Wikipedia:Reference desk/Archives/Science/2007 June 14

= June 14 =

Galaxies
What causes the bright spot at the center of galaxies? According to Galaxies it is a black hole. If it is a black hole, wouldn't the center be dark rather than bright?


 * Yes, a black hole itself is pretty dark (not completely, due to Hawking radiation, but certainly not blindingly bright). However, if a black hole is taking in matter from elsewhere, and accretion disc forms from this matter, and for various reasons it gets very hot, and, as a result, very bright, and that's what you see at the centre of the galaxy. Confusing Manifestation 01:59, 14 June 2007 (UTC)
 * Not to mention lots and lots of stars clustered together. -- Kesh 03:33, 14 June 2007 (UTC)


 * And a black hole can also act as a lens. I suspect though the amount of stars answer above is the main reason.  --Tbeatty 10:10, 14 June 2007 (UTC)
 * I agree, lots of stars! 213.48.15.234 13:06, 14 June 2007 (UTC)


 * Check out the article on quasars for one theory. Basically if a black hole is sucking in a lot of mass, the friction from the mass being sucked in and compressed against itself becomes the most powerful source of energy in the universe. It's pretty awesome. See active galactic nucleus for the general article on the bright centers of galaxies. --140.247.240.131 14:45, 14 June 2007 (UTC)

Common ancestor of modern human beings (Homo saipens)
What is the direct common ancestor, if not the Neanderthal, of modern human beings? Heegoop, 14 June 2007 (UTC).


 * Humans and Neanderthal shared a last common ancestor, when they diverged approximately 400,000 years ago. Quite what this ancestor was is not known for sure, but it will have been a species of the genus, Homo. Some suggest it may have been Homo antecessor  (Lemonick & Dorfman, 1999), but the more commonly held theory is that it was Homo heidelbergensis  Rockpock  e  t  06:03, 14 June 2007 (UTC)

Synthetic Science
While browsing Japanese Wikipedia, I came upon the term "synthetic science". In the English Wikipedia, I only found 2 pages which contains the term but no article on synthetic science itself. I haven't found a page on Google that satisfactorily explains it.

Can anyone give me a short definition of point me to the relevant web page?
 * Well, I don't suggest checking this google search: . Will do some more looking. Anchoress 06:37, 14 June 2007 (UTC)


 * Viewing abstracts in google scholar indicates that synthetic science is "the science of synthesis", the science of aggregating data (as far as I can tell). So 'synthetic' in this usage is meant to convey 'of synthesis', not 'artificial'. I know that's not much, I'll keep looking. HTH. ed. The most accessible of several google scholar articles to use the term is HERE. Anchoress 06:58, 14 June 2007 (UTC)


 * edit conflict Facinating question; I have never heard the term before and have no idea what the correct answer is, but in the fine tradition of internet communication (dating back to at least Usenet), a little web surfing is all I need to sound confident.
 * One of the Wikipedia references was on the Henri Poincare article. Another source clarifies what he meant (or is meant) by sythentic science:
 * For Poincaré, arithmetic is a synthetic science whose objects are not independent from human thought.
 * Another reference, a book review in Ecology in 1959, along with a website on marine genomics, seem to use it to describe interdisciplinary studies:
 * Biogeography is a synthetic science, bringing in aspects of many other types of sciences.
 * Finally the third reference in Wikipedia uses the term in a third manner. this article seems to use it to mean false or manipulated science.
 * My conclusion is that it is that there are several meanings. Google seems to indicate that the second meaning--interdisciplinary research--is the most prevelant, but it does not appear there is a consistant, agreed upon meaning.  But of course, all I know is what I read on the internet (with apologies to Will Rogers).  --TeaDrinker 06:55, 14 June 2007 (UTC)


 * Not to be a pill but if we're going to interpret how a Japanese term translates into a better English understanding we're going to need to know some of the context in which the Japnese term was used. The word "synthetic" has a number of meanings in English. --140.247.240.131 14:43, 14 June 2007 (UTC)


