Wikipedia:Reference desk/Archives/Science/2007 July 29

= July 29 =

solar flares
I guess solar flares don't create a sound/sound waves (i.e. no medium), is that correct? ```` —Preceding unsigned comment added by John Bragdon (talk • contribs)
 * Correct. While there would certainly be vibrations within the sun itself, which you could call sound if you wanted to, no sound eminates from the sun, in the form of solar flares or otherwise.  Someguy1221 00:55, 29 July 2007 (UTC)


 * Considering that a absolute vacuum does not exist, not even in deep space, there could in theory be sound. An affected particle is bound to bump into another one at some point. But the sound would be extremely faint (negligible, I suppose). That is, if one can call that sound. Sound is a wave, which is more than just moving particles, and a wave needs enough density. At which density would sound become possible then? DirkvdM 08:04, 29 July 2007 (UTC)
 * For any combination of density and temperature, different amplitudes and frequencies would have different thresholds of detectability. That threshold would be wherever the sonic vibrations become detectable over random motions (though for sufficiently low densities, it would always be beyond our ability to detect).  Where that threshold is, is dependent on our technology.  There is probably also a fundamental threshold based on the random motions (I'm deliberately avoiding the word "noise" due to the confusion it would create).  Now, how to actually calculate either the fundamental threshold or the tech-dependent one, I have absolutely no idea.  Someguy1221 10:08, 29 July 2007 (UTC)
 * Shock waves exist in space and they are detectable. See Bow Shock.


 * You might check these links:
 * http://www-pw.physics.uiowa.edu/space-audio/
 * http://soi.stanford.edu/results/sounds.html
 * http://quake.stanford.edu/~sasha/SOUNDS/sounds.html
 * SteveBaker 12:51, 29 July 2007 (UTC)
 * My fav solar site http://sohowww.nascom.nasa.gov/data/realtime/ Vespine 01:56, 31 July 2007 (UTC)

Paraphilias
How many people have paraphilias? A.Z. 02:39, 29 July 2007 (UTC)


 * You guys don't know? I asked this on the article talk page as well, but no one replied. I don't want the exact number, just an approximation would be fine. A.Z. 18:37, 29 July 2007 (UTC)


 * One could argue that everyone probably has paraphilic tendencies somewhere deep in their psyche. They may be mild and we may never explore them, but they are there all the same. However, there is a more formal, clinical definition of paraphilia, and if you wish to use that as your basis, then, "It is estimated that there are 15 to 40 million Americans with paraphiliac tendencies in one fashion or another" according to Wikibooks . Assuming this is correct and that Americans are no more kinky than anyone else, then we could estimate 5% to 14% of the population have paraphilias. Rockpock  e  t  22:50, 29 July 2007 (UTC)

IS there something such milk allergy
some freind of mine asked me that question he told me that whenever he drinks milk, eat yougurt, cheese ... he feels sick and next think he does is throw out ?????? could anyone help me please in giving him an answer ?
 * Milk allergy. Your friend should also consult a doctor, as Wikipedia can give neither medical advice nor a medical diagnosis.  As a bit of common sense, your friend should stop consuming anything that makes him sick immediately.  Someguy1221 06:50, 29 July 2007 (UTC)


 * Yep. It might also be a psychological effect, vomiting upon eating certain foods due to some mental reason isn't totally unheard of. However, unless he's being forced to eat it (peer pressure or such), I doubt it's that. In the mean time, try having soy milk instead -- L ie! 07:18, 29 July 2007 (UTC)

It might actually be lactose intolerance. But yes, do tell him to see a doctor. Recurring dreams 12:05, 29 July 2007 (UTC)


