Science desk
< January 10	<< Dec \| January \| Feb >>	January 12 >

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.

January 11

Sweet potatoes don't grow on trees

Or at least that is what I still believe, despite my friend in Israel just telling me via IM that they do. Is there a food available in Israel that might be called a sweet potato that does grow on trees? Or is someone just pulling her leg? Anchoress 01:29, 11 January 2007 (UTC)[reply]

First, make sure it really is a sweet potato she is talking about. In the US sweet potato is synonymous with yam. But there is another true yam that is unrelated to sweet potato. It also has edible tubers, however, one, the vine Dioscorea bulbifera, also has an above ground tuber (bulbil) known as an air potato. It too can be eaten so it is possible that this is what your friend is describing. David D. (Talk) 04:44, 11 January 2007 (UTC)[reply]

Good information! I'm assuming, since she grew up in Canada, that when she says 'sweet potato', she's referring to what we both were familiar with from our years as friends and co-chefs. ;-) I think the above-ground tuber you mentioned is probably the source of confusion, and I suspect it is the person who told my friend about it who is confused, not my friend. Thanks for the info! Anchoress 21:00, 11 January 2007 (UTC)[reply]

Or the person told your friend they were yams, (no confusion there), your friend then told you sweet potato (translating to common usage) not realising there is a different yam? The thing that makes me doubt that Dioscorea is the source of this story is the tree part. these are definitely vines and could not be confused with trees. I suppose the vines might grow in trees. David D. (Talk) 06:23, 12 January 2007 (UTC)[reply]

Possible, but unlikely. My friend is definitely familiar with the difference between sweet potatoes and yams, but the person who told her might not be. There's also a whole lot of hydroponically grown food in Israel; maybe that's part of the confusion. ;-)) Anchoress 06:41, 12 January 2007 (UTC)[reply]

OMFG American's call sweet potatoes/kumara yam? I always assumed whenever I hear people talking about yams in Americans books and TVs they were really referring to yams, not sweet potatoes. Silly Americans. You learn something new every day I guess... Speaking of which, I just realised the yams I purchased once or twice before to try and make a yam ring ([1]) weren't real yams either but ocas which we silly kiwis call yams evidently (I've lived here for 5 years and didn't know that!). No wonder it didn't work. Nil Einne 14:44, 13 January 2007 (UTC)[reply]

The most fascinating thing about yams is how they revolutionised medicine. The secondary metabolite of diosgenin caused the price of medicinal corticosteroids to drop massively. [2] David D. (Talk) 21:43, 13 January 2007 (UTC)[reply]

Red Blood Cells

Why is that red cells in humans do not show a nucleus

Because they don't have nuclei. :-) See red blood cell. Basically, an RBC is a packet of hemoglobin. --David Iberri (talk) 01:45, 11 January 2007 (UTC)[reply]

They are prokariots, like bacteria, and the lack of a nucleus means they only live for a few months :(Hidden secret 7 18:57, 11 January 2007 (UTC)[reply]

They are not prokaryotes they are just very specialised. David D. (Talk) 19:19, 11 January 2007 (UTC)[reply]

A similar question came up before so unless the article has significantly changed, you should find BTW it mentions that RBCs in some animals do have nuclei Nil Einne 14:33, 13 January 2007 (UTC)[reply]

Chemistry - What is a plasma

What is a plasma

Plasma is an ionised gas or substance; it's also a blood product excluding red blood cells. Read up on different types of plasma and let us know if you have any specific questions. Anchoress 02:21, 11 January 2007 (UTC)[reply]

Plasma is the 4th state of substances and is reached when someting reaches a few hundred degrees C

Well, not necessarily fourth, else you'd need to number other states like Bose-Einstein condensates, quark matter, etc. But that's just a point of pedantry. GeeJo ^(t)⁄_(c) • 22:40, 11 January 2007 (UTC)[reply]

It is not accurate to cite a temperature requirement. A plasma is simply a gas which is ionized to the point where interactions with electromagnetic fields are significant. Much interstellar gas is a plasma, but it is extremely low temperature - around 4 degrees kelvin. --bmk

What is this psychological phenomenon called ("illusion" seems too general)

