Wikipedia:Reference desk/Archives/Science/2008 September 14

= September 14 =

Thallium Stress Test (Side Effects)
I am wondering if anyone has had a Thallium Stress Test ? If so; did you have any side effects ?

My cousin just had a test and since then has had terrible discomfort in his chest area that he never had before.

Thank You. —Preceding unsigned comment added by 74.235.199.159 (talk) 00:29, 14 September 2008 (UTC)


 * Well, it is a stress test. It stresses the heart, and most people who take the test either have known or suspected heart disease. So a report of discomfort following such a test needs to be made to a doctor, not to the Wikipedia reference desk! If your cousin has chest pain, he needs to call his doctor, so that it can be determined if he's suffering a heart attack or not! - Nunh-huh 00:49, 14 September 2008 (UTC)

'''Contact the doctor. That is what they are there for.'''--mboverload @ 02:18, 14 September 2008 (UTC)

No, call for an ambulance unless there is a doctor right at hand. "Terrible discomfort in the chest area" is an emergency situation! --Anonymous, 05:10 UTC, September 14, 2008.

If you had a stress test they must have give you an emergency contact number. Use it.  Plasticup  T / C  02:30, 14 September 2008 (UTC)

Chemical Name
I'm trying to figure out the name of a molecule, but I'm out of combinations. It looks like cyclopentane, but there is a nitrogen atom in place of one of the carbon atoms. No, this is not homework or anything, I'm just curious. Calamus Fortis  04:54, 14 September 2008 (UTC)
 * Perhaps Pyrrolidine? You don't mention how saturated the molecule is, but maybe this helps. --Scray (talk) 05:02, 14 September 2008 (UTC)
 * That was it exactly. Thank you. Forgive me for neglecting to mention saturation. Calamus Fortis  05:18, 14 September 2008 (UTC)
 * For future, you can search google or wikipedia for the chemical formula ("C4H9N" in this case) for many organic compounds and find their name and relevant articles. ChemSpider is another good free chemical search engine. DMacks (talk) 15:49, 14 September 2008 (UTC)
 * For browsing according to structure, the WikiCommons compounds tree is near perfect. --Ayacop (talk) 16:02, 14 September 2008 (UTC)

Swimming Pool (Hydrochloric) Acid
What is the gravelly, grinding noise that can be heard when pool acid is poured from the bottle into another vessel, or swirled in its own bottle ? It sounds as if there is a layer of gravel scratching around the bottom of the plastic container. --196.207.47.60 (talk) 05:00, 14 September 2008 (UTC)
 * I don't know about that, but a minor correction. It's Chlorine. Not Hydrochloric Acid (often wrongly called Hydraulic or Hydrolic acid). Hydrochloric Acid would irritate your skin to a point where you would have to get out because it stung so much. OK? OK. See also: Chlorine and Hydrochloric Acid.-- Editor510  drop us a line, mate  17:08, 15 September 2008 (UTC)
 * Er, hydrochloric acid (concentrated HCl, often labeled "muriatic acid") is used in pools also to lower pH (all that chlorine is pretty alkaline). DMacks (talk) 17:11, 15 September 2008 (UTC)
 * Oh, actually maybe I do know.


 * In the swimming pool, that'll be the ripples from when you pour it in slapping around in the little open venty thingys on the sides of the pool.
 * The bottle? My only guess is some trapped air inside there...


 * -- Editor510  drop us a line, mate  17:18, 15 September 2008 (UTC)


 * I think that the disinfectant used is sodium hypochlorite. This leads to precipitation of calcium carbonate inside the bottle. Axl  ¤  [Talk]  12:55, 19 September 2008 (UTC)

Dark matter
wat is meant by dark matter? —Preceding unsigned comment added by Donlesnar (talk • contribs) 05:47, 14 September 2008 (UTC)


 * see dark matter. --Shaggorama (talk) 06:52, 14 September 2008 (UTC)

Name for animals that can change colour
Does anyone know what the scientific name for this capability among animals is? We have a list at Category:Animals that can change colour and a request to fill in this missing information. (Can;t seem to link to it but it's there in fact) Thanks, Julia Rossi (talk) 11:46, 14 September 2008 (UTC)
 * It's at Category:Animals that can change color. DuncanHill (talk) 11:53, 14 September 2008 (UTC)
 * (edcon) yes it is thanks DuncanHill, Julia Rossi (talk) 11:58, 14 September 2008 (UTC)


 * For the edification of other readers, you link to a Category (or Image) like so: Category:Animals that can change color  Plasticup  T / C  16:08, 14 September 2008 (UTC)

[http://biology.queensu.ca/~biol431/topics.htm#How%20do%20animals%20undergo%20adaptive%20colour%20changes? The mechanisms responsible for colouration strategies differ between species depending upon the nature of the pigment, the control over pigment distribution and the time frame over which pigments change]. If different species do it in different ways, there may not be a catch-all phrase.  Plasticup  T / C  16:11, 14 September 2008 (UTC)
 * Oh, I was hoping for something like "changer of colour" or "environment mimic" in Latin, but never mind. Thanks anyway, Julia Rossi (talk) 10:05, 15 September 2008 (UTC)