 * Well, myself and some of my family have minor lactose intolerance (in large doses), but I've never heard of lactose intolerance causing vomiting. It tends to have... 'other ways' of showing itself -_ L ie! 12:14, 29 July 2007 (UTC)

computer INTELLIGINCE how far ?
Is it possible that a computer connected to 2 chambers ,can transfer objects in between by moving the particles one at the time if yes !!!! then what about humans or the DNA will cause a problem ???
 * In theory, existing nanoassembly procedures could work like this, but very slowly and only to very very small things. Such procedures have never been developed for large things, in part because the process is quite time consuming.  Even if ever possible on large objects, the problem with any living thing would be that living things are ever in a state of constant chemical activity.  If you were to try and transfer a human one molecule at a time, during the process you would have two parts that could not function without eachother, and the human would die.  The two obvious solutions would be to either do it very very fast, or freeze the human.  The former would be extremely difficult, as it may generate too much heat (breaking and reforming the bonds of an entire organism in a fraction of a second takes a lot of energy), and essentially vaporize the person.  The latter is the current science of cryonics, which has its own problems.  Someguy1221 06:55, 29 July 2007 (UTC)

See also our article Transport layer, especially TCP and UDP for how computers move data from one place to another, and what sort of problems are involved -- L ie! 07:15, 29 July 2007 (UTC)


 * I completely agree with Someguy1221's summary - and would add that it's not enough simply to put the particles in the correct place - they would have to be moving in the correct direction and speed (notably to keep things the right temperature and to account for blood flow). Electrical flows in the brain would have to be correctly maintained.  For objects that are made from solids (eg a block of wood), you might imagine we could do this - but for something made of liquids, gasses, colloids and other more dynamic materials such as living things - I think it would be very tough indeed.  Your best approach would probably be to try to do it very rapidly - but the insane number of molecules involved in even a microscopic organism would make this all but impossible.  The data rates required would be far, far higher than any frequency we are able to produce over any distance.


 * It is also possible that Heisenbergs Uncertainty Principle might cause problems here. For small particles, there are issues of being able to measure where they are and how fast they are moving that simply cannot be overcome because of fundamental physics limitations.  If you don't know precisely where each particle is, you can't place it in the correct position in the reconstructed object.  In Star Trek, the Enterprise's transporters (which are generally supposed to work in the way you describe) are equipped with 'Heisenberg compensators' (wouldn't you just know Wikipedia would have an article about this!) One of my favorite lines from the Star Trek authors: When asked "How do the Heisenberg compensators work?" by Time magazine on 28th November 1994, Michael Okuda, technical advisor on Star Trek, famously responded, "They work just fine, thank you."...and that's that!


 * SteveBaker 12:36, 29 July 2007 (UTC)

Speaking very conceptually, theoretically, and long distance here, like Leonardo in the 1400's describing things made practical in nthe 1900's, or like poeople in the 1700's describing electrical telegraphy made practical 100 years later, or like those in the 1860's describing airplanes made practical 50 years later, we presently have databases showing the human body sliced into very thin sections. In the one case, this has been done by CT scan, and in another case by literally freezing a human body and grinding away one thin layer at a time. At the present time, we have 3D printing, in which a device analogous to a computer printer lays down one layer at a time of a 3D object, using a variety of techniques, for rapid prototyping. We also have the ability to assemble atoms one at a time (in an early demo, they spelled out "IBM.") So in principle, in the future we should be able to analyze a small 3D object at one location, and fabricate a replica of it at another location. This capability in the foreseeable future does not extend down to the molecular or atomic level, but only captures the larger 3D details. To transport a small plant or animal would require molecular resolution, and vast bandwidth. We would not be turning the matter to energy at the sending end and energy to matter at the receiving end, but just sending assembly instructions. Certainly it would be at extremely low temperature: imagine trying to add atoms to a worm which was wiggling! I suppose the result would be a frozen creature at the receiving end which replicated a frozen creature at the sending end, starting with tiny objects like simple single cell organisms. Edison 13:42, 29 July 2007 (UTC)