 * The Japanese article that uses the English term 'synthetic science' is 総合科学, which it using it in the context of interdisciplinary science. There is a vaguely related article at Interdisciplinarity, but it's rubbish. 222.129.218.142 02:43, 15 June 2007 (UTC)

Ship propeller efficiency
Is there a known non-trivial upper bound on the efficiency of ship propellers? If the answer is yes, is it known what propeller shape achieves the theoretical maximum efficiency (under the right conditions)? What is the typical efficiency of a real propeller?


 * There certainly is a limit - it's caused by an effect known as cavitation in which the drop in pressure behind the blade is sufficient to cause the water to boil - causing the propellor to spin freely in a ton of bubbles instead of moving water out of the way. Cavitation can also erode the propellor causing it to fail prematurely.  I have no clue how to calculate that though.  Anyway - you should certainly start by reading our article on Cavitation - it seems to be pretty good. SteveBaker 10:46, 14 June 2007 (UTC)


 * Even more satisfying is the read on Propeller 81.93.102.185 16:59, 14 June 2007 (UTC)
 * I fixed your link Root4(one) 20:28, 15 June 2007 (UTC)


 * No, not really. A truly high efficiency blade would probably have a single blade, and very high pitch, and slow speed, and large diameter, with most of the blade area at the tip. The limit is reached for practical reasons - typically you are limited by depth of water, hull interactions, and a desired power output, and strength of the components. The spar that supports the airfoil would cause drag, etc. A real propeller is typically around 70% efficient- it varies with power and speed, but efficiencies as low as 45% have been measured. I'm not convinced that a high efficiency blade would be at the cavitation limit.Greglocock 22:37, 16 June 2007 (UTC)

Burning sensation in throat
Every so often (like today), I wake up in the morning with an intense and painful burning sensation in my throat. Now, I'm not asking for medical advice here, but I was wondering if there was any information on this sensation. A search right here on wikipedia didn't turn up anything for me, except the possibility that I have a black-throated sparrow lodged in my throat. Someguy1221 04:35, 14 June 2007 (UTC)
 * Acid reflux? David D. (Talk) 04:40, 14 June 2007 (UTC)
 * I thought about that, but I suffer none of the characteristic symptoms. Someguy1221 04:49, 14 June 2007 (UTC)
 * That has happened to me occasionally since I moved to a street-facing suite in a building right on an arterial road. I sleep with my windows open 12 months a year. I assume (since it doesn't happen every morning), it's a combination of dehydration and exhaust fumes. AND, talk to your doctor! :D Anchoress 04:55, 14 June 2007 (UTC)
 * I know a dry throat can cause a sore throat, but I'm not sure how intense burning you're feeling compared to that. --Wirbelwind ヴィルヴェルヴィント (talk) 07:02, 14 June 2007 (UTC)


 * Hi, can everyone please bear in mind that saying "I'm not asking for medical advice" doesn't magically mean that answers to the question are not medical advice? (Actually, the phrase is usually not a bad indicator that medical advice is being sought.)
 * To the original poster&mdash;if you're suffering intense pain, it's your body's way of telling you that it's unhappy about something. There are few trained medical doctors on Wikipedia, and those who are here are generally sensible enough not to offer diagnoses to people sight unseen and without medical history information.  If you're concerned about your health, contact your physician, a walk-in clinic, a local government telehealth number, or an emergency ward; we can't help you here, and we might well hurt you. TenOfAllTrades(talk) 15:52, 14 June 2007 (UTC)


