Wikipedia:Reference desk/Archives/Science/2007 September 10

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

September 10

Problem with Video Divs on the Reference Desk

Hello fellow reference deskers. There seems to be a glitch in syntax which is botching up the formatting for the video files posted above. (My guess it is in Template:Video, but I'm not sure). Can anyone figure this out? Surely it's wreaking havoc on other pages which use the video template, and it's doing terrible things to the Reference Desk. Nimur 01:26, 10 September 2007 (UTC)

Glitch is right! For some reason the two videos are sitting at the bottom of the page now (at least under my version of Firefox). I tried removing the <div>'s and <br> that Nimur had inserted, thinking that would help, but that led to a cascading-indent problem. Then I tried inserting a {{--}} template, which usually fixes those, but that rendered all the following sections bizarrely uneditable! WTF?! —Steve Summit (talk) 02:37, 10 September 2007 (UTC)

I've commented out the offending videos - we can't have one fscked up question screwing up the entire ref desk. SteveBaker 03:41, 10 September 2007 (UTC)

I just fixed what looked to me as two bugs in Template:Video, one of which was related to <div> usage. Now this historical form of the page appears to render correctly (or at least not crappily) for me (x11 build of Firefox1.5 on OS X). DMacks 04:23, 10 September 2007 (UTC)

Can you kill yourself with a knife

I was watching "Rome", the HBO show, and it shows a woman standing on her knees, bringing her knife to her breast quickly, thrusting, and immediately falling dead. How realistic is that? It seems quite hard to be able to a) thrust the knife in the point which contains the right spot on the chest (wherever that is), b) to thrust it with enough strength by yourself, without being weakened by the pain which occurs right after you break the skin and c) to die pretty immediately (as opposed to dying from somewhat slow-occurring blood loss).

What are the chances of successfully doing a? What are the chances of successfully doing a & b? What are the chances of doing a & b & c?

Assuming the person has lay understanding of anatomy and average strength, of course. —Preceding unsigned comment added by Knyazhna (talk • contribs) 01:38, 10 September 2007 (UTC)

See Hara-kiri.

The dagger to the breast is indeed a popular device in fiction, but I don't find it too far-fetched. A stab wound to the heart is, if not immediately fatal, nonetheless quite definitive and unrecoverable. You may not bleed out instantaneously, but it won't take long. (It most certainly will not be "somewhat slow-occurring".) And with a sharp knife, you can pretty easily slip between the ribs and puncture the heart. Yes, there'll be a moment of intense pain, but once your hands and arms are in motion I'd imagine you could follow through.

[ObDisclaimer: The Wikipedia Reference Desk cannot dispense suicide advice. If you need to kill yourself, consult a qualified professional. Jack Kevorkian's out of jail now, isn't he?] —Steve Summit (talk) 02:14, 10 September 2007 (UTC)

Thank you for your answer, but it's not quite "there". First of all, harakiri does not really apply, since you can see that by the ritual (first you cut your stomach, then your helper cuts off your head), one could be quite unsuccessful in actually killing oneself by one's own knife, and still complete harakiri (you just need good help). Also, Japanese swords are quite known for their sharpness. What is the likelihood that a woman's dagger is that sharp? Or at all sharp on any given day? Were there regular weekly sharpenings for lady's knives?

Secondly, I realize that it's possible for a&b&c to occur; I was wondering about the actual probabilities. Is it 80%? Is it 30%?

And, no, I'm not going to "try it at home" :) It really won't result in a scientific answer to my question, just anecdotal evidence. 02:57, 10 September 2007 (UTC)02:57, 10 September 2007 (UTC)~~

a: 89.1%. ("You can pretty easily slip between the ribs and puncture the heart.")

b: 76.4%. ("Once your hands and arms are in motion I'd imagine you could follow through.")

c: 93.7%. ("You may not bleed out instantaneously, but it won't take long.")

a & b: 89.1 × 76.4 = 68.07%

a & b & c: 89.1 × 76.4 × 93.7 = 63.7838%

Better than 50-50 odds. You're right: not something to try at home. —Steve Summit (talk) 03:36, 10 September 2007 (UTC)

In Seppuku, only the men disembowled themselves. Women put the knife through their throat. I suspect their is a way to rapidly reduce blood pressure in the brain which would cause near immediate unconsciousnes. --DHeyward 08:02, 10 September 2007 (UTC)

I think the original poster is referring to the suicides ordered by Nero after the discovery of the Pisonian conspiracy. Our article on Seneca the Younger says that he cut his wrists and took poison and his wife attempted suicide by cutting her wrists. Our article on Lucan says he "opened a vein". I suspect that the dagger to the heart scene is a piece of dramatic licence. Gandalf61 08:54, 10 September 2007 (UTC)

Cato pulled out his own intestines following the Caesar-Pompey Roman Civil War, there's a new method for you to consider! He supposedly ripped out his own stitches from a previous semi-first-stage-hari-kari attempt and just yanked them out.... SGGH ^speak! 14:41, 10 September 2007 (UTC)

Cato really had guts, and no one could deny it. Edison 14:51, 10 September 2007 (UTC)

Under the subsection Seppuku in modern Japan it says that in “In 1999, Masaharu Nonaka . . . slashed his belly with a sashimi knife to protest his forced retirement. He died later in the hospital.” So I guess you can at least cut your belly. I have also heard however that there is a reflex that stops most people from stabbing themselves, which is why people must literally fall on their knives. Either way I’m pretty sure it would be a quite painful death. I think if you were hyped up enough on adrenalin it might be realistic though. One other thing, I saw a performance of Romeo and Juliet where Juliet stabs herself UNDER her right ribcage. Anybody know if this is realistic? --S.dedalus 22:57, 10 September 2007 (UTC)

Probably she was stabbing up under the ribcage towards the heart instead of trying to go between the ribs. I could not recommend the ease of this route in practice, but I believe that it is at least easier theatrically. Eldereft 20:25, 11 September 2007 (UTC)

aircraft weapons

i herd that during one of the world wars a fight aircraft was built and it had the machine gun placed behind the propeler.when the pilot was shooting the bullets would fly right between the propellers arms without ever touching them.please tell me if this is possible and explain if you can.thanx (please excuse the spelling not an english native) —Preceding unsigned comment added by 70.1.213.243 (talk) 02:43, 10 September 2007 (UTC)

See Synchronization gear. —Steve Summit (talk) 02:50, 10 September 2007 (UTC)

Yep. The earliest planes had a V-shaped metal plate bolted to each blade of the propellor that would deflect bullets from the machine gun so they wouldn't shoot off the propellor blades - but this was kinda dangerous because the deflected bullets would fly off in all sorts of dangerous directions! Other aircraft were built with 'pusher' propellors mounted on the back of the plane so that a machinegun could fire forwards - but those planes had unwieldy twin-boom tailplane setups. Yet others used machineguns mounted on the top wing so that they would clear the prop - but those were harder to aim. The later invention of the 'interrupter gear' had a cam mounted onto the engine shaft that would push a lever to turn off the machinegun for a fraction of a second to allow the propellor blade to go past unscathed. These things eventually became used on all aircraft on both sides of the war. By WWII, the wings of modern monoplanes were sufficiently strong that guns could be mounted out to the sides of the prop - some planes had hollow prop-shafts with a gun that fired right through the center of the hub of the prop. Between those things, the interrupter was pretty much obsolete.SteveBaker 03:50, 10 September 2007 (UTC)

But numerous WWII aircraft continued to use them, such as the Me-109, IIRC. Someguy1221 04:42, 10 September 2007 (UTC)

Shotgun speaker

Would the "shotgun speaker" design at http://forums.keenspot.com/viewtopic.php?p=3063548#3063548 actually work, and if so, how does it manage the directionality? --Carnildo 03:22, 10 September 2007 (UTC)

A parabolic dish with a small speaker at the focus of the parabola and aimed back at the dish should do the job. The larger the dish the better (because - relative to the size of the dish - the speaker will be more concentrated at the focus). SteveBaker 03:33, 10 September 2007 (UTC)

You can see (and hear) this latter design in many museums, where they are used so that only a listener located directly below the speaker hears the narration for the exhibit they're looking at/interacting with.

Atlant 17:09, 10 September 2007 (UTC)

I know a parabolic reflector works. What I want to know about is the "shotgun speaker" design at that link. --Carnildo 21:18, 10 September 2007 (UTC)

That was the answer. There is a parabolic reflector inside and that's how it manages directionality. If you need more information, tell us specifically what you need. Perhaps you don't understand why a parabolic reflector results in strong directionality? If so, reply here and I can explain it. SteveBaker 14:20, 11 September 2007 (UTC)

I don't see any parabolic reflector in that description. As far as I can tell, the post is describing a bundle of steel pipes of selected lengths encased in a PVC pipe. --Carnildo 20:46, 11 September 2007 (UTC)

I'm assuming that a "shotgun speaker" is the logical inverse of a shotgun microphone; I suppose there's no reason such a device shouldn't work.