I'm curious as to what the name of this is -- for example, when you spot a distant rock in the forest, and you are convinced it's a resting bear or a stationary wolf. Or, at night, you see some white pipes at a construction site and they appear as a small group of people in white t-shirts. Basically, when your mind/imagination makes up decisive assumptions about a vague, uncertain shape with little information (but the assumption usually keeping in line with the context of the surrounding area and its theme). I think this generally fits into "illusion", but is there a more specific, narrower name for this? My original guess was mirage, but reading the article on that, a mirage is something very specifically different. --67.161.84.158 02:27, 11 January 2007 (UTC)[reply]

It's a misperception, more specifically a pareidolia. - Nunh-huh 02:33, 11 January 2007 (UTC)[reply]

Reminds me of Gestalt! I think pareidolia comes from our instincts for face recognition and anthropomorphization to try and understand [and copy] other humans to learn. X [Mac Davis] (DESK|How's my driving?) 05:26, 11 January 2007 (UTC)[reply]

It's definitely a useful paranoia to have; if you're alone in the dark, it's better for your brain to err on the side of caution, and assume that you're surrounded by wolves and bears. Vranak

This sounds almost similar to what I see :) Actually I don't see it, but that is still the same :) Could it be because we want to see something, or caused by something we think we should be seeing :? What about seeing clouds as shapes, is that paraidolia too :?Hidden secret 7 18:55, 11 January 2007 (UTC)[reply]

This was once termed "perceptual set" as at [3]. Your expectation condition how you perceive a sensory stimulus. If a policeman thinks someone he has stopped is a fleeing felon, he is more likely to perceive the celphone in her hand as a gun and shoot her. Edison 20:56, 11 January 2007 (UTC)[reply]

Volume of Atmosphere

How would one calculate the volume of Earth's atmosphere? Maybe this page will help, but I don't know how. Thanks.--68.205.179.107 03:45, 11 January 2007 (UTC)[reply]

Since the atmosphere doesn't have a definite upper limit, it doesn't have a definite volume either. If you want to compute the volume below a certain altitude above ground level, just multiply that altitude by the surface area of the Earth. --Anon, January 11, 04:05 (UTC).

I don't think you can simply multiply the surface area by the height. To do that, you would have to integrate the surface area equation with respect to radius of a sphere from the surface of the earth to the end of the atmosphere (anyone want to back me up on that?). I think to properly do it, assume the earth and its atmosphere are spheres and subtract the volume of the earth from the volume of the earth + atmosphere. Treat them as concentric spheres. :-) --Bennybp 04:09, 11 January 2007 (UTC)[reply]

If R stands for the radius, V the volume and A the area of a sphere, for a small increase of R by an amount of ΔR you can approximate ΔV = (ΔV/ΔR)·ΔR by (dV/dR)·ΔR = AΔR. The relative error in doing so is ΔR/R. For the Earth R ≈ 6400 km. Even if the thickness of the atmosphere is arbitrarily set at 100 km, that is less than 2% – rather good for something that depends on an arbitrary choice to start with. --Lambiam ^Talk 04:35, 11 January 2007 (UTC)[reply]

Still, why not just calculate the difference between the volumes of the spheres with the atmosphere radius and the surface radius? — Kieff 04:56, 11 January 2007 (UTC)[reply]

Good point. Although if I had to do it I'd still do the difference of two volumes method. Plus, the volume of the earth may be on the Earth page, although it doesn't say if that's the volume of everything or just the (solid) earth. --Bennybp 05:02, 11 January 2007 (UTC)[reply]

The volume of the two is essentially the same - the Earth's atmosphere has very negligible height (however you reckon it) with the depth of the earth ... so surface area times height probably induces very little error compared to the error of where you apply the cutoff. The atmosphere probably "ends" around 100 Km, or ~1% of the total distance from the centre of the earth. WilyD 14:19, 11 January 2007 (UTC)[reply]

I would say that attempting to calculate the volume of the atmosphere should probably be done by first determining the mass of the atmosphere (i.e. taking into account that the atmosphere tapers off) and then determine how much volume that equates to under standard temperature and pressure. That said, you would also have to remember that the atmosphere is composed of different gases at different altitudes. Andrewjur e n(talk) 07:29, 11 January 2007 (UTC)[reply]

Names of the toes

The above question about medical terms reminded me that I once heard on the radio that there were no medical names for the different toes, so a doctor had invented some Latin (or they might have been Greek) names based on the nursery rhyme. For example, the big toe was called whatever is Latin for "market piglet" ("this little piggy went to market"). I would love to know the complete list of names he invented but have had no success in Googling this. Perhaps they are lost for ever? (If nobody knows the answer, I'll take this to the language desk and see if somebody there would like to recreate them.)--Shantavira 09:42, 11 January 2007 (UTC)[reply]