 * I feel that a problem with the people here is the assumption that any medical question is a medical advice request and must be met with "GO SEE A DOCTOR!!!" Any person with average intelligence will consult a doctor.  However, they will want to have some idea of how to explain the problem to the doctor.  Having a better understanding of the symptoms is a great help for allowing the doctor to quickly understand the problem.  Of note, I work in a hospital.  Every wall in every waiting room is covered in pamphlets about every symptom you could imagine.  The goal is to get the patients to understand enough to say more then, "it hurts when I do this." --Kainaw (talk) 15:59, 14 June 2007 (UTC)
 * I don't think you quite understand the concern here. Sure it's helpful to understand your symptoms. The problem is, when people ask questions about medical conditions they are suffering, and receive advice, there is a very real risk they may decide their condition is not serious enough to warrant seeking medical attention. Even worse if they receive faulty advice. You can call these people stupid or say they have below average intelligence if you want, but it doesn't change the fact that this could easily happen. There is a very good reason why we don't give medical advice. At the very least, messages such as the above from TenOfAllTrades should help to remind people that they should definitely see a doctor regardless of what advice they may receive. (N.B. Of course in some instances the opposite can occur and a person who wouldn't have otherwise seen a doctor may see one when they realise their condition could be serious) Nil Einne 18:28, 14 June 2007 (UTC)


 * The reason I do not consider this a request for medical advice is because I have absolutely no concern about this condition, nor am I asking how to treat it. I was merely wondering if there was an explanation for the phenomenon of feeling a burning in the back of the throat when one wakes up, and if this is a common occurance, as innocuous a question as asking why I sometimes have a cramp in my shoulder when I wake up.  The reason I added that disclaimer was to discourage a rabid assault on my question as a request for medical advice, which I see here sometimes innaproipriately to medically based questions.  Someguy1221 22:33, 14 June 2007 (UTC)


 * And the responders here do go overboard with the "don't ask for medical advice" disclaimer. If someone asks anything remotely related to the medical profession, they start screaming "don't ask for medical advice."  Even if it is something as mundane as, "Does Motrin have the same pain reliever chemicals as Tylenol?"  That is not a request for medical advice, but sure enough, there will be responders freaking out about it. Youth in Asia 01:00, 15 June 2007 (UTC)
 * You are foolishly maligning the editors here who have a sense of what they don't know and enough humility to say so. If you recall the discussion on the talk page about this a few months ago, the potential legal risk to someone actually qualified to provide answers here may be small but is not zero, regardless of disclaimers. Unlike the answers to questions about physics or chemistry, willingness to answer clearly medical questions appears to be inversely proportional to the answerer's actual expertise. This may go a long way toward explaining why the rate of accurate information on medical questions here is often below 50%, even when there are multiple answers from ostensibly inteligent people. Your criticism tells us more about your own knowledge and maturity than that of those you describe as "screaming" and "freaking out". alteripse 11:49, 15 June 2007 (UTC)


 * For people confused about what constitutes medical advice (and where to draw the line between general questions about medicine – which are acceptable – and questions seeking medical advice) see the medical advice primer. I also put together a set of real-life examples pulled from the Reference Desk back in January; feel free to have a look.
 * While it is somewhat heartening (I suppose) to know that in this case the original poster plans to ignore our advice, he nevertheless is seeking medical advice here. TenOfAllTrades(talk) 12:32, 15 June 2007 (UTC)


 * .....I still say it's an innocuous question. Why do I feel a burning sensation in my throat when I wake up now and then?  Why do I see funny images while I'm sleeping?  Why does my foot randomly itch for no apparent reason?  NO ONE ANSWER ME, I'M SEEKING MEDICAL ADVICE.  When I posted the original question, I was not looking for a diagnosis, nor did I believe a diagnosis existed, as I was truly wondering whether this was a simply a common occurance, like having an itchy foot now and then (that's common too, right?  Or should I see my doctor about that, too?).  If you feel it's something worth going to the doctor over, say so.  If you don't feel it can be answered without giving medical advice, say so.  Someguy1221 22:26, 15 June 2007 (UTC)


