Wikipedia:Reference desk/Archives/Science/2010 February 24

= February 24 =

Traffic fumes versus tobacco smoke
How does the deadliness of traffic fumes compare with those of tobacco smoke? Would living a few feet away from very busy roads - unfortunately not uncommon in the UK - be equivalent in its health risks to smoking X number of cigarettes a day? The (very) microscopic particles from diesels are one serious risk for example. 92.29.57.43 (talk) 00:51, 24 February 2010 (UTC)
 * Prob'ly not -- when you smoke cigarettes, you deliberately inhale the smoke, maximizing your exposure to all the nasty stuff in it. As opposed to just breathing air that happens to contain a certain amount of smoke, which is what you do when you live next to a busy road.  Plus, the natural air currents tend to dilute the traffic fumes to a very low concentration, unlike when you smoke tobacco.  So no, living next to a busy road is nowhere near equivalent to smoking X cigarettes a day -- more like sitting in a bar where other people smoke.  But if you want a gram-for-gram comparison of engine exhaust vs. tobacco smoke, diesel exhaust contains more aromatics and heavy metals, while cigarette smoke contains more of the nasty carbonyl compounds (aldehydes/ketones) and amines/nitro compounds (but some aromatics and heavy metals as well).  So gram-for-gram, I'd say it's too close to call.  FWiW 24.23.197.43 (talk) 02:00, 24 February 2010 (UTC)
 * You forget an important difference. A smoker breathes in cigarette smoke about 10-20 times per cigarette (10-20 puffs). With about 10-20 cigarettes per day, that's about 300 breaths. The surrounding air, with all its exhaust fumes, you breath in constantly, every breath you take, day and night. With 20 breaths per minute that would be about 30.000 breaths per day. That's 100 times more! And quite often, constant exposure to something unhealthy is in the long run more damaging than more severe, but interrupted exposure. Of course, smokers often breathe in their own 'second hand smoke' as well, but that's a bit harder to assess (and becoming less common with smokers stepping outside for a smoke). DirkvdM (talk) 16:31, 24 February 2010 (UTC)


 * A few years ago this was a newsitem in the Netherlands. A research had shown that children who grew up (or went to school) near busy roads had lung problems which were sometimes very severe. It was said that their lungs were like those of a long time chain-smoker. I can't remember if that was just the worst cases, though. If I remember correctly, they spoke of a reduction in lung functionality of 10%.
 * However, that's the Netherlands, where most people live near the sea (Randstad). In the UK, you've got London, a metropolis that exceeds anything we have in the Netherlands in terms of size and congestion, and in the centre of which you are not likely to get much relief from a sea-breeze. Cities have always been an unhealthy surrounding. I just wonder if it isn't getting worse. DirkvdM (talk) 16:26, 24 February 2010 (UTC)

what is the most likely avenue for curing cancer?
What, in specific terms, is the most likely route being pursued for curing cancer? 84.153.231.223 (talk) 00:52, 24 February 2010 (UTC)
 * Every type of cancer is different, and there isn't going to be a single approach that works for all of them. The most promising approach is usually some combination of chemotherapy, radiation, and surgery.  Once a cancer has metastasized, though, it seems to be generally incurable by any approach that is currently envisioned. Looie496 (talk) 01:34, 24 February 2010 (UTC)
 * Come on, Looie -- certainly the inquisitor was not asking for an explanation of current methods -- being pursued suggests a look into the future. So while we do not make predictions here at the ref desk, I would say the phasing out of all three methods mentioned by Looie would be quite welcome for pretty much the same reason: the target is too large.  Chemotherapy works by targeting speedily growing cells, which certainly includes malignant cells, but also unfortunately includes those found in hair follicles and reproductive organs, among others.  The effects of the medication are also embraced by unspeedily growing cells.  Radiation therapy targets any and all cells, and the focus in this realm has been to narrow the beam and decrease the effective dose so that only the most targeted cells die -- but this again is not a perfect method.  While surgery is great at removing the entire lesion assuming the lesion hasn't metastasized, clean margins are necessary and resections can often leave the cancer patient severely disfigured, although still alive.  If I'd have to say what the pursuit of cancer research is in terms of defined therapy, I'd think it would be a more refined target derived from the specific type of cancer cell, so that the therapeutic agent would be a poison for only that group of cells but as harmless as sodium Na+ for the remainder of the body's cells.  DRosenbach  ( Talk 01:51, 24 February 2010 (UTC)
 * You really think sodium metal is harmless for human cells? :-) 24.23.197.43 (talk) 02:06, 24 February 2010 (UTC)
 * You got me -- I was too lazy to find the <"sup"> <"/sup"> button :)  DRosenbach  ( Talk 05:14, 25 February 2010 (UTC)
 * I took being pursued to mean being actively worked on, as opposed to being fantasized about. Regards, Looie496 (talk) 02:12, 24 February 2010 (UTC)
 * Only very recently has medical science discovered the connection between viruses and cervical cancer as well as at least one other type (I read about it recently, but can't remember which). The 20th Century bias toward looking for environmental, genetic, psychological and "life-style" causes of cancer led to an absence of reserach into viruses and bacteria as causes of cancer (or, for that matter, of all other chronic illnesses).  (Remember when ulcers were caused by a bad attitude?  Thanks, Sigmund.   Meet my friend Dr. Pasteur.)  It may be that the most fruitful preventative measure against cancer will eventually be innoculation, anti-biotics, and the like.  See the book (circa 1999) Plague Time, by an Amherst College professor of evolutionary virology whose name escapes me. 63.17.65.39 (talk) 02:46, 24 February 2010 (UTC)


 * It's odd that people still talk about finding "a cure for cancer". We already have several cures for cancer. A very large proportion of people diagnosed with cancer these days recover fully (exactly what proportion depends on the type of cancer). As with any disease, we can expect our cures to improve over time or be replaced by entirely different cures (more effective, fewer and less serious side effects, cheaper, etc.). There is no way to predict what the improved or new cure would look like. --Tango (talk) 02:59, 24 February 2010 (UTC)
 * As Looie points out, the fact that pretty much every cancer is different means that different strategies are being pursued for different types of cancers, and each has different chances of success. A few examples:
 * for cancers that are highly associated with viral infection, vaccines hold great promise. The National Cancer Institute says, "Widespread vaccination has the potential to reduce cervical cancer deaths around the world by as much as two-thirds..." which is pretty promising (though is dependent on the usual vaccine caveats).
 * Another use of vaccines is against markers of the cancers themselves, see Stimuvax as a promising example of this.
 * The rapid decrease in cost, and development of third generation DNA sequencing, means we are approaching the time when it may be feasible to sequence the genome of individuals. Thus instead of being told "you have liver cancer", your doctor may be able to determine the exact mutation that has caused your liver cancer. This will make targeted therapy more effective and opens up the door to personalized medicine. It could also identify those at high risk of certain cancers, permitting earlier screening and detection, leading to higher survival rates.
 * Some companies have tried using viruses to kill cancer cells specifically, or use viruses to carry targeted chemotherapeutics. One of the early examples, Onyx-15, was not very successful but the concept seems to be working and other systems are in development.
 * There are many, many more (see Experimental cancer treatment for some examples), but comparing them is a bit like comparing apples and oranges and asking which is better for you. And if anyone knows for sure which is going to prove to be most successful, then they should invest in the company that is developing it and wait for the money to roll in.  Rockpock  e  t  03:31, 24 February 2010 (UTC)
 * "Plague Time" (referred to above) was written by Professor Paul W. Ewald. A reviewer from The Science Advisory Board writes: "Though there has been much investment in studies of genetic causes of disease, the most significant returns were generated on investments made in the studies of infectious diseases. Polio, measles, hepatitis, liver cancer, ulcers and cervical cancer were all controlled or shown to be controllable during the last half of the twentieth century through the control of infectious agents. This track record provides a sense of how to invest in our future: focus on the germs." http://www.scienceboard.net/resources/bookreviews.asp?cat=1&book=159 63.17.65.39 (talk) 05:08, 24 February 2010 (UTC)


 * I keep referreing to this comic: for a quick explanation of the issue. It gets the point across EverGreg (talk) 09:22, 24 February 2010 (UTC)


 * It's a question of inputs versus outputs. Less noxious gases breathed in, less questionable food and drink, more fresh air and fresh food. That will be the avenue to cancer disappearing. In a lab? Oh please! Vranak (talk) 01:57, 25 February 2010 (UTC)


 * How would doing those things prevent infection by the viruses correlated with cervical cancer and liver cancer? (It took a long time to persuade the mainstream that stress doesn't cause ulcers ...)  The "life-style" theories may be a post-Freudian, puritanical 20th century bias, now moving toward a dead end ... as viruses, bacteria, and other infectious agents are ignored until, as in cervical and liver cancer, they become too obvious to ignore. 63.17.57.56 (talk) 02:35, 25 February 2010 (UTC)