I Googled on "toe" "market", "piglet", and "Latin", and found the answer here on the second hit. (For fun I also looked in Gray's Anatomy, 1958 edition, to see about the statement that there are no medical names for the toes. Indeed it simply numbers them from "first toe" through "fifth toe", also using "big toe", "great toe", and "little toe" as synonyms for the first and fifth. It doesn't even use the word "hallux" that that web page mentions, at least not on the pages I looked at.) --Anonymous, January 11, 11:11 plus 8 minutes (UTC).

Oh well done! Now my challenge is to wheedle pocellus fori etc into the appropriate articles! ;-) --Shantavira 13:32, 11 January 2007 (UTC)[reply]

free engineering handbook downloads

On which web-sites can i download free engineer's handbooks legally?

Tatenda

If they usually cost money, any way to get them for free is illegal. You might try Wikibooks, but you'd have to be more specific about which field in engineering you're referring to. - Mgm|^(talk) 12:14, 11 January 2007 (UTC)[reply]
So are there any that "usually" don't cost money and can be downloaded? --Lambiam ^Talk 19:55, 11 January 2007 (UTC)[reply]

Your best bet would be to search for U.S. government publications, which are usually free. A search like this in Google will pick up only US government sites, and seems to have gotten a few hits, though they are fairly specific (Naval Engineering, Hydrologic Engineering, etc.). --24.147.86.187 15:30, 12 January 2007 (UTC)[reply]

Some universities now publish their course books online. These aren't exactly handbooks. There are also a number of textbooks available from pubmed. Dunno if they cover engineering. They aren't usually downloadable tho Nil Einne 14:30, 13 January 2007 (UTC)[reply]

Minimal diet

I have been asking myself for quite a long time what ingredients should have a human diet a person could follow without future health problems by the premise of beign as less diverse as possible. Is possible to survive only eating one kind of food? Maybe with two combined? I am not going to follow the task but theoretically I think the question es interesting and not easy to answer. Thank you for your valuable help!

Survive for how long and with what quality of life? 100% probably doesn't allow a very restricted diet, but my Grandfather only eats about 12 food items and is not "noticably sick" --- but I doubt he's 100%. And where food comes from can make a difference too ... people in China are often Selenium deficient while North Americans may be exceeding their recommended daily allowance just from the differences in it's concentration in soil. WilyD 14:45, 11 January 2007 (UTC)[reply]
I guess something like "normal health". For example, someone who is almost living in Mc Donald's can not have a healthy life and perhaps he will have cancer or heart disease in the long term, but he is not going to have a serious short-term vitamin deficit disease like Beriberi or Scurvy.I think a man on their fourties beign able to get confortably into seventy years old.

I will say this: if you go on a very limited diet, you will eventually begin to crave foods that contain nutrients that you've been missing out on. So if you eat nothing but grains and fruit, one day you might wake up with an incredible appetite for calamari. Our bodies are smart that way. Vranak

I usualy eat almost nothing except noodles ommelette and pasta but I am still reasonably healthy :) I suppose it also depends on what the food is made of, some food may have a good mixture of nutrientsa &c, whilst other food is almost entirely one thing :)Hidden secret 7 18:50, 11 January 2007 (UTC)[reply]

You say you're still reasonably healthy, but how long will you stay reasonably healthy with such an unhealthy diet? That is the relevant question here. How long have you been following this diet? My guess is, not very long, at most a couple of years. --Lambiam ^Talk 20:03, 11 January 2007 (UTC)[reply]

Also, what do you mean 'resonably healthy'. Have you had a recent medical checkup with a blood work up? If not, I question whether your really resonably healthly. IMHO, appearing healthy doesn't mean your healthy. If e.g. your cholesterol is way out of wack are you really healhty even if you don't notice any ill effects? You may say yes, but some people with cancer also seem healthy and then are dead in 2 months. I myself very rarely get sick, and feel quite healthy (except perhaps when I try to exercise/exert myself too much). But I definitely have concerns about my health given that I know I have a poor diet, eat too much, and don't exercise much. Nil Einne 15:32, 13 January 2007 (UTC)[reply]