 * I think the problem here is that you didn't make this clear. You just said you weren't asking for medical advice. If you had mentioned 'it's not something that concerns me enough to see a doctor' then people would understand where you'r coming from. Of course, people would still have concerns and rightly so. But note that even Kainaw who semi-defended you was thinking along the lines of you wanted help understand your symptons so you could better explain them to a doctor not that it wasn't something you were planning on seeing a doctor about. Personally, I had similarly planned at one stage to ask a similar question about something medical related that interested me for general reasons rather then personal health concern but I've forgotten what it was. I don't think this is a problem provided question askers and reponders are abundantly clear where they're coming from. Nil Einne 21:19, 17 June 2007 (UTC)


 * To be frank, I think you've completely missed the point if you think "Does Motrin have the same pain reliever chemicals as Tylenol" couldn't easily be a request for medical advice and why answering it may be an exceptional bad idea. A person could easily be asking because they're considering substituting one for the other. Since these are not the same compound, provided anyone who answered was right, there should be no problem. But there is always a risk someone could be mistaken and answer yes. If they did, then if no one else responded or they didn't see the response then they could easily make the potentially fatal mistake of substituting one for the other. On the other hand, if they were the same compound, this doesn't mean answering yes is a good idea. In some cases, there could be some subtle differences in formulation etc. So one should usually one should consult a pharmacists or perhaps a doctor before changing medicines even if they have the same active ingredient. Even for over the counter medicines, IMHO if you need to ask, you should ask someone properly qualified not someone on wikipedia. Nil Einne 21:19, 17 June 2007 (UTC)

Um..Someguy, I think that it would be better for you to go see a doctor. And please do not take any offense whatsoever. We argue about everything. Heh. -Zachary crimsonwolf 13:55, 17 June 2007 (UTC)

Color force and free quarks
If the color force doesn't decrease with distance, how come the forces between the constituent quarks of two protons don't smash them together immediately, but instead create the residual strong force, which is relatively weak? Or have I horribly, horribly misunderstood something? Veinor (talk to me) 05:54, 14 June 2007 (UTC)


 * You need to understand the concept of color charge, particles like neutrons and protons have a net color charge of zero, and can only attract each other when they are close enought for thir constituent quarks - which have color charge can interact, at a distance their effects are cancelled out. GB 07:20, 14 June 2007 (UTC)
 * So basically the reason atoms don't smash together; thanks! Veinor (talk to me) 01:22, 15 June 2007 (UTC)

photons consist of an electric and a magnetic field . but why are not they affected by electric or magnetic field ?
in the article about photon in wikipedia, i found photon consist of both an electric and a magnetic field. light consist of photon, so if i place a magnet beside a light source the path of light should be changed but that not happen. why ?


 * Here is an interesting discussion of what's happening. DMacks 06:45, 14 June 2007 (UTC)


 * For those too lazy to click the link, light is unaffected by magnetic fields, or electric fields. This is because electomagnetism is linear, the fields add up.  This allows light to pass through other light without having a collision.


 * To have an effect of magnetism on light, you would need to have some other nonlinear effect. This can happen if there is a material substance for the magnetic field and light to pass through.  The substance could absorb light or rotate its polarization.  See Zeeman effect, magneto-optic Kerr effect, Voigt Effect or Faraday effect.  The Faraday effect article looks to be the easiest one to understand. If you have an extreme amount of magnetic field, general relativity predicts that space would be warped, and the path of light would be bent.  But this requires such a large field strenght or volume of field that it has never been observed. GB 11:43, 15 June 2007 (UTC)

Nuclear explosions...
I'm just thinking about this... Please someone join in with me here :)

Do nuclear blasts actually accelerate the Earth? Do they accelerate it any more than the launching of the bomb decelerates it? Some of the mass gets changed into energy at the explosion site.. I assume that all the pressure and shockwaves from the blast cancel each other out at some point? Hmmm, any ideas? if it does move the earth, how many Mt to change the orbit by a significant amount? 213.48.15.234 06:49, 14 June 2007 (UTC)