 * Yes, it's possible to imagine how it might be done, and I'm not as pessimistic on this as SteveBaker. For example, you don't need to duplicate the thermal motion of every atom - you just need to put the particles in the right places and make sure that the temperature profile is about right. OK, you might have to jump-start the blood circulation to get the momentum going, but then you might not - after all, they can (usually) electrically restart hearts that stop beating. The same goes for electrical properties: you don't need to duplicate the position and trajectory of every electron, since all that matters are the relatively large-scale potential differences across membranes and synapses. (OK, so my arms are waving about wildly here.)  I don't think that the Uncertainty Principle is going to be a show-stopper.  You might disagree if you believe that consciousness is a spooky quantum thing, but I don't - I think it's an emergent property of matter.


 * Like Edison, I would start with bacteria and iron out the little niggles, like accidentally turning the organism inside-out, before moving on to multicellular organisms. --Heron 18:58, 29 July 2007 (UTC)


 * Let's get RepRap working first eh? SteveBaker 04:03, 30 July 2007 (UTC)


 * One thing that seems to be missing from the RepRap prototypes is a big red STOP button. That's the first thing I would have designed in. ;-) --Heron 20:26, 31 July 2007 (UTC)


 * Well, these are just lab prototypes - they move exceedingly slowly and are driven by fairly feeble stepper motors. You'd have to be amazingly careless to get hurt by one.  They are comparable to an inkjet printer in terms of power - and much, much slower. In all likelyhood, a consumer grade machine would be fully enclosed with a power cut-off when you open the cover (like a dishwasher or a microwave).  You'd want the machine to be enclosed so you could keep dust and such out of the molten plastic - and also to control airflow because the rate that the plastic cools is somewhat important. SteveBaker 02:37, 1 August 2007 (UTC)

"Shunning" in gulls?
Does anyone know the correct name for the behaviour wherein a sickly or injured gull will be driven from the larger gull flock by force and abandoned to fend for itself/die? From what I've read, albino gulls often get the same treatment? Shunning immediately came to mind but upon reading the article, that term seems to refer only to humans. --Kurt Shaped Box 08:20, 29 July 2007 (UTC)


 * May I ask why you've been asking about Gulls for so long now? Whoops, already asked. PitchBlack  08:44, 29 July 2007 (UTC)


 * Simple answer. I think that gulls are great. Why this question? Well, I saw an injured (broken wing) gull being 'shunned' yesterday. Every time it approaced the other gulls on the beach, they would attack it and chase it away (yet it kept trying to return). Its head was already covered in blood when I encountered it. Poor thing was only a fledgling too. I managed to catch it and take it to the local wildlife rehab man. Apparently, it's doing okay today. --Kurt Shaped Box 22:02, 29 July 2007 (UTC)


 * I still have Reference desk/Seagulls on my watchlist. Good times -- L ie! 11:54, 29 July 2007 (UTC)

So, does anyone have a serious answer to my question? Guys? --Kurt Shaped Box 16:10, 31 July 2007 (UTC)

what happens when photon struck proton ?
and when electron is strucked by photon ?


 * When a photon hits an electron that is part of an atom, the electron absorbs the proton energy and bounces up to a higher energy level. However, the electron cannot stay at this level for long, and when the electron falls back down, it releases that energy again as more photons, which produces light by a process called "photoluminescence"; fluorescent jackets emit light in this way. Laïka  17:37, 29 July 2007 (UTC)

sunrise to solar noon?
On a typical day in North America, how long roughly is the period of time:
 * between sunrise and and solar noon?
 * between solar noon and the beginning of civil twilight?
 * the beginning of solar twilight and solar midnight?
 * between solar midnight and sunrise?