All I know is, if they ever sell a tasteless gray paste with all nutrients I'd ever need for a good living, I'd live off the stuff. — Kieff 20:23, 11 January 2007 (UTC)[reply]

Wasn't there a urban myth that you could have a healthy diet purely on Guiness and bananas? But the caveat was that you'd have to dring 15 pints of guiness a day or something.Vespine 21:48, 11 January 2007 (UTC)[reply]

I bet you could live off human flesh pretty well, assuming that the person you were eating was in good health -- apart from being dead I mean (see Soylent Green). Seriously though, there are several lab animal "diets" that might work (monkey chow). It would probably need to be slightly modified for people, but I'm sure that will happen someday (the opening sequence of Futurama advertises bachelor chow). --Cody.Pope 04:40, 12 January 2007 (UTC)[reply]

physical exercise and aching after

Hi. I went to a circuit training class on tuesday (for the first time in 7 years, so I expected to ache after). why though do my muscles ache more now on thursday than I did yesterday? Why does it get worse over time (and then obviously gets better after a few more days)? thanks, Spiggy 16:04, 11 January 2007 (UTC)

found it! thanks anyway guys. here's the url http://wiki.riteme.site/wiki/Delayed_onset_muscle_soreness

spiggy 17:01, 11 January 2007 (UTC)

Heh, I stumbled onto that article the morning after the I got my Wii. Cyraan 19:37, 13 January 2007 (UTC)[reply]

Aloneaphobia?

Ok, I searched List of phobias, Loneliness, and Solitude and haven't been able to find it. I haven't tried google yet as I don't know what I'll find searching google.

Is there a name for an unreasonable fear of being alone? Any one term I can search for to find information? ~ ONUnicorn^{(Talk|Contribs)}problem solving 16:22, 11 January 2007 (UTC)[reply]

Fear of being alone is called autophobia - see here and here. Gandalf61 16:43, 11 January 2007 (UTC)[reply]

The first link's mildly helpful; the second is exactly the sort of thing I did not want to find by searching Google. CTRN (change thats right now) claims to be able to cure fear of anything, and if there's not a word for it they make it up (usually several of them). Thank you though. ~ ONUnicorn^{(Talk|Contribs)}problem solving 17:08, 11 January 2007 (UTC)[reply]

Links were more or less picked at random just to show I wasn't making the term up. At least you maybe have a starting point for your research now. Gandalf61 17:33, 11 January 2007 (UTC)[reply]

Ernst Ruska

I can not find out any information about: Was Ernst Ruska ever married and did he have any kids? I am doing a project on him and need to know this information.

Thanks70.17.236.192 17:55, 11 January 2007 (UTC)[reply]

If you visit our article Ernst Ruska, you will see a link at the bottom, "Homepage of the Ruska family". If you follow that link, you can find the answers to your questions – although I had to apply some combination and deduction to the information given before I figured out his wife was called Irmela. --Lambiam ^Talk 19:20, 11 January 2007 (UTC)[reply]

Peanuts!!!

Is there any benefits or dangers to eating peanut shells?216.253.128.27 18:51, 11 January 2007 (UTC)nicholassayshi[reply]

On the positive side it is low calorie and high fiber. On the negative side it is non-nutritious, unappetizing, and an extra risk of ingesting aflatoxin. --Lambiam ^Talk 19:28, 11 January 2007 (UTC)[reply]

I used to hate peanut shells and deshell peanuts. Nowadays I prefer peanuts with them. So I wouldn't say they're unappetizing Nil Einne 14:27, 13 January 2007 (UTC)[reply]

Questions regarding a Rainbow

I have been looking at rainbows since I was a kid. I was also able to creat rainbows using our garden hose. I questioned why people didn't know that a rainbow was a full circle. I also have wondered when reading information regarding rainbows if the reason that we see different shapes of a rainbows caused by the rainbow being perpendicular to the sun?

I have learned from reading and I try to get more interested in the facts about rainbows. That is why I give friends and family members questions I create to get them to wonder about things more themselves.

