Wikipedia:Reference desk/Archives/Science/2009 January 30

= January 30 =

Rice and Play-doh
Having visited my baby brother recently, and having decided to make rice for dinner, I'm struck by the similarity in scents given off by the cooking rice and the new Play-doh my brother got for Christmas. Why do they smell nearly the same? It's kind of putting me off my dinner plans... Kuronue | Talk 01:04, 30 January 2009 (UTC)


 * Was your brother's Play-Doh home-made? It's possible to make your own with rice flour. Apparently the real stuff uses wheat flour though. — Matt Eason (Talk &#149; Contribs) 02:07, 30 January 2009 (UTC)


 * Nope, brand new, little yellow containers. He got a set designed to make hamburgers and hotdogs as well as a set of four neon colors. Someone on IRC suggested maybe the surfactant is a rice protein? Kuronue | Talk 02:11, 30 January 2009 (UTC)


 * I'm not sure about the smell, but rice and play-doh may have a few similar properties. They are both sticky and easy to mold into shapes. It's easy to smudge cooked rice and use it as a type of glue, which dries after a while. ~ A H  1 (TCU) 19:32, 30 January 2009 (UTC)


 * I'm extremely glad you noticed that too. I've used the-point-at-which-rice-doesn't-taste-like-play-doh as my cooking indicator for years, and people never seem to know what I mean. School rice always tasted like play-doh, presumably because it was undercooked. While unable to answer your question, I just wanted to thank you for reassuring me :) 79.66.71.197 (talk) 23:14, 30 January 2009 (UTC)

Digestive grinding stones
Dinosaurs and birds eat stones and this is supposedly good for the digestive system. I do not drink 2 litres of water any more because I know that if I do not pump the whole thing around, it's not very good for your stomach and your kidneys. If I started swallowing big stones, would I eat less and digest more or would it constipate me until I got surgery? What shape and size of a stone and how often to swallow one or what stones are the best mineral? ~ R . T . G  02:24, 30 January 2009 (UTC)
 * You are not a bird or dinosaur. Eating stones will not help your digestion, and may well do you harm. Don't do it. Algebraist 02:28, 30 January 2009 (UTC)


 * interesting idea. Here's a question ... what's the easiest but most dangerous weight loss techniques? a) intestinal parasites - tapeworms Giardia, b) amphetamines, c) fasting (I hear you aren't hungry after a week or so)? TungstenCarbide (talk) 02:57, 30 January 2009 (UTC)


 * Drinking more (water not softdrinks or coffee/tea) is actually good for you. See Dehydration and Fluid balance. While one can get into trouble drinking excessive amounts of water in one sitting (Water intoxication), drinking 2 liters throughout the day may just about cover what you need.  Not drinking water when you are thirsty doesn't sound like a great idea.  Your body tells you when it needs water.  No clue where you found the information this might be bad for you, but I'd check whether you might not have misunderstood something or whether maybe the writer might have not thoroughly researched the topic.  For certain medical conditions doctors may advise you on restricting your water consumption, but that should always be done as instructed by a qualified medical professional.  Dietary minerals are only the same as minerals on a chemical element level.  The body requires certain forms of these minerals and in combination with certain other chemicals.  Even dietary supplements which are a far cry from eating rocks  aren't metabolized as efficiently/in the same way as minerals from food sources. 76.97.245.5 (talk) 04:05, 30 January 2009 (UTC)


 * DIY surgery is an easy but very dangerous weight loss technique.- gadfium 04:21, 30 January 2009 (UTC)


 * FYI, under Crocodiles it says this: "Many large crocodilians swallow stones (called gastroliths or stomach stones) and they are believed to be of use in acting as ballast to balance their body. Other suggestions have been made that they may have a function similar to that of grit in birds, which is in crushing food." In other words, to help them dive deeper, and birds chip away at grit, not stones. And opera diva Maria Callas was rumoured to have lost 80 lb thanks to a tape worm. She put it down to chicken salad.  Julia Rossi (talk) 07:59, 30 January 2009 (UTC)


 * I was looking at Speckled Mousebird which appears well written and says they swallow "pebbles" and I just know that some dinosaurs and lizards eat rocks. The truth may be that drinking only water does more good for you. I am 6 feet and between 11.5-12.5 stone, I eat a medium to large cornflakes in the morning and around five medium to large teas every day, fairly average but if I add two full litres of water to that without exercising to exhaustion (at least) I get runs to the toilet or sore kidneys/sore larger stomach/thirst for loads of water (like diabetes). I always intended to drink 2 liters as per doctors recommend but I just can't do it. I do know water is good for me but took me a while to see the over-excessive part. I think what is meant to be said is that "The most healthy people drink 2 liters of water a day" rather than "Drink to liters of water a day to make yourself healthy". I may have small kidneys or something but that is unlikely (lol, say nothing) and I can eat a lot so my stomach couldnt be too small. I would have thought that swallowing stones big enough for grinding stuff would be difficult for people. It's funny, when my family were all on Slim Fast, the rumour went around that there was worms in it and that it was recalled but I don't see that on snopes or the search engines, lol, 90s paranioa! I beleived that whole-heartedly. Crocodiles only eat once or twice a year (true carivores do not eat all the time, I !can't! find a reference to that if anyone knows of one for the crocodile article, I think they eat between 3 and 18 or 3 and 6 months or something the [wikiversity] page is good but can't find that on animal planet or anything). ~ R . T . G  13:01, 30 January 2009 (UTC)
 * Birds and reptiles swallow stones because they can't chew. Humans have molars for that, swallowing rocks won't help your digestion because your food is already mashed enough by the time it gets to your stomach. Rocks would either get stuck in your digestive system requiring surgery to remove them, or cause a very unpleasant bathroom experience when they passed through. -- Mad031683  (talk) 17:26, 30 January 2009 (UTC)


 * Some snakes can eat without even biting... they don't swallow rocks do they? (I think it's right you would need a surgeon) ~ R . T . G  20:54, 30 January 2009 (UTC)

Eosinophil
The normal range of eosinophil counts is 0 to 4 %. What does 7% mean? Thank You! AJ —Preceding unsigned comment added by Adrianajensen (talk • contribs) 03:49, 30 January 2009 (UTC)


 * Eosinophil granulocyte? Whith questions like yours it always helps to let us know what you need the answer for.  We can't give medical advice and won't do homework. 76.97.245.5 (talk) 04:12, 30 January 2009 (UTC)


 * Don't get me wrong, but isn't a 7% eosinophil count simply termed 'increased eosinophil count'? —Cyclonenim (talk · contribs · email) 07:46, 30 January 2009 (UTC)