 * A similar question had been brought up before actually. The conclusion, IIRC, was that it takes a huge amount of nuclear bombs to move the orbit any measureable amount, since the Earth is a relatively large mass. And as for the launching of the bomb cancelling out the force of the blast, that's not really true, since the force of the bomb taking off pushing on the Earth is nowhere near as powerful as the blast. Else, you'd have the same impact without a warhead on the bomb. I'll look for the question if I remember to. --Wirbelwind ヴィルヴェルヴィント (talk) 06:58, 14 June 2007 (UTC)
 * This may or may not be the thread you're thinking of. Anchoress 07:03, 14 June 2007 (UTC)
 * The blast would have to remove material from the earth and shoot it into space, never to return, a bit like a rocket or gun, otherwise if the fragments fall back, momentum is conserved and the net result will be earth does not shift. GB 07:09, 14 June 2007 (UTC)
 * This is along the course of waht i was thinking, I'm aware that the earth would not move very much in any case, but does it move at all? 213.48.15.234 07:12, 14 June 2007 (UTC)
 * Yes, an itsy bitsy teeny weeny bit. The blast applies a force to the Earth. Clarityfiend 07:22, 14 June 2007 (UTC)


 * So it works somewhat like a rocket? all the stuff that accelerates off out into space has to have it's momentum conserved by a movement of the earth in the opposite direction? an Earth-rocket? or is there something else going on? 213.48.15.234 07:26, 14 June 2007 (UTC)
 * A ground-level blast will not accelerate the earth, because it will not result in any material escaping from earth orbit. The solid part of the earth will receive a brief acceleration in one direction, and the air over the bomb will receive a brief acceleration in the other direction, but they cancel out when the energy imparted to the air equilibriates. If, however, you launch a bomb high enough into the atmosphere, (I'm guessing you need to reach LEO) then when it explodes parts of the bomb and the air above it may reach escape velocity. In this case, the earth will be accelerated in the opposite direction. -Arch dude 09:06, 14 June 2007 (UTC)
 * Exactly what I thought, thanks. Anyone have any idea of particle speed/mass (total mass) from a typical blast? I know that's a lot more involved. 213.48.15.234 10:07, 14 June 2007 (UTC)
 * The original question asked if there was an acceleration, not about the overall net result. Also, some of the material would be irretrievably lost. Clarityfiend 16:11, 14 June 2007 (UTC)
 * It's much easier to get estimated energy released by a blast (unfortunately, this is often measured in "megatons" - which is a rough unit for comparison. 1 megaton blast is "the same sized explosion as 1 million tons of TNT."  It is not easy to convert this into a momentum or impulse; that would depend on specifics of the blast.  10:21, 14 June 2007 (UTC)


 * Megatons can be pretty easily converted into other energy units. See TNT equivalent. --140.247.240.131 14:38, 14 June 2007 (UTC)


 * And the place to look forr information about using nuclear weapons to rocket things into outer space is nuclear pulse propulsion. --140.247.240.131 14:38, 14 June 2007 (UTC)


 * A minor quibble&mdash;a nuclear blast (or, for that matter, any process which generates photons which can escape the atmosphere) will have an effect – albeit a very small one – on the Earth's course.  Photons have momentum, and dumping them out into space will necessarily impart a small impulse to the Earth.  (See solar sail, light pressure, etc.)  No conventional particles (macroscopic bits, or even matter that has rest mass) The same effect, of course, can be produced by pointing a flashlight upwards. TenOfAllTrades(talk) 15:48, 14 June 2007 (UTC)


 * And any such effect would be miniscule compared to the amount of photons the Sun sends at the Earth constantly, which also have no real appreciable effect on the course of the Earth. --24.147.86.187 18:14, 14 June 2007 (UTC)


