Wikipedia:Reference desk/Archives/Science/2007 May 23

= May 23 =

Do other animals snore besides humans? Possibly gorillas and other species that share very similar traits to humans?
I was really curious about this as I would assume that not only human beings are susceptible to snoring since other species also have respiratory systems with throats and mouths.


 * Budgerigars definitely snore. I'm pretty sure that I've heard dogs do it too. --Kurt Shaped Box 00:12, 23 May 2007 (UTC)

Dogs snore very loudly...--Zeizmic 00:15, 23 May 2007 (UTC)

Dogs -- especially bad dogs named Giles -- snore like they're sawing logs. Cats too. --TotoBaggins 00:17, 23 May 2007 (UTC)


 * One of my hedgehogs snored - though it sounded more like wheezing than a snore. --Kainaw (talk) 01:36, 23 May 2007 (UTC)


 * If anyone knows about this, they might want to add information to snoring, which is presently humanocentric (if that's a word).--Shantavira|feed me 08:29, 23 May 2007 (UTC)


 * Shantavira, I think the word you were looking for is anthropocentric; it is not exactly what you meant, but close enough. Googling for the word "humanocentric" yields links to a specific "humanocentric theory" (e.g. here) which seems unrelated. Cheers, Dr_Dima.


 * Haha, I love how all the dog owners are coming out in droves. I was about to post about dogs too. Cats can snore as well, though more quietly. I think you're probably right that most things with respiratory systems can snore. --24.147.86.187 13:39, 23 May 2007 (UTC)

What is the word that means a meeting place of both salt and fresh water in a river?
Excuse me but what is the word that means a meeting place of both salt and fresh water in a river?


 * Brackish . --TotoBaggins 00:17, 23 May 2007 (UTC)


 * Estuary. —Steve Summit (talk) 01:02, 23 May 2007 (UTC)
 * Estuary. [' Mac Δαvιs '] ❖ 01:07, 23 May 2007 (UTC)


 * How about tidal bore? Carcharoth 01:57, 23 May 2007 (UTC)

River delta ? --Tbeatty 06:55, 25 May 2007 (UTC)

Help! my dog ate Lisinopril
My Yorkshire Terrier ate part of a 20/25 tablet of Lisinopril-HCTZ and I don't know if it's toxic to pets. Does anyone know?24.250.50.162 02:02, 23 May 2007 (UTC)


 * It's sometimes used in dogs, but that may be too high a dose (depending on the size of your dog, and other meds or diseases involved). Your best bet is to call the ASPCA Poison control center  - (888) 426-4435  --Joelmills 02:16, 23 May 2007 (UTC)


 * Er, I mean if you are in the USA. --Joelmills 02:17, 23 May 2007 (UTC)


 * Be sure to have whatever documentation / papers about the prescription available when you speak to a medical or veterinary professional. It will enable them to respond faster.  Such information is usually in the box with the medication and contains technical emergency information.

Solar System
In many diagrams of the solar system, all of the planet's orbits are coplanar. Is that actually true of the orbits, or does it just make it easier to diagram them that way? If not, can somebody find a diagram with the real orbits?


 * It's a simplification, but not that much of a one. See Ecliptic. --Robert Merkel 02:17, 23 May 2007 (UTC)
 * No diagram but see Table_of_planets_and_dwarf_planets_in_the_solar_system


 * Orbits of all planets are nearly coplanar. The orbit of Pluto (which used to be a planet for quite a while) is 17 degrees out of the plane, though. See Pluto for details and a simple diagram. Another diagram is here. Cheers, Dr_Dima.

Insect Identification
I found this bizarre insect on my screen door a few minutes ago. I live in northern Connecticut near a small forest and a small river. It is slightly smaller then a soda can (have a reference picture of that too). Didn't seem to mind the photography though. Click for full image. Any ideas on what this is? Chris M. 03:58, 23 May 2007 (UTC)




 * Also, don't let the guys at Yahoo Answers beat you! Chris M. 04:02, 23 May 2007 (UTC)


 * Looks like they did, they say it's a Luna Moth. Comments? Chris M. 04:13, 23 May 2007 (UTC)


 * Luna moth, definitely. [' Mac Δαvιs '] ❖ 04:37, 23 May 2007 (UTC)

You guys capitulate too quickly. It's a Male luna moth.