 * I will simply state that the human body is an extremely capable machine. It fights off degeneration for ages and ages and ages. It takes a lot to bring down a man -- about 80 years of sucking in nasty houses gases, most notably. Vranak (talk) 04:04, 25 February 2010 (UTC)
 * Whether healthy living is the "avenue to cancer disappearing" is very controversial. The reality is pretty much every environmental factor - even so-called "healthy ones" - can have mutagenic potential when you add up exposure over a lifetime. You may be able to combat some cancers by shutting yourself in a controlled, sterile room for most of your life away from mutagens and infectious agents, but good luck convincing anyone to do it. You will certainly be able to decrease your personal risk of some cancers by adopting a healthier lifestyle and avoiding risky behaviours, but that is hardly going to abolish all cancer. Moreover, with our increasing population and pollution levels, it simply isn't realistic to expect that human population can address cancer by returning our planet to an idyllic garden of Eden, spending out time in the fresh air eating organic food and avoiding pollutants. Ironically enough, if we did that rates of skin cancer would increase (unless we all used strong sun blocks which, incidentally, are developed in the lab). Like it or not, lab researched therapeutics, in co-ordination with education on healthier lifestyles, is the most realistic chance we have to combat cancers.
 * Finally, I take issue with your suggestion that our body "fights off degeneration for ages and ages and ages".
 * 80 years is just a trifle to you then is it? Well, very well! I'm 30 and it feels like I've been around for an incredibly long time. Ten thousand days in fact. Maybe it's just that I have a clearer memory than most. Vranak (talk) 19:22, 28 February 2010 (UTC)
 * It doesn't. Degeneration (cellular, genetic, physiologic) is a continuous process that occurs pretty much throughout our lifetimes, certainly from our twenties onwards. Its called aging and no amount of healthy eating and fresh air will stop it. Cancer is the ultimate conclusion of that process. You pick up mutations in the very process of living your life, and eventually you will get one or two that hit a tumor suppressor gene or an oncogene. Unless something else gets you first, everyone on this earth will get a cancer eventually. It is completely inevitable, which is why it is so difficult to "cure" cancer. Rockpock  e  t  20:59, 25 February 2010 (UTC)
 * Your pessimism and defeated spirit have tainted your thinking. The body has DNA repair mechanisms. Earl Grey tea (specifically, bergemot oil) stimulates those in fact. Vranak (talk) 19:25, 28 February 2010 (UTC)
 * See deoxycholic acid and Pacific yew. ~ A H  1 (TCU) 00:59, 28 February 2010 (UTC)

bleach cover up
there is an employee of Clorox editing the bleach articles trying to minimize the risks of bleach and the carcinogenic and caustic nature of it. can someone stop him and revert his edits? —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 03:29, 24 February 2010 (UTC)
 * Try asking here: Conflict of interest/Noticeboard. --Tango (talk) 03:39, 24 February 2010 (UTC)


 * it would also help for you to give their user name so that we can check it out. -- Ludwigs 2  05:17, 24 February 2010 (UTC)

it is user  http://en.wikipedia.org/wiki/User:GVB012009  —Preceding unsigned comment added by 67.246.254.35 (talk) 00:19, 27 February 2010 (UTC)

Does gasoline float on water? Will it dissolve sugar?
Will water, for example in a gas tank, float on top of the gasoline or sink to the bottom (and why)? Also, does sugar dissolve in gasoline, or will it stay granular? I think sugar will not dissolve due to the non-polar nature of sucrose and gasoline. —Preceding unsigned comment added by 161.165.196.84 (talk) 08:32, 24 February 2010 (UTC)


 * Gasoline floats on water, and sugar does not dissolve in gasoline. Read the Wikipedia article on solubility for more information on this. 217.158.236.14 (talk) —Preceding undated comment added 11:11, 24 February 2010 (UTC).
 * Snopes.com: Sugar in the Gas Tank might be of interest to you. AlmostReadytoFly (talk) 11:42, 24 February 2010 (UTC)
 * Snopes says "No", but The Straight Dope claims to have run the experiment and gotten a "Yes". Followup: are you sure sugar in the gas tank will wreck a car engine? APL (talk) 16:31, 24 February 2010 (UTC)
 * So we need Mythbusters to break the tie... --Tango (talk) 18:30, 24 February 2010 (UTC)


 * I note that the Straight Dope article notes that it clogs the fuel filter sock, exactly the result described by Snopes. They agree that sugar won't destroy an engine, and they agree that sugar can stop a car from operating.  So I don't see a need for a tiebreaker, although giving the Mythbusters new excuses to destroy stuff is always entertaining. &mdash; Lomn 18:57, 24 February 2010 (UTC)


 * The Mythbusters did do "sugar in the gas tank" (I think it was episode 15) - and it didn't work. The engine ran just fine.  They tried a bunch of other things too.  What did finally kill the engine was bleach. SteveBaker (talk) 03:46, 25 February 2010 (UTC)

Electrolysis and Photolysis of Water
If you use electricity to split saltwater into hydrogen into oxygen, what would happen to the salt in the saltwater? Would it also split into sodium and chlorine or would it remain as salt?

If you use light or radiation to split saltwater into hydrogen and oxygen, what would happen to the salt in the saltwater? Would it also split into sodium and chlorine or would it remain as salt?

Bowei Huang 2 (talk) 10:07, 24 February 2010 (UTC)


 * When salt is dissolved in water, it already is split into sodium and chlorine ions. See the articles Ion and Solution. DVdm (talk) 10:59, 24 February 2010 (UTC)


 * WIth electrolysis you can get chlorine gas formed and sodium hydroxide at the other electrode. Hydrogen is formed in preference to sodium metal. Graeme Bartlett (talk) 11:21, 24 February 2010 (UTC)

If you use electricity, heat, light, or radiation, etc, to split saltwater into hydrogen and oxygen, then what happens to the sodium and chlorine in the saltwater?

Bowei Huang 2 (talk) 09:09, 25 February 2010 (UTC)
 * The above answers and electrolysis of water explain what happens when you use electricity (the sodium in particular will remain in the water, although you may get some chlorine and sodium hydroxide forming at the electrodes). Using heat or light or most forms of electromagnetic radiation will not split saltwater into hydrogen and oxygen (when you boil water you just get steam).  (I'm not sure what high doses of ionizing radiation would do, but I wouldn't recommend you try it.)  If you use the heat/light/radiation to generate electricity (in a steam turbine, photocell, nuclear power station, etc) then the answer for electricity applies. --Normansmithy (talk) 11:48, 25 February 2010 (UTC)

very hot water + some cold water = just warmed water?
If I want to heat a pot of water to a certain "quite warm" temperature, but overshoot my target and get a raging boil, will adding some cold water, and mixing, produce the equivalent "quite warm temperature" water as if I had just heated to that temperature directly? Or will the cold water "ruin" some aspect of the water? Please answer from both a scientific and practical standpoint. Thank you. 82.113.121.93 (talk) 12:41, 24 February 2010 (UTC)
 * Practically speaking, it can be a very bad idea to have hot and cold things together in glass or ceramic containers as thermal shock can cause them to break, but for a metal pot, addition of cool water to hot water will change nothing but the temperature and mass of the whole. Googlemeister (talk) 13:57, 24 February 2010 (UTC)
 * Adding to the practical warning, it's not so much an issue in this case. You're likely to encounter thermal shock issues if you plunge a raging hot container into an ice bath, or dump boiling water into a frozen glass, but adding cold water to a hot pot full of hot water will avoid the effect -- there's enough thermal inertia there to avoid the shock.
 * On the other side of practicality, some people claim that their boiled tap water tastes different from their unboiled tap water. They might consider such mixing as you suggest to be "ruining" the water, and from their subjective standpoint, that's fine.  Note, however, that it's strictly a case-by-case basis.  If mixing the water bothers you, don't do it.  An alternative option would be to dunk a plastic bag full of ice water into the hot water; that will generate the cooling effect without mixing the water. &mdash; Lomn 14:02, 24 February 2010 (UTC)


 * I have no idea what you mean by 'ruining' the water (do you mean for making tea or something?).
 * But the temperature-thing is easy. If you add an equal amount of water then the resulting temperature will be the average of the two. For example, if you have boiling water that'll have a temparature of 100 C (a 'raging boil' just means that it is working harder at losing the heat added to it by the heat-source). Suyppose it's 1 l. If you add 1 l of water at room temperature, say 20 C, then the resulting temperature will be (100 + 20) / 2 = 60 C. If you add just 50 cl, then you get three parts, two of which are the boiling water, so it will be (2*100 + 20) / 3 = 220/3 = 73,8 C. If you add just 10 cl, it'll be (10*100 + 20) / 11 = 1020/11= 92,7 C. In other words, if you want just 'quite warm' water, say about 40 C, then you'd have to add more water at room temperature than the water in the pot.
 * But it would be easier to use ice-water (water in which some ice cubes have been floating for a while without completely melting). This is more practical because you can create both temparatures without a thermometer (one with a boil the other with ice). And it makes for easier mathematics as well because you've got a 'point zero' and the other number is 100 (note that this only works for Celsius, not for Fahrenheit). To get at a certain temperature, divide 100 by it and you get the proportion of boiling water you need in the mix. For example, to get 25 C, that has to be 25/100 = 1/4. So the proportion of ice water has to be 1 - 1/4 = 3/4. So 1 part boiling water, 3 parts ice water. If you want 40 C it's 40/100 = 4/10 and 1 - (4/10) = 6/10, so 6 parts boiling water and 4 parts ice water.
 * I'm sure there's an easier way to explain this, but I hope this helps. DirkvdM (talk) 15:50, 24 February 2010 (UTC)
 * Just a practical point: use only the water that had the ice in it. Don't add the ice; it counts as "below 0 °C" even if its temperature is exactly that because of the heat of fusion.  --Tardis (talk) 16:41, 24 February 2010 (UTC)


 * Our water memory article is good reading. Comet Tuttle (talk) 17:51, 24 February 2010 (UTC)
 * For a sufficiently warped definition of "good"! --Tango (talk) 22:09, 24 February 2010 (UTC)


 * Avid tea drinkers claim that over-boiling the water drives out oxygen and perhaps other dissolved gasses and makes it taste 'flat'. There may be some truth to this...but shaking it up with some air ought to solve that pretty quickly so "ruined" is perhaps a bad choice.  SteveBaker (talk) 03:23, 25 February 2010 (UTC)

Surface of Gas Giants
While reading 2010: Odyssey Two, I remember ex-David Bowman observing that Jupiter's core was a diamond the size of Earth, due to the intense pressure on the gases in that region. I, personally, don't believe there is enough carbon in the Jovian atmosphere to create a diamond, but is it at all possible that this theory could be true?  MMS  2013  14:19, 24 February 2010 (UTC)
 * Unlikely. ~ Amory ( u •  t  •  c ) 15:32, 24 February 2010 (UTC)
 * But there are serious "diamonds in space" hypotheses: Neptune, BPM 37093. -- Coneslayer (talk) 15:42, 24 February 2010 (UTC)