Things that weigh on Milligram.
What are some common things that weigh one milligram? —Preceding unsigned comment added by 80.148.22.232 (talk) 12:30, 14 September 2008 (UTC)


 * There's one at Orders of magnitude (mass). Fribbler (talk) 12:51, 14 September 2008 (UTC)
 * (For those who don't want to click through, it is a mosquito)  Plasticup  T / C  16:06, 14 September 2008 (UTC)


 * Five grains of table salt.--Stone (talk) 17:03, 14 September 2008 (UTC)

VEGA LAUNCHER
My cousin (a nuclear enginneer) said that Vega can be used also as military rocket.Which distance is it able to do? Thanks. —Preceding unsigned comment added by Vindobona (talk • contribs) 14:02, 14 September 2008 (UTC)


 * Not sure what you're refering to. Do you mean Vega (launcher), Lockheed Vega, or Percival Vega Gull? --Ayacop (talk) 14:26, 14 September 2008 (UTC)


 * Given that the title of his question is "Vega Launcher", it seems a safe bet that he is referring to Vega (launcher). All of your questions are answered in that article. The first launch is scheduled for 2009.  Plasticup  T / C  16:04, 14 September 2008 (UTC)


 * If you realy want you can use the space shuttle or any other rocket. For military the liquid stage especialy LOX LH2 stage is stupid, you can not leave it in the silo for long an fueling the thing costs time, so most military nuclear rockets are solid fuel and the last upper stage of Vega is only for orbit insertion. So yes, but for which country? France und GB have already what they want, and the other ESA members have no nuces.--Stone (talk) 17:00, 14 September 2008 (UTC)

Italy has (like other EU contries) is able to build a nuke actually very quickly.It doesn't build because he decided to do not build it and so itself decided it! My cousin teaches nuclear physics in Milan.He says that country like Italy officially haven't the nuke because of NPT,but Italian Army did several years ago what it wanted.It had nuclear research centres only for military aims.Vega derives from Scout so he said it's very good for military aims(it's also too much!).He told me also that EU (by a small law wanted by Italy and Germany;at that time EU didn't exist)can declare itself nuclear power.The same thing i heard by the Italian ambassador in UN.I think they know more than us. PS Nowhere is written that you have to keep the rocket in a silo especally if you set it on something moving. Thanks. —Preceding unsigned comment added by Vindobona (talk • contribs) 18:41, 14 September 2008 (UTC)
 * To build a nuce is not much of a poblem if you have a HEU research reactor. But to declare to be a nuclear power would make you a nation nongrata in europe. One thing is you have to get all the others helping you to build the Vega for you, and France and GB for sure will not give you the Vega parts they provide for a rocket. To have a a couple of Vegas somewhere else than Koru makes only sense if you build them for military purpose. The silo or on a truck does not matter the -200°C liquid will give you trouble.--Stone (talk) 20:54, 14 September 2008 (UTC)

In UK are built no parts of Vega. Italy builds the 65% of launcher and it's able to build everithing it wants.Be sure!I haven't yet received an answer about its distance on Earth! —Preceding unsigned comment added by Vindobona (talk • contribs) 09:53, 15 September 2008 (UTC)
 * Since, from the article, it can put 2 tonnes into polar orbit, it can hit anywhere. Saintrain (talk) 14:17, 15 September 2008 (UTC)

This isn't a rational answer.The rocket can also landing!The problem is going up and not landing!It's also too strong !Certainly it 's able to cover many many thousands Km.Also Stone said "Yes it can be used!".Thanks. —Preceding unsigned comment added by Vindobona (talk • contribs) 14:52, 15 September 2008 (UTC)

Thyrotropin Releasing hormone in Gastrointestinal tract
What does TRH do in the gastro-intestinal tract? can someone give further links to reading sources? 117.97.145.59 (talk) 14:06, 14 September 2008 (UTC)
 * According to de:Thyreoliberin, any effects are indirect, i.e., through stimulation of nerves in the brain. We have (no references, sorry)
 * through the vagus, stimulation of stomach acid production and peristalsis
 * through the sympathetic nerves, stimulation of insulin secretion
 * stimulation of exocrine function of the pancreas
 * --Ayacop (talk) 14:35, 14 September 2008 (UTC)

Dog ESP
I went to my friend's home with him. His home is in another city, some 7 hours away by train. He was away from his home for several weeks. When we got there their dog was waiting at the gate for him. His dad told us that the dog had been standing outside and waiting all day long, as if he knew my friend was coming. He said it happens every time he's about to come home. Any scientific explanation for this? ReluctantPhilosopher (talk) 14:22, 14 September 2008 (UTC)


 * I'm willing to bet it's more a matter of confirmation bias and the father just ignores all the other days when the dog is waiting by the gates. -- MacAddct &#xF8FF; 1984 (talk &#149; contribs) 15:12, 14 September 2008 (UTC)