Atlant 14:21, 12 September 2007 (UTC)

urgent biology question

Here is a situation " Some babies are allergic to milk. A similar fluid made from plants can be used as a milk substitute.These fluids must be well tested to ensure that they are as nutritious as milk. They are usually tested on rats.

what is a suitable method that could be used to carry out this experiment and what apparatus would be required?

Your assistance would be much appreciated. Thank you. —Preceding unsigned comment added by 208.131.186.18 (talk) 05:18, 10 September 2007 (UTC)

This looks like homework. Have you seen Laboratory rat? Graeme Bartlett 06:59, 10 September 2007 (UTC)

Would "a similar fluid made from plants" be soy milk?--Shantavira|^{feed me} 08:08, 10 September 2007 (UTC)

Just in case you have an "urgent biology question" because you want to test your milk substitute befoe you give it to your baby, I must remind you that wikipedia does not give out medical advice SGGH ^speak! 14:42, 10 September 2007 (UTC)

Well, you'd take two bunches of rats - feed one lot milk and the other lot your plant-based concoction. Measure growth rates, disease rates, test IQ by running them through mazes, look for behavioral abnormalities, measure life span, fertility, etc. However, that wouldn't be enough. There could be chemicals in your plant-based pseudo-milk that would be carcinogenic over a period of time longer than the life-span of a lab rat. In practice, I suspect the process with Soy Milk was more like "We know there is nothing nasty in Soy beans because people have been eating the stuff for millenia - so if we liquidize them and feed it to babies, it shouldn't kill them." - you'd also have to look carefully for signs of deficiencies in the babies diets - probably adding a bunch of vitamins and minerals to make up for whatever is missing. SteveBaker 19:04, 10 September 2007 (UTC)

How many times has flight evolved?

Our article on flying and gliding animals says that flight has evolved at least four times in the animal kingdom: in insects, pterosaurs, birds, and bats. However, I seem to recall that the number should be five times, as insects have evolved two separate forms of flight; the mechanism works differently for a dragonfly than it does for a moth, for example. Is this correct? Has flight evolved four or five different times? — Brian (talk) 07:13, 10 September 2007 (UTC)

Would ya believe that we have a whole article on insect flight? It sounds like what you are talking about is the difference between direct and indirect flight, according to that article. Fascinating stuff, I had never given it a moment's thought before! --24.147.86.187 07:40, 10 September 2007 (UTC)

I think the key here is the "at least" part. In any case, I did a Google search for "the evolution of flight" and the first hit was a UC Berkeley site. It doesn't say much about insects, but has a good deal of vertebrate info. After the first search, I did a new search for the "evolution of flight in insects". And I got a bunch of cool stuff, but no dice on your question. So I plugged in "how many times did flight evolve", and I got this article, which says:

1. some investigators regard winged insects as polyphyletic (Matsuda, 1981)

2. majority favor monophyletic origin

3. Marden and Kramer (1995) defend idea flight could have evolved more than once

So I guess it is a bit, up in the air, so to speak. If you need me to find those specific refs for you, contact me on my talk page, I can email you pdfs (I gots lots of access to library sites :) ) --Cody Pope 09:08, 10 September 2007 (UTC)

The original quote said at least 4 times. The answer might well be more than 5 because we do not have the opportunity to study all of the billions of extinct species. It's perfectly possible that other animals evolved flight - but subsequently became extinct. Hence an at least statement is probably the best we can make. SteveBaker 12:29, 10 September 2007 (UTC)

Well, I suppose the subtext was "How many times has flight evolved individually in insects?" From Cody Pope's research, it seems that the majority opinion is once, although some folks think it's twice. — Brian (talk) 12:39, 10 September 2007 (UTC)

Flying fish, anybody? — PhilHibbs | talk 12:44, 10 September 2007 (UTC)

I'll see your fish, and raise you a flying squirrel. --LarryMac | Talk 14:49, 10 September 2007 (UTC)

Both flying fish and flying squirrels (+foxes, snakes, spiders, frogs, etc) are gliding - they can't sustain flight. After an initial jump, they can only lose altitude. Birds, some insects and bats can gain altitude by flapping. SteveBaker 18:51, 10 September 2007 (UTC)

Actually, The Flying Nun was only a glider, too. :) — Scientizzle 21:25, 10 September 2007 (UTC)

The Flying Nun? — Scientizzle 16:29, 10 September 2007 (UTC)

I know you're joking, but I think it's fair to count human flight. We can fly farther, faster, higher, and longer than any other species. And if we haven't "evolved" a way to fly, then neither have chimps "evolved" a way to get termites out of their nest with a blade of grass. --Sean 17:53, 10 September 2007 (UTC)

Are you sure about that? It's perfectly possible for a species to have a gene for making and using a specific tool. Human flight isn't "evolved" (in the genetic sense) - but (for example) Starlings can smash open a snail shell with a pebble even if they've never seen another starling do it - which suggests a genetic basis for their tool use. A single human would be unlikely to be able to build and fly an airplane if they'd never met another human before. I don't know whether tool use in Chimpanzees is genetic or learned. SteveBaker 18:57, 10 September 2007 (UTC)

Unfortunately I can't remember any specific examples just now, but there are definitely some animal behaviors that are passed on by observation and imitation, rather than being instinctive. --Steve Summit (talk) 20:00, 10 September 2007 (UTC)

My Flying Nun link was definitely a joke. :) I would understand the question "How many times has flight evolved?" to be strictly bounded by heritable genetic information resulting in body designs capable of true flight (not gliding). Human flight has no genetic root, so it's not an "evolved" behavior in the classic biological sense. The concept, however, might qualify as a meme; memetic theory incorporates many Darwinian elements. — Scientizzle 21:25, 10 September 2007 (UTC)

Here's an article that ties together two recent reference desk threads: [1] R. Dudley, Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance. Journal of Experimental Biology, Vol 201, Issue 8 1043-1050. --Reuben 22:06, 10 September 2007 (UTC)

which is the largest flower?

• email removed to prevent spam* —Preceding unsigned comment added by 59.92.30.8 (talk) 10:23, 10 September 2007 (UTC)

Probably Rafflesia arnoldii? --antilived^{T | C | G} 10:25, 10 September 2007 (UTC)

Or perhaps Amorphophallus titanum? Capuchin 10:30, 10 September 2007 (UTC)

• No, Antilived had it right. The thing that looks like a flower on the A. titum is actually a spadix (a stalk for holding clustered flowers which have no pedicles) surrounded by a modified leaf called a spathe. The actual flowers are arrayed in their thousands deep down in the spathe. Here are some pictures of them after having been pollinated: [2]. --Sean 18:14, 10 September 2007 (UTC)

what is the phenolics of lemon grass

what is the phenolics of lemon grass —Preceding unsigned comment added by 210.213.146.100 (talk) 10:48, 10 September 2007 (UTC)

Did you look at Cymbopogon? --Mdwyer 20:46, 10 September 2007 (UTC)

Distance travelled by the Space Shuttle

Space Shuttle Endeavour has flown 19 flights, spent 206.60 days in space, completed 3,259 orbits, and flown 85,072,077 miles (136,910,237 km) in total, as of February 2003.

What does this mean? How is this distance calculated, given that at some point the vehicle leaves Earth's atmosphere and enters orbit, involving a change of context - technically, it was already travelling at 900 miles per hour (0.4 km/s)while on the ground, but at some point we consider it to be "travelling". When does this change take place?

For example, if I am on the ground, I am stationary. If I hover 10m above the ground, then I am still stationary. If I hover a mile above the ground, most people would say that I am still stationary. If, however, I hover 35,786 km above the ground, then I am travelling at 3 km/s in geostationary orbit. When does this change take place? How far up do you have to be to be considered moving as against stationary?

For a spacecraft like the shuttle, you could just measure the distance travelled since take-off, and count the motion gained from the Earth's rotation as a bonus. However, in a more general case of measuring space travel, the Earth is travelling around the sun at 30 km/s. A craft that leaves Earth orbit and goes around the sun independently is then considered to be going considerably faster than it was when it was in orbit.

I think the question of "how far has a spacecraft travelled" is even more meaningless than "how long is the coastline of mainland Britain". It all depends how you measure it, there is no "correct" answer.