 * Avast! We've been shown up!  Nimur 06:25, 23 May 2007 (UTC)


 * Well, it is probably the most recognizable and well-known moth, with the Death's-head Hawkmoth coming in a close second, I'd reckon'. --24.147.86.187 13:07, 23 May 2007 (UTC)

re:electromagnetic waves>>wireless energy propagation
thanx for perevious answers

if emf would be induced then i've deviced a intresting apparatus,please verify this one..

i propose that no emf is induced in a metal piece in open atmosphere because the phae of incident electromagnetic wave changes alternately thus creating a positive and negetive charge thus cancelling each other. my device would change the phase of incdent electromagnetic wave in such a way that the  wave strike the metal piece in the same phase everytime.thus we must get a net emf across its terminals.(must be sufficient for a micro ammeter if sunblight is used as source of em wave.) my basic idea is to use a slotted metal piece in a semicircular shape and then incident the em wave at its one end .taking out the supply from tho slots. if every thing is correct then this method would make possible transmission of energy through air. please investigate the above device if possible.Sameerdubey.sbp


 * Please sign your posts with ~ . I'm not really sure what you're talking about, but you may be interested in some of Tesla's work. He did, at one point, intend to distribute electricity through giant towers to homes, through the air, but unfortunately his funding was cut when he said that it would be freely distributed -- Phoeba WrightOBJECTION! 07:34, 23 May 2007 (UTC)


 * Agreed. You might get a charge out of our article on Tesla. StuRat 20:04, 23 May 2007 (UTC)


 * If the phase of the incident wave keeps alternating, wouldn't that just produce an alternating (or at least oscillating) current? Do kids still build crystal radios? DMacks 17:03, 23 May 2007 (UTC)

Architecture is music made solid
Can anyone remember seeing a newspaper item maybe 3 weeks ago telling of a couple of guys in Britain who'd cleverly decoded some strange, cube-shaped architectural features in an old church to discover that a piece of medieval music had been enctypted in it? I can't remember where I saw the article, which church it was etc.

Thanks,

Adambrowne666 07:02, 23 May 2007 (UTC)


 * A quick search at Google News turned up this story. --Anon, May 23, 2007, 07:41 (UTC).


 * That'll be pretty much the same story. I saw the article too in Melbourne's The Age newspaper, which is probably where Adambrowne666 saw it. As the linked article above says, it's the Rosslyn Chapel, which is the chapel featured at the end of The Da Vinci Code. --jjron 08:07, 23 May 2007 (UTC)

Thank you, both; I didn't know about google news - will use it from now on - so thanks for that, too, Anon Adambrowne666 03:10, 24 May 2007 (UTC)

fusion
what are the difficulties associated with fusion? why don't we have fusion reactors?125.63.107.134 12:54, 23 May 2007 (UTC)
 * Naturally, we have an article on that. Nuclear fusion.  Let us know if it answers your questions.  We are always interested in properly matching the target audience (ie. if it is too simple, or too complex). --Zeizmic 13:01, 23 May 2007 (UTC)


 * Fission is relatively easy — you are taking something already somewhat unstable (a uranium nucleus) and giving it the little extra push it needs to fall apart. Fusion, though, requires taking things which are already stable and then forcing them to do things that they don't want to do. Hydrogen nuclei would naturally not want to get too close to each other, due to electrostatic repulsion (protons are positive, and positive repels positive at most distances), but if you can overcome that, then the strong nuclear force will kick in and they'll form a new, fused nucleus (and release some energy). It's getting over that initial barrier that's the biggest hurdle. Fusion reactors are all attempts to do that on a scale large enough to actually generate more energy from the reactions than is taken to initiate them in the first place. But it's hard to do in a controlled way, so far — it is difficult both as an engineering problem and as a theoretical one, and there are a lot of complicated factors. Fusion reactor is a pretty good article on different approaches taken so far — most have involved trying to create a fusion plasma held together by a magnetic field (has been very hard to do), or trying to compress and head fusion fuel with lasers (probably not as hard to do, but requires big ol' lasers). --24.147.86.187 13:34, 23 May 2007 (UTC)


