faster than light. It's still impossible. Rckrone (talk) 05:25, 11 April 2010 (UTC)

What do these formulae mean?

$W={\frac {\lambda x}{d}}\,$

$v={\sqrt {\frac {T}{\mu }}}$

$\theta _{I}=\theta _{R}$

${\frac {\sin {\theta _{i}}}{\sin {\theta _{r}}}}={\frac {v_{1}}{v_{2}}}=n$

$n_{1}\sin {\theta _{1}}=n_{2}\sin {\theta _{2}}$

What do each of these various formulae mean?--Alphador (talk) 02:14, 11 April 2010 (UTC)

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn how to solve such problems. Please attempt to solve the problem yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

MISEVALUATION--Alphador (talk) 02:56, 11 April 2010 (UTC)

You might find Snell's law a helpful article to start at. Your first equation looks like a common representation for the result of a double-slit experiment. Technically, any of these equations can mean anything, because you have not defined what the variables represent - but most of them are standard-form, standard-notation equations for some elementary optical physics. Nimur (talk) 02:44, 11 April 2010 (UTC)

And your second equation looks like uncommon notation for the frequency of a pendulum. Again, it can mean anything if you don't define v, T, and μ. Nimur (talk) 02:50, 11 April 2010 (UTC)

Thank's for the article on Snell's law, it is very helpful. I don't know what the variables stand for, that's primarily what I want to find out.--Alphador (talk) 03:04, 11 April 2010 (UTC)

You might be better off looking for more information at wherever you got those equations from. They all look like items from the waves and optics chapter of an introductory physics text. However, the symbols used in equations often vary from text to text and course to course. We could make educated guesses about what they each mean, but to be certain you'd need to know where they came from. Dragons flight (talk) 03:36, 11 April 2010 (UTC)

I do not recognize the first equation, the second equations is the speed of propagation of a wave in a vibrating string, the third one is the law of reflection, and the last two are two different ways to express Snell's law. Dauto (talk) 04:02, 11 April 2010 (UTC)

First equation could be to do with diffraction, although I would expect to see an expression involving sin(θ) on the left hand side. Gandalf61 (talk) 08:55, 11 April 2010 (UTC)

Owl species

What is the species of these owls? --Tyw7  (Talk • Contributions)   Changing the world one edit at a time! 03:02, 11 April 2010 (UTC)

• 
  Unknown owl #1
• 
  Unknown owl #2
• 
  Unknown owl#3

#2 looks like a variety of Barn Owl. --Jayron32 03:14, 11 April 2010 (UTC)

The second one is without a doubt a Barn owl (Tyto alba). The second one is maybe a Northern Saw-whet Owl (Aegolius acadicus) or a Screech-owl (Megascops)? --The High Fin Sperm Whale 03:17, 11 April 2010 (UTC)

Whale, I take it the 2nd second is really the 1st ? StuRat (talk) 03:21, 11 April 2010 (UTC)

I think the one on the left is a Little Owl -- Athene noctua, the white 'eyebrows' are the clincher. I agree that the one on the right is a Barn owl -- Tyto alba. SteveBaker (talk) 03:23, 11 April 2010 (UTC)

How about the 3rd owl? --Tyw7  (Talk • Contributions)   Changing the world one edit at a time! 04:20, 11 April 2010 (UTC)

My guess is the Great Grey Owl (Strix nebulosa). --The High Fin Sperm Whale 04:50, 11 April 2010 (UTC)

I was going with Barred Owl - but now that I look, I think I agree that it's a Great Grey Owl. SteveBaker (talk) 04:52, 11 April 2010 (UTC)

Is there a way to create a barrier to light rays that LOWERS THEIR FREQUENCY using light or energy?

I have a question.

Is there a way to create a temporary "barrier" (that does not use matter, but energy or light) that would cause all light particles that contact it to reduce in frequency —for instance, turn visible light into infrared rays, or infrared into microwaves.

And could such a "barrier" be created with energy or light waves, and not any actual physical matter? Pine (talk) 03:03, 11 April 2010 (UTC)

No - there is no such thing. SteveBaker (talk) 03:17, 11 April 2010 (UTC)

You could use gravitational redshifting. Gravitational fields contain energy, though it's not like you can just make it like you can light. Also, any form of energy will have a gravitational field, so technically that works. This only will reduce the frequency going in one direction, and will increase it if it goes the other way. — DanielLC 06:06, 11 April 2010 (UTC)

Also, there is no such thing as energy that exists by itself without associated matter or light. So by asking for a barrier made of energy but not matter you already reached the impossible, even without trying to reduce the frequency. Ariel. (talk) 07:26, 11 April 2010 (UTC)

Well, you can have energy without matter - a photon has energy, but it is a boson, whereas all matter consists of fermions. What you can't have is energy without mass (or vice versa) because of mass-energy equivalence. Gandalf61 (talk) 08:49, 11 April 2010 (UTC)

In a certain sense, you can do it with matter. Just let the light heat up an object; it will then re-radiate light at a frequency, or rather a spectrum of frequencies, determined by its temperature. If you don't let it get too hot, the bulk of that radiation will be at a lower frequency than the incoming light.