— PhilHibbs | talk 12:31, 10 September 2007 (UTC)

It's only meaningless if you don't define your terms carefully enough. The addition of the five words "relative to it's launch pad" to the question would be sufficient to give you a very clear definition of what is meant with a nice, simple, unambiguous answer. For the shuttle, that's actually a fairly useful and meaningful definition - and is almost certainly what is intended here. But if you were thinking of one of the Apollo moon missions, it would be less obvious that this makes sense because all the time the LEM was parked on the moon, it would be racking up miles relative to Houston without "moving" at all (relative to the moon). Without some kind of qualification, you can't talk about the distance that anything travels. The odometer on your car fails entirely to measure the distance travelled by the body of the car relative to you - or relative to the moon - or relative to it's own gear shifter knob for that matter. When we talk about distances travelled, we generally assume we're talking about 'relative to some fixed point on the surface of the earth' - this convention only starts to break down when we're talking about spacecraft and such. "How long is the coastline of Britain?" is a MUCH harder concept to pin down. SteveBaker 17:19, 10 September 2007 (UTC)

So you'd expect that distance to be relative to a point on the earth. That would mean that its speed relative to the launch pad is constantly changing as it passes over it and goes round the other side of the world. The constant change of speed relative to the launch pad would make measuring the distance travelled very difficult. I'd expect that at some point they disregard the launch point and start measuring distance travelled relative to the centre of orbit, as circular paths are a lot easier to calculate than the twisty turny loopiness of a path measured relative to a rotating starting position. Maybe I'm wrong, and the start point adjustment is just a single matrix transformation applied to the velocity. — PhilHibbs | talk 11:06, 11 September 2007 (UTC)

Don't confuse 'speed' and 'velocity'. Velocity is speed+direction. The velocity of the shuttle does indeed change continually with respect to it's launchpad as it orbits. But it's speed doesn't change much in a stable circular orbit. In an elliptical orbit, yes, the speed changes - but the shuttle isn't normally in anything very far from a circular orbit. The calculations involved in changing the place you are measuring distance relative to are pretty trivial. I could do it with just a handful of lines of computer code (given a suitable math library - which you can be sure NASA will be using). But "distance travelled" isn't really important to either the navigation of the shuttle itself or it's controllers on Earth - these kinds of statistics are really only there to impress the press corps (who are easily impressed!).

Doing some 'mathematical archeology', my guess is that they are simply taking the number of orbits - which they know exactly (3259) and multiplying by the circumference of a 'typical' circular orbit. I guessed that they'd calculate that from the mean equatorial radius of the earth plus 300km as a 'typical' orbital altitude (the shuttle can orbit anywhere between 185 and 1000km altitude - but 300km is typical because that's roughly the altitude of the ISS). Multiply that out and if you pick the right approximation for PI and the right approximation for the mean equatorial radius of the earth and round the result to the nearest million kilometers and by an AMAZING coincidence, you get 137,000,000km - which is almost exactly what you quoted above.

This means that it's almost certain that the figure you have is a horrible approximation. They did the exact same very rough 'back of envelope' calculation based on the number of orbits and a guesstimate for the mean altitude. Since they count orbits relative to the launchpad, that distance travelled is (very roughly) the distance travelled relative to the launchpad. QED. The only horrifying thing here is that they unscientifically quoted the result to 9 significant digits. They should have said: "About 100 million kilometers" given the way they probably did the math. SteveBaker 14:13, 11 September 2007 (UTC)

And here we have the reason I asked this question. Should a "horrible approximation" be presented as fact in an encyclopedia? Wikipedia isn't in the business of impressing the press corps. But this has strayed beyond the scope of the Reference Desk, this is a topic for the Talk Page. — PhilHibbs | talk 09:30, 12 September 2007 (UTC)

Well, for the purposes of the encyclopedia, it is enough to say who says that this is the case and provide a reference. "NASA says that...yadda, yadda^[23]." is OK because you are documenting the fact that they claimed this - not that Wikipedia necessarily believes it to be true. Personally, I'd round off that number though. Giving the answer accurate to the nearest klick out of 137 million is ridiculously precise and more or less guaranteed to be wrong. SteveBaker 14:59, 12 September 2007 (UTC)

Roundness

Why when you take everything down to atoms is everything round? From soap bubbles to stars to elctrons to the universe. Why is it all round? 89.240.69.176 14:54, 10 September 2007 (UTC)

The sphere is the only shape that looks the same from every direction. —Keenan Pepper 14:57, 10 September 2007 (UTC)

Who said electrons are "round"? Or the universe for that matter? And atoms don't really have a shape either; their wavefunctions stretch outward forever. --Spoon! 15:23, 10 September 2007 (UTC)

And if you did have to assign a shape to an atom, it would most likely not be spherical. The electron cloud is described by the atomic orbitals, some of which have quite unusual shapes, not just a huge non-descript blob of "all electrons spread around the nucleus". DMacks 16:34, 10 September 2007 (UTC)

Circles and spheres are efficient in many natural processes. Check out the On Being Round lecture by Neil deGrasse Tyson (also available in his books and DVDs, though they are a bit pricey.) Weregerbil 16:26, 10 September 2007 (UTC)

Among all solid shapes, the sphere has the smallest ratio of surface area to volume (same applies to circles when you're talking about 2 dimensions). A circular orbit (be it planet or electron) is the shortest orbit with the most constant velocity. If an object (or wave) expands equally in every direction, it makes a sphere (or circle... picture the ripples in a pond). --SB_Johnny | ^PA! 16:33, 10 September 2007 (UTC)

The question is, why isn't something round? If there are no particular features to make something have a corner or a side, it ends up round. Gzuckier 17:40, 10 September 2007 (UTC)

I have to say that diagrams/pictures of what objects look like do seem to reduce everythign to being circle/spherical...Search electron in google image search - the first page is virtually all spherical shapes. The same is true for atom, and also proton. If these images are not what things actually look like even in their simplest shape then you can see where the confusion would lie. Certainly I was under a similar impression to the original questionnaire - everything looks like spheres connected with cylinders in the minature world...at least artists impressions do! ny156uk 19:44, 10 September 2007 (UTC)

That's a huge problem, and one that can't really be solved well. A real danger I see in my classes is when people think one explanation or one model is the complete and exact picture of something. What subatomic things "actually" look like often isn't known and sometimes can't be known, often doesn't matter, and sometimes doesn't even actually exist. But we can still talk about them and describe them and draw them. We can draw them many different ways and make many different sorts of models of them, each way illustrates certain properties well, but is not useful (and sometimes very misleading) if one uses it to illustrate things for which it wasn't designed. A paper airplane sorta looks like an airplane and it flies, but there's nowhere to put luggage, but you wouldn't say "therefore real planes generally don't have luggage compartments". Drawing an atom as a circle or dot, and electrons as dots or circles around a nucleus does give a good general idea of what and where things are. If someone says "draw it", then you gotta draw something, and if you need to talk about the relative positions of two things, you need to draw "two things". So best we can usually do is to draw a circle or a blob. DMacks 14:44, 11 September 2007 (UTC)

I would think it better to draw a large circle around the nucleus to represent the highest probabilities, and for a more advanced diagram play with the orbital diagrams. -Wooty [Woot?] [Spam! Spam! Wonderful spam!] 05:30, 14 September 2007 (UTC)

downloading something to a persons brain

is it possible that something like a new language can be downloaded to the brain of someone as waves a brain can understand , which will possible make him learn something new easily ????? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:29, 10 September 2007 (UTC)

Save it for the future...128.163.170.178 15:39, 10 September 2007 (UTC)

I don't have sources, but no, I do not think it is possible, yet. It will definitely be possible in the future, as it doesn't break any laws of nature. — Adriaan (T★C) 15:47, 10 September 2007 (UTC)

Probably not (or at least not for a long time). Brains "grow" their knowledge in a sense by making or modifying physical connections between neurons. It's a bit more complicated than changing the polarity of magnets to make 1s and 0s like we do in computers. --SB_Johnny | ^PA! 16:37, 10 September 2007 (UTC)

FYI, the theme is explored in film The Matrix, the short story/film Johnny Mnemonic (short story)/Johnny Mnemonic (film), and the short story/film We Can Remember It for You Wholesale/Total Recall, as well as the Star Trek episode "Spock's Brain".

Atlant 17:14, 10 September 2007 (UTC)

I think the problem is that the memories within a brain are made up of connections between cells. The way those connections form is different for everyone. To take a wild (but true) example - I'm British - before I came to America I had no need to know which US political party was which. I arrived here during the Clinton impeachment stuff - and I remembered that Clinton was a democrat because 'democrat' sounds a bit like 'DAME-o-crat' (dame==woman, woman==reason for Clinton's impeachment) and the opposition were behaving weirdly - like they were drunk or something - so I formed the connection "re-PUB-lican"...weird - but for a while that was how I recalled which was which. Now I have some brain connections that associate those things together. I'm fairly sure that nobody else made that same set of connections - everyone has a different means to remember facts like that. Hence to teach someone something (like perhaps to teach me which US presidents were with which political party), you'd first have to understand how all of their knowledge fitted together - then develop some kind of custom neuronal re-wiring that would be unique to that person. It's also likely that learning one thing changes your perception of other things. It might be exceedingly dangerous to have a machine teach you something because it could easily mess up what you've already learned. This seems exceedingly difficult - even in a sci-fi setting. It's tough to say it would be impossible though - as Adriaan90 said - no physical laws seem to need be broken to make this happen. SteveBaker 17:32, 10 September 2007 (UTC)