--Sonjaaa 10:50, 29 July 2007 (UTC)


 * It depends on the time of year and your latitude. There is no 'typical'. Nights are longer and days shorter in the winter - so time between (say) sunrise and noon is shorter in the winter than in the summer.  The further north you go, the more pronounced this effect is. Coming up with a 'typical' number means what?  At an average latitude an average day of the year? SteveBaker 12:19, 29 July 2007 (UTC)


 * Exactly right. Case in point: think about in parts of Alaska when they have full days that are either light or dark.Mrdeath5493 16:56, 29 July 2007 (UTC)


 * Note that the period between sunrise and noon is rarely exactly the same as the period from noon to sunset. Astronaut 17:21, 29 July 2007 (UTC)


 * But the question was not about exact details. --Anon, July 29, 2007, 19:43:06.5 (UTC).


 * Yeh, but there are so many variables affecting daylight that the question is comparable to asking how big is an animal? H YENASTE 22:52, 29 July 2007 (UTC)


 * Yes, and there are pedants here who would reject even the question "What color is the sky?" with "Well, it depends" or "that depends on so many variables that it's impossible to say" (or, perhaps, "it depends on what the meaning of 'is' is").
 * If I knew the answers off the top of my head, or if I had time to do the research just now, I'd provide an answer for, say, 40&deg; north latitude near the equinox, then explain how the answer varied towards the solstices, then explain how the answer varied at different latitudes. But I don't and I don't, so I can't just now. --Steve Summit (talk) 23:01, 29 July 2007 (UTC)
 * So you can't be bothered to work it out - yet you complain that nobody else will either? I think you'd have an exceedingly hard time convincing anyone that the particular latitude and time of year that you happened to choose was "typical" per the OP.  The OP also went to a lot of care to list the precise meanings of terms like dawn and noon - which suggests that some measure of accuracy was forseen (if you are talking about the difference between midwinter in Alaska, midsummer in Alaska and any time of year in southern New Mexico - then the subtle distinctions between solar noon and 12:00pm are utterly negligable due to an error of something like +/- 6 hours due to picking the location.  Note further that the error is of comparable size to the answer - which means that the answer is in every sense meaningless - which is why I (for one) chose not to try to find an exact answer.  The best we can say is "between 0 and 12 hours" in answer to most of those questions.  We are doing a better job by telling the questioner that they have made a poor assumption in asking the question he/she did than by misleading them with an utterly valueless answer. SteveBaker 04:01, 30 July 2007 (UTC)
 * Steve. Peace.  I didn't say I couldn't be bothered, and I'm sorry if it sounded like I was complaining. —Steve Summit (talk) 04:13, 30 July 2007 (UTC)


 * Some useful data: US Naval Observatory &mdash;Tamfang 04:29, 30 July 2007 (UTC)

The original question is too general to really answer with precision but, I'd be interested in knowing: Is there a difference between the last two? JAXHERE | Talk 14:41, 30 July 2007 (UTC)
 * what is the precise moment which is called "sunrise"?
 * what is "civil twilight"?
 * what is "solar twilight"?
 * Twilight notes the specific definitions of Civil and Astronomical (what I presume is meant by "solar") Twilight. Sunset isn't quite as clear -- it notes that an optical illusion causes the sun to be visible even when entirely below the horizon, but I don't see a hard definition of sunset being defined geometrically versus optically. &mdash; Lomn 17:01, 30 July 2007 (UTC)

Disposal of medications
What is the proper way to dispose of medications that are controlled substances? The local hazardous materials disposal group won't accept them, and I'm worried that just flushing them may cause environmental damage. 69.123.113.89 14:39, 29 July 2007 (UTC)


 * Well, if you're just worried about environmental damage, sell them on the black market. Really, ask a doctor -- L ie! 14:44, 29 July 2007 (UTC)


 * At least in the UK (and surely other places too) any pharmacy will take them (not just the one that dispensed them). -- Finlay McWalter | Talk 15:29, 29 July 2007 (UTC)