 * Our article on fusion power (of course we do) may address some parts of your inquiry. Also, our cold fusion article is an interesting read. ~ hydnjo talk 13:45, 23 May 2007 (UTC)

TTL digital output to +10V/-10V analog output
Is there a simple way to control a single analog output line usign two digital output lines in a way that you can generate a -10V or +10V voltage at the analog output? Ideally, a single power supply of +5V, +12V or +24V would provide the necessary electrical power to the circuit. --Jcmaco 15:20, 23 May 2007 (UTC)


 * Sounds like the truth table is "A minus B", so a basic difference amplifier would work here. DMacks 14:58, 23 May 2007 (UTC)
 * Hadn't thought of that, thanks! --Jcmaco 15:20, 23 May 2007 (UTC)


 * You could also arrange a few transistors so that when the A input is low, a summing junction is pulled towards -10V and when the B input is low, a summing junction is pulled towards +10V. When neither is low, no "pull" is applied on the summing junction and a resistor presumably pulls it towards ground (if required). When both are low, the countervaling pulls toward +10 and -10 cancel out, still leaving the summing junction near ground. I haven't thought this all the way out, but if you're lucky, two transistors (one NPN and one PNP) should do it. If you're unlucky, you'll need one more transistor as an inverter/driver.


 * Atlant 16:03, 23 May 2007 (UTC)


 * Or if you are already working with a digital system, you can arrange a 2-bit system with an "output enable" bit and a "Positive/Negative" bit. Nimur 14:44, 24 May 2007 (UTC)

This sounds like simple MUX logic. You need four analog muxes (i.e. TTL level transistors) that can pass -10 to +10 volts. Then set them up so that each decoded and mutexed selection state passes the correct value. You can use the tranistors as the decoder especially if you have both NPN and PNP TTL devices. --Tbeatty 07:04, 25 May 2007 (UTC)

Help identifying tree
Hi. I'm trying to identify a pine tree that's growing at my place of work in Mercer Island, Washington. I took a couple of photos and uploaded them to ; they can be seen at Talk:Pine. Can anybody help me determine which species of pine it is? -GTBacchus(talk) 14:58, 23 May 2007 (UTC)


 * I'm thinking it's a Western White Pine. What you really need to do is find an online tree identification key and go through it step by step - there are several online, especially for evergreens. Matt Deres 16:15, 23 May 2007 (UTC)


 * I only came here after failing to identify it with an online tree identification key. I'm getting more and more convinced that it's a Pinus nigra, but I'm not 100%. -GTBacchus(talk) 19:02, 23 May 2007 (UTC)


 * Hmmm. Not being a native tree, it probably won't be in most ID keys. The page mentions that it's used as an ornamental tree in the US, which would explain why it's at your place of work. If you think it's an actual planted tree (rather than something that happened to grow wild there), the simplest method might be to just ask someone in maintenance what the tree is :). Even if they don't know offhand, there still might be the bill from the nursery. Even if the tree isn't identified on the bill, you would know who to call for more info. That's a bit of work, but there you go. I hope it is a Pinus nigra; we could use a couple of nice close-up shots on that page! Matt Deres 16:19, 24 May 2007 (UTC)

Landing on Jupiter or Saturn
I know that it would not be possible to survive but please detail what would happen to my physical body once I am on the surface of Jupiter or Saturn.