 * I didn't say it was a large effect. Still, the radiation pressure of sunlight on the earth is on the order of a few micronewtons per square meter, or a few newtons per square kilometer.  Over the entire exposed face of the Earth, it works out to a force on the order of 109 newtons.  (Acting on the mass of the Earth, that's a pretty feeble acceleration&mdash;about 10-16 m/s2.  Over the last billion years, it works about to a few meters per second.) TenOfAllTrades(talk) 19:07, 14 June 2007 (UTC)

Opposite side of the Earth
Is there a name for a location located exactly opposite side of the Earth of any location? For example, we know that the North Pole is on the exact opposite side of the Earth as the South Pole. What about other pairs? An article like that listing the pairs would be nice. I think most people would be interested in city pairs. --Kvasir 18:26, 14 June 2007 (UTC)
 * See and  antipodes. BTW, I found both of these with Google within a minute... I had no existing idea what to look for. Edit, see also Antipodes Nil Einne 18:46, 14 June 2007 (UTC)
 * OOO thx. --Kvasir 19:02, 14 June 2007 (UTC)
 * If you look at the map, virtually all the antipodes are uninhabited (either ocean or Antarctica on one side), although I have found one: Medina del Campo, Spain is almost precisely on the other side of the world from Wellington, New Zealand (the cities miss their antipodes by about 10 miles), while Madrid is the antipode of the wonderfully named "Taumatawhakatangihangakoauauotamateapokaiwhenuakitanatahu". Laïka  19:12, 14 June 2007 (UTC)
 * Ze Frank created the find your opposite tool: . He designed it so that we could turn the world into a sandwich. see: . good stuff. 80.229.228.229 19:16, 14 June 2007 (UTC)
 * The formula is pretty simple from a given grid-coördinate, really; you swap the sign of the northing (ie; 30°N becomes 30°S), and you subtract the easting from 180 and swap its sign (45°W becomes 135°E). Laïka  19:44, 14 June 2007 (UTC)
 * Using that tool you can see that South America has a significant number of on land antipodes. Root4(one) 20:44, 15 June 2007 (UTC)
 * Antipode may be the word you are looking for. Nimur 21:20, 14 June 2007 (UTC)


 * But Laïka, the Antipodes article mentions that Palmerston_North is the antipode of Madrid ? -- WikiCheng | Talk 07:01, 15 June 2007 (UTC)


 * They are not exact antipodes: it's close (less than 1 degree difference), but the Taumata..... hill is closer. --antilivedT 08:01, 15 June 2007 (UTC)


 * I have changed Palmerston_North to Tauma... in antipodes -- WikiCheng | Talk 14:09, 15 June 2007 (UTC)

This is a fun map showing antipodal relationships, plus a short table of antipodal cities (within a fairly large range of error). Pfly 18:50, 16 June 2007 (UTC)

2006 Construction
How much money was spent on Construction in the US in 2006? Thanks!
 * Around 1.2 trillion dollars, according to the Department of Commerce. source.  --TotoBaggins 21:17, 14 June 2007 (UTC)

injured parrot
there is a parrot with what looks like a broken wing in my balcony. it cannot fly and appears to be in a state of shock. we kept some pieces of fruit next to it but it does not eat them. i was wondering how long it will survive without nourishment and what to give it to eat (and how to make it eat). i live in Delhi, India. 59.180.88.250 19:19, 14 June 2007 (UTC)rsp


 * The parrot will almost certainly die unless you get it veterinary attention. Can you catch it? --Kurt Shaped Box 19:27, 14 June 2007 (UTC)


 * In Australia parrots like to eat seeds. They know how to open pods, or break up fruit to get the seed inside.  You should be able to get bird seed from a stock feed or pet shop.  When there are no seeds available, as in spring, they are vegetarian and eat fresh green leaves. GB 21:12, 14 June 2007 (UTC)