Of course this is rather indirect — it's quite unlike a frequency doubling crystal, which can be thought of much more directly as shining infrared light in and getting green light out. --Trovatore (talk) 09:30, 11 April 2010 (UTC)

Of course you can do it with matter. —Preceding unsigned comment added by 92.8.98.253 (talk) 22:21, 11 April 2010 (UTC)

Filling a volcano with water

This might sound like a strange idea but I thought I'd ask about it anyway... If you were to fill the craters of the world's volcanoes with water, what would happen? Would the cap of the volcano be kept cooler and therefore possibly stave off an eruption? And if there was a violent eruption, would the water either A) decrease the amount of ash that was ejected into the atmosphere or B) be vaporized and therefore provide the moisture necessary for that ash to rain back down sooner? Dismas|^(talk) 03:32, 11 April 2010 (UTC)

Well, if it's an active volcano, the water will likely boil away faster than you can pump it in...but eventually, I suppose, you'd make a thin insulating crust over the lava pool that might allow you to fill things up a bit. But the power of a typical volcano isn't going to be suppressed that way - either you'd end up with an explosion instead of a slow oozing of lava - or you'd maybe cause the lava to force it's way to the surface via some other route. I don't think you have a hope in hell of shutting the thing down. SteveBaker (talk) 03:40, 11 April 2010 (UTC)

Agreed. Note that many calderas already contain a crater lake. StuRat (talk) 03:43, 11 April 2010 (UTC)

Explosive volcanic eruptions (as opposed to comparatively gentle flow of lava) are directly correlated with the amount of water in the magma: more water, more explosion, since the water flashes to steam when pressure is released. Water on top of the magmatic mass would exert little cooling effect (there are submarine eruptions all the time, although explosive eruptions are suppressed in deep water by pressure). See Phreatic eruption for a discussion of the role of water in volcanism. On land, water + magma = boom. Acroterion _(talk) 03:48, 11 April 2010 (UTC)

The OP should keep in mind that the part of a volcano you can see (the mountain bit) is actually only a small part of the actual volcano. Think "iceberg". The actual structure is many orders of magnitude larger than the mountain you see at the surface; and the processes that cause an eruption occur many miles underground, and nothing you can do at the surface is going to affect it. It would be like trying to stop a bullet by placing a thimbleful of water into the barrel. --Jayron32 03:51, 11 April 2010 (UTC)

There have been some very active submarine volcanoes. Surtsey started out as a volcano 130m underwater. Kolumbo in the Aegean Sea is another example. Gandalf61 (talk) 08:42, 11 April 2010 (UTC)

Okay, so it wouldn't stave off the eruption. What about the plume of ash in the second half of my query? Dismas|^(talk) 03:53, 11 April 2010 (UTC)

No, it would just add steam and water vapor to the ash cloud. --The High Fin Sperm Whale 04:48, 11 April 2010 (UTC)

Wet ash probably will not travel as far as dry ash. The amount of ash will be the same, but it will fall down faster. Ariel. (talk) 06:51, 11 April 2010 (UTC)

I doubt even that. Any water in the caldera will be vaporized in seconds, and the mass of water that any such caldera would contain would be insignificant compared with the mass of ash. Perhaps for the first few seconds of an eruption, one might see such a wet-ash effect (and that's a very small maybe, I still doubt it will have any effect), but for the bulk of the eruption, there will be zero effect. --Jayron32 12:06, 11 April 2010 (UTC)

Water makes volcanoes worse, not better. John Riemann Soong (talk) 21:40, 11 April 2010 (UTC)

Enough water can make them better, like if they are under miles of water. Volcanoes down there rarely pose problems for those of us on the surface. StuRat (talk) 00:40, 12 April 2010 (UTC)

Water + volcano? Bad ideas. See Lahar 66.133.196.152 (talk) 09:28, 12 April 2010 (UTC)

The Cumbre Vieja volcano is already partly filled with water, increasing the risk for a potential collapse of its western flank. The Erta Ale volcano may have water surrounding its base due to sea level rise and this may initiate the rifting in the area. There are also active subglacial volcanoes underneath the West Antarctic ice sheet such as the one under Pine Island Bay, which if they erupt could have an effect on global sea levels. ~AH1^(TCU) 00:38, 15 April 2010 (UTC)

Destroying the Earth

Is there any weapon by which the entire planet Earth can be destroyed into pieces? --Galactic Destroyer (talk) 07:12, 11 April 2010 (UTC)

You probably want this website for complete and detailed instructions. Ariel. (talk) 07:20, 11 April 2010 (UTC)

No. (At least not one known to humans.) Axl ¤ [Talk] 08:07, 11 April 2010 (UTC)