 * Or the dog picks up on changes in the father's behavior on the days when the father expects a visit. Or both. - Nunh-huh 15:19, 14 September 2008 (UTC)


 * I'd go with what MacAddct and Nunh-huh are saying. I'd also like to add that this is a classic case of anecdotal evidence, which is unreliable. There are all sorts of reasons why the premise -- that the dog always waits for him all day -- could be wrong: perhaps the father exaggerates (consciously or otherwise), because it makes for a good story, or because it reinforces the idea of a loving and loyal dog, or because he knows it makes your friend feel good, for example. In order for us to even begin honestly entertaining the idea that the dog is actually doing this (and I think the other explanations are far more likely), there should be some kind of actual evidence of the dog really standing by the gate all day long on the days your friend is coming home (and not doing so on any other day). -- Captain Disdain (talk) 15:34, 14 September 2008 (UTC)


 * My dog always knows when my wife and I are about to go on a trip—all day long she frets about us leaving in a very distinct way. She also knows when people are going to be visiting and is similarly antsy. How does she know these things? She's not psychic (she's many things, but it's clear she's not that!). She knows we are going to go on a trip because she sees us doing things we don't usually do (e.g. packing). Before people come over, we are always cleaning things up that usually we don't bother with. The dog observes us, and can pick up on very subtle changes in activity and emotion. The dog always knows when one of us is sick. She isn't psychic, she's just able to tell when we're doing things we don't normally do. Dogs are very capable of noticing routines (including the much beloved "time for dinner!"), and are very keen to what differences in them mean. One of the things we love about our dog is that after seven years or so we all understand each other very well. We can tell what she is thinking and feeling just as well as she can tell what we are thinking and feeling. It's not ESP, it's empathy. --98.217.8.46 (talk) 16:14, 14 September 2008 (UTC)


 * Another possibility is that your friend's Dad told the dog he was coming home, mentioned his name, opened the door to his bedroom, things like that. When my Mom tells her dog I'm coming to visit, he insists on staying out in the yard with his eyes on the gate until I get there. I bring doggie treats for him you see and pat him a lot. He knows exactly what my name means when it's linked with "is coming". Franamax (talk) 17:39, 14 September 2008 (UTC)


 * Thank you all guys, that was very helpful. ReluctantPhilosopher (talk) 15:34, 15 September 2008 (UTC)


 * I remember hearing that one of the suggestions for the Longitude prize (essentially for timekeeping at sea) was that litters of puppies were raised together, and then distributed to ships with one being left at home. Exactly at midday the dog left at home would be jabbed with a sharp object: the theory was that all the other dogs in the litter would howl at the same time. I don't have a reference to show it really was proposed, but it makes a good story. It didn't win. DJ Clayworth (talk) 21:38, 15 September 2008 (UTC)


 * There have been scientific studies of the phenomenon: http://en.wikipedia.org/wiki/Sheldrake#Seven_Experiments_That_Could_Change_the_World

What's it called when...
You look at a lamp or the sun and it leaves an imprint in your eye, which discolours what you are looking at, making it purple, black-and-white, or just false colour?-- Editor510  drop us a line, mate  16:56, 14 September 2008 (UTC)
 * It is called an after-image. DuncanHill (talk) 17:01, 14 September 2008 (UTC)

Help identifying flowers
Hi. I'm trying to identify the species of a couple of plants from my mother's garden. For geographical/climate information, these plants are growing in North Texas.

The first is a vine with bright pink flowers that bloom at night. (These photos are taken during the day):

If they turn out to be pictures we could use, I'll re-upload them with more useful file names. Thanks in advance to anyone who can help. -GTBacchus(talk) 19:12, 14 September 2008 (UTC)


 * Do the pink flowers have a sweet scent? They look like a honeysuckle to me. DuncanHill (talk) 19:32, 14 September 2008 (UTC)

I think the pink night-bloomer might be Angel's Trumpet (Datura). According to our article on that, it comes in pink, is shaped like the flowers in your picture and blossoms at night. 128.239.177.28 (talk) 13:26, 15 September 2008 (UTC)Hana


 * The blue ones could be are Ruellia brittoniana and the article (needs pictures) has a link to a French language site with similar pix. The pink one is Four o'clock flower or Mirabilis jalapa and the article could use pix like yours for its different states.Julia Rossi (talk) 09:54, 16 September 2008 (UTC)
 * Wonderful, thank you! I will re-upload the pictures with proper names, and add them to the articles. -GTBacchus(talk) 19:24, 19 September 2008 (UTC)

Ornithopters
Lets say we want to turn the F-22 into an ornithopter. Its empty mass is about 19,700 kg. If we assume its wing area remains the same (840 ft² (78.04 m²)), how fast does it have to flap in order to hover? I'm aware of the technological limitations of such things, but for this thought experiment, lets just ignore how we could build such a thing. ScienceApe (talk) 19:36, 14 September 2008 (UTC)
 * Simply flapping flat wings won't produce any lift at all, since you're doing a symmetrical motion on both up and down strokes. The wings would have to bend somehow, and the rate of flapping required will depend on how that bending is done.  --Sean 12:58, 15 September 2008 (UTC)