Do you have a stopwatch? --Tbeatty 06:21, 15 June 2007 (UTC)
 * That's a pretty rude comment, given the situation. --24.147.86.187 17:09, 15 June 2007 (UTC)
 * No, it was a perfect answer to the question. 80.229.228.229 22:19, 15 June 2007 (UTC)
 * Especially if you're an afficionado of vile insensitivity to suffering. Then it's a real pip. - Nunh-huh 22:22, 15 June 2007 (UTC)
 * Maybe you just mean parrot suffering. --Taraborn 08:05, 16 June 2007 (UTC)
 * I would have to disagree. I have no idea how long the parrot will survive but I would have to guess, at least a day. Many stop watches will have gone thru at least one cycle by then meaning if you're relying solely on the stop watch you wont obtain a proper answer. Besides that, the accuracy afforded by a stop watch seems pointless given that the starting time is arbitary. Far better to just take the current time and record the time of death. Nil Einne 16:00, 16 June 2007 (UTC)


 * If death is a certainty then using any kind of clock instead of a shotgun is far less humane. Ugly bag of water 19:35, 16 June 2007 (UTC)
 * Charming. - Nunh-huh 03:11, 17 June 2007 (UTC)

People! There's a parrot dying and a user trying to get some help for the poor bird, and all you can talk about is how long it takes for it to die? Well, I admit, its rather humorous, but given the current situation, it would be better if we check on the parrot. To the questioner, it would be advisable to take him/her (the parrot) to a vet immediately. -Zachary crimsonwolf 13:45, 17 June 2007 (UTC)
 * Well actually, the first answer has already recommended a vet. While tbeatty may have been a bit cold, he or she did perhaps emphasise the point that it's wise to seek attention ASAP (or alternatively to have the parrot put down) Nil Einne 21:00, 17 June 2007 (UTC)

Dissolving Powder
Does anyone know why powders dissolve better in hot water than in cold water? 66.241.90.112 19:30, 14 June 2007 (UTC)


 * See solubility. Friday (talk) 19:38, 14 June 2007 (UTC)


 * Thats not always the case. See solubility and rate of solution for more. 209.53.181.65 20:21, 14 June 2007 (UTC)


 * Indeed, it's not always true - but in general, chemical reactions go faster when the temperature is higher because the molecules are zipping around faster and there are more opportunities for them to collide in whatever way allows the reaction to take place. So hotter water lets the dissolution reaction go faster. Also, the amount of something that can stay in solution may depend on the temperature too. One way to make nice crystals is to dissolve whatever the crystals are made out of into really hot water - and keep putting more and more stuff in until no more will dissolve - then let the liquid cool down. As it cools, the liquid cannot hold so much of the chemical - so it has to turn back into a solid - and this quite often is a way to grow large and beautiful crystals. SteveBaker 00:21, 15 June 2007 (UTC)
 * Aside from any chemical interactions with the water, you are just causing the molecules of the powder to go from a solid structure to a liquid structure; the same physical formulae that cause that to increase with temperature in the absence of a solvent also serve in the presence of a solvent. Same thing goes for why gases dissolve better in cold water. Gzuckier 18:17, 15 June 2007 (UTC)