I agree - the answer is "No". If you absolutely, utterly have to find a way to do it (eg, for quasi-believable fictional purposes) then I recommend the idea of using the Large Hadron Collider to make a particle called a strangelet - which has the peculiar property of changing anything it touches into another strangelet. This would result in a chain reaction that would result in the entire planet turning into a blob of strangelets about the size of a golf ball over the course of just a few minutes. However, the idea that strangelets actually exist is highly speculative and controversial - the idea that you could create one using the LHC is even more speculative and even less likely - and the idea that they would be stable enough (when not at the core of a large neutron star) to remain stable for long enough to achieve the destruction of the earth is yet more speculative than that. But, it's not currently known to be definitely impossible - and for the purposes of sci-fi, that's usually good enough! SteveBaker (talk) 14:03, 11 April 2010 (UTC)

Is it possible to change the orbit of a large comet using a space probe so that it can collide with earth? --Galactic Destroyer (talk) 16:04, 11 April 2010 (UTC)

Changing the trajectory of asteroids has been suggested before, usually to avoid an impact event but I don't see why it couldn't be used to create one as well. But even if you were to turn a near miss into an impact using a method like this, it wouldn't blow the world into little pieces. You'd need a huge body to do something like that, something closer to the size of the moon than the size of a comet, and I don't think it's feasible to make the moon smash into the earth with current technology. TastyCakes (talk) 16:26, 11 April 2010 (UTC)

Even the moon would not be enough. It might hurt people, the the earth itself will still be there in one piece. You would need something much larger, like venus. Ariel. (talk) 18:11, 11 April 2010 (UTC)

"Hurt people"? I'm pretty sure if you drop the moon on the Earth, you'd boil most of the seas and atmosphere and kill all macroscopic life. But you're right, the chunk of rock would mostly remain in one piece unless you somehow gave the moon far greater velocity than it has now. Dragons flight (talk) 18:20, 11 April 2010 (UTC)

Also see giant impact hypothesis: scientists think that the moon may have come from a collision between Earth and a Mars-sized object. It presumably had a big effect on surface conditions, but Earth is still around. Paul (Stansifer) 19:11, 11 April 2010 (UTC)

It would have turned the Earth back into a molten ball. To actually permanently blast the Earth into pieces that would never re-accumulate to form a new Earth, the object would have to be going a substantial portion of the speed of light, I'd think. StuRat (talk) 19:18, 11 April 2010 (UTC)

You'd need something of order several times the gravitational binding energy of the Earth (2×10³² J). So you'd "only" have to get a mass the size of the moon up to a few hundred km/s or so. Dragons flight (talk) 19:32, 11 April 2010 (UTC)

Would that be enough to blast all the parts of the Earth out of the solar system, in different directions ? Otherwise, if they are all left in about the same orbit the Earth has now, I'd expect them to come back together over million or billions of years. StuRat (talk) 22:51, 11 April 2010 (UTC)

Well, first, if the earth was blown into little bits, which over the next 1,000,000,000 years reformed into a planet, I would argue that it is not the same planet, especially since there would be no one left who could differentiate. Googlemeister (talk) 19:16, 12 April 2010 (UTC)

See also this discussion Count Iblis (talk) 01:28, 12 April 2010 (UTC)

Try the Illudium Q-36 Explosive Space Modulator. Are you having trouble seeing Venus? Nyttend (talk) 02:07, 12 April 2010 (UTC)

Or, you might try using a Death Star. 24.23.197.43 (talk) 07:47, 12 April 2010 (UTC)

Yes. I just finished testing a Earth Destroying Weapon yesterday and it did a very good job of the portion of the Earth which I used to test it. I need more money though to make it large enough to destroy the whole Earth. You can make an offer to lease it on my talk page and if I accept I'll provide you with the email address for my PayPal account. CHeers.

Nitrogen/neon atmosphere

According to our article on the gas neon, it is a common element in the universe. So, here's a question. Let's assume you have a planet that has an atmospheric mixture of 60% nitrogen, 20% neon and 20% oxygen at say, about 0.95 atmospheres at datum level. Would there be any impediment to human life in such an atmosphere? We're assuming "liveable" temperatures here. Googling suggests that neon poses no problems re: toxicity at Earth-like conditions, but I thought I'd ask. Thanks in advance. Peter Greenwell (talk) 09:07, 11 April 2010 (UTC)

Neon is entirely inert; even moreso than nitrogen. I suspect there would be little differnce, vis-a-vis breathability with any atmosphere that was about 20% oxygen and 80% inert gases, regardless of the identity of the inert gases, be they argon, neon, or nitrogen. --Jayron32 12:03, 11 April 2010 (UTC)

Deep ocean divers sometimes use a mixture of neon and oxygen as a Breathing gas - so we have definite knowledge that it's harmless as a replacement for Nitrogen. Since it is a 'noble gas' it won't react with anything, so that's no surprise. SteveBaker (talk) 13:48, 11 April 2010 (UTC)

However, some articles related to trimix find the presence of various amounts of nitrogen (and alternative non-oxygen gases) has some effects on, for example, High pressure nervous syndrome. Those all seem to be about reducing negative effects seen at high pressure, so it's not clear if the studies are relevant to nitrogen-content at normal atmospheric pressure (i.e., where we have evolved to live, and where our "normal" for health baselines is). DMacks (talk) 17:42, 11 April 2010 (UTC)