Another way might be to add external memory (be it electronic or biological or whatever), let's say in the form of a helmet, to make connections short (an 'even neo-er cortex', let me call it the neoneocortex). But for that to work instantly, the brain of that person would have to be intricately analysed, at least the parts that deal with whatever knowledge you're adding. If those can be localised, that is, because a specific bit of knowledge is not in one specific place. Knowledge is not localised, it consists of connections between other pieces of knowledge, which in turn are just connections between yet other pieces of knowledge (I think that's what Steve meant to say). What is more feasible is to just make some connections between the 'two brains' and let them work out the right connections themselves through learning. In which case you're back to square one - the person still has to learn it the old fashioned way, he just has more brainpower. But this opens another avenue. What if it were seen not as an extension, but as an interface. On one side it talks to the original brain and on the other side to a computer. Then, at a conscious level, the person could download info to the computer and then absorb it on a subconscious level through the neoneocortex. Note that those are both actions of the brain, with higher levels helping lower levels through the use of a tool. DirkvdM 07:06, 11 September 2007 (UTC)

Communicating with animals ??

animals produce sound waves that probably they understand but we humans dont, so it is possible to make a convertor that can converts animals sound waves to understandable sound waves to humans ??? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:32, 10 September 2007 (UTC)

How we experience what we're communicatiing might be so different that the signifiers would make little sense. See qualia for some discussion. --SB_Johnny | ^PA! 16:39, 10 September 2007 (UTC)

Are you asking if it's possible to modify inaudible sounds so that we can hear them? Then yes, I think whale songs often need to be adjusted before humans can hear them. If you're asking if it's possible to translate animal 'language' into human language, the answer is typically 'no' because most animals don't have a structured language, but check out Waggle Dance 69.95.50.15 17:55, 10 September 2007 (UTC)

I think we understand some animal "languages" just fine. We all know that when a cat is happy it purrs and when it's upset it yeowls and so forth. My dogs use a very particular 'hurt puppy' yap when they want to be let back into the house from the back yard and big deep barks when they are trying to scare off people who come up to the front of the house. They use distinctive body language too - who can mistake the big side-to-side wag (meaning "welcome") and the smaller wag (meaning "happy") and the front-end-down, rear-end-up-in-the-air (a "play bow" - meaning "What is about to happen is all for fun!")? There is even a sense of 'word order': A play bow followed by growling means something very different from a deep bark followed by growling. Barking+Tail wagging means something different from barking whilst jumping up and down with fore-feet only (which indicates frustration and a need to rush off and do something). I think we can learn and understand the language of familiar animals just fine. We know that cat's wag their tails when they are annoyed and dogs do it when they are happy (this explains a lot about why cats and dogs don't always get on very well!) You are assuming that what they are saying is a lot more sophisticated than that...but it's not - most animals are simple creatures with simple communication needs that they have evolved to deal with. SteveBaker 18:46, 10 September 2007 (UTC)

That very last bit ('evolved') goes against the bit just before it ('simple'). Along the lines of what SB_Johnny said, they evolved in a different mindset and therefore speak (or communicate in whatever way) about very different things. Sort of like Eskimos having 20 words for snow, just taken much further. The only common grounds we have are basic things like anger and joy, as you described for your dog. Dogs don't understand most things we say, so we think they are stupid, but the reverse might also be true. So how do we find that out? Maybe a mind merger with the neoneocortex I described above, one for us, one for the dog? DirkvdM 07:33, 11 September 2007 (UTC)

We might not be able to understand what they're thinking, because their brain is structured differently (ever read Thomas Nagel's essay, "What is it like to be a bat?") That doesn't mean that other animals have a complex language we simply don't understand. We can study a dog's brain and vocalizations and come to the conclusion that there is no complex speech behavior. -- JSBillings 20:39, 11 September 2007 (UTC)

How does/does this theory apply to talking parrots, as a matter of interest? --Kurt Shaped Box 23:39, 11 September 2007 (UTC)

As far as I know, the parrot mimics the sound, but does not usually comprehend the meaning of the words. Nimur 17:01, 12 September 2007 (UTC)

Hire a consultant. I recommend Dr. Doolittle, if he's available.--Eriastrum 16:48, 12 September 2007 (UTC)

I don't know if there has been extensive studies of parrot (or other bird) speech centers, so I couldn't comment. I'm just saying that in the case of User:DirkvdM's comment, it is possible to determine if there is complex speech by studying behavior and brain imaging. -- JSBillings

What makes you assume that communication between other animals is solely vocal? Once again you're antrhopomorphing (or what is the verb for that?). They may communicate with a combination of sounds, facial expressions, tail wagging, the way certain hairs stand up, and farting for all we know. I once heard of a people who can't communicate in the dark because they rely too heavily on gestures. (Sorry about this bit of QI trivia. :) ) Btw, you say we might analyse their speech. But has any such test been done? This reminds me of how we might test the presence of life on other planets based on such complexities. The Russians built a gadget to do that, which, when tested on Earth, concluded there is no life here. And that was when they knew what they were looking for. In the case of animal communication we don't even have that luxury. DirkvdM 19:13, 13 September 2007 (UTC)

Cloning Machine ?

is it possible to clone an apple for example by a machine, as a begining we add all the elements the apple made up of and place it in a machine , then give the machine the information of how these element are joined or made up , and then the machine uses this information and elements to make an identeical apple ??????? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:36, 10 September 2007 (UTC)

Again, I don't have sources, but no, I do not think it is possible, yet. It will definitely be possible in the future, as it doesn't break any laws of nature (or does it? can't think of any). — Adriaan (T★C) 15:48, 10 September 2007 (UTC)

Impossible for now or in the foreseeable future. The field of organic chemistry, where chemists make compounds found in nature (and compounds inspired by those in nature), has been able to make complex molecules--but many molecules that are diagrammable on paper are still impossible to make due to their complex bondings and unknown reaction mechanisms. An apple consists of millions of cells, and each cell contains millions of such complex molecules, that it's practically impossible to make a machine like the one you described. It would take us not only a complete knowledge of reaction mechanisms, but also a machine that can do things in detailed 3-dimensional molecular level. I say it would never happen. 128.163.170.178 16:22, 10 September 2007 (UTC)

It's certainly utterly impossible to create a perfect replica. For that you'd need to measure the position and speed of every electron and every atomic nucleus in the apple simultaneously and you can't do that because of the uncertainty principle. So we know for 100% sure that this is going to be a less-than-perfect copy (although perhaps it would be flawed in some way that we don't particularly care about - perhaps we didn't catch all of the vibrational modes of all of the atoms - so the temperature distribution in the copy is a bit incorrect). So if we admit that the copy only has to be good enough to fool the average person - perhaps it would suffice for the machine to analyse a single cell of the flesh of the apple, some representative cells from the skin, the pips, the stalk, etc - then to simply fill the volume of the flesh with identical copies of that one cell, coat it with a representative number of skin cells...and so on for all of the major structures of the apple. This (whilst still an exceedingly daunting task) would at least put the data capacities and bandwidths down to something conceivable at some time in the far distant future. There are still problems though. Assembling all of these structures atom-by-atom will take time - and during that time, some parts of the newly forming apple that have never been exposed to the air in the apple we are copying would indeed be exposed to the air in the copy (and no - doing it in a vacuum wouldn't help either). If you (say) started off by making the skin of the apple - it would collapse long before you could make all of the flesh inside. If you made the flesh first, it would start to go brown in the air before you could get the skin onto it. So it wouldn't be the same. You can't assemble the copy infinitely rapidly - and that's a problem. So this is another one of those ideas that seems reasonable in theory - but which has such an astronomical number of practical problems that seem insurmountable. —Preceding unsigned comment added by SteveBaker (talk • contribs) 17:48, 10 September 2007 (UTC)

• See also No cloning theorem for more pessimism on this topic. --Sean 18:30, 10 September 2007 (UTC)

Also see 3D printer for something that can do a similar thing inorganically. -Wooty [Woot?] [Spam! Spam! Wonderful spam!] 01:03, 11 September 2007 (UTC)

A 3D scanner - coupled (via some fairly heavy computational stuff) to a 3D printer could reproduce the external form of an object to some degree of precision - a fraction of a millimeter for the best ones. So you could certainly (today) scan an apple then make a plastic model of an apple that was more or less the same size and shape. If you used something like a CAT scanner that can image the interiors of things - then the 3D printer could make the pips inside the apple. Some 3D printers could even make the skin, the flesh and the pips be roughly the right colour - but you can't "scan" the colours of the insides of things with any technology we have right now (or are every likely to have) without slicing up and destroying the object you are scanning. However, you most certainly cannot use a 3D printer to print an apple that you'd be able to eat - or plant into the ground to grow a new apple tree from - so in that sense, you can't reproduce an object like that. If course if the object you are copying were made out of the same kinds of plastics that your 3D printer is using then perhaps a reasonably exact copy could be made using these techniques. SteveBaker 13:37, 11 September 2007 (UTC)

One of the goals of the RepRap Project is to create a 3D printer that can fabricate each of its own parts. Not quite self-replication, however, as these parts would still have to be assembled to create a duplicate printer. Gandalf61 13:53, 11 September 2007 (UTC)

Plus there are a heck of a lot of parts that the RepRap won't be able to replicate - motors, computer chips, nuts and bolts, threaded rod, etc. SteveBaker 15:00, 11 September 2007 (UTC)

The term "clone" when applied to organisms usually means that another individual is made that has an identical genome. We do that all the time for apples (the plants, not the individual fruit) and thousands of other plants. Any plant multiplied by vegetative reproduction (usually by cuttings or grafting) results in clones of the original plant. This is what cultivars are. Thus if you buy a 'Red Delicious' Apple you are acquiring a clone of the original Red Delicious. The original poster used the term "clone" in the sense of making an exact, atom-by-atom replica of a particular piece of fruit. As pointed out above, this is, of course, impossible. I don't think that "clone" defined as a replica is the usual definition, although meanings do change over time. What do the rest of you think about using the word "clone" in this sense?--Eriastrum 17:05, 12 September 2007 (UTC)

Wiktionary says:

1. A living organism (originally a plant) produced asexually from a single ancestor, to which it is genetically identical.
2. A copy or imitation of something already existing, especially when designed to simulate it.