What is the shape of a rainbow? —A circle
What is the white ring that can sometimes be seen around the moon during the winter? —A Lunar Rainbow
When light from the Sun enters a raindrop what happens? —It is both Reflected and Refracted and is broken down into its primary colors
What are the primary colors of a light? —Red, Green and Blue (True Blue)
The reflected and refracted light from one raindrop creates how many colors? —Only one
How many raindrops does it take to create a rainbow? —Millions
The center of a rainbow is in-line with the center of the sun, which is in line with what point of your body? —Between your two eyes
A rainbow can sometimes look like the shape of an ellipse but it is actually perpendicular to what? —The Sun
A rainbow can only be seen when the Sun is from the horizon to what degrees? —42 degrees
The colors of a secondary rainbow is what? —Inverted
When light comes out of a raindrop is comes out at what angle? —42 degrees
When up in an airplane with clouds down below you sometimes can see a total rainbow. What is in the middle? —You are
Forms of a rainbow can be seen: a. In the morning dew; b. When the sky is almost black; c. High in the cirrus clouds; d. All of the above; e. None of the above? —d: All of the above
What three colors are the primary colors of the Positive Spectrum? —Red, Green and Blue (True Blue)
What three colors are the primary colors of the Negative Spectrum? —Red, Yellow and Blue
When Green light and Blue light is combined what color is created? —Cyan (Sky blue)
What causes us not to see a full rainbow? —The Earth
Light is both reflected and refracted by each raindrop. How many angles can the light be seen? —Only one
When you and a friend are looking at a rainbow, can your friend see the same rainbow as you? —No
When light enters the lower part of a raindrop a secondary rainbow is created. At what angle? —52 degrees
When Red light, Green light and Blue light are combined what color light does it produce? —White Light

—The preceding unsigned comment was added by 76.174.186.108 (talk)

Neat stuff, rainbows are! Your #14-16 aren't self-consistent on their face though...maybe you've oversimplified a bit? How can the same color be part of both the positive spectrum and negative spectrum ("if you take something away, it's not still there")? See also subtractive color. Also, #5 is wrong (or at least poorly worded along with #11)...each raindrop acts as a prism and creates the full spectrum over a (perhaps narrow) range of angles. Perhaps what you mean is that an observer is only situated to see a single color from each raindrop? DMacks 19:56, 11 January 2007 (UTC)[reply]

Just adding a few comments:

4) Not quite. Red, green and blue are only the primaries of our color perception. See also: visible spectrum

5) No. Each raindrop refracts light entirely. The reason the transition between colors is gradual is because of the angle we're seeing the rain drops at.

15) If you mean the primary colors for a subtractive color space, they're actually cyan, magenta and yellow. See CMYK.

16) Cyan is not really the color of the sky.

18) Several. The incident light is refracted to several different angles.

19) Well, that'd depend of how you define "rainbow" as an entity — Kieff 20:21, 11 January 2007 (UTC)[reply]

(after edit conflict) Have you read our article Rainbow? I hope you enjoyed it. In the lsit you posted there were two questions numbered 18. I've taken the freedom to renumber them, using the inbuilt numbering of the wiki markup, so that all now have different numbers.

If you allow me to nitpick a bit, I have a few remarks.

Re 3. Rather than breaking white light down into primary colours, the refraction breaks it down into spectral colours, which form a continuum; see also Prism.

Re 4 (and also 14 & 15). See our article Primary colour.

Re 5. It is true that the rays of light reaching your eye from any single raindrop are (almost) the same colour. But rays of all spectral colours emerge from each raindrop, and while your eye may be hit by blue rays from some raindrop, the eye of your friend, who is standing next to you, may be hit by red rays from the same drop of rain.

Re 7. Actually each eye receives the image of a slightly different rainbow. For each eye, the centre of that rainbow lies on a straight line coming from the sun and passing through the eye. Since these lines are parallel for all practical purposes, the images are seen as coming from the same direction, which our brain interprets as coming from very far (recall that parallel lines "meet" at infinity). That is why a rainbow looks as if it is far away while it is actually quite close -- or, more precisely, the drops contributing to the illusion are usually not far away.

Re 8. The way this is formulated is a bit puzzling. The image always forms (part of) a neat circle. An ellipse, looked at under an angle, may also appear as a circle. If our brain is somehow misled into thinking the image is on a plane that is not perpendicular to the straight line from the Sun through your head, it may interpret the image as being that of an ellipse.

Re 12. You can also sometimes see this when you are on the top of a mountain. I've seen it. More precisely, it is the shadow of your head that is in the middle – except when looking while enclosed by a plane you only see the shadow of the plane at the spot where your head's shadow would have been.

Re 18. This question is not very clear.