Right: nitrogen's not quite inert: see for example nitrogen narcosis. Interestingly, that article suggests that helium and neon are the only gasses that don't have a narcotic effect at high temperature pressure. I guess the narcotic effect is due not to the chemical reactivity of the gas (as oxygen toxicity is), but rather to the physical process of the gas dissolving in body tissue at high pressures. Huh, I learned something new today. Buddy431 (talk) 20:43, 11 April 2010 (UTC)

That should be high pressure in the second sentence. Argon#Safety does not mention its narcotic properties, should it, or is it so close to oxygen and nitrogen that it doesn't really matter? --NorwegianBlue ^talk 21:30, 11 April 2010 (UTC)

Right you are (fixed now). As for Argon, I don't think that it's typically breathed under high pressure, (as nitrogen or oxygen might be, in SCUBA equipment), so there's probably not much of a need to state that it has narcotic effects at high pressures. If the nitrogen narcosis article is right, that nearly every gas has this effect at high pressures, then it seems sort of pointless to list it for every gas, and should probably be only listed for gasses that might be breathed at high pressure. Buddy431 (talk) 22:45, 11 April 2010 (UTC)

Usually, they breathe helium and oxygen - but that makes their voices squeaky - so in some applications, they use neon and oxygen because the neon has more similar density to nitrogen and hence does not distort voices noticably. Neon is more expensive than helium though - so not many divers use it. In either case, the entire point of doing it is because those gasses DON'T dissolve in the body tissues when under pressure to the extent that nitrogen does - and hence avoids most of the problematic depressurization issues. SteveBaker (talk) 13:32, 12 April 2010 (UTC)

Nitrogen narcosis isn't a depressurization issue (the bends are though). Nitrogen narcosis happens at depth due to... well the articles not real clear on it, but it doesn't involve gasses coming out of solution, as the bends do. Buddy431 (talk) 14:16, 12 April 2010 (UTC)

Plants

Hi. Are there any plants that benefit from the use of a slice of lemon placed on top of the soil in a pot? Thanks. ~AH1^(TCU) 16:06, 11 April 2010 (UTC)

Not sure about lemon particularly but there are plants that like acidic soil (http://www.winsfordwalledgarden.com/development.aspx?Page=Acid_lovers). ny156uk (talk) 16:16, 11 April 2010 (UTC)

(edit conflict)I would think lemon juice (namely the citric acid) would make the soil somewhat more acidic, which would benefit any plant that likes acidic soil. But that would depend on the soil pH before you add the lemon, the amount of lemon you had and so on. I would suspect one slice wouldn't have much effect since they're not that acidic, but that's just a guess. TastyCakes (talk) 16:20, 11 April 2010 (UTC)

Note that the lemon slice will soon rot, and may give off a strong smell once it gets fuzzy. For this reason, you may do better to squeeze out some juice and discard the slice, at least for indoor plants. StuRat (talk) 16:25, 11 April 2010 (UTC)

What causes the strong smell? ~AH1^(TCU) 01:24, 12 April 2010 (UTC)

Mold spores ? StuRat (talk) 02:38, 12 April 2010 (UTC)

Stains

Why are stains, especially water-based ones (even for water alone), invariably darker at their perimeter, yet frequently invisible at the center?--Shantavira|^{feed me} 17:12, 11 April 2010 (UTC)

"Invariably"^{[citation needed]}--can you be more specific about what sorts of stains you are talking about--the effect of a water-based material spreading out on the surface and/or the water (and possibly stuff it in) altering the surface itself could be two different effects. For example, if I spill water on a not-water-proof painted surface, the water can dissolve the paint at the point of the drip and carry it outward as the drop expands until the water evaporates. Repeat, repeat, repeat, and now the wood winds up bare in the middle and the extra paint spread out from it. DMacks (talk) 17:26, 11 April 2010 (UTC)

I can think of several possible reasons:

1) Miniscus. Since water droplets on non-absorbent materials are curved, there's more surface area near the edges, so, when they dry, those items carried on the surface of a drop (like dust and pollen) accumulate more on the edge than in the middle.

2) Diffusion. Since the water is pulled by capillary action along an absorbent material, and pulls the contaminants along with it, they tend to continue to be carried along until the water dries, and the stain thus forms at the boundary where the drying occurs.

3) Perception. In the middle you are comparing it with areas stained nearly the same amount, while, at the edge, you're comparing it with unstained areas. Thus, the edge appears to be stained more, by comparison. StuRat (talk) 17:36, 11 April 2010 (UTC)

The stain dries from the edges first. As it does, water plus dirt is pulled toward the edge to equalize the wetness. This causes more dirt to be at the edge vs. the middle. Ariel. (talk) 18:07, 11 April 2010 (UTC)

Ah, that sounds right. Thanks. Re my "invariably", see the illustration accompanying the stain article, or Google images of "water stain".--Shantavira|^{feed me} 18:56, 11 April 2010 (UTC)

Yes, it is right. It's an effect similar to the one that leads to the formation of moraines. Dauto (talk) 03:23, 12 April 2010 (UTC)

Of course, wikipedia has an article: coffee ring. Enjoy, Robinh (talk) 07:58, 13 April 2010 (UTC)

Systolic and diastolic blood pressure

Hi everyone, I know what systolic and diastolic blood pressures are but I'm not really sure what are the different factors that increase/decrease systolic and/or diastolic blood pressure. Can anyone explain to me what the factors are and a little about the mechanism behind it?