So I think both meanings are OK - it was just unfortunate that the second meaning was intended when the object (being a plant) could easily be cloned (meaning the first meaning). However, the form of the question shows that the OP clearly intended the second meaning. SteveBaker 17:31, 12 September 2007 (UTC)

Acid rain effect on churches

Dear Sir/Madam,

I am looking for pictures that clearly illustrate the effect of acid rain on churches, Plus a brief simple explanation of why for my 15 yr old son

Thanks for your help

Happy Monday

Graham —Preceding unsigned comment added by 81.247.197.62 (talk) 16:19, 10 September 2007 (UTC)

Our article on acid rain has a few pictures, I don't see one of a church though. There is an image of a statue damaged by acid rain in that article. Splintercellguy 16:57, 10 September 2007 (UTC)

(Although I haven't tried it,) A Google search for "Gargoyle acid-rain" will probably reveal something.

Atlant 17:17, 10 September 2007 (UTC)

I don't know about churches - but the most clear example I can think of is the Caryatids in Erechtheum in Athens. These are female figures that support the roof of a temple of some kind. One of the Caryatids was taken by the British in the early 1800's (before acid rain was a problem) and kept safe indoors and in museums. The remaining Caryatids had to suffer the worst of Athen's pollution. Compare the sharp/well-defined carving in the leftmost photo of the Caryatid kept in the museum versus the smooth rounded-off ones that spent nearly 200 years in Acid rain on the right. (Actually, the one in the second photo is a replica - the originals having FINALLY been taken into protective storage to prevent further damage - but it is an exceedingly good copy). Look particularly at the details of the faces! You might argue that 200 years out in the rain and other weather did this - not acid rain - but recall that both the statue in the museum and the ones still outdoors had been there since 400BC. So the indoor one shows 2200 years of weather + 200 years in the museum and the outdoor ones suffered 2400 years of weather. The amount of weathering due to rain is therefore almost identical in both cases - but the last 200 years made all the difference. This is the clearest example of how modern pollution affects stonework because we can see what the objects would have been like had they not been exposed to it. SteveBaker 18:09, 10 September 2007 (UTC)

Acid rain is a big problem for buildings made of limestone, as many statues, monuments and churches, certainly in the UK and probably elsewhere, are. Limestone is made of calcium carbonate, which is also used as an antacid. When a carbonate meets an acid, the carbonate reacts to form water, salt and carbon dioxide gas, which weakens the limestone. You can see this effect for yourself if you put a few drops of a weak acid like vinegar or lemon juice onto an antacid tablet: the antacid begins to fizz as the carbon dioxide gas is released, and then crumbles until you are left with just a sludgy residue - the same effect is happening with limestone buildings, just much slower. Laïka 10:39, 11 September 2007 (UTC)

And, as this it the "science" desk, do the experiment. Go to a stone shop (quarries are cool!) and pick up a chip or two of limestone and marble. Take photos of them. Feel the sharpness. Then toss them into a cup of kitchen vinaigre. Look at them every day or so and take some more photos (and give it a stir). Watch what happens. No better explanation. Saintrain 22:36, 14 September 2007 (UTC)

Can changes in proportions of oxygen in our atmosphere affect combustion?

I've heard that the ratio of oxygen to inert gas in earth's atmosphere is finely tuned: that a greater proportion of oxygen would enable global incineration, and that a lesser proportion could make combustion impossible.

In my explorations of combustion and atmosphere on Wiki, I see no mention of anything like this. I'm attempting to help a friend with a sci-fi story idea, and need to know more about this. Do noble gases play a role in combustion in our atmosphere? Would an increase in argon or xenon affect combustion?

Thanks 216.151.17.169 17:31, 10 September 2007 (UTC)

I've heard the same thing; it's part of the Gaia hypothesis, although our article doesn't seem to touch in that facet. Where I remember reading about it is in James Lovelock's Gaia book, where it's discussed at some length --Steve Summit (talk) 17:52, 10 September 2007 (UTC)

See Earth's_atmosphere#Evolution_on_Earth for some discussion. Speculation: I would think that a highly combustible atmosphere would be self-limiting, as each little spark would burn off enough O2 to get it back down to a reasonable level. --Sean 18:34, 10 September 2007 (UTC)

The noble gasses (which used to be called 'inert gasses' when I was in school) are inert - they don't react with anything (almost). So they are not implicated in this process. (The Gaia thing is pure pseudo-science though - ignore it!) Oxygen forms a balance with plants chucking it out and animals and combustion eating it up. It appears that magically the density of oxygen is just perfect because anything that would spontaneously combust at this density has ALREADY combusted and there is none of it left. There is no free hydrogen in the atmosphere because as fast as it forms, it gets combusted into water. Ergo, whatever is left is things that don't spontaneously combust at this oxygen density. No magic - no "The planet is a life-form called Gaia" - just basic chemistry. SteveBaker 18:35, 10 September 2007 (UTC)

Hydrogen is the ninth most common gas in the atmosphere, so "none" is an overstatement. 76.231.189.193 16:09, 11 September 2007 (UTC)

Here's one of a set of lecture notes from the University of Michigan called Evolution of the Atmosphere. According to this class: "Why does present-day oxygen sit at 20%? This is not a trivial question since significantly lower or higher levels would be damaging to life. If we had < 15% oxygen, fires would not burn, yet at > 25% oxygen, even wet organic matter would burn freely." --Reuben 18:52, 10 September 2007 (UTC)

But that's the point. If there was <15% then animals would start to die off and things wouldn't burn - so the oxygen produced by plants would not be consumed as quickly as it is now. The oxygen density would then build up until animal life could recover and things would be able to burn again - to the point where the amount of oxygen produced equalled the amount consumed - probably at around 20%. If there were 25% oxygen and vegetation would burn much more easily - then we'd have a huge increase in the number of forest fires, etc - and these would consume oxygen until it fell back to the point where those fires would cease to happen...right around 20% probably. It's a feedback system that maintains stability at a particular point. SteveBaker 19:31, 10 September 2007 (UTC)

Which is, of course, exactly what the Gaia hypothesis is really about. The whole 'life-form' thing is like Le Chatelier's principle. Skittle 23:08, 11 September 2007 (UTC)

That's an interesting speculation, but it doesn't always appear to have worked that way. From the same lecture notes:

According to recently developed geochemical models, oxygen levels are believed to have climbed to a maximum of 35 percent and then dropped to a low of 15 percent during a 120-million-year period that ended in a mass extinction at the end of the Permian. Such a jump in oxygen would have had dramatic biological consequences by enhancing diffusion-dependent processes such as respiration, allowing insects such as dragonflies, centipedes, scorpions and spiders to grow to very large sizes. Fossil records indicate, for example, that one species of dragonfly had a wing span of 2 1/2 feet.

so I would want to see some evidence that such a feedback cycle actually operates. --Reuben 19:34, 10 September 2007 (UTC)

Here's an article that ties together two recent reference desk threads: [3] R. Dudley, Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance. Journal of Experimental Biology, Vol 201, Issue 8 1043-1050. --Reuben 22:06, 10 September 2007 (UTC)

The evidence for such a feedback cycle is that it makes perfect sense. But that does not mean there are no other factors. Something else could thrown it completely off balance. So maybe something caused a mass extinction of animals, which led to a sudden rise in the oxygen level, which led to a mass extinction of plants, which led to a massive drop in the oxygen level. In other words, a chaotic system that eventually finds its balance again. Note that I have absolutely no factual knowledge in this field and I probably misused the term 'chaotic system'. DirkvdM 08:16, 11 September 2007 (UTC)

Not really. Oxygen levels rose due to excess organic burial in the Carboniferous following the biological invention of chitin. 6 CO2 + 6 H2O <-> C6H12O6 + 6 O2 represents a balance between respiration and photosynthesis. By burying organic matter (i.e. the C6H12O6) before it can be consumed one gradually accumulated an excess of O2 over tens of millions of years. While combustion would become more common it didn't provide much of a control if concentrations can nearly double due to gradual imbalances. 76.231.189.193 16:09, 11 September 2007 (UTC)