 * First of all, how much are we talking about here? If you have a huge stash and have decided to change your ways, wash them down the tub and go have a beer.  If you have extra that are out of date, or still in date and that you don't need, then contact your local DEA office here.  They will probably tell you to just wash them down the sink.  Don't sell them or give them away, as we all know this is illegal. Mrdeath5493 16:54, 29 July 2007 (UTC)
 * EDIT: I see now that most waste treatment plants in the states can't filter/treat organic waste like that found in medication. So, if you are from the U.S., contact the DEA for advice. I work in a pharmacy and we don't accept previously dispensed medications, not sure about others. If there is a Cardinal Health in your area, they're probably the only distributor of controlled substances and will likely have methods of disposing of them.Mrdeath5493 19:26, 29 July 2007 (UTC)


 * In Sweden, washing medications down the sink is considered highly polluting! We're urged to bring back our old medications to the pharmacy. As far as I know, they dispose of the medications by burning them. Lova Falk 18:44, 29 July 2007 (UTC)


 * Indeed New Zealand as well. It appears that this is sometimes practiced in the US too although obviously not as common as it appears to be in most other developed countries Nil Einne 01:31, 30 July 2007 (UTC)

Uterine Fibroids
Uterine fibroids.... does it have any dangers longterm ?? shortterm?? —Preceding unsigned comment added by 212.107.116.244 (talk • contribs)


 * I've no idea, but your doctor is probably the best person to ask. Astronaut 17:16, 29 July 2007 (UTC)


 * Did you read our article on uterine fibroids?--Shantavira|feed me 17:18, 29 July 2007 (UTC)

Zoloft pill life
How long can a bottle of zoloft pills last? I was thinking they could last for years. Would the chemicals and powders in the pills still work after they expired.--logger 17:14, 29 July 2007 (UTC)


 * If, as you suggest, the bottle has an expiry date, that would answer your question.--Shantavira|feed me 17:24, 29 July 2007 (UTC)


 * You should consult a medical professional for this type of advice. Don't take expired medications without consulting with them first.Mrdeath5493 19:27, 29 July 2007 (UTC)


 * Because it's expensive to test drug's effectiveness as they age, most drugs are simply not tested for that and a blanket expiry date is put on all of them. It is therefore likely that it's completely unknown how long they last - or what adverse consequences might come from taking them after that time.  There was a study done by the US army (I believe) who scrap millions and millions of dollars of drugs every year - and they found that most of the drugs they used would last well beyond the official expiry date.  But there is no way for you to know whether this particular drug really does expire on that day or not - or what the consequences are of taking them after they've expired.  So the safe advice is "Don't take them!". SteveBaker 03:48, 30 July 2007 (UTC)

Salt and health
The article on salt says: Overconsumption of salt can increase the risk of health problems, including high blood pressure. Anybody who knows what other health problems overconsumption of salt can lead to? Lova Falk 18:33, 29 July 2007 (UTC)


 * Theoretically, there is a lethal dose of salt. So you could technically eat enough straight salt in one sitting to kill you.  The Salt Institute has a library of information on their website.  Also they have one specifically addressing sodium and health.  However, the tone of all the articles on the site seem to be more pro-salt than most medical publications.  I personally believe that they represent a neutral standpoint and that most medical articles concerning salt apply to very few people.  :) Mrdeath5493 19:36, 29 July 2007 (UTC)


 * Ah, an institute of salt producers. Reminds me of when I was working in the food sector and we used to get press releases from the salt association. Do you know, they didn't think people eating too much salt was a problem? In fact, they tended to emphasise that athletes need enough salt to replace what they sweat out, even when the discussion was about the average person who got less than half an hour's exercise a day. I assume they were neutral, and the government-funded medical research was biased.... Skittle 23:04, 29 July 2007 (UTC)


 * I wasn't referring to any sort of actual scientific research, public or privately funded. When I said medical articles, I meant magazine or newspaper articles which tend to misinterpret the actual message (my fault as I was initially vague).  A healthy person needs salt.  Most people without a blood pressure problem can eat just about as much salt that might exist in whatever food they eat, and remain perfectly healthy.  However, 20-30 year-olds read some mistaken magazine article and think they should be on a low sodium diet.  The truth is that there is absolutely no proof that a young (<40) person that is healthy will see benefits from a low sodium diet...none.  So, salt is bad if you have high blood pressure.  Otherwise it helps you move, feel, and think (3 process that require sodium ions). Mrdeath5493 06:10, 1 August 2007 (UTC)