Thanks a million! :) —Preceding unsigned comment added by 116.15.143.83 (talk) 17:23, 11 April 2010 (UTC)

Our blood pressure article would be a good place to find this information, as well as specific articles related to Systolic and Diastolic parts. DMacks (talk) 17:30, 11 April 2010 (UTC)

internal balance

All life must maintain an internal balance, despite environmental changes. This is called _____. —Preceding unsigned comment added by 98.236.88.134 (talk) 20:04, 11 April 2010 (UTC)

This is called a homework question. DMacks (talk) 21:02, 11 April 2010 (UTC)

Aw, come on. We could at least tell the questioner that the word s/he seeks begins with the same four letters as "homework", and that our article Life would be a reasonable place to start looking. --NorwegianBlue ^talk 21:07, 11 April 2010 (UTC)

Or you could paste the sentence into Google, which gives the answer in about two seconds. Looie496 (talk) 21:43, 11 April 2010 (UTC)

Venus of Willendorf

Were there fat people around ~20,000 years ago? I had the impression nutrition was pretty poor for everyone, but Venus of Willendorf suggests other wise. Would she have to be a queen or something, while her minions ran around desperately trying to gather/kill enough food to feed her? Aaadddaaammm (talk) 20:10, 11 April 2010 (UTC)

From the article, clearly we don't know for sure what it was for (it's not like it came with a book of instructions). As the article notes "not a realistic portrayal but rather an idealization of the female figure"; I guess when you live in a world with naught but skinny nomad women, that's what you'd idealise. Thinking it's meant to actually display a real person is like some future people discovering images of Jessica Rabbit or Jordan and mistakenly thinking such forms could actually exist. -- Finlay McWalter • Talk 20:26, 11 April 2010 (UTC)

Even at the Last Glacial Maximum when things were at their worst, there surely would have been isolated places and times when there was way more food than people to eat it. Looie496 (talk) 21:09, 11 April 2010 (UTC)

Lol, that’s really funny when you think about it! It's not like the women you see in magazines these days are "realistic depictions of real people" either! 2000 years from now they might dig up some playboy magazines and wonder if anyone ever actually looked like that. :) Vespine (talk) 04:12, 12 April 2010 (UTC)

"Professor, it appears that AIDS was more wide-spread than we thought, as clearly all the women in this magazine are suffering from some terrible disease. Yet, somehow, they still managed to smile. Weren't our ancestors brave ?" StuRat (talk) 00:34, 12 April 2010 (UTC)

Female body shape discusses some of the cultural norms regarding female body shape in various places and at various times. --Jayron32 02:02, 12 April 2010 (UTC)

All it takes for obesity is agriculture and the social stratification that allows a few people access to excess. alteripse (talk) 10:41, 12 April 2010 (UTC)

Alteripse hit the nail on the head of what I am asking. Was there agriculture and social stratification ~20,000 years ago in Europe? Aaadddaaammm (talk) 13:28, 12 April 2010 (UTC)

Things may have changed since the last time I read anything about this, but I'm pretty sure the standard interpretation of Venus of Willendorf and similar figurines is that the depicted females are pregnant and symbolize fertility - of humankind, of earth and nature in general or both. Of course, she's also rather plump and well-fed, which was probably the ideal back then, as pointed out by others. Again, as far as I remember, Venus of Willendorf is not believed to reflect a society with social stratification but a relatively primitive and egalitarian one.--91.148.159.4 (talk) 15:23, 12 April 2010 (UTC)

To answer aaadddaaammm's first question, there was certainly no agriculture in Europe, or anywhere, in 20 000 BC. There may have been extremely limited social stratification (i.e. people who fight better get to eat more, or something), but agriculture and "civilization" won't arise until after 10 000 BC. Buddy432 (talk) 16:58, 12 April 2010 (UTC)

Interesting, so then how did people know what a fat woman looked like? Aaadddaaammm (talk) 17:27, 13 April 2010 (UTC)

Probably, there were occasional periods and areas of relative well-being, and during those periods and in those areas people stuffed themselves - until they became plump, if given the chance. Then they starved again, then they stuffed themselves again, etc.. Fortunes change. There were always reasons for some clans to have more success as hunters-gatherers than others, and hence to become fatter.--91.148.159.4 (talk) 18:53, 13 April 2010 (UTC)

Miscellaneous Meteorology

These are newbie questions, and I would appreciate answers to them, because they pertain to a piece of writing I'm working on. How does the coriolis effect work on the Thermohaline Current? I understand what it is, roughly, and I think it would determine what direction the current would turn if it hit a coastline, but I'm not sure. There's a type of wind that comes down from high mountains as the air there cools slightly and falls, and warmth is carried along. What is this type of wind? Assuming that one were to take a mountain area where there was such a wind, would increasing the absorbent ability of the rock (i.e. making it blacker) increase the heat of the area and increase the heat and strength of the wind?