I don't get that last bit. Over millions of years, even evolution could have reacted by putting more oxygen-consuming animals on the planet. Unless something else prohibited that or killed them off. DirkvdM 18:40, 11 September 2007 (UTC)

I read a story by Edgar Allen Poe that has the Earth intersect the orbit of a comet consisting almost entirely of oxygen. For a while plants start growing like wild, but at a certain point the entire Earth combusts. Pretty cool.BungaDunga 01:09, 12 September 2007 (UTC)

Good one. The Conversation of Eiros and Charmion. --Reuben 01:17, 12 September 2007 (UTC)

electronics and communication

can some one help me out in telling me how does the the information transmission take place in wireless communication.what methods r used to modulated a signal and what is the method for the reconstruction of the original signal. is the wireless transmission take place as a analog or as a digital way? —Preceding unsigned comment added by Kamuali (talk • contribs) 18:28, 10 September 2007 (UTC)

You asked this question [[4]] and got some good responses. You should read those articles (radio, modulation, etc.) and ask questions about those if you have them. --Sean 18:37, 10 September 2007 (UTC)

Gray Hair

Why does gray hair not only lose pigmentation but also turn wiry? --WonderFran 18:46, 10 September 2007 (UTC)

Presumably it is losing its strength and thus becomes more frayed/frail looking. Grey hair might help, that is if that is even an article...ny156uk 18:59, 10 September 2007 (UTC)

In regularly colored hair, melanin is produced in melanocytes around the hair root, and "injected" into hair root cells. Melanin inhibits cell division and promotes the hornification of these cells. During aging, less melanin is produced as the melanocytes die and fail to be replaced. Less melanin means a higher rate of cell division in hair root cells and, consequently, an increase in hair shaft diameter. When you increase shaft diameter the result is wiry hair. Rockpocket 08:27, 12 September 2007 (UTC)

MEDICAL EDUCATION IN CUBA

DEARS, i want an answer of a question related to the medical education in cuba. Does medical education in cuba is up to world level of medical education? How much importance is given to a student who has a medical degree from cuban medical institutes in europe, america and in other parts of world if he wants to study there or wants to job there? what about its curriculum? Is it cmpatible with other courses that are taught in other world universities? Level of practical work ? What about surgery ? Would you like to try to answer mi , if you know, because it is very very importante for mi?

  asifji  —Preceding unsigned comment added by 201.220.222.140 (talk) 20:17, 10 September 2007 (UTC) 

Might I direct you to Education in Cuba. Students who have obtained their medical degrees in Cuba have been permitted to practice medicine in the United States. I can't speak for Europe. Someguy1221 20:23, 10 September 2007 (UTC)

Permitted? Of course, why not? Hell, if even the US permits it .... . But I understand the questioneer is asking if a medical study in Cuba is likely to get him/her a job or extended study elsewhere. DirkvdM 08:21, 11 September 2007 (UTC)

The news articles cited in my link, as well as the link itself, suggested that those American doctors who received their degrees in Cuba did all find practices in the United States afterwards. However, it also mentions they worked for low cost healthcare, which might imply low-income jobs. Someguy1221 19:31, 11 September 2007 (UTC)

In that case, Europe might be a better choice. At least here in the Netherlands, there is no such thing as low cost health care. Everyone is treated equally. For example, when prince Bernhard was very sick, he had to await his turn, like everyone else. We are very proud of that (no irony). DirkvdM 19:20, 13 September 2007 (UTC)

Douglas-fir in Europe

I would like to know

1. When Douglas-fir tree species only come from North America, Mexico and East Asia, where do the Douglas-firs in Europe come from?
   1. Do they all descend from American trees introduced to Europe? Can they be traced back even to David Douglas himself?
2. I have heard a story that the Douglas-fir became extinct in Europe during the last Ice Age. Is that true?
   1. And if yes, was it of an own species or the same still found today?
   2. Is it known what the distinctive ecological influence in Europe was, that it vanished there but survived in America and Asia, who both had an Ice Age too? --Vancouver robin 21:26, 10 September 2007 (UTC)

Cells

what are the functions of cells ? —Preceding unsigned comment added by 69.122.140.71 (talk) 21:32, 10 September 2007 (UTC)

Howdy, you're question is pretty broad. You might start at the Cell (biology) article, and see if that doesn't answer your question. --TeaDrinker 22:08, 10 September 2007 (UTC)

Or whichever type of cell you are referring to.--Shantavira|^{feed me} 07:39, 11 September 2007 (UTC)

If you're talking about biological cells, well, they're the stuf we're made of. So what functions? All of them. DirkvdM 08:25, 11 September 2007 (UTC)

The functions of cells is life - all of life (except for Viruses - which some people claim are alive and others claim are not). Our article on life says: Growth through metabolism, reproduction, and the power of adaptation. Which is pretty much the function of cells. SteveBaker 13:26, 11 September 2007 (UTC)

Cells also make sure that prisoners do not escape from prison.Mrdeath5493 18:16, 11 September 2007 (UTC)

Says Mr Death ... is 5493 your cell number? DirkvdM 18:43, 11 September 2007 (UTC)

beaver diet

I just read a kids' magazine that says that beavers eat wood. This doesn't seem right to me, since I don't think anything bigger than a termite eats wood. The article mentioned that they store branches underwater to eat during the winter. Wikipedia's beaver article mentions wood being stored underwater for building, but I didn't see anything about them eating it. So, do beavers eat wood? And why do they store branches underwater? Couldn't they just cut down a tree whenever they needed it? Thanks Ingrid 22:34, 10 September 2007 (UTC)

http://www.nhptv.org/Natureworks/beaver.htm suggests that tree bark is part of their diet. I would expect they store wood for building because in the winter food may be harder to come by and the energy required to cut down trees/get their wood would be too vast at that time of year? ny156uk 23:25, 10 September 2007 (UTC)

Beavers eat bark and leaves, not wood. They do bring branches underwater to store and preserve for the winter, much like people store crops in root cellars, spring houses or freezers. Come to think of it, an ice-coated pond probably has a similar temperature range to a refrigerator, so perhaps that's the best analogy. They probably don't do much in the way of construction in winter, unless they're in a climate where the pond doesn't freeze. --SB_Johnny | ^PA! 11:42, 11 September 2007 (UTC) Yikes! check out that root cellar article!

Date of Death

I am not sure how to phrase my question, or even if it is a "science" question, so please bear with me. Thanks. (Perhaps this is a humanities / sociology question? Unsure.) Can anyone offer some entries on a list of advantages versus disadvantages of an individual knowing his precise date and time of death, while being oblivious to the manner of his death? A related question #1: would any of those advantages / disadvantages on the list change if the individual were also to know the manner of death in conjunction with the precise date/time of it? A related question #2: same as above, but for another individual (i.e., not for one's self) -- such as having that info about your spouse/child/sibling/parent/best friend/boss/neighbor/mailman/etc. In other words, I am not trying to take a poll such as "If the information were available to you, would you elect to know or would you elect to not know your date/time/manner of death?" I am asking, what are the factors that one would consider (i.e., the advantages and disadvantages) in order to make such a decision? And what are the advantages / disadvantages to society as a whole and to individuals of having versus not having this information? Assume that the information is 100% accurate and unable to be manipulated (i.e., you can't change it -- it is 100% certain). Thanks. (Joseph A. Spadaro 23:07, 10 September 2007 (UTC))

This isn't a scientific question, but it certainly could be a science fiction question. ;-) It seems to me that the entire thing revolves around the notion of predestination (fate), which is of course against our notions of free will, self-determination, and all that. We all like to think that the future is undecided — and maybe it is — and knowing anything that certain about it, especially something as monumental as our own deaths, definitely throws a wrench into that. Now, of course, we all know that we will die, eventually, but the timing could make a lot of difference: if I were to die tomorrow, would I be doing something which is onerous in the short term (graduate school) but beneficial in the long term? Would I bother making long-term investments in people, places, things? Would my balance of life swing much farther towards "live for today" than "invest for the future"? --72.83.173.248 00:53, 11 September 2007 (UTC)

Well, yes -- and, to that extent, it is essentially a question of psychology (of the individual) and perhaps sociology (of society in general). Thus, perhaps appropriately, a "science" question. (Joseph A. Spadaro 00:58, 11 September 2007 (UTC))

You really can't demand a scientific answer to an impossible and entirely hypothetical question. Clearly, nobody can know the precise date of their death with any degree of certainty (unless perhaps they are literally dying and the answer is clearly "today"). Even if you had a good estimate from your present age, health, etc - and if you stayed at home to avoid car accidents - there could always be a mountain-sized meteor smacking into your house at any time. Since knowing your death date precisely is impossible - how could anyone investigate how an individual might react? At best you're going to get a bunch of non-scientific speculation - and this reference desk is the wrong place for that. But there is an even worse problem here. If by some amazing feat of research, you could figure out this "exact date" - wouldn't the person involved immediately change their behavior? If you know you'll live to be 100 years old - why bother exercising and driving carefully? You "know" you can't die from a car crash or a premature heart attack - so why be careful? This is truly an unanswerable question. SteveBaker 13:21, 11 September 2007 (UTC)