 * It's called Eosinophilia. Meaning um.... "increased eosinophil count". Medical jargon eh? Fribbler (talk) 10:42, 30 January 2009 (UTC)


 * More to the point, eosinophilia can mean either "a larger proportion of eosinophils among the white blood cells" (which is all that 7% tells you), or "a higher than normal absolute number of eosinophils in the body" which is what an absolute eosinophil count would tell you. In either case, there's virtually no significance to a single reading that's marginally high (like 7%), unless there's a clinical setting that would make it so. So as in all these cases, the doctor who ordered the test is the one who has to tell you if this (mildly elevated) value means [1] nothing or [2] something. Persistent elevated values, or isolated significantly elevated values, would make one think of allergies and parasites first, and other things in the differential in the eosinophilia article second. - Nunh-huh 11:35, 30 January 2009 (UTC)

What makes heating a house using geothermal inefficient in the US
When I was in Germany I encountered many people who had installed geothermal heating in their houses. (Geothermal heat pump) When geothermal is mentioned in the media in the US there is usually a comment that it's inefficient here. Comparing the climate information for Germany and Georgia temperature can't be the factor that makes the difference. Climate of Georgia (U.S. state) Since I find it hard to believe that the Germans would install inefficient heating systems, does anyone know what makes things that different here? 76.97.245.5 (talk) 05:46, 30 January 2009 (UTC)


 * I'm surprised that you'd say "inefficient". The reasons I've heard (and they aren't unique to the USA) are that geothermal is expensive to set up - and that it's not necessarily "renewable".  The way it works is that you pump cold water down into some hot rocks and then pump it back out again - and when it comes back, it's hot water that you can use to heat your house and make hot water via heat exchangers.  There are two problems with that:


 * It's great when your primary energy cost is heating - but it would be useless in large parts of the USA where you need air conditioning to cool the house over a large fraction of the year. To convert the hot water into electricity and then use the electricity to run your A/C is a much bigger problem.
 * The capital cost of all of that drilling and pumping is not a one-time problem. The rocks at the depth you can afford to drill down to aren't really all that hot - and after years of use, you can actually drop their temperature significantly - causing the geothermal plant to run less and less efficiently.  So the geology of the area matters.


 * What is really needed is a larger scale plant - where you drill much deeper so that instead of getting water back out, you get steam - then you can run a turbine and easily generate electricity from that.


 * However, I'm a little surprised that there isn't more emphasis on that approach here. But honestly - I think a combination of large wind farms and nuclear power will ultimately be the US solution...possibly augmented by rooftop solar panels.


 * For homes - our best bang-for-buck would be to sink some serious money into better insulation. My house (which has four times better insulation of a typical American home consumes about a third of the amount of electricity that my neighbours use.  This added about 5% to the construction cost of the house - and pays for itself in about 5 years.  Why aren't all houses built like that?  Well, it's because of 'sticker shock'.  People buy what's cheapest without looking at the future running costs.  What is needed is government grants that pay that extra 5% directly to the home builder - and recoup the money from the electricity companies who are required to charge (say) twice as much for domestic electricity to houses that were built under this scheme - giving half of that back to the government as a tax.  That way, everyone wins.  The consumer gets slightly reduced electricity bills - and without having to pay a cent more for their houses.  The electricity companies get to build less power plants yet still make more profit in the long run once they don't have to pay the "new house" tax on their electricity.  The government gets reduced dependence on non-renewable fuels and could (with care) make a profit on the grant scheme.  Everyone wins through greenhouse gas emissions reductions.  You could also give people the option to pay the extra 5% on their house cost - and NOT have doubled electricity prices from then on.  This is easy to do - all it takes is someone in government to sign the right bit of paper to make it happen.


 * That's a much better bang-for-buck than any other form of new power generation system - and it works in hot climates as well as cold ones.


 * SteveBaker (talk) 12:03, 30 January 2009 (UTC)


 * Also, geothermal energy is far more efficient when there are "hot rocks" near the surface. In the US, such places tend to be public land, like Yellowstone National Park, and thus unavailable for this kind of development.  I'm not aware of Germany having much of this geology, but Iceland does, so geothermal is far more practical there than in the US.


 * Finally, when comparing whether geothermal energy makes sense in a nation, we should consider the cost of alternatives. The US has vast, cheap supplies of natural gas, which is used for heating in much of the US.  If Germany lacks this, and must instead import natural gas from unreliable sources like Russia, then investigating home-grown alternatives like geothermal energy makes more sense. StuRat (talk) 13:06, 30 January 2009 (UTC)


 * Thanks Steve and Stu. The "only works with hot rocks and large plants" arguments was what didn't work for me in comparison since in Northern Germany there aren't hot rocks where I saw it done (it's mostly leftover ice-age rubble and marshland) and they do it in small units, too. So the difference is that they don't do AC and don't have local fuel resources (if you don't count canola oil which is used in some diesel engines there.)  That makes more sense. 76.97.245.5 (talk) 15:28, 30 January 2009 (UTC)


 * I believe Steve and Stu are confusing Geothermal heat pumps with Geothermal power. It is the latter where you pump water over very hot rocks and use the steam for heating and for electrical generation. Most geothermal heat pumps don't need hot rocks, and in fact work best when the ground source is a moderate temperature, usually slightly below room temperature (50-75 F, 10-25 C). Unlike geothermal energy, you're not trying to extract energy from the ground, you're simply using it as a stable, very large capacity heat bath, to which you attach a heat pump (a conventional air conditioner is a heat pump). As the efficiency of heat pumps is related to the temperature differential between the two sides, having the "outside" being very close to the inside temperature greatly increases efficiency. So instead of running an air conditioner where you dump excess heat from your 72 F (22 C) into the 100 F (38 C) outside, you dump it into the 60 F (15 C) ground, which is much more efficient, electrically speaking. Also in winter, you can "reverse" the heat pump, pulling heat from the ground and dumping it into your house, which takes much less electricity than creating the heat directly from the electricity. As to why they aren't common in the US, I'm not sure. One reason may be that most people, even otherwise well read and knowledgeable ones, haven't heard of them. Part of that may be due to installation costs. There's a big up-front cost to put the radiator in the ground and to buy the size/quality heat pump needed. Although it'll probably save you money in the long term, when building the house it's much cheaper to put in a simple furnace/air conditioner combo. Adding the system after the house is build means tearing up the lawn. Another big reason may be that natural gas, propane, fuel oil, and other petroleum based products are massively less expensive than electricity in the US. I think it's cheaper to burn gas/oil for heat in winter versus pay for the electricity to run the heat pump, even though the heat pump is more energy efficient. Without the winter savings, the payback period gets much longer, especially in the north where air conditioning is only lightly used. Increases to petroleum prices in the future, however, may see more systems installed in the US. -- 76.204.94.153 (talk) 18:33, 31 January 2009 (UTC)