 * They're gas giants: they start out like air, and then get denser and denser until you are eventually at a solid core, but you're unlikely to notice it as you'll be at the bottom of a miles-deep sea of metallic hydrogen, and in all likelihood dead. See Jupiter.  --TotoBaggins 16:23, 23 May 2007 (UTC)
 * So, the pressure would slowly increase. You would suffocate due to the lack of oxygen (gas giants are mostly hydrogen and helium), then your body would eventually be crushed as the pressure increased to unbearable levels. Vultur 16:52, 23 May 2007 (UTC)

Would the same happen on Neptune? --209.0.0.29 18:28, 23 May 2007 (UTC)


 * Yes, and on Uranus. I suppose some type of ship (like a bathyscaphe) could be devised to "land" on the solid cores or those planets, but there wouldn't be much point in putting a person in such a ship.  Some type of probe might some day be designed to sample to core and return to space, however. StuRat 19:07, 23 May 2007 (UTC)


 * A probe has indeed "landed" (or at least been vaporized) on Jupiter. Presumably its heavier bits sunk to the bottom. --TotoBaggins 20:45, 23 May 2007 (UTC)


 * I read a sci-fi story long ago about a Jupiter probe which sank into the atmosphere until its own density and that of the planet's atmosphere cause it to float. So how about Jovian aeronauts?Does any physical principle say that a probe's density has to be such that is sinks below its crush depth? How would the Hindenberg or a hot-"Jupiter atmosphre" balloon fare in Jupiter's atmosphere? Edison 22:58, 23 May 2007 (UTC)


 * It's theoretically possible that if you could make it down to a depth where your craft displaced it's own mass - it would float at that level. But the problem is that the density of the atmosphere at that level would have the same density as you do.  A human in a simple spacesuit or something has a density similar to that of water - so 1kg/litre - by the time the atmosphere has gotten to that density, the pressure would be truly spectacular!  Unless you have some kind of a large balloon, your crush-depth would be reached long before you were deep enough to float.  But a large helium balloon should work just fine on Jupiter.  Of course the radiation and heat might very well kill you too - Jupiter generates an enormous amount of both.  Even an unmanned probe would need shielding for it's electronics and such. SteveBaker 11:05, 24 May 2007 (UTC)
 * In an atmosphere which is mostly hydrogen and helium, with little or no oxygen, I would go with a heated hydrogen balloon. No O2 means no "suffering humanity " or even "suffering instrumentation" from an explosion like the Hindenberg. Use the waste heat from the instrument power plant to heat the bag of hydrogen for more lift. Edison 15:30, 24 May 2007 (UTC)
 * Yeah - good point. I'd forgotten about that.  A Helium balloon would be about as effective as a CO2 balloon here on earth!  So yes - hot hydrogen is where it's at.  Probably just a conventional hot air balloon would work - what you'd use for fuel to heat it might be a bit tricky.  No big propane burners!  I guess you'd carry oxygen - use it to burn hydrogen from the atmosphere - but since the product (steam/water vapor) is lots heavier than the atmosphere - you'd probably need a heat-exchanger to get hot gasses up into the envelope.  It would be an interesting looking machine! SteveBaker 01:41, 25 May 2007 (UTC)

Hooke's law (physics - elasticity)
In hooke's law, what is the relationship between the tension and the temperature? say for exmple, I have a following problem in phyics' elasticity:

"An aluminium wire with a cross-sectional area of 3 squre milimeters is fastened between two posts which are located 2m apart. There is no slack or tension in there wire when the temperature T = 22°C. What is the tension when the temperature is falls to -15°C? Assume that the pots remain fixed. hint: use Hooke's law." 192.206.119.3 16:05, 23 May 2007 (UTC)


 * You'll need to look up a couple of constants to do this calculation. First, figure out how long the wire would be at -15&deg;C if it weren't attached to the posts.  (It's going to shrink as it cools; see coefficient of expansion.)  Then determine how much force you need to apply to the wire to stretch it back to the full two-meter length, using Hooke's law; this is your tension. TenOfAllTrades(talk) 16:14, 23 May 2007 (UTC)

Static cannon
I read somewhere that static electricity can move objects, so would it be possible to create some sort of static cannon that can either push someone over [a non lethal weapon] or propell a rubber bullet etc? Thanks

Is a charged capacitor on a DC circuit an example of taking kinetic electric potential and converting it to static electric potential?DrPierson 18:37, 23 May 2007 (UTC)