Aspirin from a tree?
I recently went on a jungle trip, on which my guide showed me a tree the sap of which was supposedly good for stomach-aches. He let me try a bit and it tasted very much like aspirin. At the aspirin talk page someone mentioned that "salicylic acid is similar to the acetylsalicylic acid in aspirin, and is found naturally in some plants, such as the willow tree." So is that all basically the same stuff? Or might a new source of a similar chemical still be useful for medicine? (In other words, can this make me and/or the locals very rich? :) ) DirkvdM (talk) 15:09, 24 February 2010 (UTC)


 * See salicylic acid. It is a well-known product, not a new discovery. Of course, you could get rich off it.  There are a lot of people who sell plants and herbs that don't do much and make good money.  All you need to do is find someone to buy it.
 * I don't know what plant you were shown, but the substance in willow bark essentially is asprin. Acetylsalicyclic acid is just a synthetic version - it is much cheaper to use fancy chemistry to make it than to grow lots of willow trees (and I think it is slightly more effective/has fewer side effects). Using willow to treat pain was well know long before modern chemistry. --Tango (talk) 16:44, 24 February 2010 (UTC)
 * Actually, no &mdash; that's what I used to think too. In fact it's what pretty much everyone used to think.  But they set me straight on the talk:aspirin page.
 * Aspirin has a different mode of action from salicylic acid (the stuff in the willow trees). Aspirin irreversibly acetylates some enzyme, probably COX but I'm not sure about that.  Obviously salicylic acid can't acetylate anything, as it has no acetyl group. --Trovatore (talk) 21:46, 24 February 2010 (UTC)
 * It's also not true that aspirin is easy to make than salicylic acid. Aspirin is made by acetylating salicylic acid. Aspirin is was preferred mostly because it attacks the stomach much less strongly. Algebraist 21:56, 24 February 2010 (UTC)
 * Well, no, it's preferred because it acetylates COX, whereas salicylic acid doesn't. Salicylic acid has some independent effect; I don't know what it is.  I don't know whether it's an anti-inflammatory at all.  --Trovatore (talk) 21:58, 24 February 2010 (UTC)
 * Sorry, I should've made it clear I meant that's the reason aspirin was preferred when it was first devised. I think you're right that salicylic also lacks the non-analgesic effects that were discovered for aspirin later. Algebraist 22:03, 24 February 2010 (UTC)
 * The "new source of a similar chemical" would have to be more effective, or have fewer side-effects (or preferably both) if you want to make your fortune out of it (without "quackery"). If you have found a new "wonder-drug", then you must take out world-wide patents as soon as possible.  You should be aware, however, that most similar chemicals have already been tried and rejected long ago.    D b f i r s   21:40, 24 February 2010 (UTC)


 * Ah, 'similar drugs' is what I was getting at. So there are variations on the drug. (Also see the polymorphism section, although I suspect that that gives just a limited range of variation.) Might there be a list somewhere of plants and trees that contain similar drugs?
 * I suppose one first question is whether this is a willow tree. Comparing my pictures with these, it may very well be, although I'm by no means an expert. Also, it had shoots that look rather willowish to me. I assumed willows didn't grow in the tropics, but they seem to grow just about anywhere (just mostly in moderate climates). But even if it is a willow tree, there appear to be many species of willow, with lots of variation (not surprising since they grow just about anywhere) and this might be an uncommon one (possibly even unknown to western science, given where I found it). Do they all have the same salicylic acid? If so, and if this is a willow tree, then I suppose that's the end of it.
 * One more thing, though. Which drugs taste like aspirin? Is it the salicylic acid that gives it the typical taste or the acetyl, or what? DirkvdM (talk) 09:25, 25 February 2010 (UTC)


 * You should bear in mind that it costs a pharmaceutical company like Bayer (very roughly) about $500,000,000 (yes, that's five hundred million US dollars) to take a "candidate molecule" all the way from discovery of its existence (or its invention), through all the various testing and trials and licencing processes required by governments, to being a marketed product. The subsequent profits it makes for the company also have to cover the costs of all the (many more) candidates that didn't make it all the way, a roughly comparable sum.
 * Because pharmaceutical companies are working with such vast sums they can afford to employ extensive research staffs who are well aware of the potential for new drugs in locally known remedies such as this; it's therefore very probable that this one has already been, or at best is being, investigated by one or more of them [Disclosure: I used to work at #12 on (both of) the above-linked lists].
 * On the very slim chance that you have stumbled upon something not yet investigated, you might consult (probably at considerable expense) a lawyer specialising in such matters about how to retain some interest in it, but consider also that most people and legal systems would probably consider that the indigenous people from whom you learned about it would have a far greater claim than you on the fruits of its exploitation.
 * There are of course less currently regulated and consequently less costly (but also less lucrative) areas of "hebal", "folk" and other "Alternative medicines." Again, it would be surprising, if less so, if this particular local remedy were not already known to such industries. It seems likely from recent trends and events that regulation of these (in the "Western World") is going to be tightened up in future. 87.81.230.195 (talk) 16:23, 25 February 2010 (UTC)
 * Some studies link Asprin to Reye's syndrome. Also, there are plenty of "herbal" remedies such as those for Ovarian and breast cancer from the Pacific yew and for leukemia from Madagascar Periwinkle seeds. ~ A H  1 (TCU) 00:55, 28 February 2010 (UTC)

r-tree structure for image retrieval
Hi

please, I have 16-dimension color histogram, i need to use r-tree indexing in order to speed up the image retrieval. how can I determine the MBR in the tree?, and How the overlapping happen? ,how many level I need to represent r-tree? please any help زينب —Preceding unsigned comment added by Dania2009 (talk • contribs) 15:15, 24 February 2010 (UTC)


 * Have you read the article R-tree? Cuddlyable3 (talk) 23:12, 24 February 2010 (UTC)

rebok
is castro wearing rebok sneakers in this pic?

http://en.wikipedia.org/wiki/File:Fidel_Castro8.jpeg —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 15:22, 24 February 2010 (UTC)


 * They are obviously trainers of some kind - but the photo was taken in 2003 and because Reebok change their designs at least several times a year - it would be very hard to find an exact match for them by searching for images on the web to get a match for the design. However, he clearly likes to wear sneakers here, for example. He's also not above advertising some western brand names either: Adidas!.   So I doubt we can say that he was wearing Reeboks - but it's very likely some kind of brand-name sneaker. SteveBaker (talk) 00:57, 25 February 2010 (UTC)

why is the universe so dumb?
It's obviously a huge oversight that just be speeding around for a while relative to the other, two twins can end up with arbitrarily different ages. That obviously doesn't make much sense. Therefore, the Universe is very stupid. My question is: why is it so stupid? Why isn't it more sensible? 82.113.106.92 (talk) 16:32, 24 February 2010 (UTC)


 * Your argument is just an opinion, not a fact. What you are asking is "Why do I think the universe is stupid?"  From your statement, the best answer that I can give is "Because you don't understand it."
 * Time dilation is an inevitable consequence of the speed of light being the same to all observers. There isn't really a reason for it, though, the universe is just the way it is. --Tango (talk) 16:45, 24 February 2010 (UTC)


 * well isn't it pretty dumb that if you are a photon of light going the opposite way of another photon of light, and you're both travelling at c, then you are not moving away from the other one any faster than if the other one were a brick wall? That seems really dumb to me, but if you say that it is only my opinion, why don't you give me ONE good reason why it's not dumb?  I can't see any reason why it's not dumb of the universe to be such that hurling away at c from a brick wall doesn't move you away from it any faster than hurling away at an object going 186,000 miles per second in the opposite direction.  I'm open to any reason why this shouldn't be a really dumb set of laws...  (I don't mean that they don't apply, but that it's dumb that they should, that our universe should be so shoddily hacked together in this way).  Thanks.  82.113.106.92 (talk) 17:09, 24 February 2010 (UTC)
 * Stupidity is a factor of intelligence, which means you're suggesting the universe is either a life form, or was created by one. Science can't answer those kind of questions. Vimescarrot (talk) 17:18, 24 February 2010 (UTC)


 * The universe is wise, which has no bearing on intelligence.   -- Ludwigs 2  17:20, 24 February 2010 (UTC)


 * Is time dilation really that much less counter-intuitive than, say, the doppler effect or redshift? In other news, where do you want us to go with your assertion that you find the universe dumb, beyond "so what; get a clue"? --Tagishsimon (talk) 17:25, 24 February 2010 (UTC)
 * The universe is not dumb, and neither are the laws of relativity (or, at the other end, the ones of quantum dynamics). It's quite literally us, who only experience "the middle world" who form wrong assumptions by looking at a small part of the world with bad focus and then expect our assumptions to apply to all of reality. Newtonian physics is not the law and relativity the exception, rather, relativity is the law and Newton's laws of motion are an approximation that works in some limited case. --Stephan Schulz (talk) 17:28, 24 February 2010 (UTC)