 * Geothermal heat pumps use an electric compressor to increase the temperature of a fluid. This fluid is used to collect heat from outside the buiilding at a low temperature and transfer it to an internal space at a higher temperature.  Rather than measuring 'efficiency' of these systems, it is better to use the measure 'coefficient of performance'.  This is a measure of how much heat is transfered to the building as a proportion of the electricity used by the system to transfer this heat.  For many systems, this coefficient is around 3 - ie 3 times as much energy is transfered into the building as is consumed by the compressor.  However - the electricity that is being used has probably come from burning coal or gas (depending on where you live).  These power plants generally have an efficiency of around 30% - ie 30% of the energy in thc coal or gas ends up in your home as electricty.  From an environmental viewpoint then, you are using the same amount of raw energy if you intall a gas heater in your home as a ground source heat pump (assuming coefficient of performance of 3 and power system efficiency of 30%).  Before purchasing systems, it is worth carrying out a study to calculate the net energy gain and how much this will cost you.  Im afraid I dont know what other reasons would alter the 'efficiency' of such a system between nations. TomStroud 16:50, 5 February 2009

Just to update my figures - modern gas power stations can be about 50% efficient and good ground source/air source heat pumps can have a cop of 4 - therefore providing an overall system efficincy of 200%!! TomStroud 22:08, 9 April 2009 (UTC)

UFOs
So if I understand correctly, accroding to currently established thinking in the scientific world, it is mathematically highly probable that extraterrestrial life exists, but it is too unlikely that such an alien life has the means or intelligence or technology to conduct intersteller travel - so UFOs being real is ruled out. That is, alien civilisations probably exist, but we can never contact them. Is that correct? ReluctantPhilosopher (talk) 09:35, 30 January 2009 (UTC)


 * See Fermi paradox and Drake equation. It's all a giant guess where those little green buggers are. Someguy1221 (talk) 09:48, 30 January 2009 (UTC)


 * Wow, I never knew there was a named paradox for that. Thank you, Someguy1221 :-) ReluctantPhilosopher (talk) 10:21, 30 January 2009 (UTC)


 * We know that the speed of light is the cosmic speed limit. We know that the closer you get to that speed - you need exponentially more energy to accelerate and decelerate.  This makes interstellar travel exceedingly difficult and costly no matter what technology you use.  Also, aliens that do have the capability will have to dedicate a large fraction of their resources to each craft they launch - so they are unlikely to simply go out visiting stars randomly looking for life.  No - they are going to do what we do.  Search the skies for radio signals - and look closely at exo-planets with spectrographic signatures that indicate life.  Then they'll probably beam a high power, tightly focussed beam of radio waves containing the usual stuff like sequences of prime numbers and digital pictures with prime-number dimensions.


 * Consider that we've only been putting out radio broadcasts at any reasonable power for about 50 years. Even with close-to-the-speed-of-light spacecraft, an alien civilisation would have to be within 25 light years to even know we're here and then come visiting.  Worse still - it is interesting to note that with the most powerful radio telescopes we have - we would be unable to detect the most powerful radio transmitter we have at the distance of the nearest star (4 light years).  So the aliens would not only have to be close enough to have heard us and have had time to get here - they ALSO need to have some pretty amazing radio-telescopes.  So the fundamental limits of the laws of physics (the speed of light, relativity, the inverse square law of electromagnetic radiation) make it unlikely in the extreme that an alien civilisation could possibly show up on our doorstep anytime in our lifetimes.  Unless these aliens are VERY close to us already they have literally NO WAY to even know we're here.  There really aren't many stars that close to us - so unless intelligent alien life is VASTLY more common than even the most optimistic Drake-equation predictions, it isn't coming visiting anytime soon.


 * IMHO, unless our alien species has extraordinary long lifespans and/or a biochemistry that allows them to shut down cognitive facilities and preserve their bodies without consuming resources over a long trip (eg cryogenics) - we aren't ever going to see them in person.  What we MIGHT get would be their computers...some kind of robotic emmisary.  We know that if we had to send something to (say) Alpha Centauri (4 light years away), we'd probably send a robot because it could take a few hundred years to get there - and four years to report back - but since it could be shut down for most of the ride, we could probably do it.


 * But think about that for a moment. If that's all they are going to send, they might as well just transmit the plans to build that computer - plus all of it's software and data over a radio link and have us build it for them - rather than spending all of that effort to physically transport the computer to us.  So IMHO, the SETI effort has vastly more chance of success than the UFO spotters do!


 * The only time I could imagine an alien species coming to visit us in person would be in some vast colony ship. If aliens see the imminent demise of their star - then they might consider packing everyone into some vast 'generational' ship - maybe a hollowed out asteroid or comet - maybe spin-stabilised for gravity with huge nuclear/fusion power plants providing energy with a complete 'biosphere' on board to provide their people some kind of a bearable lifestyle.  This craft might take thousands of years and hundreds of generations to slowly plod from one star system to the next.  If something like that shows up - we're in real trouble because they'll have started out on their journey thousands of years ago - having looked carefully at our planet by astronomical means.  But thousands of years ago was back before we dominated the place.  And seen from 50 light years away, there would have been no indication of a pre-industrial society living here.  So they'd have seen a highly suitable environment for their people and set off.  Then, (presumably to their extreme horror) as they start to approach their new home, they see a budding intelligent civilisation start to appear on it!  As time goes by they see us develop nuclear weapons and space craft - and then (worse still) we start screwing with the atmosphere and heating the place up!   They have millennia to plan what to do about that - but when they get here, they won't be happy - and that'll be a big surprise to us!  Think "Independence Day (movie)" - but without the possibility to use a computer virus to take them down (which was one of the worst "and then the aliens all die" endings since the cop-out at the end of War of the Worlds!).