 * Ah, sorry, I thought you were being sarcastic. I would never suggest that the Salt Institute represents a "neutral standpoint". Humans need a small amount of salt, much smaller than the amount most people consume in the typical western diet. For most people, eating a larger amount of salt than necessary (within limits) will not have a negative effect, and for a small group of people (professional athletes for example) a larger amount than the typical level is desirable. For a different small group of people, eating too much salt causes serious health problems. Since it would be very hard, if not impossible, to identify this group, it makes sense to limit salt intake for all people to what they actually need. For a professional athlete, this level would be high. For most people, it is rather lower than they currently consume. As for the original question asked by Lova Falk, this site which I would not describe as impartial (although it doesn't seem to profit from the advice it gives) gives an overview of possible health problems that it says have been linked to overconsumption of salt in studies. This is a rather more sceptical BBC article. Here is a government website which only specifies blood pressure as being a problem. Generally, I think the other problems from too much salt are as a result of the high blood pressure, at least at the levels usually consumed. Skittle 23:25, 1 August 2007 (UTC)
 * I would imagine a sodium imbalance would have a negative effect on your nerve cells... SGGH speak! 14:35, 4 August 2007 (UTC)

Walnuts - idle thought whilst snacking...
Why do walnut halves look like the human brain? --Kurt Shaped Box 19:46, 29 July 2007 (UTC)


 * Do they? I would have asked: why does the human brain look like a walnut half?- hydnjo talk 20:48, 29 July 2007 (UTC)


 * Its likely to do with trying to cram a large surface into a small volume, with a connection to a stem. The surface is folded, and comes out with bilateral symmetry do to the shape of the case or shell. GB 21:51, 29 July 2007 (UTC)


 * But why do the walnut and the brain need large surface? A.Z. 21:54, 29 July 2007 (UTC)


 * The cerebral cortex contains about two-thirds of the human brain's 100 billion neurons, organised in a thin layer of cortical columns. Higher brain functions (such as perceptual awareness, "thinking", language and consciousness) requires more neurons organised in this manner, but you are limited by the confines of the skull. In order for this large surface area to fit, the cortex folds in on itself, resulting in a series of ridges and grooves ((gyri and sulci) that give the brain its "wrinkled" appearance. I don't know why the walnut requires a large surface area. Rockpock  e  t  22:32, 29 July 2007 (UTC)


 * As our walnut article points out, the modern walnut is the product of centuries of horticultural selection, so looking for a strictly "naturalist" evolutionary answer may be misleading. All that being said, I'm not sure why that particular nut would need that much surface area, though my guess would be it had something to do with water absorption/retention. --24.147.86.187 00:58, 30 July 2007 (UTC)


 * So they should amend that old -- ahem -- chestnut about apatosaurus brains being the size of a walnut to "apatosaurus brains are the size and shape of a walnut"! :) --TotoBaggins 18:28, 30 July 2007 (UTC)


 * Actually - probably not. Many modern species of lower intelligence have much smoother brains because they simply don't need the density of cerebral cortex that humans, dogs, chimps, dolphins, etc need.  It's possible that Apatosaur brains were both small and fairly smooth...like the mouse brain in the photo.   I doubt that Apatosaur needed to be much smarter than a mouse. SteveBaker 23:48, 30 July 2007 (UTC)
 * Indeed. It is commonly said that the huge Stegosaurus had a brain the size of a walnut. --Taraborn 22:52, 31 July 2007 (UTC)
 * If only someone had mentioned this earlier in the conversation, some sort of joke could have been made about it. Skittle 23:11, 1 August 2007 (UTC)