(ec) Come on, obviously I'm not talking about 'intelligent' design in the Universe. I mean, in human terms, the way things are are pretty dumb. Actually 186,000 miles per second isn't that fast. It takes an easily discernable amount of time just to ping someone in China and get their response - it is physically palpable lag. And that's on just a local, Earthly basis. On a galactic basis, this universal speed limit is ridiculous. I'm not saying "SOMEBODY" made the speed limit be 186,000 miles per second. I'm saying, it's a stupid state of affairs, regardless of whether anything intelligent (or lack thereof) caused it. It's just stupid. But, for anyone who actually is taking the effort to understand what I'm SAYING here, I'm open to anything you know that makes the above aspects of the universe I mentioned actually be not-stupid, but pretty cool. Here is an alternative way of phrasing it: If reality really were that conceived by classical physics people thought we were living in in the 18th century, NO ONE, but NO ONE, would wish "sigh.  If only there were a universal speed limit of 186,000 miles per second.  If only you could never move, even in the vacuum of space, even close to that speed.  If only twins could end up with different ages if one takes a fast trip." Why would anybody want that? Nobody would want that: it's dumb. Unless you know of some reason why somebody WOULD pine after the state of our universe, if they were like us but lived in a nonrelativistic place. Also, relativism is just one aspect of our dumb universe, don't even get me started one quantum mechanics. One thing at a time: is there anything good or nice about living under relativistic physics? Or, is it merely dumb for the reasons I outlined? Thanks. 82.113.106.92 (talk) 17:39, 24 February 2010 (UTC)


 * This thread should probably be collapsed for trolling, but I have a good answer. I like living in this awesome relativistic universe because if the speed of light constant and time dilation were any different, it would affect things like the formation of stars and galaxies in unpredictable ways, and human life would most likely not exist.  Comet Tuttle (talk) 17:48, 24 February 2010 (UTC)


 * That's a very good answer, actually, despite the fact that you dismiss my question as a troll. I hadn't thought of that answer.  However, that is not due to real stupidity on my part, but because of a lack of science education.  All of the humanities (human affairs) are inconsequential spots in the formation of the stars, and so the fact that we are inconvenienced by ping times, for examples to a planet as close as Mars, is nothing compared with the benefit of existing.  I guess it's like some really stupid human laws, that nevertheless serve an important purpose, and "but for" them, the place would go to hell in a handbasket.  82.113.106.92 (talk) 17:54, 24 February 2010 (UTC)


 * It seems that the OP is equating "counterintuitive" with "dumb." This is a huge fallacy.  First of all, things are only ever intuitive because you have daily experiences with them, and can perceive events and judge generally what you expect should happen.  But physics is the quantitative analyis of the mechanisms of the universe at many different scales.  Relativity in particular is concerned with the physics of very large masses, very high energy, very fast speeds (and similar).  Since humans are small compared to the scales necessary to observe many relativistic effects, we have no daily experience with them; nor have we evolved biological sensors which can make meaningful sense of those relativistic effects.  The same applies to quantum mechanics - which deals with very small energy scales, length scales, and time scales.  Again, the behaviour of the universe is very different at such scales - so it seems to contradict your "gut sense" of what should happen.  But if you spend a lot of time observing things at quantum or relativistic scales (which means learning to use the mathematical machinery and understanding the experimental observations that are available) - then you will see that the universe actually is quite ordered and follows well-defined rules.  Nimur (talk) 18:50, 24 February 2010 (UTC)
 * It sure seems to follow rules given the current level of sensitivity of equipment. Is it possible that finer analysis may reveal that it does not, in fact, follow any rules at all? 82.113.106.89 (talk) 19:23, 24 February 2010 (UTC)

Also: I don't equate "dumb" with "counterintuitive" -- I call it dumb because no one would ask for them in their absence, but there are a lot of counterintuitive things that people DO ask for, in the absence of any such effect. Two great examples are replication and teleportation, neither of which make any sense on an intuitive level, yet both of which are commonly requested. In other words, every single one of the aspects of the universe"I've described is more readily described by its users as bugs, not features; meanwhile, actually requested features are totally absent.  That's what I'm getting at: that what we get, is a wet blanket.  I'm especially talking about relativistic effects.  They are not useful, but on the contrary, dampen many ambitious plans (such as the trillion mile per second rocket etc). 82.113.106.89 (talk) 19:27, 24 February 2010 (UTC)


 * "My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose." J.B.S. Haldane. --TammyMoet (talk) 18:57, 24 February 2010 (UTC)
 * Why would you expect the universe to be how human science-fiction writers want it to be? --Tango (talk) 19:43, 24 February 2010 (UTC)

As you can see we already have a pretty long thread and we haven't even started answering your question yet mainly because of your poor choice of words. I'm sure there is a lesson somewhere in there... Dauto (talk) 20:32, 24 February 2010 (UTC)


 * I know you were exaggerating, but actually you have started answering the question, viz. Commet Tuttle's "if the speed of light constant and time dilation were any different, it would affect things like the formation of stars and galaxies in unpredictable ways, and human life would most likely not exist". That's the anthropic principle, and kind of a good answer.   By the way, you said I used a poor choice of words, but I don't really have better ones for the question and feeling that I'm addressing.  What would you suggest I say, given the clarification to the question I've since given?  84.153.235.131 (talk) 21:20, 24 February 2010 (UTC)


 * Words like 'frustrating', 'annoying', or even 'unfair' would have worked better than stupid and dumb. Dauto (talk) 22:49, 24 February 2010 (UTC)


 * A complaint that something is "obviously a huge oversight" should be addressed to the one you think is responsible. Unfortunately there Ain't Nobody Here But Us Chickens. Cuddlyable3 (talk) 23:09, 24 February 2010 (UTC)
 * Personification is not science. If you wanted the science, ask science questions. If you wanted to know why the Universe is stupid to you...that would be psychology, one of the Humanities? The question, as you asked it, seemed to be applying psychology (concepts of intelligence, or lack thereof) to physics. The two are incompatible. Vimescarrot (talk) 23:27, 24 February 2010 (UTC)
 * I once read a short sci-fi story (Far Centaurus by A. E. van Vogt, I think) where the means of travelling faster than light involved work in the field of "electron psychology". What this meant was never really explained... --Tango (talk) 01:02, 25 February 2010 (UTC)


 * The problem with the universe is not with it - but with us. We've evolved to clamber around in trees, chase after small furry animals, clonk them on the head so we can eat them and frolic through the grasslands picking delicious nuts and berries.  Nothing we've evolved to deal with goes faster than maybe 100mph and no event that we ever care about takes less than the literal blink of an eye.  Nothing weighs more than a smallish planet - nothing is (perceptably) larger than however far you can run in a day.  So when we find that the rules at scales that our brains have evolved to cope with do not apply for anything that's very heavy, very large, very fast, very tiny or very brief, we're not really equipped to handle that.  When we're exposed (through our own science) to things that are as downright weird as time dilation or quantum theory - we're inclined to the kinds of response that you're feeling.  It's not at all a strange or inexplicable reaction to how the universe is...it's simply that (for most of us) the boundaries of our intellectual knowledge has outpaced our ability to truly internalize those things.  The universe is actually rather cool (I wouldn't say "dumb" or "intelligent") - some of this weird stuff is really useful.  Without all of that quantum theory, most of the fancy electronics that we love so much wouldn't be possible.  The speed of light thing is a bit of a bummer for the science fiction fans who really wanted to go and explore other star systems - but you've gotta admit it's interesting.  SteveBaker (talk) 00:41, 25 February 2010 (UTC)


 * The real question is, why do you care if the Universe is stupid? If you are so smart then it shouldn't trouble you in the slightest. Only if you were also stupid would other people's stupidity (or universal stupidity) be a hassle. Vranak (talk) 01:56, 25 February 2010 (UTC)

The OP writes "don't even get me started on quantum mechanics." Without quantum mechanics, the protons in the sun wouldn't fuse because they would invariably repel each other (both being positively charged; that's intuitive and sensible, right? -- for an "intuitive" but wrong analogy, think of trying to force "the wrong ends" of two magnets together). The hydrogen in the sun wouldn't produce helium, and so on. It would be very cold and very dark and none of us would exist. Fortunately, quantum tunneling and and velocity distribution allow hydrogen protons to fuse (after a few tens of millions of years of hanging out in the sun). Thanks, stupid quantum mechanics! 63.17.57.56 (talk) 02:56, 25 February 2010 (UTC)


 * Theology is adept at discussing vaguely phrased and confusing questions. In your question we see a parallell with the well-known Problem of evil (POE) in your Problem of stupidity (POS). Some of the answears to the POE can be easily amended to answear the POS, such as mankinds limited ability to assess the universe or the existence of free will. Or maybe the POS is a variant of the Omnipotence paradox? You could start with that and move on to the Euthyphro dilemma with some very interesting conclusions. (There must be a forum for such ideas somewhere :-) EverGreg (talk) 09:27, 25 February 2010 (UTC)


 * Adept at discussing - certainly. Able to come to a true, useful or even comprehensible answer?  Never. SteveBaker (talk) 04:06, 26 February 2010 (UTC)

I think that the best answer so far is form Comet Tuttle. All of the physical constants of the universe (not just the speed of light) are important for determining the state of the universe. If any of them were different we probably wouldn't be here. If I fell out of a tree and broke my leg, I might say gravity is 'dumb', but I don't, because without a specific gravitation constant there may very well be no tree, no earth, no me, and quite possibly no universe. 24.150.18.30 (talk) 03:26, 27 February 2010 (UTC)

Salt ionizing in water
If salt is ionized in water, why does the water still taste salty? I know that sounds dumb, but if the salt gets separated into Na+ and Cl-, wouldn't it stop being salt and stop having its properties? Maybe not all of the salt gets ionized? Or maybe I just don't understand the process fully. —Preceding unsigned comment added by 160.36.39.222 (talk) 16:50, 24 February 2010 (UTC)
 * Don't forget that any undissolved salt entering your mouth will dissolve soon enough in your saliva. So judging from that alone, it seems to me that all you ever taste is the ions. Vimescarrot (talk) 17:21, 24 February 2010 (UTC)