 * That's not true actually. The upstroke does not cancel out the downstroke. Bending the wing on the upstroke helps, but it's not required. Check out http://www.ornithopter.org/how.wing.shtml. In short the angle of attack allows for the wing to constantly gain lift, even on the upstroke. So both the upstroke and downstroke create lift. 98.221.85.188 (talk) 14:06, 15 September 2008 (UTC)


 * The problem is that flapping flight depends on "wing loading" - how many kilograms of weight is there per square meter of wing area? The problem with making things bigger is that when you double the size of something, you typically quadruple its area and octuple it's weight.  So when you double the size of a flying machine, you double the wing loading.  So tiny insects fly really well and seemingly without much effort.  Small birds also work pretty well - but as birds get bigger, they have more and more unwieldy wings and rely more and more on gliding and less and less on flapping.  So ornithopter flight is inherently difficult for "human sized" flying machines.  I don't know how fast an ornithopter the size and weight of an F22 would have to flap - but I'm pretty sure it's impossible.  There comes a point with flapping flight where the wing would start to "cavitate" - that is to say that the air pressure beneath it would drop to zero - and at that point, flapping faster wouldn't win you any additional lift because you're essentially just pumping vacuum...I suspect that would happen before you got to that scale - but I don't know how to calculate that.


 * There have been efforts to make light-aircraft-sized ornithopters - but so far, none of them have worked - they are probably right on the edge of what's possible.


 * SteveBaker (talk) 15:25, 16 September 2008 (UTC)


 * That's also not true. There have been working examples of ornithopters that are plane sized. Your vacuum hypothesis doesn't seem any more likely than a helicopter would create a vacuum. Big birds do not glide. They soar. That's a completely different flight mechanism. We do know that it's possible to create a large ornithopter because we know large animals that can fly. Specifically pterosaurs. Hatzegopteryx in particular is probably one of the largest animals ever that was fully capable of flying through flapping and soaring. Therefore, if biology can achieve this, then it's entirely possible to create a machine that can do the same. 98.221.85.188 (talk) 22:18, 16 September 2008 (UTC)

It would probably be dependant on wing dimensions and hence the F22 probably isn't a very good choice. Something like a B2 Spirit (due to its massive wingspan compared to the body) or a C-130 because presumably from its ability to take off from very small runways it must create a lot of lift, and be light. 88.211.96.3 (talk) 13:07, 18 September 2008 (UTC)

Inverse Compton effect and nuclear weapons
I was told by someone who was very much involved in the US H-bomb program that in the 1950s the inverse Compton effect was regarded as a big secret because it had major implications for hydrogen bomb design.

Can someone more literate in physics explain to me why this might be so? And if the Compton effect is relatively common, would it be much to expect that someone scientifically literate would not happen upon the likelihood that the inverse Compton effect would exist and have relevance to such an endeavor? The article on Compton scattering didn't really help me in wrapping my mind around this question, other than indicating that the inverse effect seems pretty rare under Earth conditions (i.e. it seems like it only takes place in regards to astrophysics, and presumably in nuclear weapons though it doesn't say that). --98.217.8.46 (talk) 20:10, 14 September 2008 (UTC)


 * If you google h-bomb and inverse compton effect, there's some documentation to be found. For instance according to the i.c.s. effect created a problem for the H-bomb by cooling the electrons, but the challenge was more in doing the calculations surrounding this, and they may have been kept a secret. I believe i.c.s in itself must have been well known in the 1950s. EverGreg (talk)  —Preceding undated comment was added at 21:57, 14 September 2008 (UTC).


 * The fellow who told me about it said that it wasn't well-known at all at the time, though he conceded that if you thought about it, it wasn't too hard to imagine that it would exist (he thought the idea of trying to keep something like that a secret was stupid). I interpreted this as meaning that it's the sort of effect that really doesn't come up under earth regimes, and so would be counterintuitive unless you were really trying to figure out things in extreme regimes (like the idea that solid plutonium can be compressed under extreme pressure regimes, which only occurred to Edward Teller because he had been working with Gamow on things relating the core of the earth).
 * What I'm asking for, basically, is a straightforward explanation by someone who understands the physics, for a non-scientist. --98.217.8.46 (talk) 22:56, 14 September 2008 (UTC)
 * Oh, an explanation! :-) That's actually very easy. The compton effect is all about a photon (light) and an electron colliding. These hit each other like billiard balls and recoil in opposite directions. In typical situations, it is the electron that speeds up after the collision and the photon looses energy. It still moves at the speed of light, but with a longer wavelength. "Typical" as in typical photon energies and typical electron speeds. But in some situations, like in astrophysics, some physics experiments and the H-bomb, the electron is moving so fast it is the photon that gains energy after the collision. For an H-bomb this seems to have been a bad thing because the energy "leaked out" of the process with the photons. But I'm not familiar with the details here. If you like, you could perhaps edit the compton effect article to provide a better-worded lay-man explanation. EverGreg (talk) 08:19, 15 September 2008 (UTC)

Why is gold leaf opaque when it is only one atom thick and each atom is mostly empty space?
Please could someone explain why it is not easy to see through gold leaf, when the material is only one atom thick? It is possible to see through the material if you hold it close but it is not transparent in the same way that air or many types of glass are.