Anyways, I agree that rainbows are fascinating stuff, and a good way to pick up some science. Cheerio. --Lambiam ^Talk 21:07, 11 January 2007 (UTC)[reply]

The optic nerve

last year, when I was doing an internship at a neuroscience institute, a question popped into my mind. Namely, why do the optic nerves (partially) cross over eachother and why is the central visual processing unit of the brain, the ocipital lobe, to the back of the brain? Wouldn't it be smarter to have the ocipital lobe to he front of the brain so the incoming signals can be processed more rapidly? I asked one of the researchers I worked with and he just told me I should know the answer to that by now. Sadly I had no previous history in neurosci let alone any knowledge of neuro anatomy or evolutionairy biology. So can any of you guys give me a clue? PvT 20:58, 11 January 2007 (UTC)[reply]

In the same vein, why do the nerves coming from the retina pass in front of it, so that they need to go through it somewhere to pass to the other side, causing a blind spot. The design of the eye of an octopus is very similar but doesn't have this blooper. I think such bloopers (problems with teeth and child birth come to mind as other examples) can best be explained by the theory of Dumb Design: our body plans are not the result of evolution, which would have optimized this away, but the result of a homework assignment in bio design, unfortunately executed by not-the-brightest kid in the class (if you allow me to call a juvenile extraterrestrial being a "kid"). --Lambiam ^Talk 21:24, 11 January 2007 (UTC)[reply]

I think the standard term is "unintelligent design" actually. For some intertesting reading about the design of the human eye, try Evolution of the Eye. DMacks 22:28, 11 January 2007 (UTC)[reply]

A better theory would be just that evolution isn't an intelligent process at all, and mistakes happen. The fact is that our blind spot never gave us much trouble for survival in the past (it was never a significant handicap,) so the trait was passed on. Perhaps the same can be said about the occipital lobe and everything else: they worked well that way, and so that's how they were kept. — Kieff 22:31, 11 January 2007 (UTC)[reply]

Not clear that it's even a "mistake" or harmless chance, or that there aren't specific benefits to this layout. See Bergman, Jerry (March 2000). "Inverted Human Eye a Poor Design?" (reprint). Perspectives on Science and Christian Faith. 52: 18–30. DMacks 22:49, 11 January 2007 (UTC)[reply]

Note that even if there is a benefit to this design, the actual principle in regards to evolution still holds since other organisms don't have our 'better' eye [4] Nil Einne 14:26, 13 January 2007 (UTC)[reply]

I asked this to a neurosurgeon, and this is his reply to the best I can remember it: Much of the body grows outward. So, the cells that eventually become the optic nerves develop from the middle of the brain outward. It would be possible for them to develop as non-crossing paths, like ><, but it is just as easy to develop in a crossing X. The main question isn't why they cross in the middle of the brain - it is why do they need to develop from the start. If they developed very late in growth, the entire optic part of the brain could be consolidated right behind the eyes. --Kainaw (talk) 22:32, 11 January 2007 (UTC)

During embryonic development the retina forms from the brain. The part of the neural tube that forms the retina folds over another nearby part that forms the retinal pigment epithelium. The rods and cones are metabolically very active and they shed a large part of their structure every day. The adjacent cells of the pigment epithelium act like a garbage disposal to phagocytize the discarded chunks of the visual cells. Thus, it is very useful to have the photo-detector cells "inside". The other cells of the retina are essentially transparent, so it hurts nothing to have them on the "outside", with light having to pass through most of the retina to get to the light-sensitive part. It is a simple matter for axons to follow the "stalk" of the retina back to the rest of the brain. In an animal like humans with over-lap in the visual fields of the two eyes, not all of the axons in the optic nerves cross to the other side of the brain. This allows information from the two eyes about the same object to be combined in the brain. The target for the axons of the optic nerves is not the back of the brain. The lateral geniculate nucleus is a major target for retinal axons in humans. In evolutionary terms, it was a later "invention" to send additional axons to the back of the brain and use for vision the vast amount of cerebral cortex that is available there. --JWSchmidt 05:31, 12 January 2007 (UTC)[reply]

Is it possible to convert random solid objects into liquid?

Is it possible to convert random solid objects into liquid? Feel free to laugh at me if this is a ridiculous question. For instance, can you take something like an iPod, fingernails, a pen, etc and convert them into a liquid by methods of grinding, melting, boiling, something along those lines?