 * If two people stood one meter apart, and each had one percent too many electrons, the electric force between them would be enough to accelerate the Earth quite visibly. The problem is actually getting charge to stay somewhere long enough for it to push something.  See Dielectric strength.  Essentially, whenever you have a static field strong enough to propell anything of appreciable mass, the charge will simply arc through whatever was seperating it, and byebye static electricity.  You can use static charge to levitate light objects, but I've never heard of anyone pulling off any kind of gun with it.  Someguy1221 21:19, 23 May 2007 (UTC)


 * In addition, both objects must be charged in order for them to repel each other (or attract, if the charges have opposite signs). So to push someone over, you'd not only need to get the weapon to maintain a charge without arcing to the ground, but you'd need to put a charge on that person without it arcing to the ground.  This is impossible in a normal environment; even the small charges of static electricity that you build up in normal life when your shoes rub on the carpet (for example) are readily discharged easily, and a large enough charge to have the effects we're talking about would discharge that much more easily.  And besides that, if you could generate a dense enough beam of charged particles to build up a large charge on someone, without putting dangerous amounts of energy into it, then the beam would tend to disperse itself due to repulsion of the particles.


 * The second idea, the electric gun, seems like it might be possible, but pretty much pointless. We already have conventional guns, air guns, etc., and if you want to launch the bullet less violently, you just make it with a smaller charge, use less air, etc.


 * --Anonymous, May 23, 2007, 22:57 (UTC).


 * You don't need both objects charged. Look at electrostatic induction.  Someguy1221 23:50, 23 May 2007 (UTC)


 * Good point, but then you're talking about an even stronger electric charge on the weapon, in order to induce a force on the target by just creating charged areas within it. --Anon, May 24, 23:53 (UTC).


 * About the energy question: I don't know whether there is any sense in talking about kinetic electric potential and static electric potential. It's just electric potential. The capacitor stores a certain amount of the power supply's energy (chemical, if it's a battery) as electrical potential energy. If you are thinking of the kinetic energy of the charge carriers in the circuit during the charging process, this energy is actually dissipated through the resistance of the circuit, and doesn't contribute to the capacitor's stored energy.


 * As an observation on the use of electrical charge attraction/repulsion to do impressive things, you could say we already have such a system, called magnetism. As Someguy says, you only need a tiny imbalance between positive and negative charges in ordinary matter for large forces to be generated. From a relativistic point of view, this is what indeed happens when a current flows in a circuit: the Lorentz contraction effect on the moving charges changes their charge density so that the charge balance is upset, and the magnetic force is the result. --Prophys 11:13, 24 May 2007 (UTC)

Bought two "9 db" gain wifi aerials - disappointed with performance.
I just bought two of these: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=007&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=170104912815&rd=1&rd=1 supposed 9 db gain antennaes to swap for the one that came supplised with my Trust router and CNet wireless card.

Notes: When I opened the packet (they weren't in retail packaging, just a 'Jiffy bag', if you know what that is (might be British term)). The plastic aerial was split in two parts - it seemed as though some weak glue has been used to put the two peices together. I was thus able to see inside the plastic sheath to what was basically a peice of coper wire with a few points at which it curled into a helix. The lenth of the copper wire was less than the length of the plastic sheath. The signal acheived is no better than before (between 40 and 50%). Given that I must have had about two 3 db-gain aeriels to begin with, I would expect the signal to have increased significantly. The signal only has to go through one floor with very little horizontal displacement (I'm virtually above the router downstairs).

Have I been sold misrepresented (advertised as 9 db) goods? How would a quality antenna have constructed? Is the design of the plastic sheath mostly down to aesthetics? Seans Potato Business 14:55, 23 May 2007 (UTC)


 * You might want to read the fine print, it may very well be that they only promise a 9 db gain if you start with no antenna. I don't know about this specific case, but it's common in marketing to find an atypical case where the max benefit is derived, and advertise that.  For example, when selling a toothbrush, they give stats about how much healthier people's teeth are using their brush than not brushing at all (since there would be no difference in a realistic comparison with their brush versus other brands).  StuRat 19:00, 23 May 2007 (UTC)


 * What orientation are the antennas in? The strongest signal will be perpendicular to the antenna. Since you are above the router, place the antennas horizontally. —Preceding unsigned comment added by 208.160.159.147 (talk • contribs)