My understanding of the scale of the atom is that if the nucleus was the size of the circle at the centre of Wembley Stadium, then the electons would be vastly smaller and whizzing around within a cloud the size of the whole stadium.

I also understand that gold has 79 electrons, but these are so, so small then surely, even as a fast-moving cloud I cannot believe that they could form the illusion of a solid space to the human eye.

Using the same argument, I also struggle to understand why it is possible to see through vast volumes of air. On a clear day, from a reasonable height, it is possible to see around 20 miles (and much further from the top of some skyscrapers). When looking this far, the observer is looking through a block of air. I would have thought that, as sparse as the atoms/molecules in air are, over this distance the chances are that there would be many atoms or molecules 'obstructing' the observer's line of sight - yet he or she can still see through.

So...what property of materials makes us able to see though some and not others (oher than their depth)? Thank you Jilly (talk) 20:21, 14 September 2008 (UTC)


 * One thing that comes to mind is that your gold leaf is thin but it is tightly packed, and the atoms aren't moving. In the air, you have a very low density collection of atoms that are constantly moving about. It would seem to me to be the equivalent of shooting bullets at a tight-knit chain link fence in the case of gold, whereas air would be more like setting up a long tennis court with a bunch of constantly bounding balls. In the latter case you are likely to hit one every once in awhile but a constant spay would make it through pretty well; in the former case each shot has a pretty high chance of getting scattered in the same general area. But this is obviously a very off-the-cuff sort of reasoning. And it doesn't take into account transparent solids like glass, obviously, though I would guess that glass is more like the chain linked fence, but with very wide linkages. --98.217.8.46 (talk) 20:34, 14 September 2008 (UTC)
 * A few things here:
 * Is there actually gold leaf one atom thick ?
 * Light interacts with matter through electrons that absorb and reemit certain wave lengths (so basically, what we "see" is the electrons really).
 * Regarding air, not all light makes it through, that's why for instance the sky is blue (as some wave lengths are absorbed), some light is scattered (things become blurry in the distance), ultimately, it's just a matter of distance and density of the air, it just so happens the atmosphere on earth is not "thick" enough to block/scatter light entirely (whereas visible light on Venus is too scattered for us to see anything of the surface). Equendil Talk 20:59, 14 September 2008 (UTC)


 * (edit conflict with Gandalf61) I am extremely skeptical that someone could make gold leaf that was just one atom thick. Our article on Goldbeating says that "The finished leaf forms an unbroken sheet of gold with a thickness of 1/250,000 of an inch." Now, that's really amazingly thin, absolutely, but nonetheless, the leaf is still 0.0000001016 meters thick. That's pretty hefty compared to the "size of a typical atom, which is 0.000000001 meters across", according to this RHIC physics primer. That's plenty of room for a whole bunch of atoms to be stacked on top of each other. -- Captain Disdain (talk) 21:27, 14 September 2008 (UTC)


 * Our goldbeating article says that gold leaf is 1/250,000 of an inch thick - that's about 10-7 m or 100 nanometres. Typical atomic radius is 0.1 nanometre, so gold leaf is hundreds of atoms thick. Gandalf61 (talk) 21:19, 14 September 2008 (UTC)
 * When you get gold leaf extra thing it does permit light to move through and becomes nearly transparent when really thin. Graeme Bartlett (talk) 21:28, 14 September 2008 (UTC)
 * Indeed. Most space suits for extra-vehicular activity have their outer visor coated in a thin layer of gold, to protect the occupant from the intense sunlight. The astronauts actually look through the gold layer. (I'm having a hard time finding a WP article that says so explicitly, the best I can come up with is Krechet - note the gold-colored viewing bubble.) -- 128.104.112.147 (talk) 21:52, 14 September 2008 (UTC)
 * Well, the article does say, "The outer visor was coated in gold for reflectivity." That's pretty explicit! -- Captain Disdain (talk) 22:00, 14 September 2008 (UTC)
 * The outer visor is coated in gold. Not gold leaf. - Nunh-huh 22:53, 14 September 2008 (UTC)
 * Gold leaf is just an extremely thin layer of gold. What distinction are you trying to draw here? Algebraist 00:30, 15 September 2008 (UTC)
 * Possibly the distinction between rolling/beating (to form gold leaf) and methods like vacuum deposition to place a thin layer of metal onto a substrate. I'm not sure that the latter would be called "leaf".  -- Coneslayer (talk) 14:14, 15 September 2008 (UTC)
 * Well, yes, it would make absolutely no sense to apply a visor coating as gold leaf. There'd be no way to make it as uniform as it needs to be. Gold leaf is not just "an extremely thin layer of gold". It's a thin sheet of hammered (or rolled) gold; it's applied by hand; it's difficult to accurately approximate the sheets without overlapping, etc. all of which make it unsuitable for visors. Which of course it is anyway, because it's opaque! - Nunh-huh 22:47, 15 September 2008 (UTC)
 * While the "diameter" of an atom is about 100,000 times that of its nucleus(!), it's the (outside) electrons that interact with the light rays. The distance between gold atoms in its crystal structure is about 270 picometres.  (Gold remains a crystal even after you beat the crap out of it, that's why it's done so much.)  Visible light has wavelengths that vary between about 400 (blue) and 700 (red) pm (less than an octave!).
 * See-through gold (visors etc.) is "sputtered" on to the surface. It's not a continuous crystal layer but a bunch of dots with lots of space in between (if you're a photon).
 * Transparent materials like glass don't "allow" light to "pass through" (silicon and oxygen atoms, the principle components of glass, are (about) the same size as gold and as tightly packed and made of exactly the same stuff.) The atoms "relay" (I know.  I know.  I can't think of a better word.) the light all the way through.  Saintrain (talk) 01:52, 15 September 2008 (UTC)