 * It is the sodium ions that cause the salty taste - our article on taste says "Saltiness is a taste produced primarily by the presence of sodium ions". Other alkali metal ions produce a similar taste. I doubt it is possible to know what undissolved salt tastes like - before it gets anywhere near your taste buds, it will have dissolved in your saliva. Gandalf61 (talk) 17:22, 24 February 2010 (UTC)
 * Other alkali metals tasting roughly the same is why potassium is often used to replace the sodium in low-sodium salt. (Not that potassium is any better for you in large quantities than sodium, unless you have some medical condition that makes sodium really bad.) --Tango (talk) 18:08, 24 February 2010 (UTC)
 * I'd say very roughly. I can easily distinguish KCl from NaCl.  KCl is subjectively much more "sour".
 * It's too simple to compare K to Na as "which one is better for you". The main issue is that most people eat far too much sodium.  On the other hand it takes (IIUC) significantly less potassium to outright kill you (quickly, as opposed to via hypertension, which generally takes years or decades to be lethal). --Trovatore (talk) 23:39, 24 February 2010 (UTC)

Galactic Plane and Rotation
Relative to the equator (or ecliptic) what is the angle of the galactic plane? Assuming the north pole of the earth faces upwards does the galaxy rotate CW or CCW? Is there some rule determining which way a galaxy rotates? TheFutureAwaits (talk) 17:23, 24 February 2010 (UTC)


 * See Galactic coordinate system, I think it answers all your questions except the last. The way a galaxy rotates will depend on the random motion of the matter than collapsed to form it. That motion will, due to random chance, have had a slight net rotation when you average it out. As the proto-galaxy collapses, conservation of angular momentum means the rotation gets faster and the galaxy flattens out into a disk. Which direction it rotates will be the same direction as that tiny net rotation the original cloud had, which is random. The same principle is what results in all the rotations in the solar system (rotations of planets on their axes, orbits of planets around the sun, orbits of moons around planets, etc.) which are almost all in the same direction (anticlockwise when viewed from above the north pole, if memory serves). The exact mechanism for the formation of galaxies is still up for debate, but what I've described should be accurate as far as it goes. --Tango (talk) 18:06, 24 February 2010 (UTC)

Numbers and diagrams only get you so far in getting a real gut feel for this. So how about thinking about it like this: The photo at right of the Milky Way was taken at a Telescope facility in Paranal in Northern Chile (More info about the photo comes from here). It was taken in the middle of winter and Paranal is well south of the equator - so we're somewhere "underneath" the planet. The bright dot in the middle of the photo is Jupiter. The laser beam is pointing towards the center of the galaxy. It takes a bit of mental gymnastics to get your head around that. But since Earth and Jupiter both lie in the plane of the solar system's ecliptic - and the photo was taken in the middle of the night - so the sun is somewhere off the bottom of the photo beneath our feet - so if you imagine a triangle with one point where Jupiter is, one where we're standing and another point way below our feet - then you can get a feel for how the plane of the solar system ecliptic doesn't line up well with the plane of the galactic disk. Hopefully, this conveys the fact that the solar system is tilted at about 85 degrees to the plane of the galaxy. When you look at the Milky Way, it fills about 100 degrees of your field of view - if you put your arms out to try to grab it(!) they make an angle bigger than a right angle. Imagine you're holding a gigantic round disk in your hands while they are 100 degrees apart - and that should give you a feeling of just how far on the outer edge of the galaxy we really are. SteveBaker (talk) 00:15, 25 February 2010 (UTC)
 * Where does that 100 degrees come from? The Milky Way surrounds us on all sides as a belt. That's 360 degrees. How much of it you can see at any given time will depend on where on the planet you are. The bit towards the centre of the galaxy is much more dramatic, of course. --Tango (talk) 00:35, 25 February 2010 (UTC)
 * Yeah - of course you're right - the galaxy is all around us. The number I quoted is for the bright stuff - and it's very approximate - no science behind it.  If you get someplace where you can see the Milky Way clearly - it just looks like you could grab it with outstretched arms at a bit more than 90 degrees.  The number "100 degrees" is mentioned at the link I pointed to here. SteveBaker (talk) 01:23, 25 February 2010 (UTC)

Thanks guys, this explains a lot regarding the angle. The only part I don't get is why the gravity of the galaxy wouldn't be enough to cause stellar systems to align their planets with the galactic plane. If the gravity is strong enough to make everything rotate around the galactic core then why aren't stellar plane's aligned? TheFutureAwaits (talk) 14:15, 25 February 2010 (UTC)


 * Looking at redshift for nearby galaxies would likely determine their rotation. As for the orbits of stars and their planes around galaxies, see Sun's orbit. ~ A H  1 (TCU) 00:47, 28 February 2010 (UTC)

Weather and Axial Tilt
What would the weather and seasons be like on Earth of the axial tilt was 90 degrees instead of 23? Would the change have prevented life from evolving? TheFutureAwaits (talk) 17:26, 24 February 2010 (UTC)

The more I think about it there could be two answers couldn't there? If the "south pole" of a 90 degree axial tilt was pointing along the orbit of the Earth (aka 90 degrees from the direction of the sun) then there would be no seasons, just a 12 hour day night cycle right? If the "south pole" was facing the sun then there would be extreme seasons resulting in 6 months of darkness for every location on the planet. I imagine that would be enough to cause catastrophic weather likely preventing any life. Is my understanding correct? TheFutureAwaits (talk) 17:41, 24 February 2010 (UTC)


 * Not quite. The axis stays put as the Earth orbits the Sun so, relative to the Sun, it rotates once a year. This is what causes the seasons. Your two scenarios are actually just different parts of the same scenario. At one point the north pole will be pointing at the sun, then 3 months later the axis will be pointing along the Earth's orbit, then 3 months later the south pole would point at the sun, then 3 months after that it is pointing along the orbit, just in the other direction, and then 3 months later the north pole is back facing the sun. During spring and autumn you would get normal 12 hour days, during summer you would get constant sunlight and during winter constant darkness. It's just like what happens inside the Arctic/Antarctic circles in real life, but the circles will now be the equator so the whole northern hemisphere is the Arctic and the whole southern hemisphere is the Antarctic. --Tango (talk) 17:51, 24 February 2010 (UTC)


 * Somewhere above about 70 degrees of tilt it is predicted that the poles would have an annual average temperature higher than the equator (due to many months of 24 hour sun at the poles) and the equator would start to form an ice belt due to the generally oblique sunlight it sees most of the year. Dragons flight (talk) 19:04, 24 February 2010 (UTC)
 * Average temperature is irrelevant to life. Far more important is the extremes. The equator may be colder on average, but it would be much more stable, which is what is important. --Tango (talk) 19:45, 24 February 2010 (UTC)


 * That's not true. Average temperature matters a lot when you put snow and ice in the mix.  Whereas many forms of life, e.g. deciduous plants and hibernating animals, have adaptations to specifically deal with seasonal variability.  If the equator had permanent ice sheets (which is likely  at a 90 degree tilt), then I think it would be rather barren of life the same way our polar deserts are relatively barren now.  Stability matters, but so does staying away from 0 C for us water based lifeforms.  Dragons flight (talk) 22:19, 24 February 2010 (UTC)
 * If you have an ice belt, I would expect the life to be underneath it where there would be liquid water. If the equator is always frozen there will be belts on either side that are seasonal and life could migrate between. --Tango (talk) 00:02, 25 February 2010 (UTC)


 * As for the consequences for life, it is difficult to say since we only have a single example of a planet where life can evolve. You certainly couldn't have life like we have, there would need to be major changes. The equator would be fairly stable temperature-wise, so I suppose life could evolve there. Some very simple life might be able to survive the massive temperature changes elsewhere or complex life could migrate (as many species do now). Exactly how great the temperature variations would be would depend on whether winds can transfer heat from the day side to the night side effectively. The issues are very similar to those found with tidally locked planets, like many of the planets we've found around other stars are thought to be. See Hot Jupiter for some information. --Tango (talk) 17:56, 24 February 2010 (UTC)
 * As I understand it, the current best theories for abiogenesis involve white smokers underwater. For this, plate tectonics (and hence a large hydrosphere) are more important than climate. What happens after that is a lot harder to predict, but I would trust evolution to find ways of coping with the different scenario. --Stephan Schulz (talk) 19:03, 24 February 2010 (UTC)


 * I assume that life first formed in the oceans, in which case as long as you don't freeze the oceans solid, I'd say the existence of life is still quite likely. Life on the surface would have to deal with greater extremes, but the oceans are a pretty good buffer for many forms of life.  Dragons flight (talk) 19:04, 24 February 2010 (UTC)


 * No matter how the planet spins or points, there have to be some places that get a bearable amount of sunlight for a bearable amount of time. When the south pole points towards the sun, it cooks and the north pole freezes - but around the equator, there is a nice belt that gets a reasonable amount of sunlight.  When the north and south poles line up along the path of the orbit, then at the equator, you have a fairly normal day/night cycle - so living on the equator would be kinda like living at the poles for us with months of perpetual twighlight followed by months of more normal conditions.  The third extreme is when the poles point at right angles to the plane of the orbit...which is more or less what we have.  Even if the planet isn't spinning at all, there are still places that get a reasonable amount of sunlight.   Probably the worst case is not spinning but not tidally locked so that the nominal poles of the earth point toward the sun for months and then along the orbit for months - but even then, there are two points on the equator that get reasonable sunlight all year round.  There ought to be liquid water no matter what (although not necessarily everywhere).  So long as life has a way to get started, it's hard to imagine that between migration, hibernation and simply living in the right places, it could not evolve and continue.   The most significant issue is what these peculiar arrangements do to weather and water - if it's enough to cause crazy energetic stuff to happen - then life might have a hard time of it. SteveBaker (talk) 23:51, 24 February 2010 (UTC)
 * I could imagine very strong currents in either the atmosphere, the oceans (under the ice) or both. Whenever you have localised heating of a fluid, you get convection currents. They could be really strong. --Tango (talk) 00:02, 25 February 2010 (UTC)

This is a really interesting subject. Steve, I'm having a hard time visualizing the two points on the equator you mentioned:"Probably the worst case is not spinning but not tidally locked so that the nominal poles of the earth point toward the sun for months and then along the orbit for months - but even then, there are two points on the equator that get reasonable sunlight all year round." Is there any chart or map which would explain this more clearly? In fact any graphic of any of these scenarios would be most appreciated. TheFutureAwaits (talk) 11:11, 25 February 2010 (UTC)
 * OK - so for some months of the year, (let's say around January) the planet's North pole faces the sun. Any point on the equator sees the sun on the horizon for months at a time whether the planet is spinning or not.  The same for the months when the South pole is facing the sun (July).  This is the same whether the planet is spinning or not.   But in the intervening months, as the north-south axis becomes parallel to the direction that the planet is moving around it's orbit (April and October), then (if it's not spinning on its axis) there will be a circle of points running around the planet from one pole to the other via the equator that see the sun on the horizon.  So during the course of three months - we go from one pole cooking (December) and the other freezing with the equator being in partial sunlight and therefore potentially livable - to a situation in April where (let's say) the Eastern hemisphere is cooking and the Western hemisphere is freezing with a circle of points going through both poles that is in partial sunlight.   OK so now, imagine - as the planet moves between those two extremes, that circle of "reasonable temperature" gradually rotates from one of these positions to the other.  However, there are two points on the equator where the April circle of reasonableness crosses the equator that are in partial sunlight all year round  Everywhere else gets cooked and frozen alternately.