 * SteveBaker (talk) 11:37, 30 January 2009 (UTC)


 * "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." Douglas Adams Gandalf61 (talk) 12:40, 30 January 2009 (UTC)


 * I think someone else pointed this out before. If an alien civilization did send a probe to our solar system (assuming their probes are similar to ours) it would be so small that it could pass through our system without ever being noticed. A Quest For Knowledge (talk) 14:53, 30 January 2009 (UTC)


 * There's also the problem that if life DOES exist, that it somehow must exist at only a slightly (say a thousand years or two) more advanced state than we are in. It is entirely statisticly more likely that alien life does exist, but is millions of years, evolutionarily speaking, behind us, or millions of years ahead of us.  Either way, there is a good chance that the evidence of that life has either not reached us yet, or that civilization is long past, and the evidence of it has already blown past us.  The idea that there is an alien civilization at all in history is pretty good; the idea that there is an alien civilization close enough to us to detect and within that relatively narrow window of emiting the sorts of radiation that are detectable is mindbogglingly small.  Also, consider that we generally confine out understanding of alien civilization to this Galaxy.  Make a few tweaks to the Drake equation, and you may well find that you can come up with an average of one technological civilization per galaxy.  In that case, we may not be alone, but there may very well be no conceivable way for us to ever contact or have knowledge of these other civilizations.  --Jayron32. talk . contribs  16:38, 30 January 2009 (UTC)

I little aside here: can people PLEASE stop using "UFO" as a synonym for "Spacecraft from a sentient alien race". I can't tell you how much that pisses me off, even these renowned so-called "Ufologists" do it. There is no doubt in the entire world that UFOs exist. What is in doubt is whether some of these UFOs were alien spaceships. - Running On  Brains  17:26, 30 January 2009 (UTC)
 * It has definitely not been ruled out that UFOs that are alien spaceships exist. Tens of thousands of sightings have been reported worldwide, from an unusual light in the sky, to multiple witnesses reporting a spaceship over a mile wide, to reported abductions by aliens. Most of these reports can be explained by more rational possibilities, and most scientists reject the notion that alien spaceships have visited Earth, citing lack of evidence. The always remains, however, a handful of sightings with very good credibility and which still cannot be explained. I personally don't believe the Fermi paradox is so hard to solve, and this is just one reason why. There is also a list of UFO sightings. ~ A H  1 (TCU) 19:23, 30 January 2009 (UTC)
 * I'm not sure if that was directed at me, but I certainly wasn't implying that all UFOs have logical explanations. You can't prove a negative, so obviously its possible that some unsolved UFO incidents are in fact extraterrestrial craft of some kind. I'm just saying saying that sometimes people get caught up in the hype of a supposedly-paranormal event and don't look for obvious solutions. I cite Occam's razor: is it more likely that that mysterious craft in the sky is an alien spacecraft, or some secret government project? Since we know that governments perform classified experiments with aircraft, and we don't know if extraterrestrial life exists, it makes sense to believe the latter unless there is serious evidence to the contrary. Similarly, is it more likely that the person telling the story about the spacecraft that landed in his yard had a hallucination, is crazy, or is lying? We know those kind of people exist in the world, but we don't know if aliens exist. It's certainly not a foolproof argument, but it helps me sleep better at night.- Running On  Brains  19:42, 30 January 2009 (UTC)
 * "The always remains, however, a handful of sightings with very good credibility and which still cannot be explained. I personally don't believe the Fermi paradox is so hard to solve, and this is just one reason why" - so there are credible non-explained UFO sightings? That's what I wanted to know. Thanks ReluctantPhilosopher (talk) 17:35, 3 February 2009 (UTC)

Mitochondrial DNA from sperm to zygote
I recently saw a cautious quotation in a book saying that in most organisms the mitochondrial DNA is derived only from the egg. So what exceptions are known ? Shyamal (talk) 11:39, 30 January 2009 (UTC)
 * Never mind, found it here http://mbe.oxfordjournals.org/cgi/content/full/18/7/1168 Shyamal (talk) 11:44, 30 January 2009 (UTC)

Scientific question
number of stars which appear from earth incerase? —Preceding unsigned comment added by Sovit mundhra (talk • contribs) 13:15, 30 January 2009 (UTC)


 * You need to clarify your question, especially the use of the word "increase". Are you asking if the number of stars visible from Earth is increasing ?  If so, I'd say not with the naked eye, no.  It's possible that better telescopes could increase the number of stars we can see, but such new telescopes tend to be located in space, like the Hubble Space Telescope, to avoid interference from Earth's light sources and atmosphere. StuRat (talk) 14:06, 30 January 2009 (UTC)


 * If you're asking whether the number of stars visible from any one location on Earth to the naked eye is usually increasing, then no. Most locations are suffering from more and more light pollution. ~ A H  1 (TCU) 19:13, 30 January 2009 (UTC)

To add insult to injury the universe is expanding, looks like a solid no on all fronts.Bastard Soap (talk) 08:09, 5 February 2009 (UTC)

Firing a pistol sideways
Is there any real advantage in turning a pistol 90 degrees to the right when shooting? Gangsta style, in other words. If not, why do people do that? --84.66.59.206 (talk) 14:08, 30 January 2009 (UTC)


 * We seem to have two articles on pistol shooting technique: "Modern Technique of the Pistol" and "Point shooting". I skimmed them both, and neither seems to mention specifically the style you're asking about. "Point shooting" does, however, suggest there is value in this style, especially at close quarters, speaking of methods that "do not rely on the sights, and ... strive to increase the shooter's ability to hit targets at short range under the less than ideal conditions expected in self defense and combat situations." The stereotypical Hollywood "gangsta" style of firing—with one hand, held above the level of the head, and with the gun held sideways—would lend itself to certain combat situations, such as firing blind over a wall or in through a high window. Also, the one-handed style leaves the off hand free for other uses, such as balance, reloading prep, or parry. The high hold makes it more difficult for your opponent to seize the gun or disarm you at close quarters, and the downward angle keeps the muzzle on your foe if he ducks, an instinctive reaction. Offhand pistol shooting can be made fairly accurate through practice, and whatever style one uses, practice will probably bring sufficient accuracy for short-range work. Also, being accustomed to firing from awkward positions and around obstacles, and combining hand-to-hand fighting with pistol must surely increase a combatant's chances of survival. So, "gangsta" style would be a valuable addition to a pistol fighter's repertoire, I think. On the other hand, if you don't practice and are more than ten feet away, it would be pure luck if you hit anything that way. You might as well shut your eyes, too. The prescribed methods were arrived at by discovering what works; the guy who lived through the gunfight wrote the book.
 * As for "why", I can't even say that the style is ever used in the real world. I don't live in an area where people do any such thing ever, and I don't go where they are likely to. But, if it is a common practice, my guess would be it's done for intimidation—to express the earnestness of one's intention to shoot—and to keep a downward trajectory with an eye to minimizing collateral damage in an urban setting. --Milkbreath (talk) 14:56, 30 January 2009 (UTC)


 * Anyone who was really serious about hitting someone, gangster or not, would fire in a way to maximize that—which doesn't look as "cool" so nobody does that in music videos. --98.217.14.211 (talk) 15:08, 30 January 2009 (UTC)


 * Mightn't be relevant, but standing side-on presents less of a shooter's body to his opponent - so perhaps it's defensive. Bazza (talk) 16:03, 30 January 2009 (UTC)