 * I think the physics of light on the atomic scale is more complicated than the simple model I have in my head. I understand electron transitions releasing light but I'm struggling with objects that do not emit light themselves. Could you tell me a bit more about how the wavelengths and electron interactions affect what we see (or point me in the direction of an article where I can learn more?). I've never understood how solid things are made up of tightly packed 'things' of mostly empty space and I think this is the lead I was looking for. Thank you all for all of the answers so far. 90.211.244.242 (talk) 21:06, 15 September 2008 (UTC)


 * Practically speaking, there are several easy ways to see that very thin layers of metal can be quite transparent. One way is to find an old piece of cut glass (a wine goblet, etc.) that is decorated with gold leaf. You'll often find that if you hold the glass up to a bright light, you can see through the gold. If you have a gold-metalized CD, that's a more-uniform, thinner layer (sputtered, not leaf) and you'll definitely be able to see through that. (Aluminized CDs show a similar effect and are far more common, of course.) Switching to other metals, if you're looking at this article on a LCD, you're looking through transparent Indium tin oxide electrodes within the LCD panel. And if your car (like many Fords) has a transparent, electrically-heated front windshield/windscreen, again, you're looking through transparent ITO (I think). And then there are always mirrored sunglasses.


 * Atlant (talk) 19:23, 15 September 2008 (UTC)

Prostate Treatment
The articles on Prostatitis and on BPH don"t mention treatments such as ejaculation, eating radishes, drinking cranberry juice. Is this type of treatment addressed somewhere? They do mention avoiding caffeine as a prevention.  Also, if antibiotics such as cipro and doxycycline alleviate symptoms for a period of months is there an antibiotic that offers longer relief? Bigprostate (talk) 20:35, 14 September 2008 (UTC)
 * You can edit article to improve them, this is wikipedia the encyclopedia you can edit. We cannot offer medical advice here though. I have linked your words in case someone want to check out the articles. Graeme Bartlett (talk) 21:40, 14 September 2008 (UTC)
 * Do you have any sources that suggest that those treatments are commonly used, or effective? Wikipedia articles need reliable sources to back up their claims, and in this instance I'd say a medical journal would be about the level required. Confusing Manifestation (Say hi!) 23:41, 14 September 2008 (UTC)
 * Having a bit of knowledge about effects of cranberry juice, that only works as preventative of infections where it actually touches the skin/mucus. You couldn't prevent or even heal prostatitis. --Ayacop (talk) 13:54, 15 September 2008 (UTC)


 * The Merk online medical resource mentions frequent ejaculation as a relief for prostatitis but does not mention radishes or cranberry juice. Treatment for benign hypertrophic prostate does not mention either frequent ejaculation, cranberries or radishes. Cranberry juice has scientifically been shown to alleviate mild urinary infections (sorry, no refs) and by association may have been included to alleviate prostatic patholgies. I would expect Merk to make reference to any accredited treatments. There are many references on the internet regrading radishes and protatitis, and many of these seem to be rehashes of this bizarre specimen., which seems to have no valid scientific backing but sources back to a Chinese address. Richard Avery (talk) 13:53, 15 September 2008 (UTC)

Parallel universes
I parallel universes exist, is it possible to communicate or travel between them? —Preceding unsigned comment added by 79.76.164.210 (talk) 22:03, 14 September 2008 (UTC)
 * Well, it depends what definition you give to "universe" and "parallel universe" really, then the answer is pretty much in the definition. If you define "universe" as "everything that exists anywhere", then by definition, there is no "parallel universes". You might want to check the article on existence here. Equendil Talk 23:29, 14 September 2008 (UTC)


 * You might find time travel in the article Many-worlds interpretation stimulating. As if my mind doesn't branch enough, along comes your question, so I am stepping inside and may be gone for some time. Julia Rossi (talk) 23:26, 14 September 2008 (UTC)


 * Also see Multiverse; there are various ways and senses in which there could be multiple universes. --Allen (talk) 04:31, 15 September 2008 (UTC)


 * It's impossible to know whether there ARE parallel universes. In my personal opinion, the theory of multiverses is much more understandable than alternative interpretations of bizarre quantum theory effects.  If we can't possible know whether they exist - it's very premature to ask whether we could travel between them.  My best guess is "No" - but it's a guess. SteveBaker (talk) 18:10, 15 September 2008 (UTC)

So, an aging rockstar has taken so much speed and cocaine over the decades...
...that it has somehow permanently altered his entire blood chemistry, meaning that a transfusion of normal, healthy blood would kill him - and turned his own blood so toxic that if transfused into another person, it would kill them instantly.