 * But if the planet is spinning about its axis - then in December and June, half the planet is frozen and the other half cooks - but in April and October, everywhere sees a 24 hour day/night cycle. In that scenario, anywhere on the equator gets normal days for six months out of the year - and perpetual twilight for the other six.


 * SteveBaker (talk) 04:00, 26 February 2010 (UTC)

Joseph Jenkins
is ther a link between jenkum and Joseph Jenkins? (humanure) —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 17:57, 24 February 2010 (UTC)
 * This isn't really a science question. I'm trying to give you the benefit of the doubt, but it seems that your post is an effort to troll the desk so that people will search for shock sites.  Little do you realize that the Ref Desk regulars are savvy internet-jockeys who will not be taken in by such antics.  If you disagree with this point of view, and have a valid reason why you posted this to the Science Desk, please elaborate.  Nimur (talk) 18:54, 24 February 2010 (UTC)

put my question back up. i was not trolling, your paranoid. humanure is something i do. its been around since 1990 and jenkum is a new thing. i wanna now if theres a correlation. —Preceding unsigned comment added by 67.246.254.35 (talk) 13:01, 25 February 2010 (UTC)
 * I have restored your question. Abecedare (talk) 16:45, 26 February 2010 (UTC)


 * Almost certainly "no". The word "Jenkem" seems to have originated in Zambia. Whereas the Joseph Jenkins of humanure fame is from USA.
 * It would be a really bizarre twist if Jenkem turned out to be not just urban legend, but complete hoax designed to parody Joseph Jenkins. A bit too obscure of a gag, though.APL (talk) 15:54, 26 February 2010 (UTC) copied reply originally posted on talk page. Abecedare (talk) 16:45, 26 February 2010 (UTC)


 * Urban dictionary notes that jenkem is known on the streets as Sir Author Leroy Jenkems.Cuddlyable3 (talk) 16:55, 26 February 2010 (UTC)


 * To elaborate on APL's reply: while the reports of Jenkem abuse in US are almost surely an urban legend, its use in Lusaka, Zambia seems to have corroboration. See for example this WHO report (page 58 of the pdf), which says "Staff discovered that some were using 'jenkem' made by fermenting raw excrement, waste and/or sewerage over a few days and then inhaling it", where the staff refers to members of the Zambia Red Cross. The report dates back to 1996, more than a decade before the 2007 media interest in the US. So it's likely that the term and concept arose originally on the streets of Zambia, and that makes it improbable that the term is related to Joseph Jenkins. The conclusion would change if we find evidence that, besides writing the book on the subject, Joseph Jenkins had led some projects to popularize humanuring in Zambia in the 1980/90's; I haven't found anything to support that yet. Abecedare (talk) 17:08, 26 February 2010 (UTC)

Black holes
Every black hole will try to pull object towards it's center. Now the same force will be be from (far end) to its center at both the sides meaning that any object it pulls cannot come out from other side as it will be attracted towards the center. So then will the object will remain always at center and not come out from other end? Is there any way to measure the pull of the Black hole? —Preceding unsigned comment added by Itsrohit (talk • contribs) 18:14, 24 February 2010 (UTC)

what? —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 18:22, 24 February 2010 (UTC)
 * I don't think this has anything to do with your question, so I've given it a new section heading. --Tango (talk) 18:29, 24 February 2010 (UTC)


 * See the answer provided at the section below, and in the future, please only ask the question once. &mdash; Lomn 18:48, 24 February 2010 (UTC)

is this a rigorous procedure?
what do you think of this methodology for debunking the idea of plants responding to prayer or bioenergy. I think the easiest would be something like buying a bag of potatoes, putting each one in a separate paper bag with a number on it, placing them along on a table in order (this configuration to be retained throughout, no touching them or the tables until after the experiment) then, say there are 50 numbers. Then I would with a program randomly partition each one into one of two lists, like with a random binary number, if it's 0, it goes on the first list, if it's a 1 it goes on the second list, and at the end a coin flip determines if I'll be praying and bioenergating up the first or the second list. I print the two sheets of paper twice, once to be put on the table inside an envelope but not touched again (one of each list), and the other copy is the one I use. Of the other copy, I flip a coin at the start of the experiment to see if I will be praying up and bioenergating the first or the second sheet of paper. The one I'm not bioenergating/praying up I discard. Then every day, for my remaining key, the ones that are listed I individually go to and pray and bioenergate up for 5 minutes, giving the ones that aren't on the list absolutely no love or attention. (However, I do not touch them or the table or interfere in any way, they are literally just splayed out, before they were even assigned to the first or second list).

Then, after an amount of time that is normally enough for sprouts to grow (however I don't look inside the paper bag! I still don't touch them, I simply discard the key I had been using (randomly either the first or the second sheet of paper).  Then I invite a statistician student to help with my 'science project' showing him the envelope that I never touched, and telling him that it has two lists of potato numbers, one of them is the ones I fed with Miracle-Gro, and the other ones I didn't.  I don't tell him anything else, but let him go to work.

If he comes back with high statistical confidence that he's determined which list is the miracle-gro group, and it matches the group I've been praying for, then uh-oh, the prayer and bioenergy must have done something, or I picked a bad statistics student :(( :((. If, on the other hand, he has no statistical confidence as to which one had been miracle-grown, then Euroka! Prayer + bioenergating debunked.

Is this a correct procedure? Thank you. —Preceding unsigned comment added by 82.113.106.92 (talk) 18:19, 24 February 2010 (UTC)


 * Your research student shouldn't be given a key, you just ask him to look in each bag and write down how many sprouts it has (or how long they are, or whatever). Someone that knows a bit of statistics then compares his list with you key and sees if there is a statistically significant correlation. There is no point lying to anyone about what the experiment is about. As long as the research student doesn't see the key, he can't bias the results. --Tango (talk) 18:27, 24 February 2010 (UTC)


 * What if I get someone else to rate each potato on a subjective scale, 1-10, for how "healthy" and "sprouty" and "energetic" it looks (third obviously very subjective). If they don't see the key, and there are enough potatoes, will it still be rigorous?  For example, the statistitician then just gets a list like:

1-5/5/7 2-3/5/7 and they aren't told what the three factors are, just that the scale is 1-10. Also, there would be no evaluation at the beginning, only the end, and obviously the evaluator doesn't get to see the key. In that case, is that enough information for the statistician to say whether there is statistical confidence in differentiating the two lists based on one or several of the factors (without knowing what they are)? Thank you. 82.113.106.92 (talk) 18:38, 24 February 2010 (UTC)


 * One hole I see in this procedure is that since you have already decided you are "debunking" the prayer idea, your prayers are unlikely to be sincere. You should locate a person who really believes they can affect the potatoes with their bioenergy, and have them do the prayers.  Hey, I'm with you on the likelihood of this one; I'm just sayin'.  Comet Tuttle (talk) 18:41, 24 February 2010 (UTC)


 * Oh no, I have very strong prayer and bioenergy: it just doesn't do anything. 82.113.106.92 (talk) 18:45, 24 February 2010 (UTC)
 * Or more open-mindedly I should say: I would just like to show rigorously if it does anything to potatoes that is statistically discernible. :) 82.113.106.92 (talk) 18:46, 24 February 2010 (UTC)
 * By using the term "debunking" you have already invalidated the experiment. --TammyMoet (talk) 18:52, 24 February 2010 (UTC)
 * Actually, I think the opposite thing will happen, that there will be statistical effect from personal bioenergy. The reason I used "debunking" was so I wouldn't be called a troll/crank/all manner of other things here... :) 82.113.106.89 (talk) 19:18, 24 February 2010 (UTC)
 * Yes, the statistical effect will be the opposite of what you are doing precisely because you have already set your intention. I hear what you're saying about being called a crank - I'm probably the only person here who holds cranky beliefs! And it is generally held in the metaphysical community that your intention affects the outcome. Therefore, you have already set your intention and the outcome is therefore assigned. --TammyMoet (talk) 20:52, 24 February 2010 (UTC)
 * Such criticism only goes to show that prayer is not scientifically definable. How can you measure intent?  In order to make a scientific definition of prayer, we need a set of observables - for example, a critical number of specific words must be chanted; a specific number of hand movements must be performed; etc.  Any set of actions which meet that definition, whatever it is, are prayer.  Since sincerity is not measurable or well-defined, it is silly to put it as a required criteria for defining some set of actions as a "valid" or "invalid" prayer.  Without a rigorous operational definition for prayer, I think it is impossible to decide whether a plant has been "prayed at" or not.  (How could you deal, for example, with a corner case of somebody unconnected with the experiment who has prayed that science will prove, or disprove, the efficacy of prayer?  If their prayer changes the outcome of your experiment, the resulting conclusion might contradict itself.) If something as subtle as subconscious intent affects the definition of "prayer", then we need some way to measure that so that we can make the experiment repeatable.  Since it is impossible to come up with a widely-acceptable objective definition of prayer, the experiment cannot be expected to attribute any measurable effect to such a hazy, ill-defined cause.  Nimur (talk) 22:12, 24 February 2010 (UTC)
 * To maximise the Signal-to-noise ratio of your results use potatoes that have been grown by atheists (but not in holes) and do the experiment well away from churches and casinos. Cuddlyable3 (talk) 22:53, 24 February 2010 (UTC)
 * Hmmm - the trouble with that is that you can't tell whether atheist potatoes are responding to the prayer or benefitting from the humor of watching you do it! SteveBaker (talk) 23:37, 24 February 2010 (UTC)