Thanks. —Preceding unsigned comment added by 69.109.172.138 (talk) 21:39, 11 April 2010 (UTC)

Foehn wind such as the chinook. The effect doesn't arise from the heat of the mountains but from their height and shape. Rmhermen (talk) 00:13, 12 April 2010 (UTC)

Also take a look at Thermohaline circulation, which is influenced by the shape of coastlines in addition to wind circulation caused by pressure gradient. ~AH1^(TCU) 00:33, 15 April 2010 (UTC)

Swallowed by a whale

Has there ever been a verifiable recorded case of a human being swallowed whole by a whale, but managing to get out somehow and living to tell the tale? Except for Johah, I mean - as with many stories from the Bible, there can be considerable doubt as to whether it happened exactly as described, or if it even happened at all (and isn't just a legend or a metaphor for something else). Did it ever happen during the days when whaling was far more widespread than it is now? --95.148.104.124 (talk) 21:44, 11 April 2010 (UTC)

The only recorded story that I've heard is the James Bartley story, which is purely fiction. It has been repeated with a different character replacing James Bartley to make it a local legend to various seaports - which makes it even more fiction. -- kainaw™ 22:16, 11 April 2010 (UTC)

Does whale physiology even allow such a thing? How far into a whale could a human-sized object get? 149.169.59.6 (talk) 02:04, 12 April 2010 (UTC)

Let's think for a moment about the conditions in the whales' stomach. There is no air there. The liquid is hydrochloric acid. It's an environment that's highly tuned to digesting the very stuff your body is made of. It's REALLY hard to imagine you surviving in those conditions for more than maybe 30 seconds to a minute. So - your only chance is to hack your way through several feet of muscle, fat and super-tough blubber. Seems astronomically unlikely to me. SteveBaker (talk) 02:35, 12 April 2010 (UTC)

Answering the question about whale physiology, some guy did a LOT of research into the James Bartley story (I'm sure the guy's name/research is easy to track down on Google). I remember reading a synopsis of his story in which a biologist stated that the largest whales could swallow a man whole, but most whales could not. As for the fake story, they understand about the air and digestion. The claim was that James was swallowed while the whale was being brought aboard a whaling ship. So, he was only in there for a short time - but was still partially digested and required medical treatment. The guy who did the research tracked down the ship he supposedly fell from and talked to both the captain and his wife - both refuted the story. He went to the hospital which supposedly gave him treatment. All there refuted the story. He checked the ships logs, which had no record of a James Bartley. He even went further, but honestly, is there any reason to believe that a while swallowed a man who lived through the process? -- kainaw™ 02:57, 12 April 2010 (UTC)

As to whether it would be possible for a whale to even swallow a human whole, probably not. Most toothed whales like dolphins and orcas aren't nearly large enough to do so, and baleen whales, which look large enough, aren't apparently built right. Blue Whale#Size indicates that, while their mouths are large enough to hold something like 90 metric tonnes of food and water, their throats are only large enough to fit an object the size of a "beach ball". I suppose, if it was a small man, and if he were oriented just right, he could wiggle down there. --Jayron32 04:18, 12 April 2010 (UTC)

"...your only chance is to hack your way through several feet of muscle, fat and super-tough blubber." - or be vomitted up by the whale, which could conceivably happen in the required time frame (assuming that you could be swallowed in the first place). Mitch Ames (talk) 09:14, 12 April 2010 (UTC)

Do whales have a gag reflex, as a matter of interest? --Kurt Shaped Box (talk) 10:03, 12 April 2010 (UTC)

They do seem to spit out unwanted items. In one of the David Attenborough specials, they were filming the whales make a bubble net and then lunge for the fish at the surface. Birds were also diving for the fish, and one got swallowed. The whale spit it out, and it survived. The divers filming underwater hoped the same would happen if they got swallowed, but were lucky enough to not have to test that theory. Note that "swallowed" here probably just means "taken into the mouth", not the stomach. StuRat (talk) 16:01, 12 April 2010 (UTC)

Sperm Whale, Physeter catodon at MarineBio.org says the following.

The gullet of Physeter catodon is the largest among cetaceans; it is in fact the only gullet large enough to swallow a human.

-- Wavelength (talk) 14:32, 12 April 2010 (UTC)

Not a whale per se, but how about a Whale shark? Is it's digestive system capable of ingesting an entire human with minimal harm? Googlemeister (talk) 15:47, 12 April 2010 (UTC)

No, it's set up like a whale, to digest small food, not people. StuRat (talk) 15:55, 12 April 2010 (UTC)

According to http://mlbible.com/matthew/12-40.htm, Jesus Christ believed that Jonah had been swallowed by a sea creature.

-- Wavelength (talk) 16:30, 12 April 2010 (UTC)

A lot of people believe a lot of things that aren't true...it doesn't make them true. But I don't think we're seriously objecting to the idea that someone might somehow be swallowed by a whale - the issue is how they might possibly survive to tell the tale. SteveBaker (talk) 17:59, 12 April 2010 (UTC)

Well, the way I see it, you have three options if actually swallowed by a whale:

1. Make the whale vomit
2. Pull out your knife/machete (presuming that you have one) and try to cut your way out
3. Climb back up its oesophagus and out the mouth

2. and 3. may also work to elicit 1. I don't suppose that the whale would enjoy having a signal flare set off in its innards either.