 * IIRC in the microwave bands antennas are rated relative to a hypothetical perfectly isotropic antenna. Antenna gain always comes at the price of being more directional, any antenna that talks about gain but not directionality is probablly a bad buy ;). Note that in the world of antennas "omnidirectional" means a donut shaped coverage. Maximum gain in a plane purpendicular to the antenna but rapidly falling off as you move out of that plane going down to near zero paralell to the antenna. Plugwash 00:18, 24 May 2007 (UTC)
 * An excellent point. If you are directly above the router, then you are in a null zone with respect to the router's antenna. Try orienting the router's antenna horizontally and orienting your antenna horizontally. More generally, if you and the router are in fized locations, you should find a directional antenna of some sort, such as a cantenna. -Arch dude 12:52, 24 May 2007 (UTC)

Can blood type change over your lifetime?
I found your blood type article highly informative even though it didn't answer the question that prompted my search. Can a person's blood type change? My mother was B- and received B+ blood during an angioplasty several years ago. She's not sure whether she was typed B+ before the transfusion, but she has certainly been typed as B+ since. Is it possible that her blood type changed? What is the likelihood of this happening? What causes it to happen? I thought people with B- blood could receive an Rh positive infusion only once because the introduction of the antigen would cause the blood recipient to produce an antibody that would react to subsequent positive infusions.

My mother is certain of her previous Rh negative status as she faced issues having children in the 1960s. Doctors tried to dissuade her from having more than one child. She miscarried several times after the first child (who was Rh positive and likely introduced the antigen into her bloodstream at birth). She had three children in all. Wkndfarmer 19:35, 23 May 2007 (UTC)


 * Short answer: no, one's blood type is immutable. Longer answer: it depends on what you mean by "positive" and how modern tests evaluate Rh-status. Check out this link. -- MarcoTolo 22:11, 23 May 2007 (UTC)

Could your mother be a chimera ? StuRat 03:58, 24 May 2007 (UTC)


 * That doesn't make sense: even if a person is a chimera and has some cells that would produce Rh+ blood and others that would produce Rh-, the blood is all mixed together, so the person would be Rh+. However, the "Du variant" explanation at Marco's link does make sense. --Anon, May 24, 2007, 09:15 (UTC).


 * You may want to check out about bone marrow transplants, since you are effectively replacing the tissues that generate blood cells. I thought I had read up on one BMT that changed the person's blood type.  I've seen some websites of people claiming this has happened (either to themselves, or a friend or others), but as of yet I've found nothing medical verifying this.  It seems highly plausible to me, though. Root4(one) 22:14, 26 May 2007 (UTC)

Psychology - methods of coping with solitude?
Having had no luck with Google, can anyone name a published psychologist or psychiatrist with a specific interest in coping mechanisms for social marginalization, especially for adolescents and children? I.e. healthy ways of coping with loneliness, low social status, or forced solitude, assuming that - for whatever reason - socialization isn't possible or is unlikely? A focus on cognitive psychology would be useful. Thanks. --Brasswatchman 21:34, 23 May 2007 (UTC)


 * May not be directly relevent to coping mechanisms, but Harry Harlow's Pit of Despair experiments might be of interest. Rockpock  e  t  23:19, 23 May 2007 (UTC)


 * Oh, trust me, I have heard of those experiments, thank you. Brr. A bit infamous, aren't they? --Brasswatchman 19:32, 24 May 2007 (UTC)


 * Have you read Cognitive behavioral therapy? It is a popular therapy mode which seeks to deal with some of the conditions which might be underlying causes of the loneliness and lack of social interaction you describe. Edison 00:40, 24 May 2007 (UTC)


 * I have, thank you. What I'm really hoping to find, in fact, is something akin to CBT, but specifically aimed at loneliness. Maybe I'll check into the publishing history of some of the authorities mentioned in that article. Thanks for bringing it to my attention again! --Brasswatchman 19:32, 24 May 2007 (UTC)

Does it need to be a psychologist or psychiatrist? If not, check out [Anneli Rufus]'s book, "Party of One". In it she gives a Loner's Manifesto that includes coping techniques.