 * Making an experiment totally rigorous is very difficult. Suppose, for example, that your mere presence near the plant makes it grow (let's say maybe the CO2 from your breath helps it out).  You'd pray to half the plants and they'd do better than the ones you ignored.   So that's not a rigorous experiment at all!   So maybe you have to do a 'blind' experiment:  Recite 'fake prayers' in front of one half and 'real prayers' in front of the other.  But the experimenter might be the cause of the problem here.  Maybe you get more excited when doing the 'real' praying and accidentally exhale more CO2?   To fix that, you need a double-blind experiment...but that's kinda tough because you know what you're saying.  Perhaps you need to find someone who doesn't understand a word of english to do the reciting - so they can't tell which random-seeming words are a "real" prayer and which are fakes.  But if that fails to show a result - then maybe the problem is that the person doing the reading these words has to really believe in it.  As you can see, it's exceedingly hard to get this right.  HOWEVER, you can first do a very simple, poorly controlled experiment and just see if there is a massive difference to be observed.   If there is, you can't make direct conclusions - but you can at least see if it's worth going to the next step.   If your simple experiment shows no difference (as seems to be overwhelmingly likely in this case) - then you may not wish to proceed with the difficult stuff. SteveBaker (talk) 23:34, 24 February 2010 (UTC)


 * Ha! I caught Steve Baker not understanding something!!! Yay :) :) :).  So, what you don't understand Steve Baker, is the meaning of "blind".  You mean a placebo (fake prayers).  It doesn't make sense of a potato experiment being single blinded or not, as a potato can't be told or not told whether it is the control.  However, a person can be: if I am not a blind subject, I know if I am being given medicine under evaluation or just the current gold standard medicine for the piercing headache I have.  I can then report my results to my researcher.  In this case, the self-reported headache lengths and intensities will be skewed by the idea of having received a super-new drug being tested.  (you can test this effect by giving the subjects the same old gold standard drug, but just telling one half of them that it is super new and being tested - they will not report exactly the same effects).  now if the doctor doesn't tell the subject if she is getting the old or the new drug (here, fake or real prayers), then that is single-blind (which obviously isn't relevant to a potato - since they can't be told, all experiments on non-sentient objects are automatically blind).  However, there is still a problem as in cases where it is very important to the researcher (say, in an aids vaccine the researcher personally helped develop) to show an effect, the researcher might consciously or unconsciously affect the behavior or reporting of the control group.  Say, by just mentioning them casually a few factual pieces of information about the risks of unprotected sex with stranges, perhaps just a casual reminder that the drug is not effective and the common saying that for highly contagious diseases, from the disease's perspective, when you sleep with someone, you sleep with everyone they've slept with and so on.  This could be totally subconscious, yet the brief mention could so affect the control group that they are simply disgusted by that idea; maybe they still sleep around just as much as before, but out of the pool of people they could be sleeping with, they just take ONE second to choose the ones that are less obviously slutty or shady, the ones who at least make a tiny effort to judge the other person and maybe don't say yes right away, but after 2 minutes.  That SLIGHT change in behavior could, depending on the demographics and so on, TOTALLY change the epidimiology, maybe the control and test group would have both had a lot of sex, but only been infected by people who have averaged more than 100 sexual partners a year, but none of the subjects the doctor makes his careless warning to will choose the people averaging 100 sexual partners anymore, since this is pretty obvious to tell, and disgusting to them.  So, if you don't want to end up with a "miracle" drug that is nothing more than a casual remark the scientist happens to make more often to one group than another (because subconsciously they don't want their test group sleeping around, increasing their risk, and "outweighing" the vaccine effect the researcher really hopes is there), then you have to make the researchers who interact with the patients have no knowledge of which medicine they are giving.  They can just say: "okay, here is either the status quo drug or a candidate, I don't know which one either", and so on.  This, double-blind, you can do with inanimate objects (though I guess it should just be called blinded), by not kinowing which treatment you're giving to something.  How would it be possible to pray for plants without knowing whether you are currently praying or not-praying?  Clearly this is impossible, and so it is not possible to make this particular experiment fully blinded... (unlike say, testing miracle-gro, in which case it is easy to make is so you yourself don't have a clue if you are putting miracle-gro or water into the soil at the moment).  82.113.106.97 (talk) 15:43, 25 February 2010 (UTC)
 * Eh? That's exactly my belief - except that you are assuming that the potatoes are not capable of "understanding" (well, perhaps: "reacting to") the stimulus we're testing - but that's pre-judging the result.  If we're actually going to do this rather silly experiment, we have to take the possibility that it might work as a given.  It's "possible" that the potatoes do indeed react to being breathed on or talked to...and if so, then that might skew the results either in favor of - or against - the hypothesis we're testing.  Hence we DO have to "blind" the potatoes by randomly giving them the "gold standard" (talking to them) or the "experimental drug" (prayer).  That's a blind experiment.  But (as you correctly say), the "doctor" (the person who 'administers' the prayers) has to be blinded too just in case he does something to inadvertently give the potatoes what they need just because he knows which ones are supposed to "win".  Everything you say applies perfectly well to what I said.  I didn't misunderstand a thing. SteveBaker (talk) 03:38, 26 February 2010 (UTC)
 * ha-ha-ha, you're still misunderstanding it, and just made it explicit :). You say "we ... 'blind' the potatoes by randomly giving them [a or b]".  That's a controlled experiment (with a test and control group).  The potatoes (the test subjects) are always, automatically blinded: you can just increase it to double-blinding by not yourself (the test administrator) knowing which test you are currently administering.  Here, let me give you an explanatory example near and dear to your heart: image manipulation.  Specifically, image compression.  I want to test my lossless compression of bitmaps against the best lossless compression in existence: it doesn't make sense to "blind" the subjects.  You put the file through, then you look at the filesize, and the 'ls' (or 'dir') command can't be told or not told if it is listing the filesize of your new algorithm.  Now repeat with lossy compression and a human subject, and instead of "filesize" from a cold computer program, you get feedback for a sentient subject, whether yourself or someone else.  Now it's a problem if you don't blind them: if they know if they're judging your new lossy compression format or they're judging jpeg, this will affect the results.  ls (or dir, or Windows Explorer, or Apple Finder) can't be told if it's telling you the filesize of your new algorithm or not.  It's automatically blinded.  Humans, on the other hand, very much can be told what they're evaluating.  Now, double-blinding still makes sense: it means you the researcher, the one who's feeding the bitmap into the programs and then typing ls or dir and recording the declared filesize in the one case, and asking someone else or yourself about the subjective quality of the produced photos in the other case, very much can be blinded: double-blinding means you don't know if when you type "a.exe input.bmp out" and then "ls" to look at the filesize, and then typing b.exe input.bmp out" you've just tested your algorithm and then an existing one, respectively, or an existing one and then your algorithm, respectively.  a and b had been randomized: one is the control, one is your algorithm, but you don't know which one until you've written down the filesizes.  That's double-blinding.  There's no "non-blinded" way to test the filesizes, as "ls" simply can't be told what it's looking at.  HOWEVER in the lossy version of the same events it's different: the subject (unlike dir) can be unblinded "okay, here's my fantastically beautiful, more than typically accurate lossy image compression.  Looking at it carefully, in your esteemed judgement ___________________ ?" and then "here is the lossy old low quality jpeg from the same bitmap source.  What an awful picture.  Now looking at it carefully, in your esteemed judgment ______________________ ?".  That is an unblinded experiment.  How can you do that with 'ls'?  You can't: "look at this awfully huge file, ls, the status quo.  how large would you say it is?" and then "now look at this fantastically streamlined file made with my cutting-edge algorithm, ls, how large would you say it is?" -- inanimate objects are automatically blinded, it doesn't make sense to talk about them.  Now, returning to the lossy example: you can go from saying "please look at this status quo file" to saying "please look at a and tell me..." while you, the researcher, know what a is.  Hopefully you won't communicate any subtle hints about whether a is the status quo or your contender, but it can happen even subconsciously.  So double-blinding means that what happens is you have no idea what a and b is, and you tell your subject, "please look at a and tell me ..." and then "please look at b and tell me".  Double-blinding with a computer program means you don't type "stevebakerlosslesscandidate17 input.bmp output.sb17" and then "imagemagic -whatever input.bmp output.whatever", before typing ls to compare the filesizes of "output.sb17" with "output.whatever" (the leading lossless image compression format, even if it's just zip).  Instead, you type "a input.bmp output.a" and "b input.bmp output.b" without knowing whether a is a script to use your candidate program and b is a script to use the standard lossless bitmap compression algorithm, or vice-versa.  Only after you've written down all the 'a' and 'b' trials with all of the source images you want to test, would you "unblind" by looking at which one had been your algorithm.   In short, I hope you now understand how wrong you had been, and I want a congratulatory barn star, as this is probably the first such case.  If you need more evidence, I can emend the Blind_experiment article to include it, however I hope a careful consideration will be enough for you to admit how wrong you are, and for me to get my reward money.  Best regards 84.153.239.187 (talk) 14:08, 26 February 2010 (UTC)