Are you certain that there's no air present in the stomach of a whale, Steve? I mean, I know literally nothing about the digestive processes of Sperm Whales - but I always thought that stomachs in general had some sort of (presumably fucking foul) air/contents boundary. Do whales digest food quickly - or are they more like snakes, in the sense that food can sit in their stomachs for a couple of weeks before it is broken down? --Kurt Shaped Box (talk) 18:20, 12 April 2010 (UTC)

Why would there be air there? Whales swim at great depths - air in their stomachs would be a liability - if it got in there somehow, they'd probably just belch it out. If there were gases in there, I doubt it would be very breathable anyway. SteveBaker (talk) 02:45, 13 April 2010 (UTC)

Being mammals, I'd expect them to have a reasonably fast digestive system, like ours. But, of course, only the first stage of digestion is in the stomach, with the intestines doing most of the work. StuRat (talk) 01:22, 13 April 2010 (UTC)

You could buy a little time by hacking your way from the stomach into the whale's lungs - then you'd have enough air for several hours while you decide what to do next. Mitch Ames (talk)

Still - you arrive there - it's dark, there no air, you don't know which way is up and which down, your skin is probably burning from the pH 1 or 2 acid that's all around you. I doubt the stomach walls are staying still - so you don't have any kind of good footing. You probably got pretty roughed up by the whole business of being in the water, grabbed an swallowed. You'd be far too disoriented to make a serious plan. Get real - you don't stand a hope in hell! SteveBaker (talk) 02:45, 13 April 2010 (UTC)

You should probably count your senses :-) Mitch Ames (talk) 05:36, 13 April 2010 (UTC)

How about a Finding Nemo option where the individual were just inside the mouth cavity for a short period. This seems a lot more feasible. I believe in The Holy Bible, but you can't take some things literally. It is a physical impossibility that Noah harvested 2 of every terrestrial species. If Noah had that technology, ability to travel, and knowledge, he also could have orbited the earth in an awesome space station. Humankind today couldn't even come close to achieving this.--FUNKAMATIC ~talk 03:28, 14 April 2010 (UTC)

Mystery Box

Hi. In a recent lab I had, I had to determine the contents of a mystery box. I was told that there were two impedances, Z₁ and Z₂, and that in total there were 3 circuit elements (they can either be a resistor, capaictor, or inductor). Now, I was able to short the Z₂ element, which allowed my to isolate Z₁. I then added a resistor in series with Z₁ and ran an alternating current through the circuit (resistor is between input generator and Z₁. What I saw was a low-pass filter. I reasoned that this meant that there would be a capacitor in Z₁, because an RC circuit produces a low-pass filter when run through an alternating current (the voltage was measured across Z₁). Looking more closely, I saw that at high frequencies, the voltage died down to zero, but at low frequencies the voltage wouldn't reach the voltage of the generator (as would be expected if Z₁ were just a capacitor), but a value a bit lower than that.

When I was doing the lab, it struck me as very obvious that this implied that Z₁ consisted of a capacitor in parallel with a resistor. The problem is that I forget why. Can anyone help lead me in the right direction? Thanks. 173.179.59.66 (talk) 22:13, 11 April 2010 (UTC)

Alright, so I was able to answer my original question, but how would I get the capacitance with a bode plot? 173.179.59.66 (talk) 03:09, 12 April 2010 (UTC)

See the article Bode plot. Figure 1(b) and the section 3 Example describe the lowpass case. Cuddlyable3 (talk) 23:29, 12 April 2010 (UTC)

Least common cause of death

What is the least common cause of death in human history? Of course, every death is unique, with many just a variation on the same official cause, but what is the least common official cause. To qualify it further, if every human death had resulted in an autopsy, what would be the least common cause recorded on the autopsy reports. Thanks JohnnyShadow (talk) 22:38, 11 April 2010 (UTC)

The least common non-cause of death must be the case of Phineas Gage. Cuddlyable3 (talk) 09:36, 12 April 2010 (UTC)

Such a claim would be impossible to prove or conjecture on. There are likely thousands or millions of "unique" deaths, depending on how you define the "cause" of death. The graph of "cause of death" in the modern world has large numbers dying of things like heart disease and cancer and infectious disease and then a VERY long tail where all of the randomly weird causes of death lie. For example, there have been only been three people in the history of the world to be killed by exposure to the vacuum of outer space, see Soyuz 11. --Jayron32 23:09, 11 April 2010 (UTC)

Which also illustrates the problem of counting. Three cosmonauts died of exposure to outer space, but if you instead labeled those deaths as "asphyxiation" then it would be relatively common. At least one person has died by driving a big rig off the S-curve in the Oakland Bay Bridge, while many people die in traffic accidents. Many deaths can appear unique, or nearly so, if you describe them in enough detail, but there is nothing particularly special about that. Dragons flight (talk) 23:35, 11 April 2010 (UTC)