Urban legend/toughguy publicity posturing or genuine possibility? Not naming any names, a) due to WP:BLP, b) I've heard the same story attached to at least three different people. --Kurt Shaped Box (talk) 23:10, 14 September 2008 (UTC)


 * Definitely sounds like urban legend/pathetic boasting. Even people with a long history of heavy polysubstance abuse will clear the drugs from their blood within days.  Obviously the addiction lasts longer, but their blood is not toxic per se (assuming no HIV, hepatitis C, etc of course).  If they have liver, kidney, or other disease, then some things might be out of whack, but not enough to be fatal with the usual volume of a blood transfusion. --Scray (talk) 23:47, 14 September 2008 (UTC)


 * So, file alongside 'singer has pair of ribs removed to aid autofellatio' and 'singer hospitalized after swallowing 5 pints of semen' (hilariously, I can think of two singers who've had both these stories circulated about them)? --Kurt Shaped Box (talk) 00:18, 15 September 2008 (UTC)


 * Presuming any of that drug use was does intravenously, it seems a moot point since they'd be banned from donating blood by most or all blood collection agencies Nil Einne (talk) 17:12, 15 September 2008 (UTC)


 * Why is it always "singer"? It's never "drummer"...but they are way more crazy in my experience. SteveBaker (talk) 18:07, 15 September 2008 (UTC)


 * Probably because many drummers - unless they're particularly remarkable are seen (by fans) as to rock bands what redshirts are to Star Trek... ;) Cue all the bad jokes about 'the musicians and the drummer', groupies that were so desperate/stupid/drunk that they had sex with the *drummer*, etc.... --Kurt Shaped Box (talk) 21:02, 15 September 2008 (UTC)


 * I can only think of one for the drugs, and two for the ribs/stomach pump. DuncanHill (talk) 21:16, 15 September 2008 (UTC)

Why? as a scientific question
Is "why" a valid question in science. For example, "Why is there a universe, rather than none?" or "Why does the apple falls?" or "Why does the atomic nucleus does not integrate?" etc.

Please provide examples from scientific papers and the academia.

Is "Why" a valid of question of science? —Preceding unsigned comment added by 98.97.102.6 (talk) 23:12, 14 September 2008 (UTC)
 * Yes, certainly. 'Why' asks for an explanation, and one of the purposes of science is to explain things. Exactly what constitutes a scientific explanation is a big topic in the philosophy of science. There's some information at philosophy of science. Algebraist 23:42, 14 September 2008 (UTC)


 * Why is the sky blue? Why do objects appear to fall straight towards the center of the planet? Why is there so much variety in species? Why is just fine. It might not always be answerable at the moment (like your "Why is there a universe", which is at the moment beyond our understanding), but that doesn't make them non-scientific. --98.217.8.46 (talk) 23:48, 14 September 2008 (UTC)


 * Perhaps how is a better-accepted scientific question in general, because it leads more directly to a mechanistic answer rather than a teliological or philosophical one. --Scray (talk) 23:51, 14 September 2008 (UTC)


 * Why? ;) --Kurt Shaped Box (talk) 00:04, 15 September 2008 (UTC)


 * Isn't there a school of thought in philosophy of science that would answer "no" to the OP's question, and say that science can only describe, not explain? I can't remember the name of that position or the people promoting it, but I'm pretty sure they exist.  --Allen (talk) 00:46, 15 September 2008 (UTC)
 * Facts describe. Theories explain. That objects fall straight towards the earth is a straightforward descriptive fact. That they do so because of a mysterious force called gravity, or because that is the path-of-least-resistance in spacetime due to the warping of spacetime by the mass of the earth, is a theory. It is an explanation. Tentative, but legitimately scientific. --98.217.8.46 (talk) 01:00, 15 September 2008 (UTC)