 * NY Times: It's to look cool, but makes it harder to control the gun. WikiAnswers suggests it may be used in movies to show more of an actor's face, to look unusual, or as the result of a misunderstanding about some legitimate shooting tactics. --Maltelauridsbrigge (talk) 16:11, 30 January 2009 (UTC)
 * Yeah, pretty much all gun use in Hollywood shows a lack of basic understanding. Also, the downward angle to reduce collateral damage sounds reasonable, except that I doubt people having gunfights in cities (and not aiming) care much about that.  Friday (talk) 16:23, 30 January 2009 (UTC)


 * As I understand it (IANAG), when 'someone other than the intended target' gets shot by mistake, the attitude is very much "well, if (s)he didn't want to risk getting shot, (s)he shouldn't have been hanging around those assholes" or "some folks are born lucky, some ain't". Back on topic though - as the NYT link suggests, I think that it's often a case of the gangstas (many of whom are little more than kids) seeing the sideways-shooting thing in gangsta movies (or the dual wield thing) and simply believing that it's an effective way. Thinking about it though, if you're firing a pistol from a car window, there may be a (perceived?) benefit in being able to rest the flat of the wrist against the window frame in order to steady your shot. --Kurt Shaped Box (talk) 17:30, 30 January 2009 (UTC)
 * Whatever rational they may use in their heads to try and justify collateral damage, I'm somewhat doubtful that they really don't care at all about collateral damage. For staters, they would know the cops are far more likely to be concerned it they kill an innocent bystander then another 'gangsta'. Also as Sean suggested below it's likely many don't want to kill anyone and I suspect even less an innocent. I think most people, even criminals do still have some moral compass even if it warped and may not stop them doing incredibly bad stuff. As with most matter, oversimpfying the people involved is a mistake. Of course this doesn't mean avoid collateral damage is a consideration in sideways shooting actually I agree there's a good chance it isn't. Nil Einne (talk) 17:19, 1 February 2009 (UTC)


 * Perhaps its intent is to *reduce* accuracy. Why would a gangsta want to do that, you ask?  I can think of two reasons: 1) as a form of stotting, which is something gazelle will sometimes do to slow themselves down when being chased by a predator, as a way of saying "I'm such a badass I'll even give you a better shot at me", and 2) because even gangstas would probably prefer not to kill anyone; On Killing documented that many soldiers would deliberately miss their targets, and they -- in contrast to our gangsta -- were in a situation where they would be rewarded rather than punished for a successful shot.  --Sean 18:16, 30 January 2009 (UTC)
 * According to one cop, it's done because it looks cool. DMacks (talk) 20:10, 30 January 2009 (UTC)

Engineering Book for Children
Please advise if there is a book which explains the basic priniciples of engineering that is geared toward children between the ages of 5 and 8 years old. Any type of engineering is fine. Thanks! --Emyn ned (talk) 14:09, 30 January 2009 (UTC)


 * The Way Things Work by David Macaulay. Gandalf61 (talk) 14:37, 30 January 2009 (UTC)


 * Actually, just about anything by Macaulay would work. He's got LOTS of great books for kids on all sorts of architecture and engineering, including Pyramid and Castle and Cathedral and most of these had filmed versions as well, IIRC.  --Jayron32. talk . contribs  16:31, 30 January 2009 (UTC)

Quantam Mechanics, de Broglie wavelength, baseball
We know that the debroglie wavelength, which applies to all matter is given by h/p = h=mv. Suppose there was a baseball or pingpong ball traveling at a slow enough speed, or with a small enough mass such that the de broglie wavelength was visible (a) or the debroglie wavelength was large enough to measure, (b) on the magnitude of meters. What physical phenomenon would result? —Preceding unsigned comment added by 128.8.177.117 (talk) 14:10, 30 January 2009 (UTC)


 * What you're basically asking is "how would a very macroscopic object look if we regarded it as a quantum-sized object" which isn't terribly sensible. But let's just say, well, if a baseball could exhibit quantum wave effects, then you could do things like diffract it. It would, in certain ways, act like a wave. How would that "look"? Heck if I know. That's the problem in trying to apply quantum effects to macroscopic objects—it just doesn't make sense to our clunky macroscopic brains. --98.217.14.211 (talk) 14:26, 30 January 2009 (UTC)
 * Hm, my physics teacher tried to explain this to us at school. I really should have a deeper understanding of these matters now (and also this was back in 1988), but I don't and as far as I remember it goes like this: If you keep hitting ping pong balls through a slit (or two slits, whatever) at a wall (slit large enough for it to pass through, obviously), most of them would go through unimpeded (and hit the opposite wall directly behind the slit(s)). A few however would change direction (it'll probably look as though they bounced off the edge of the slit), *but* the funny thing is if you mark at the wall where the balls hit, over time you'd get a diffraction pattern. Wave of the ping-pong ball interfering with itself. 195.128.250.163 (talk) 22:34, 2 February 2009 (UTC)

My UFO Story or What did I see?
When I was a little kid, maybe about 5 - 7 years old, I saw what I thought to be a UFO an alien space craft. It looked like a half-moon, with red lights on each tip. That is to say that it was sort of a white-ish half circle with red lights at the tips. It flew across our backyard. I wasn't the type of kid to simply make up stuff or not be able to tell the difference between imagination and reality, so I think I really did see something. This probably would have been the mid to late 1970s. I lived in a major metropolitan area (Chicago) so if it really was an alien space craft, I would think that it would have been reported by lots of people, and I don't recall anyone else reporting this. Of course, I'm not sure I was old enough to be able to read a newspaper, so maybe it was reported, but I don't recall any of the neighbors talking about it. Anyway, I'm not one of those UFO nuts so I assume that there's a rationale explanation that doesn't involve aliens from outer space. But I don't believe it was my imagination either. Is there any type of aircraft that matches this description or comes in any way close to it? I lived a few miles from Midway Airport so there would have been a high volume of air traffic in my neighborhood. A Quest For Knowledge (talk) 14:46, 30 January 2009 (UTC)


 * You note that the UFO had red lights on each tip. Typically aircraft have a red light on one of the wing tips (presumably this is port side) and a green light on the other side (I presume this is the starboard side) as in ships. They also have a red beacon on the top and bottom of the fuselage. See: http://www.aerospaceweb.org/question/electronics/q0263.shtml You don;t mention whether it was day or night but since you could tell the colour of the fuselage was white then it must have been daytime or close to night. I can't tell you much about aircraft types but I would suggest if a plane was banking heavily, to line up with the runway of Midway for example, and orientated wierdly then just a typical jumbo could look a bit like a UFO to a 5 - 7 year old. Jdrewitt (talk) 15:28, 30 January 2009 (UTC)


 * I'm pretty sure it was night, or at least evening. A Quest For Knowledge (talk) 15:33, 30 January 2009 (UTC)