Future citizens of Earth demonstrate (Video) a 10-fold prayer-free regime for processing Solanum tuberosum. Cuddlyable3 (talk) 18:04, 25 February 2010 (UTC)


 * The relavent article is efficacy of prayer. People who use prayer in non-experimental settings indicate that prayer often does "work". ~ A H  1 (TCU) 00:38, 28 February 2010 (UTC)

Object at center of Black hole
Every black hole will try to pull object towards it's center. Now the same force will be be from (far end) to its center at both the sides meaning that any object it pulls cannot come out from other side as it will be attracted towards the center. So then will the object will remain always at center and not come out from other end? —Preceding unsigned comment added by Itsrohit (talk • contribs) 18:32, 24 February 2010 (UTC)
 * More or less correct. Anything that passes inside the black hole's event horizon is never passing back outside the event horizon.  As for the "passing through the center" bit, that needs a little more examination.  Your premise for "why" is flawed -- moving aside from black holes, there are plenty of scenarios where we can do thought experiments about dropping items through the center of some massive object.  Those items don't stop right at the center even though the gravitational force is balanced, and that's because they've still got a lot of velocity.  It's not until they've gone past the center of gravity that they slow down and eventually return.  Back to black holes, though, it's possible that something hitting the exact center (the gravitational singularity) might instantly stop -- I'm not fully up on the weird math that takes place there.  However, it's not necessarily a meaningful discussion.  From an outside observer's perspective, once an item passes the event horizon, it's gone.  We don't know what happens to it.  Worse yet, the outside observer doesn't even observe the object pass the event horizon, due to time dilation. &mdash; Lomn 18:45, 24 February 2010 (UTC)
 * My understanding is that the singularity doesn't exactly experience time &mdash; that it is the future in that region of space. So things hitting it stop, but not in the normal sense because they aren't experiencing time anymore at all.  --Tardis (talk) 19:09, 24 February 2010 (UTC)
 * Yes, if you look at the Schwarzschild metric, the radial coordinate is time-like inside the event horizon, so you cannot move outward. Icek (talk) 19:24, 24 February 2010 (UTC)

The OP refers to the black hole's "center." This is usually called the singularity. In non-rotating black holes (and probably all black holes), all objects that pass the event horizon reach the singularity, where they have already ceased to be "objects" due to spaghettification. So it is not meaningful to ask "what happens to an object" at the center, because no object remains an "object" by the time it gets there; instead, it is crushed to infinite density and simply adds to the black hole's mass. (So, to answer the OP's specific question: everything that enters eventually reaches the "center" in a different form, and "remains" there in the sense that it becomes part of the hole's mass.)  This is probably also true of all black holes, but the current state of theory allows for the possibility that in some rotating black holes an object which passes the horizon might avoid the singularity; that would be a rare event in any case, and will likely be shown to be impossible as the theory progresses. Note: some information does, however, escape from black holes, though "objects" as such do not (see Black hole information paradox). 63.17.57.56 (talk) 03:44, 25 February 2010 (UTC)
 * "Crushed to infinite density" doesn't make sense - when an infinity appears in physics like that it is mathematics way of telling us we've made a mistake. Something happens at the centre of a black hole, but we don't know what. --Tango (talk) 17:37, 25 February 2010 (UTC)

Supplementary question: When an object is attracted towards a black hole is the black hole attracted towards the object? When the object accelerates towards the black hole are the Conservation Laws of momentum and energy conserved by proportional movement of the black hole? Cuddlyable3 (talk) 17:33, 25 February 2010 (UTC)
 * Yes. At large enough distances, a black hole behaves just like any other object of that mass. --Tango (talk) 17:37, 25 February 2010 (UTC)
 * What is that mass? Cuddlyable3 (talk) 19:27, 25 February 2010 (UTC)


 * It may be any mass. There is no theoretical limit on how heavy or how light a black hole may be. Dauto (talk) 21:41, 25 February 2010 (UTC)
 * If 1gm of material falls into a black hole does the mass of the black hole increase by 1gm? Can a black hole's mass be as small as a subatomic particle? Cuddlyable3 (talk) 22:56, 25 February 2010 (UTC)
 * Yes. Maybe. Really small black holes evaporate in a fraction of a second by Hawking radiation. Working out exactly what happens to the smallest black holes would require a theory of quantum gravity, which we're still working on. --Tango (talk) 03:26, 26 February 2010 (UTC)


 * Tango states that "'Crushed to infinite density' doesn't make sense." Neither does the quantum leap (how can something go from one place to another without crossing the intermediate area?), but it's real.  When the overwhelming consensus is "A," simple standards of citation and authority make "B" incorrect; SO, it is incorrect to say that the singularity does not have infinite density.  It may eventually be shown that it doesn't, but as of the last 40-plus years (since it was demonstrated by Penrose), it has been the overwhelming consensus of all citable authority that the singularity has infinite density.  Simply google "black hole singularity" and you'll find dozens of authoritative sources stating exactly that.  Tango writes "when an infinity appears in physics like that it is mathematics way of telling us we've made a mistake," but this is an opinion supported by no citable authority and actually disproven to the extent that general relativity describes the final stages of massive stars.  "A black hole is what you get if you compress so much mass into a region of space that it collapses, under its own weight, to an infinitely small, dense, point called the 'singularity.'" -- Leonard Susskind at http://calitreview.com/790 .  See also http://www.scribd.com/doc/9517358/Michael-Good-The-Black-Hole-Singularity ... and about eleventy zillion other sources.  Yes, it's true we don't know what happens in the singularity -- and in fact it is unobservable by definition, so any theory will be strictly mathematical.  But the singularity has infinite density, whether or not that offends someone's sense of colloquial or semantic logic.  —Preceding unsigned comment added by 63.17.46.122 (talk) 03:35, 26 February 2010 (UTC)


 * There may be variants of a black hole's "center". A ring singularity, for example. ~ A H  1 (TCU) 00:15, 28 February 2010 (UTC)

Liquid-mixing scintillation effect
Sometimes when two miscible liquids are mixed, you can see a hard-to-describe scintillation effect (sort of like you can see the two liquids mixing, even when they're the same color). It works when pouring cold water into a cup of hot water, if that helps. What is this called, and what causes it? 76.204.127.175 (talk) 21:28, 24 February 2010 (UTC)
 * It's caused by the two liquids having different refractive indexes: light bends "differently" in each. See Schlieren photography. DMacks (talk) 21:44, 24 February 2010 (UTC)

Subject catgeorization
The University of Edinburgh Library has shelved some books in strange categories. When this was pointed out they gave the excuse that sometimes books have more than one possible category. That may be a valid reason sometimes but I don't think so in this case. I can't figure out why these books have been categorized in the way they have so I'm asking here in the hope that someone will be able to explain what these books have to do with the subjects they have been put in. "Measure, integration, and functional analysis‎" by Robert B. Ash was in the geophysics section, as was "The elementary process of Bremsstrahlung" By Eberhard Haug, Werner Nakel, and a book on the evolution of binary stars was also in the geophysics section. The book "Quantum Field Theory on Curved Spacetimes" by Christian Bär, Klaus Fredenhagen was in the biophysics section inbetween a book on zoological physics and a book on insect populations. I took these books to the library desk to enquire about this. The next day the books had been put back in the same place. Upon taking the "Quantum Field Theory" book back to the desk, I was told that the librarian had checked and this book has been categorized the same way in other places as well. I reckon the librarian is talking bs but I would love to be proved wrong. —Preceding unsigned comment added by 217.44.34.55 (talk) 21:53, 24 February 2010 (UTC)
 * Somebody, somewhere, has clearly screwed up. It may well not be at that library, though. Library often get their classifications from some central source. If that central source has screwed up, then the librarian could well be right that other places have the same problem. That doesn't mean the librarian shouldn't do something about it, though... Does the physics department have a designated library liaison? If so, it might be better if they talked to the librarian about the problem. --Tango (talk) 22:08, 24 February 2010 (UTC)
 * See the article on Dewey Decimal Classification in case the library uses that system of categories. You may find the librarian to be more receptive if you can point out the correct categorisation in Dewey terms. Cuddlyable3 (talk) 22:38, 24 February 2010 (UTC)
 * Looks like the University of Edinburgh Library uses the Library of Congress classification. 75.41.110.200 (talk) 23:23, 24 February 2010 (UTC)
 * I don't know why libraries have so much trouble over such a relatively simple data organisation problem. If you have all your books listed on the Internet along with their shelved position - then the library can be classified in any and all ways imaginable - books can be in multiple categories without problems.  The only reason shelf order matters in an era of near-universal computer access is for people who browse looking for books in a general category.  But even that is well handled by things like "Other people who borrowed this book also borrowed..." kinds of search criteria.  The biggest problem is when a book gets put back in the wrong place by accident - so if I were organizing a system, I'd put computer-generated colored stickers on the spines so that all of the books on one shelf should have the same combination of colored stickers - if a book is on the wrong shelf, you can spot it in seconds.  SteveBaker (talk) 23:22, 24 February 2010 (UTC)


 * First, I have spent a long time working on the "Other people who XXX this..." algorithms and I think a proper algorithm would be "Other people who borrowed this book then borrowed...". Time ordering plays a role in which books you may want to read.  Second, There are libraries that use color coded stickers.  I've seen many (ie: the public library in Charleston County, SC).  I've also seen work on using barcodes.  A robot can scan shelves very quickly at night and take note of all incorrectly shelved books.  It would be optimal if it could also correct shelving.  Finally, as for categorizing books.  Some libraries shelve books in multiple locations.  It was difficult to manage when it was all done by hand, but computers make it easy to manage multiple copies of a book sitting in multiple locations (even multiple libraries). —Preceding unsigned comment added by Kainaw (talk • contribs)