And some people would argue that we all die from the very same thing, lack of oxygen to the brain, and there are no unique deaths. Dismas|^(talk) 23:36, 11 April 2010 (UTC)

They'd very clearly be wrong. A brain reduced to a pulp by a bullet or smashed into a jelly in an explosion needs no lack of oxygen to be a very dead thing. --Tagishsimon (talk) 00:15, 12 April 2010 (UTC)

Indeed. Almost all people die from lack of oxygen to the brain. A few do die from physical trauma to the brain. --Tango (talk) 00:58, 12 April 2010 (UTC)

Not to mention that one can die from excess oxygen to the brain, as well. Like my old electronics professor said, "if it doesn't work, that means either there is a contact where there shouldn't be one, or there is no contact where there should be one". No, seriously, lack of oxygen to the brain is not the only ultimate cause of death. --Dr Dima (talk) 00:28, 12 April 2010 (UTC)

I don't think oxygen toxicity directly causes death very often. When it does, I think it is more likely to be due to damage to the lungs resulting in a lack of oxygen to the brain than the actually effects of too much oxygen in the brain (which are things like nausea and seizures). --Tango (talk) 00:58, 12 April 2010 (UTC)

Alexander Litvinenko died of a rare cause of death. Bus stop (talk) 01:03, 12 April 2010 (UTC)

That depends on how you define it. Homicide is a fairly common cause of death, and death from radiation sickness is a bit less common, but not exactly rare. If you define that more broadly as death from exposure to radioactive elements, then millions have probably died from lung cancer due to exposure to radon gas. StuRat (talk) 01:12, 12 April 2010 (UTC)

Kurt Gödel starved himself to death because of a fear of being poisoned. Count Iblis (talk) 01:19, 12 April 2010 (UTC)

Biology should be our concern. Life being a biological process, we should want to concern ourselves with that which interrupts that process, resulting in death, especially in those cases where the person is young and/or otherwise healthy. Cause of death can probably be understandably less clear in old age and/or otherwise poor overall health involving many weaknesses in the biology supporting life. Bus stop (talk) 01:30, 12 April 2010 (UTC)

I typed unusual deaths in the search box and wasn't surprised to hit a redirect: List of unusual deaths. It would have been unusual if Wikipedia didn't have something like that. See also Darwin Awards#Examples and more at http://www.darwinawards.com if you have a morbid sense of humor. PrimeHunter (talk) 01:34, 12 April 2010 (UTC)

No person has ever died because they were shot by User:Nyttend. Nyttend (talk) 02:05, 12 April 2010 (UTC)

So they all recovered from their gunshot wounds, then ? StuRat (talk) 02:33, 12 April 2010 (UTC)

No, it's just that Nyttend prefers knives.  ;-) Dragons flight (talk) 02:52, 12 April 2010 (UTC)

Apparently, two people died in a blogging accident. — DanielLC 04:42, 12 April 2010 (UTC)

You made me spray scone over my table! Vimescarrot (talk) 21:20, 12 April 2010 (UTC)

No-one has mentioned Kenneth Pinyan yet? Whoa. --Kurt Shaped Box (talk) 10:05, 12 April 2010 (UTC)

Being struck by a meteorite would probably be up there. --The High Fin Sperm Whale 18:24, 12 April 2010 (UTC)

It's hard to beat being killed by a meteorite impact, although the only recorded example involves a dog rather than a human. But my favorite story is of the Greek playwright Aeschylus, who was supposedly killed by a tortoise dropped on his head by an eagle. (Lots of people think that story is ridiculous, but it's actually pretty common for birds to drop animals with shells onto rocks to break them open, so I don't see why it couldn't have happened.) Looie496 (talk) 18:25, 12 April 2010 (UTC)

AFAIK, gulls will drop baby sea turtles onto rocks to crack them. Also, what about Soviet scientist Dr. Nikolai Ustinov? (no article?) Consumed horribly by the bioweapon that he had helped to develop and perfect after accidental exposure - and then in death, helping to advance science by becoming the source of a new, more potent strain of said bioweapon, which was named 'Variant U' by his colleagues in his honour... ---Kurt Shaped Box (talk) 18:45, 12 April 2010 (UTC)

Maybe no article because that website does not appear to be an unimpeachably reliable source. Comet Tuttle (talk) 20:05, 12 April 2010 (UTC)

Especially if he was bald. --The High Fin Sperm Whale 18:31, 12 April 2010 (UTC)

Death from laughter is surprisingly common. No more jokes on the Reference Desks, please. Comet Tuttle (talk) 20:04, 12 April 2010 (UTC)

Given the average level of funnyness of the jokes here, I don't think we have much to worry about. Buddy431 (talk) 04:48, 13 April 2010 (UTC) .

Oh dear. I'm not doing anything to remedy the situation, am I? Buddy431 (talk) 04:50, 13 April 2010 (UTC)

Backwards Ffuns video[1]. Cuddlyable3 (talk) 12:42, 13 April 2010 (UTC)

Buddy it's not the fault of your jokes, it's just the way you tell them. Cuddlyable3 (talk) 13:05, 15 April 2010 (UTC)