 * One point: You said "I saw what I thought to be a UFO". Since UFO stands for "Unidentified Flying Object", that's precisely what you saw.  Unfortunately, many people use UFO to mean "alien spacecraft", which is a horrid misuse of the term. StuRat (talk) 15:56, 30 January 2009 (UTC)


 * How large did it appear in the sky? Did it appear larger or smaller than a half-moon in the sky? Did you notice any detail other than the red lights? Did it move towards the curved part of the half-circle, or the straight-edge part? Did it appear more yellowish or more bluish? How fast did it move? Did it move in a straight line or a more erratic pattern? Did the brightness of the object change at all during its flight? How long did you see it for? These questions may be useful in assisting the possible identification of the object. ~ A H  1 (TCU) 19:27, 30 January 2009 (UTC)


 * It sounds from the description like an airliner with the top and bottom beacons and some section of the fuselage between being lit up for some reason....perhaps some of the light from a landing light glinting off of the fuselage. The circular cross-section of the fuselage would certainly produce a semi-circular or 'moon-shaped' white area - and some part of the wing could cut it off to make a semi-circle...and it's no stretch to imagine the red beacons above and below.  So there are without doubt ways to explain this UFO without resorting to little-green men.  Even if that's not a perfect explanation - even if it requires a really extended set of coincidences (eg two planes flying parallel to each other to make two red lights with a third aircraft closer to you providing the white shape...or something) then it's still vastly more likely than that it was a flying saucer.  This is the thing that UFO nuts don't appreciate.  Even if there is only a one in a million probability of some particular chance formation of lights happening on any given observation means that perhaps 300 people will see such a phenomenon every single night...in the USA alone!  In fact, when you stop to think about it - it's quite amazing that you don't hear more reports than we actually do!  20:15, 30 January 2009 (UTC)


 * If there was an airport nearby you might have seen a mirage. Good ones are so rare that one just doesn't expect it could have been that.  I once spotted a perfect one of a bicycle on a neighbor's roof.  All I could think was "What the...". Thank goodness aliens aren't reported to ride bicycles.  (Except maybe in baskets.)  76.97.245.5 (talk) 20:57, 30 January 2009 (UTC)


 * AstroHurricane001 - I think it looked bigger than the moon. Probably at least twice as big.  It was white-ish.  I don't think there was a yellow or blue tint.  It didn't streak across the sky like a lightning bolt and nor did it hover.   I guess I would say it appeared to fly at a speed consistant with an airplane.  It flew in a straight line, no crazy 90 degree turns that defy the laws of physics or anything like that.  I passed overhead in maybe 2-3 seconds.  A Quest For Knowledge (talk) 21:29, 30 January 2009 (UTC)


 * I and a friend of mine, an ex–Navy Seal, sat in a pickup truck and watched Venus for half an hour around sunset one time because it looked for all the world as if it was something in our atmosphere. Of course, we thought it was Venus, but neither of us had been keeping abreast of our planet positions, so we tested our theory by observation. I'm saying that two unsuperstitious, rather intelligent men were momentarily fooled by appearances. I have no doubt whatsoever that a similar phenomenon is responsible for 100% of the unexplained sightings of UFOs. As a kid I watched The Day the Earth Stood Still a hundred times, so I'd like nothing better than to take our new friends to our leader, but it ain't gonna happen. --Milkbreath (talk) 16:15, 31 January 2009 (UTC)

Skywarn Spotter Training
Does someone need to register with SKYWARN to take part in one of their classes. I can't seem to find the answer.Nick (talk) 19:01, 30 January 2009 (UTC)nicholassayshi

NEVER MIND!!! —Preceding unsigned comment added by Nicholassayshi (talk • contribs) 19:11, 30 January 2009 (UTC)

Atlantic hurricane tracks
Hi. In the image of the Atlantic hurricane tracks from 1851 to 2005 (see right), could anyone identify the following hurricanes shown in the map: Anyone able to identify these? Thanks. ~ A H  1 (TCU) 19:02, 30 January 2009 (UTC)
 * The storm which tracked over southern Lake Simcoe as an extratropical storm at TS strength (wait, is it the Galveston hurricane of 1900?);
 * The storm that made it across Mexico as a TD and tracked into the Gulf of California;
 * The hurricane that tracked through the center of the Cape Verdes as a cat. 1, then quickly strengthened into a cat. 2;
 * The hurricane that made it through the channel between Ireland and Iceland as a fully tropical cat. 2, then weakened to a cat. 1 as it passed north of Scotland;
 * The hurricane that crossed northwestern Ireland as a fully tropical cat. 1;
 * The extratropical storm which tracked across Ireland, Wales, and England at cat. 1 strength; and
 * The extratropical storm that hit Lisbon, Portugal while weakening to TD strength.
 * One quick answer:
 * The hurricane that made it through the channel between Ireland and Iceland as a fully tropical cat. 2, then weakened to a cat. 1 as it passed north of Scotland;: Hurricane Faith (1966)


 * You could try contacting one of the regular members of WikiProject Tropical cyclones. Someone there might be best able to answer your question.  --Jayron32. talk . contribs  20:37, 30 January 2009 (UTC)
 * The storm that crossed Mexico and entered the Gulf of California is Hurricane Debby (1988). –Juliancolton Tropical Cyclone  20:40, 30 January 2009 (UTC)

Robert Burns and gold conductor
Robert Burns wrote a poem on wedding rings She asked why wedding rings are made of gold; I ventured this to instruct her; Why, madam, love and lightning are the same, On earth they glance, from Heaven they came. Love is the soul's electric flame, And gold its best conductor." Where would he have got the idea that gold was the best conductor? I know silver and copper are better but Volta only invented the electric cell in 1800 and Burns died in 1796. Dmcq (talk) 19:17, 30 January 2009 (UTC)
 * I believe he meant that gold was love's best conductor, not gold. flaminglawyer 19:35, 30 January 2009 (UTC)


 * See history of electromagnetism. People knew about electricity (long) before batteries were invented.  --Sean 20:00, 30 January 2009 (UTC)
 * Ben Franklin had experimented with electricity during Burn's lifetime, for example.  bibliomaniac 1  5  21:25, 30 January 2009 (UTC)

Thanks very much. I hadn't realized about them testing conduction using electrostatic machines. Following up that Franklin I came upon something by Joseph Priestly where he thought gold was a better conductor than silver. Burns kept up with things like that so that's probably where he go it from. See The Conducting Power of Gold which describes Priestly's experiments on the conductance of wires. I'm really quite surprised that his method gave the wrong result. He connected wires together of the same diameter and the one that didn't melt was the one he said was the better conductor. I would have thought the gold wire would have melted before the silver one as it has a higher resistance and has only a slightly higher melting point. So seemingly Burns was right according to the best science of the day. Dmcq (talk) 23:42, 30 January 2009 (UTC)