OK. OK. OK. Calm down, Steve. Thanks for the input. But, let me re-phrase here. Actually, this is neither an impossible nor a hypothetical situation. That is -- isn't it rather "common" (for lack of a better word) for doctors to inform terminal patients things along the order of "dear patient, our best medical estimate is that you have X months to live" ...? If I had to re-phrase the question, it might take the form of something like this. Let us assume that a specific individual is given the following information, which is 100% accurate and "fixed" (cannot be changed) -- exact date / time / manner / cause of death. Repeat: This is merely an assumption, that is, a premise to the question. Assuming this set of facts: from a psychological standpoint, what would be the advantages / disadvantages of the individual having / not having access to this information? Also, from a sociological standpoint, what would be the advantages / disadvantages to society as a whole? Psychologically, is it "healthier" to know or not know? That is probably a better re-phrasing of my original question. And, the more I think about it, the less impossible and hypothetical this scenario seems. In the grand scheme of things, 99.999% of us do not, in fact, know the details of our death. Nonetheless, there are a significant number of people who do, in fact, have such details -- on some level or another, in some form or another. Examples: terminal patient informed by doctor that you have X months to live; individual who decides to commit suicide; individual who decides to go shoot up a McDonald's knowing in all probability that the police will eventually kill him; individual planning euthenasia or mercy killing; individual planning a murder; individual who decides to "pull the plug" (disconnect respirator/ventilator/etc.); kidnapping victim who is told by his captor, "I will kill you tomorrow if your parents don't pay the ransom"; individual enters surgery knowing that survival odds are slim; the six Utah (or Ohio?) miners trapped in a mine for weeks and weeks and weeks without rescue; a car crash victim in a remote, desolate area who is pinned down and can't escape; individual who survives the sinking of a ship and floats in the ocean for days upon days upon days with no rescue; individual in a car/plane/train that is about to inevitably crash; etc. etc. etc. Granted, these are extreme cases, in relatively small numbers ... yet, nonetheless, it happens. "Many" people can and do know the time/date/cause/manner of their death. So, no -- it is neither impossible nor hypothetical. The examples I gave are hardly far-fetched ... in fact, they pretty much happen every day of the week. No? Thoughts? (Joseph A. Spadaro 14:27, 11 September 2007 (UTC))

When doctors say that, they are certainly not giving anything like an exact date - it's going to be a WIDE spread "six months to a year" or something. You are saying "what if the exact date is known" - and it can't be/isn't - so how can you possibly expect a reasonable answer. Nobody can POSSIBLY know what this knowledge would do to a person. So the answers you'd get would simply be wild speculation. The cases where it's suicide or something like that - you aren't talking about a person with normal feelings - you are talking about someone who is suicidal. Their feelings are all about the suicide nothing to do with the consequences of having that exact knowledge. Even suicidal people don't have exact knowledge - they could still be run over by a car on the way to buying the poison/gun/noose and most suicides fail on their first attempt anyway. Our suicide article says there are between 10 and 20 million attempted suicides each year - but from their breakdown of successful suicides suggests maybe a million worldwide...so even if you plan a suicide, you only have a 5% to 10% chance of knowing the date of your own death. Sorry - but there is no way you'll get a well-informed, scientifically credible answer to this question no matter how you twist it around because the entire premise of it is impossible. SteveBaker 14:44, 11 September 2007 (UTC)

Steve, thanks for the reply. Hmmmmm. I sincerely do not understand your resistance to my question. Perhaps you are being too literal, or perhaps I was. However, if you read the very first words of my question (above), it says: "I am not quite sure exactly how to phrase this question, so please bear with me." As far as doctors informing terminal patients of their impending death. Yes, at the beginning of the process, it is probably a broad range ("six months to a year"). As the terminal disease progresses, however, I am sure that the "date of death" becomes more certain and fixed, more able to be pin-pointed exactly. I am sure that there are many, many, many cases where doctors say to the patient's family, something like: "You should say your good-byes to your grandmother, I don't think she will make it through the night" (or such). My point is that, at some point in the medical process of a terminal disease (not necessarily at the beginning stages / onset), the doctor can and does estimate a reasonable date of death. (Yes, OK, the doctor will not literally say: "The death is 100% certain to be on May 7 at 10:28 am exactly" -- but you know what I mean.) Furthermore, a patient can wait forever to see a doctor and then, when it is "too late", come in with an advanced stage of the terminal disease. In this scenario, the doctor can estimate more closely than that "six months to a year" broad range -- since the diagnosis is being made at such an advanced state of the terminal disease (i.e., a patient who waits until the "last minute" to visit a doctor, when he feels sick). OK, yes, literally ... I did say "what if the exact date is known" (which you say is impossible). One -- Are you more comfortable if I change the semantics to something like, "what if a statistically sound estimate of the exact date is known" ...? Come now. And two -- I gave several plausible examples (above) where a person can very well reasonably know the details of his death in advance (suicide, murder victim, plane crash, falling off a ship, miners trapped in mine, going in for a risky surgery, etc. etc. etc.). I think those are very plausible things that happen every day of the week in the real world -- hardly far-fetched at all. You also state, quote, : "Nobody can POSSIBLY know what this knowledge would do to a person." Why do you consider this an impossibility? I disagree. All you need to do is find an individual (or 25, or 100, or a thousand individuals) who have indeed experienced the scenarios I have described above and, for whatever reason, lived ... as opposed to died. (Example: All the trapped miners died on day 17 except for one miner. That one miner was rescued on day 18. Which is exactly what happened in that Sago Mine Disaster a few years ago in West Virginia (?), I think. Example: You enter a surgery with a 99% chance of not surviving, but you do survive. Example: A murderer lines up 25 people and shoots them one by one. You are next in line (#26), and the cops kill the murderer at that very moment. Etc. Etc. Etc.) I don't understand why you claim it would be impossible to know what this knowledge would do to a person. All we need to do is talk to / interview / ask the people who have had the experience and who have had this knowledge (i.e., a reasonable and sincerely-held -- but incorrect-- belief that they are to die, but they don't in fact die). You also discuss the suicide situation at length. It missed the point to the extent that I was illustrating that an individual can, with certainty, "know" his exact date/time/manner of death. In any event ... I am befuddled why you think this premise is -- as you say -- impossible. Seriously. By the way, I have not delineated any specific time frame here. Perhaps, you are mis-interpreting the question to apply to "people who know these details years and years in advance". Not necessarily. The time frame might be years in advance or it might only be a brief 1, 2, or 5 minutes in advance. You don't think that the Utah trapped miners, at some point, "knew" that they were going to die? You don't think that some murder victims, at some point, can "know" (and digest the fact) that they are about to die? Any way, respond if you like. I suspect that you and I are talking about apples and oranges, however -- and we are not really on the same page. Hence, two such widely divergent perspectives on the question -- which, granted (and, admitted) was difficult to articulate. At this point, if I had to (yet again) re-phrase, I would say something like: What are the psychological advantages/disadvantages to an individual knowing / not knowing the details of his death? And, is it "healthier" to be aware of or to be oblivious of these details? This is a premise, which I do not consider impossible at all. Perhaps the following "twists" of semantics will bring you on board with me? (1) To the two questions I posed a few sentences back, perhaps add the phrase " ... even if the person has that knowledge only for a brief moment ... " (or such). And (2) We can re-define the word "knowing" as meaning "having a reasonable and sincerely-held belief, whether such belief ultimately proves to be correct or incorrect" (or such). Maybe those semantics will clarify my question better? Thanks. (Joseph A. Spadaro 15:32, 11 September 2007 (UTC))

To take these 'examples' one by one:

terminal patient informed by doctor that you have X months to live; - doesn't know the exact date plus or minus six months probably.

individual who decides to commit suicide; - has only a 1:10 to 1:20 chance of actually knowing the date exactly - and even so, this is not someone whom we can study scientifically to get a good answer.

individual who decides to go shoot up a McDonald's knowing in all probability that the police will eventually kill him; - again, this is not someone whom we can study - so we don't know the answer.

individual planning euthenasia or mercy killing; - only knows the date on which someone else will die - not themselves.

individual planning a murder; - ditto.

individual who decides to "pull the plug" (disconnect respirator/ventilator/etc.); - ditto

kidnapping victim who is told by his captor, "I will kill you tomorrow if your parents don't pay the ransom"; - will hold out hope that they'll escape or the random will be paid or that the captor will not carry through. Also, this is another person whom we can't study.

individual enters surgery knowing that survival odds are slim; - Still doesn't know exact date.

the six Utah (or Ohio?) miners trapped in a mine for weeks and weeks and weeks without rescue; - the longest anyone survived a mine collapse is 11 days. They held out hope of a rescue and they didn't know an exact date for death.

a car crash victim in a remote, desolate area who is pinned down and can't escape; - doesn't know the exact date of death and would hold out hope of rescue and we can't study the ones who got the date right!

individual who survives the sinking of a ship and floats in the ocean for days upon days upon days with no rescue; - again, they hold out hope of rescue - don't know when they'll die.

individual in a car/plane/train that is about to inevitably crash; - It's rather hard to ask them their feelings on the matter!