Irradiated Blood
In Time magazine for June 24, 1940, there is an article discussing a technique for treating systemic infections which consisted of irradiating. with ultraviolet rays, small amounts of the patient's blood, to treat "hopeless" streptococcic and staphylococcic bloodstream infections. There is a followup Oct 26, 1942, also positive toward the technique, for treatinf asthma, although it was presented to a "Homeopathic Congress." Such ultraviolet rays had a long history as quack medical devices, but in this method the blood (2 cc at a time) was withdrawn from a vein, "gently irradiated" and returned to the vein. A "Dr. George Miley of Philadelphia's Hahnemann Hospital" had tested clinically a device made by physicist Emmet Kennard Knott. The research presented at an AMA meeting claimed that "Of 27 irradiated cases of septicemia (bloodstream infection),.... 22 recovered; 71 irradiated cases of other bloodstream infections, including peritonitis and septic abortion, all recovered." (I'm not seeing a control group)." Not asking for medical advice, but what was the eventual evaluation of this method? It sounds bogus, because it would take a very long tim eto irradiate any appreciable fraction of the person's blood 2 cc at a time, but I see from 1993 on an apparently different use of UV with blood "There are currently two major approaches to preventing alloimmunization: (i) reduce leukocytes in blood components to less than 5 million or (ii) inactivate contaminating leukocytes by ultraviolet (UV) irradiation (15). The use of UV irradiation is still at the experimental stage because of technical problems and limited clinical data demonstrating its efficacy and safety" from "Current Issues in Transfusion Medicine." Also, seems to be saying it has therapeutic merit in treating staph infections, in a 1990 publication. Edison 21:52, 14 June 2007 (UTC)


 * I don't know the full answer, but I wonder how much pathgen kill one has to acchieve in order for this to work. I'm thinking in relation to kidney dialysis, in which 4 hours is sufficient to "clean the blood" down to "some acceptible level of something". DMacks 22:03, 14 June 2007 (UTC)


 * Your instincts are correct: it was bogus. Radiation had been discovered less than 30 years earlier and still seemed like a no-risk treatment for all kinds of things, and penicillin was just around the corner as a triumphant cure for serious strep and staph infections. Hahnemann Hospital and the College of Homeopathy were at that time still one of the last havens for homeopathy in the US. Within a couple of decades even Hahnemann Medical College abandoned the pretense that homeopathic medicine was worth offering training in. The hospital and school have since been acquired by Drexel University and become one more standard medical school in downtown Philadelphia. alteripse 23:03, 14 June 2007 (UTC)


 * Ah, careful there: this wasn't about "radiation", i.e. ionizing radiation, but rather ultraviolet, which had been known for about 140 years. --Anonymous
 * You are correct; my mistake. alteripse 11:28, 15 June 2007 (UTC)
 * Yup, it's bogus. Controlled studies as early as 1943 (see, for example, Blundell et al. in the Journal of Bacteriology: "Observations on the Effect of Ultra Violet Irradiation (Knott Technic) on Bacteria and Their Toxins Suspended in Human Blood and Appropriate Diluents") were already casting doubt on the new method, but a few die-hard practitioners (and their unfortunate patients) continued to employ ultraviolet irradiation of blood until the early 1950s.  Fortunately, the advent of antibiotics mostly meant that this fringe therapy was confined to nonfatal ailments like bursitis .  Still, it remains possible even today to find so-called "doctors" who will provide you with this "treatment" for a healthy fee. TenOfAllTrades(talk) 23:52, 14 June 2007 (UTC)


 * But it has so much "face validity" that people pay "alternative medicine " practitioners to do it! Seriously, there appear to be hundreds of recent studies from Russia where they claim it decreases mortality and shortens hospital stays. Seems like a good gimmick for a future ""House" episode. Further searching found The original idea, that UV helped by killing pathogens in the blood, seems to have been disproved. More recent theories seem to be that it affects oxygenation somehow, or that it increased Vitamin D, or that it affects neutrophils which in turn have a spreading effect. Curiously, the old patented device seems to be grandfathered and still legal for use under FDA guidelines. I think of William Coley's method of treating cancer with deliberate infections as a parallel: when cancer patients around 1900 were deliberately infected, some of the cancers showed remission. That treatment caused so much harm from the infections that it outweighed the good it sometimes did the cancer. It was abandoned when radiation therapy came along, just as blood irradiation with UV was abandoned when antibiotics came along, both lacking a sound theoretical model as a basis. Then along came revived interest in Coley's work leading to Tumor necrosis factor-alpha and like uses of immunoresponse. Edison 17:36, 16 June 2007 (UTC)