Dmcq (talk) 00:45, 31 January 2009 (UTC)

Islam...
we all hear that Islam is the most expanding religion now ... why is that ... and whats the proof that its the right religion ... i heard they have scientific proofs that their book(Quraan) did talked about recentlly dicovered scientific facts before more than 1000 years ... thank you ...? —Preceding unsigned comment added by 212.38.147.41 (talk) 20:59, 30 January 2009 (UTC)
 * Extraordinary claims require extraordinary evidence. It's no good basing your whole philosophy of life on what's most popular, or what you heard; look it up!  I doubt there's anything there, but who knows, maybe while riding on his magical horse Muhammad spied a coelacanth.  --Sean 23:29, 30 January 2009 (UTC)
 * I would be interested in some evidence of these prophecies. I have not heard of them, do you have some reference that can be followed up? Dmcq (talk) 23:53, 30 January 2009 (UTC)

will i heared about how there shuttels couldnt leave the earth atmosphere but through acertain places in the atmosphere and such things ... i will look for it, but this will take time. —Preceding unsigned comment added by 94.249.99.222 (talk) 05:36, 31 January 2009 (UTC)


 * The number of Muslims is growing because, like poor people worldwide, they have a high birthrate.
 * Claims for amazing scientific insights in the Qur'an (like the old assertion that baseball is a Russian invention, and the ludicrous claims for the Kim dynasty in North Korea) derive from a deep societal inferiority complex. If the Qur'an, which among other things posits a flat Earth, were really a repository of advanced scientific knowledge, the Muslim world would not have to wait for Western scientific advances, and then claim that they were predicted 1400 years ago. Orthodox Muslims would be at the forefront of science and picking up Nobel Prizes in bunches. That they are not highlights the emptiness of such claims.
 * B00P (talk) 13:32, 31 January 2009 (UTC)

However, Islamic scholars were at one time far ahead of their counterparts in the West. Arabic Islamic scholars gave us algebra, algorithm, and alkali. Arabic Islamic mathematicians also gave us the cipher for zero. The BBC has a programme which is being shown at the moment called "Science and Islam", and the OP may wish to investigate the re-runs on the iPlayer. This link gives you Jim Al-Khalili's article. —Preceding unsigned comment added by TammyMoet (talk • contribs) 15:12, 31 January 2009 (UTC)


 * There is no doubt that at one time, arabic mathematicians and other scientists were streets ahead of the the europeans. Quite how they lost that advantage is hard to say - but I've gotta guess that adherence to overly strict religion has a lot to do with it.  When clear, open-minded thinking is discouraged in favor of mindless obeyance of some thousand-year-old tradition - science is guaranteed not to flourish.  One only has to see the rise of christian fundamentalism in America doing precisely that.  The pressure to tell our kids that evolution isn't one of the most solid scientific theories that we have - and the efforts to suppress stem cell research - signs of denial of the Big Bang - denial of global warming - these are classic examples of the same nonsense happening here.  Newton was the closest thing modern science had to a priest at the turn of the last century.  When Einstein said he was wrong - people were sceptical - when it was PROVEN that Newton was wrong (well - in realms beyond where he could test at least), the scientific world changed.   Well, now we know conclusively that the garden of eden didn't happen - it's time to drop that dusty old book and go with something a little more real. 72.183.123.248 (talk) 23:55, 31 January 2009 (UTC)


 * ...But what does the OP mean by "right religion"? The one referring to the real God? I hope he's not such a naive thinking, come on. A religion is an anthropologic and cultural phenomenon, and as such you shall explain its degree of success. And, of course, there is the individual contribution of some genial persons. Take for instance Paul of Tarsus, the inventor of Christianism: a true genial mind thinking big, like was John D. Rockefeller for capitalism. Had it been for the first Christians, they would have disappeared in few decades, like dozens of other messianic religions continuously appearing in that area. Paul was initially planning to make a career, as a Jew, fighting these Christians, but it was really not a worth job; then had the great idea (the anecdote says he drop from the horse at the illumination): "but what the holy fuck am I doing wasting my time in fighting these guys": he entered the bunch and in few weeks became their chief. He called himself "Apostolus", to make it clear. Then, he made special offers to everybody for joining the Christians: you don't need to be free man; you don't need to be circumcise; you don't need to be a man either, and many other facilities. He managed to become Roman citizen and to have the support of Rome. Nothing similar had been seen before. Recall that the oldest and more important religion of the area, Judaism, was extremely strict and very proud about its tradition. This way in few times he took over all small religions around and became the first Religious Group of the area, just like Rockfeller's Standard Oil at Cleveland when he swallowed every single refiner around. He too was thinking big, and started proselitism travelling and sending letters all around the Mediterranean sea, and finally got to Rome. To have an idea of his accuracy in all detalis, think of how he just planned the clothing. "I wanna last at least a couple of millenniums or so: who is here around that was able to do so? Egyptians, of course". Consequently, the clothings for the new religion were inspired to the Faraons fashion (look at the Pope, how dressed he goes around). Just to communicate: "We will stay here around forever". Of course you are free to think that there is the God's hand in the expansion of Christianism, or of Islam, or that Rockfeller was a philanthropist, &c... pma (talk) 00:22, 1 February 2009 (UTC)


 * A God that monitors which religion s growing fastest or is biggest or some combination of the two. A God that jumps on the latest bandwagon. That's a good one. Sounds like a politician, I am your leader, tell me what you want. Dmcq (talk) 12:07, 1 February 2009 (UTC)

will.. assuming there is agod ... and god want to give you a life way ... a path to walk on, some kind of ascale so you can know right from wrong ... now , how did you think that god should make you belive that he do exist , what kind of proof would you accept , will its easier to think that mother nature did this ... our creation not but acoincidence ... but if your ascientist then god will convince you by science

fact 1 ... in quraan ... sura(The believers) from(12-14) ([23:12]  We created the human being from a certain kind of mud. [23:13]   Subsequently, we reproduced him from a tiny drop, that is placed into a well protected repository.