Basically, what if you put an iPod into an extremely powerful juicer? NIRVANA2764 22:04, 11 January 2007 (UTC)[reply]

Grinding up something solid won't magically change it into liquid. It'll just make many small, solid pieces. Melting it would help, of course. Putting something like a tomato into a juicer is another story- the tomato was largely liquid to begin with. Maybe try reading melting or liquid for more info. Friday (talk) 22:12, 11 January 2007 (UTC)[reply]

If you were to heat an iPod, most of it would liquify, but at different temperatures, and by the time the last of it had liquified, the plastic parts would have done something other than liquify (say, burn). Fingernails cannot really be liquified. They would undergo destructive distillation. Eventually you would be left with a mineral residue that would probably melt (rather than sublime), but you couldn't really call it "fingernail" anymore. --Trovatore 22:15, 11 January 2007 (UTC)[reply]

There may be ways to liquify a variety of objects or substances. Things which would burn could be heated in a reducing atmosphere, or they could be ground up and dissolved in a solvent, creating a liquid solution. Metals can be melted and plastics, bone, minerals or ceramics can be placed in solution. Metals can also be (in general) placed in solution. Edison 22:40, 11 January 2007 (UTC)[reply]

Will it Blend? That is the question ≈Eh-Steve 01:03, 12 January 2007 (UTC)

Chemistry Naming question

Is there another name for this:

2,2,3,4-tetramethlyhexane

Like a proper nomenclature name? Thanks.

That seems like the proper (systematic) name to me. Are you looking for a trivial name? --Bennybp 00:42, 12 January 2007 (UTC)[reply]

Oh, except for the typo (2,2,3,4-tetramethYLhexane). --Bennybp 00:49, 12 January 2007 (UTC)[reply]

Plans for building a spaghetti bridge

Are there any tips for building a spaghetti bridge? Any engineering help on design ideas for added strength without compromising weight? Do share!

Most modern bridges are suspended bridges - unless you are using spaghetti and string, that design will not be of use to you. Look at older bridges made completely of steel girders (or wood planks). You will see how they built strong bridges with the least material possible. Copy their design. --Kainaw ^(talk) 23:44, 11 January 2007 (UTC)[reply]

Most? I think not. Suspension bridges are used primarily for long spans over deep water or perhaps other deep drops. Most bridges are concrete-and-steel affairs with intermittent supporting piers as necessary. See Girder Bridge. Dfeuer 00:05, 12 January 2007 (UTC)[reply]

Correct. I already jumped to the conclusion that this is a school assignment (a very common one in physics and engineering classes). The assignment is to build a long bridge span using a small and weak material. The teacher puts weights on the bridges. The bridge that supports the most weight gets the highest grade. --Kainaw ^(talk) 00:55, 12 January 2007 (UTC)[reply]

Do not boil the spaghetti. Paul Silverman 23:55, 11 January 2007 (UTC)[reply]

You could boil the spaghetti to make it soft and sticky. Then, twist a large group of them together. Wait for them to dry (put them in a dehumidifier if you have one). When they dry back out, you'll have a thick spaghetti rod that is stronger than a single strand. --Kainaw ^(talk) 23:59, 11 January 2007 (UTC)[reply]

I rather like the idea of a suspension bridge built on Kainaw's idea of boiling, forming, and drying.

Atlant 01:15, 12 January 2007 (UTC)[reply]

Yeah but how brittle is dried spaghetti?--Light current 02:50, 12 January 2007 (UTC)[reply]

You can also mold or extrude wet spaghetti into beams and even add fibers to eliminate the effect of its brittleness but don't store your finished bridge in the garage or it may become food for mice and rats. Barringa 03:17, 12 January 2007 (UTC)[reply]

The rats use the nutrients to grow, so could you then sacrifice them and use their bones to build the bridge (or better yet, feed it to your bratty little brother, etc:)? The pasta was used to make the bones were used to make the bridge, so sneak in on a technicality and the transitive property? DMacks 03:53, 12 January 2007 (UTC)[reply]

I particularly suggest the femurs for this technique. X [Mac Davis] (DESK|How's my driving?) 12:14, 12 January 2007 (UTC)[reply]

Remember that the triangle is the strongest polygon; wherever you have any squares or rectangles, add some crossbracing to turn the shape into a series of triangles. In addition, I'd guess that spaghetti has far more tensile strength than compressive strength; although a suspension bridge might would be too complicated, it would be far stronger than a simple beam or girder bridge. Laïka 15:06, 12 January 2007 (UTC)[reply]