SteveBaker 14:55, 11 September 2007 (UTC)

Hello, again, Steve. I think that our replies "crossed paths" -- so, I am not sure if you saw my immediately preceding reply? I think that we were both typing simultaneously -- oblivious of the other's reply -- and I happened to hit "Enter" a few seconds before you. Anyway ... I read your list of "one-by-one" examples above. I think that you have missed the point of what I am trying to ask. I think that you are being far too literal. Nearly all of your "one by one" examples list (above) focuses on the term "exact date of death". I am not, I repeat not, focused on the "exact" date of death. You keep focusing on that, and I don't know why. And this mis-communication is probably why you are so vehemently defending your point that my premise is impossible. So, for clarity -- I am not concerned with "exact" date of death. As I proposed above, I can play with all sorts of semantics to clarify this. (But I thought that you got the "drift" of what I was saying.) Instead of saying that "a person knows his exact date of death" ... let's say ... "he knows a statistically significant estimate of his exact date of death" ... or ... "he knows his exact date of death with a reasonable degree of statistical probability at the 99% confidence level" ... or ... "he knows his exact date of death within a plus/minus degree of statistical error" ... or whatever semantics will satisfy you. Stop focusing on the word "exact." Think of it this way. In the grand scheme of the question, does it really matter that the miners think / "know" that they will die on Day 18 versus Day 22? No. The number 18 or 22 is not important. The general idea / concept is that the miner is saying to himself: "Geez, within the next 5 or 6 or 7 or 8 days, I will die under the circumstances of x, y, and z." In my immediately previous sentence, the numbers 5, 6, 7, and 8 are not particularly relevent or important to the concept. Rather, it is the concept that: "Wow, I have come to accept the circumstances of my death and I now acccept that my death is inevitable / clearly going to happen / without question ... and whether it is on day 6 or day 8 is not particularly relevent." The second thing you seem to focus on is whether or not, in a practical sense, we can "interview" these people. That is really outside of the scope of the question. In other words, just assume that we can interview them (which, I have pointed out in my previous post, we can in fact do). So, perhaps if you do these two things, then we will be on the same page when reading this question and approaching this topic: (1) remove the literal word "exact" and be satisfied that the person has a pretty "good sense" of the circumstances of his death, plus or minus some statistically insignificant margin of error; and (2) assume that we can interview them -- which we can, in some cases. In reading through your point by point list (above), your focus is on these two issues (1 = we can never truly know the EXACT moment of death ... and ... 2 = even if we could, which we can't, we still cannot access / interview / talk to these people). But, those two points and focuses are misguided and tangential to the question. If you care to, please free your mind of those two thoughts -- accept the premise of the question -- and let me know your thoughts. It's really not that difficult. Is it a good thing or a bad thing ... is it healthy or unhealthy ... is it desirable or undesirable ... for a person to have access to this detailed death information, assuming that somehow such access can be provided? (The degree of detail in the death information is what is bogging you down.) If it helps, re-phrase the question such that a person is XXX % ( say, 95% ) certain of his exact date of death ... or 99% ... or 99.999% ... or whatever number. To placate your concerns for exactness in the date/details of death, we will agree that x cannot equal 100%. Thanks. (Joseph A. Spadaro 16:26, 11 September 2007 (UTC))

Ignoring the difficulties of muggles, I'd say it depends on whether you're thinking of a magical/'advanced science' 'fate-testing' machine which tells you exactly what you'll die of whether it's through violence, accident or health problems, or whether you're dealing with magically accurate medicine that predicts what health problem will kill you and when. With the first scenario I'd imagine you'd get a lot of people who are predicted to die at some much later date becoming extreme risk taker, even trying to 'cheat' the machine by doing ridiculously dangerous things, safe in the knowledge that they wouldn't die. Whether the knowledge given by the machine affects the accuracy would depend on the universe you've picked and how the machine 'works'. With the latter scenario, I'd imagine that people given a long time to live would become excessively cautious, as they believe they have a lot of life to preserve. Those with not long left would probably go through the same things as terminal patients currently do, which there should be studies into for you to read. I'm not convinced that knowing the exact time and day would make much difference compared to knowing 'a couple of weeks' for example, apart from making the situation seem more certain and helpless, but when you're looking at longer time-frames, it could make a big difference.

Socially, I think it would be problematic. Insurance companies, and even employers, would probably be very interested in the results. Medicine could also seem a little depressing when everyone's deathdate is known. With children, why educate the ones that won't make it past 20? Etc.

Sorry not to be more specifically helpful, but I thought I'd try to get the ball rolling again. Maybe someone else has more specifics? Skittle 23:00, 11 September 2007 (UTC)

This Google Scholar search indicates some studies in the general area, although there are a lot of other subjects there too. This sort of thing can certainly be fruitful as a psychology/sociology thought-experiment :) Skittle 23:03, 11 September 2007 (UTC)

This is my reply to the original question. Also see Last Night (a quite good film covering this subject) and Kübler-Ross model (“the process by which people deal with grief and tragedy.” according to Elisabeth Kübler-Ross).
Possible disadvantages:

• Fear
• Panic attacks
• Depression
• Sorrow
• possibly anger
• possibly attempted suicide

Possible advantages:

• having the opportunity to resolve ones worldly affairs.
• having the opportunity to possibly fulfill any religious last rights.
• having the opportunity to prepare one’s self for death.
• the opportunity to tell loved ones any final things.
• being able to think of some really good last words.
• possibly having the opportunity to engage in a few sexual orgies.
• eating anything you want without fear of getting fat.
• telling your boss just what you think of him or her.

--S.dedalus 01:52, 12 September 2007 (UTC)

I also just realized (yet) another example of a plausible (and relatively common) scenario in which an individual "knows" the details of his death in advance ... that is, a prisoner sentenced to execution. In fact, I believe that there is something referred to as "death row syndrome". (Joseph A. Spadaro 05:40, 12 September 2007 (UTC))

Well, yes, except that death row syndrome is very similar in effect to a person being informed by a doctor that they have 'x' months to live. In either scenario the individual is not absolutely certain of their time of death, commutation of death sentences do happen and this would cause a spring of hope in the individual. Richard Avery 08:04, 12 September 2007 (UTC)

Yes, I definitely agree with you -- no doubt. But, again, my original question concerns people who "know" of their death in advance -- not necessarily with 100% absolute certainty -- but 90%-95% (or whatever). Thanks. (Joseph A. Spadaro 15:25, 12 September 2007 (UTC))

Psychology

According to psychologists, strong forces are at work influencing our behavior and the way we lead our lives. Identify three examples of these forces. What are they? —Preceding unsigned comment added by 74.14.119.169 (talk) 23:37, 10 September 2007 (UTC)

Ah, homework question? Start with psychology. --jjron 00:36, 11 September 2007 (UTC)

Electromagnetism, the strong nuclear force, and gravity! Seriously, though, this sounds like a out-of-textbook sort of question. If you can't find the answer there, narrow down the question if possible. -Wooty [Woot?] [Spam! Spam! Wonderful spam!] 01:00, 11 September 2007 (UTC)

Don't forget the weak force! anonymous6494 01:33, 11 September 2007 (UTC)

"The weak force is a strong force at work influcencing our behaviour...". Hmmm. TenOfAllTrades(talk) 02:43, 11 September 2007 (UTC)

Though the weak force is stronger than gravity, of course! Cyta 07:42, 11 September 2007 (UTC)

Wooty meant to put Electroweak instead of electromagnetism (or if he didn't, he should have) :) Capuchin 08:30, 11 September 2007 (UTC)

How do you tell if the weak force is stronger than gravity? They have different units. It's like saying a mile is longer than a minute. — Daniel 22:47, 11 September 2007(UTC)

But a mile is longer than a minute..unless you're going over 60mph... -Wooty [Woot?] [Spam! Spam! Wonderful spam!] 05:38, 14 September 2007 (UTC)

Surely the main three 'forces' that influence our behaviour are sexual drive, social conformity and social competition. I can't understand why the dicussion is limited to physical forces. Richard Avery 07:47, 12 September 2007 (UTC)

Because people are sarcastically pointing out that we don't do homework for people here, although we may indicate helpful areas. Also that asking vague, textbook-specific questions here won't result in helpful answers. Skittle 11:36, 12 September 2007 (UTC)

Doh! Richard Avery 07:48, 13 September 2007 (UTC)

And I'll posit thirst over any kind of social mumbo-jumbo. Saintrain 22:44, 14 September 2007 (UTC)