 * I can't think of any such people offhand either, but one can normally find a philosopher willing to espouse any given position. Such people would, however, be opposed by the vast majority of philosophers of science and all practicing scientists. Algebraist 01:00, 15 September 2008 (UTC)
 * All practicing scientists seems extreme to me. In my experience, it seems like a lot of practicing scientists do their work with little attention to its philosophical underpinnings. And among those who think about the philosophy, I think at least some of them would try to construe their work as fundamentally descriptive, even if they use explanatory language as shorthand.  --Allen (talk) 04:14, 15 September 2008 (UTC)
 * Well, it's the sort of doctrinaire sort of thing that certain philosophers and scientists might like to impose, but any attempt to demarcate what exactly is science and what isn't is going to run into a million practical problems (ergo the demarcation problem, which is no closer to being solved today than it was two hundred years ago). --98.217.8.46 (talk) 02:03, 15 September 2008 (UTC)
 * I'm pretty sure it was Richard Feynman who drummed this into my head - that science can tell us how the sky is blue, but not why. It's a subtle but important point - the mechanisms (the how) are much more tractable for research than the reasons (the why). --Scray (talk) 01:44, 15 September 2008 (UTC)
 * Except that linguistically speaking why is often about mechanisms as much as how is. And why does the apple fall to earth is much more straightforward and unambiguous than how is it that the apple falls to earth. --98.217.8.46 (talk) 02:01, 15 September 2008 (UTC)
 * If you look up why and how in a dictionary (I just did in 3 of them) I think you'll find why wrapped up in 'cause, reason, intention' and how equated with the 'manner' in which something falls. The latter is amenable to analytical approaches, whereas the former is not.  I'll agree that the distinction has been blurred by common usage. --Scray (talk) 04:12, 15 September 2008 (UTC)
 * Richard Feynman also said [I wonder why]... manya (talk) 03:56, 15 September 2008 (UTC)


 * No, it is not valid at all. --proficient (talk) 04:50, 15 September 2008 (UTC)
 * It's okay to question, to propel inquiry, perchance to dream but doesn't guarantee there'll be valid answers. Julia Rossi (talk) 10:18, 15 September 2008 (UTC)


 * Yes, of course "why" is a valid question in science. Open-ended "why" questions have driven far more fundamental discoveries in science than closed-ended "how" questions. For example, to answer "how does an apple fall to Earth" you observe the paths of falling objects under various conditions and conclude that "a falling object experiences a constant vertical acceleration which is independent of its mass and of its velocity" (you might then go on to correct this initial conclusion to take account of drag forces and terminal velocity). This bit is easy - Galileo knew this in the 17th century.
 * But answering "why does an apple fall to Earth" in a scientific way is much harder. Newton's answer was "because each object in the Universe exerts a gravitational force on all other objects which is proportional to the product of their inertial masses". This then leads to "why is the force of gravity proportional to inertial mass" - as has been pointed out, answering one "why" question often leads to more "why" questions. The answer to this second "why" question had to wait for Einstein and general relativity. Then you have the question "why do objects even have inertial mass ?", and we are still trying to answer that question - this brings us to the Higgs boson and the LHC. If scientists had not been interested in the "why" questions we would not have advanced beyond Galileo's understanding of "how". Gandalf61 (talk) 10:44, 15 September 2008 (UTC)
 * Good points, but along the lines of what Julia said, "why" questions could be valid in the sense of being useful to the social and creative progress of science, without being valid in the sense of science truly being able to explain things. --Allen (talk) 16:29, 15 September 2008 (UTC)
 * But my point is that answering "why" questions provides a deeper level of explanation than just answering "how" questions. Not necessarily an ultimate level of explanation, but that may not be achievable anyway - reality may be "turtles all the way down", as they say. Gandalf61 (talk) 16:37, 15 September 2008 (UTC)
 * I see now; thanks. --Allen (talk) 17:54, 15 September 2008 (UTC)

When an apple falls from a tree - science says "How" is because there is this gravitational field, curved earth, etc. In that case, the "Why" is because it simply can't do anything else. "Why" isn't a problem for things that are already well-explained. Why is only a serious problem for the "end point" questions. "Why" does mass produce a gravitational field is a question we can't answer because we don't know the "How" part (yet). Perhaps studies in the LHC of the Higgs Boson will explain where mass comes from and perhaps that'll explain "Why" masses produce gravity. If we knew HOW gravity was produced then we'd probably say "Why" is (again) because it can't do otherwise. So it seems to me that once we know "How" - then in a predominantly mechanistic universe, the answer to "Why" is that things couldn't possibly have turned out any differently. Things are perhaps a little different at the quantum level because things can often turn out in multiple ways - seemingly at random. In that case - we can ask "Why did Schrodinger's cat die when we did the classic thought experiment?" - or "Why did it survive?" - the answer is "because the radioactive atom either did or didn't emit a neutron" - but we can just ask "Why did/didn't the atom do that?"...and now, we don't know "Why" because it could just as easily have done the opposite. But even in those cases, we might hypothesise the "Many worlds" interpretation in which the cat dies in one version of the universe and not in another. When you do that, the question "Why did the cat die?" boils down "Because we are in the universe in which it dies and not in the one where it survives."...then you ask "Why are we in that universe" and the answer is..."We're in both universes at the same time".

So I think we can always boil down any "Why" question into an explanation of "How" (assuming we know) - followed by "...and that's the only possible way things could have turned out." - which answers the "Why" part. SteveBaker (talk) 18:06, 15 September 2008 (UTC)