[23:14]  Then we developed the drop into a hanging (embryo), then developed the hanging (embryo) into a bite-size (fetus), then created the bite-size (fetus) into bones, then covered the bones with flesh. We thus produce a new creature. Most blessed is GOD, the best Creator.) this fact wasnt known before 1400 years ago ... i dont find any source said that this fact was known before the 1900 . so the question is did muhammed knew that ... or this is some kind of evidance from god.

fact 2 ... in quraan ... sura(women) (56) ([4:56]  Surely, those who disbelieve in our revelations, we will condemn them to the hellfire. Whenever their skins are burnt, we will give them new skins. Thus, they will suffer continuously'''. GOD is Almighty, Most Wise)

will ... this one talk about that humans couldnt feel but by there skin ... so if your skin gets burned you will feel nothing and this is aproven fact in the modern science ...

so did you still think that muhammed knew that before 1400 years ago ... if not so who did ...??? —Preceding unsigned comment added by 94.249.85.66 (talk) 17:51, 2 February 2009 (UTC)


 * It is obvious that you have not checked any of what you say. Where people pick up the slightest thing in favour of their point of view are are blinkered to conflicting evidence is called confirmation bias. The reference desk will I'm sure be happy to help you check up on each particular item in your list. Dmcq (talk) 14:51, 3 February 2009 (UTC)


 * Hey 94, have you ever read the Iliad? To make only one example, the author perfectly knows about the flies laying eggs in the dead bodies, and the generated larvae eating the corpses (Iliad T ,25-28); read it, I'm not talking of allegories to be interpreted, but of precise statements even more clear that the ones in your quotation: and they are 1000 years older than yours. And the spontaneous generation has been confuted only in 1668 by Francesco Redi. But nobody claims that the Iliad's author was inspired by God (though, concerning how to write epic poems, he is a god). Now, the point is that if you say: "what is written in this book is God's word, therefore is right because God is omnisicent", it is not correct, because the complete statement should be: "In my opinion what is written in this book is God's word, therefore is right because etc.."; and since you are not God, the appeal to God does not give any authority to that book, nor to your opinion. Without offense, I cannot understand why so many religous people are so dumb that they don't see this small yet important logic detail. I do not even understand why so many people are so concerned about claiming that God exists/ God does not exist: but why to care about it? Suppose one proves one statement or the other: will this solve one of the thousands problems of the earth? Will this stop men to kill each other? You are free to believe or not, and I will respect your feelings, but keep it for you, and remember that it's just your opinion (and if you positively happen to find a real and true proof in one sense or the other, not just bullshit, no need to tell me: I don't think I would be so interested). --pma (talk) 02:07, 4 February 2009 (UTC)

Gravity escaping black holes.
How can gravity escape from a black hole? Taemyr (talk) 21:16, 30 January 2009 (UTC)
 * Complicated question, especially considering no one is entirely sure what gravity is represented as in our universe other than a feature of space-time curvature. Although it's believed to be conducted by a particle called the graviton, there is, as yet, no proof of this particle existing. The following website goes into a lot of detail in one of it's answers. It was a good read. Clicky. —Cyclonenim (talk · contribs · email) 21:25, 30 January 2009 (UTC)
 * Thinking more, another point of view is that black holes only attract particles into them due to gravity. If gravitons mediate this force, then they are doing the attracting, and are therefore unlikely to be affected by the field itself (since they must be massless). —Cyclonenim (talk · contribs · email) 21:29, 30 January 2009 (UTC)


 * Your speculation in general would be wrong. Massless particles, such as photons, are affected by gravity.  We would however assume that massless gravitons are not themselves a significant source of gravity, which is an important distinction.  (By contrast, gluons are themselves a source of the strong force and this ultimately leads to quark confinement.)  However, as you say, gravitons are unobserved, so this is theoretical at the moment.  Dragons flight (talk) 06:16, 31 January 2009 (UTC)


 * I was under the impression that gravity can't escape the black hole, and the gravitons pulling everything in are hawking radiation. The idea that gravity isn't effected by gravity wouldn't explain why black holes can have an electric charge. — DanielLC 22:19, 30 January 2009 (UTC)
 * I've never heard anyone propose gravitons are hawking radiation. I think you have a few things mixed up. And I'm no physicist but I really don't follow your logic about gravity being affected by gravity having anything to do with the electric charge. Gravitons shouldn't be affected by gravity—they are gravity. You can't electrocute electrons, it just doesn't make sense. --98.217.14.211 (talk) 01:11, 31 January 2009 (UTC)
 * Gravity being effected by gravity has nothing to do with electric charge. Gravity escaping a black hole does. Photons, which are effected by gravity, can mediate the electromagnetic force between the black hole and another object. There's no reason why gravity couldn't do the same. Also, I find it hard to believe that any particle could not be effected by gravity. What's keeping you from sending gravitons up, changing them to photons, sending them back down, changing them back to gravitons, etc. to create a perpetual motion machine? — DanielLC 16:45, 31 January 2009 (UTC)
 * And how exactly does one turn a graviton into a photon, now? Again, I don't see the logic in "gravity escaping a black hole"—gravity escaping gravity. Doesn't make a wit of sense to me—the gravity is not attracted by gravity, it is gravity. I think you're taking the particle model a little too literally here, or at least negating that the graviton must be massless. My understanding of this is not deep, to say the least, but I really don't follow your logic at all here; it seems totally implausible, sorry. --98.217.14.211 (talk) 17:07, 31 January 2009 (UTC)
 * Gravitational waves are a form of energy, just like electromagnetic waves. If you just want an example of how to convert between the two, you could use a charged pendulum. The gravitational waves would cause the pendulum to swing, and the moving charge would emit electromagnetic waves. Why would gravitons being the mediator of gravity prevent them from being effected by it? Photons are massless too. — DanielLC 00:57, 1 February 2009 (UTC)
 * You're confusing your own logic. Gravitons wouldn't be affected by gravity, just as photons aren't affected by light—because they are light! We're not saying gravitons won't be affected by gravity because they're massless, but rather because it is gravity. —Cyclonenim (talk · contribs · email) 20:34, 1 February 2009 (UTC)
 * We were overdue for a black hole question! Gravity does not escape from the object causing it, instead it is an effect on the space time by the mass.  It may help you if you consider the formation of a black hole.  To start with the mass is not behind an event horizon, and casues gravity in the normal way.  As the mass approaches being a black hole, the mass or total energy does not change and the field remains the same.  From your point of view outside the black hole, you never see the mass enter the black hole, so you would never see a vanishing of the gravity causing material. Graeme Bartlett (talk) 23:16, 30 January 2009 (UTC)

Books on string theory
After reading the thread above, and finishing the book, The Elegant Universe], I was wondering if someone could propose a book to follow on with string theory which is perhaps a tad more mathematical but still not a full-on dive into the realms of complicated mathematics. By this, I mean I'm an A2 student so I'm not sure I'd understand much more than A level maths. —Cyclonenim (talk · contribs · email) 21:22, 30 January 2009 (UTC)


 * I haven't read any so sorry can't recommend anything but String theory gives some popular books, maybe google some of the titles and look for reviews. Jdrewitt (talk) 23:03, 31 January 2009 (UTC)