 * I'll take a look! Thanks! --Brasswatchman 19:32, 24 May 2007 (UTC)


 * I would expect that the Internet has potential for helping people deal with social isolation. Meeting people anonymously, where there is no possible physical danger, may make it easier for shy people to overcome this limitation.  A number of other conditions, such as stuttering, severe facial burns, and physical deformities, are also not apparent on the Internet, reducing the anxiety level of people with those conditions. StuRat 03:54, 24 May 2007 (UTC)


 * In fact, the internet is forcing a re-think of what we consider mental illness: See this article titled ‘Mind Control’ Experiences on the Internet: Implications for the Psychiatric Diagnosis of Delusions, which discusses internet interaction between mentally ill and "healthy" individuals. This blurs the line and may lead to obsolete definitions of certain types of mental illness.  Nimur 14:02, 24 May 2007 (UTC)


 * Very interesting. I'll have to take a look at that. Thank you! Are there any other resources along these lines any of you might know off the top of your heads? --Brasswatchman 19:32, 24 May 2007 (UTC)

Biodegradable
I am doing a science project on biodegradable variables. Is styrofoam and wax paper biodegradable? Where can I go to research? —The preceding unsigned comment was added by 209.244.188.202 (talk • contribs).


 * Hi, and welcome to Wikipedia. You should read our article on biodegradation, and come back if you have any specific questions it doesn't answer.  --TotoBaggins 22:01, 23 May 2007 (UTC)


 * (edit conflict) Great question, it sounds like an interesting project. In terms of Wikipedia resources, you may want to check out the articles on Biodegradation, Styrofoam, Polystyrene.  We have an article on Wax paper as well, although it does not appear to currently discuss environmental concerns.  The Biodegradation article does indicate that styrofoam cup is biodegradible in 1-100 years; a fact which comes from this article.
 * For more information, a good place to start is your local library reference desk. I may be able to find more information as well, if you can describe your project in more detail too.  Libraries, however, have access to a range of resources not immediately found on the internet.  If you have a solid waste division of your city, county, or regional govenment, they may also be able to answer questions.  --TeaDrinker 22:10, 23 May 2007 (UTC)

The styrofoam cup is instantly degradable with black coffee! --Zeizmic 23:08, 23 May 2007 (UTC)
 * Gasoline dissolves polystyrene. [' Mac Δαvιs '] ❖ 00:37, 24 May 2007 (UTC)


 * So does acetone, but the result is a messy goop of smelly, toxic polymer. Nimur 14:04, 24 May 2007 (UTC)


 * We should also point out that there is a difference between biodegradable and ecologically safe materials. Most rocks are not biodegradable (though lichens and plant roots provide an interesting counterexample).  Yet, we have no ecological concerns about rocks.  Meanwhile, uranium naturally degrades into safe materials without biological intervention, and it still frightens a lot of people.  You might want to look into these sorts of details when reporting on the benefits of biodegradable materials.  Nimur 14:51, 24 May 2007 (UTC)

Free Particles in Quantum Field Theory
What are the equations describing free particles in quantum field theories (eg. electron, photon, gluon, W+ and -, Z0)? Thanks, *Max* 22:59, 23 May 2007 (UTC)


 * Are the answers not in your lecture notes or your text book?

Dirac equation, Klein-Gordon equation --Reuben 00:00, 24 May 2007 (UTC)


 * The equations above are relativistic quantum mechanical equations, but they only represent the first order of a quantum field theory. See Quantum electrodynamics, Quantum chromodynamics, Electroweak interaction. There's not really one equation of each, the thing that describes them best is a lagrangian from which equations can be derived, at first order these are the equations mentioned above, but they can be expanded on. Cyta 15:37, 24 May 2007 (UTC)


 * Yes, the full Lagrangians have interactions and need to be described by quantum field theory. But the question was about free particles, so you can turn all the coupling constants to zero.  This falls back to the Dirac equation and the Klein-Gordon equation.  Each component of the SU(2) and SU(3) will follow the Klein-Gordon equation independently (this may require the correct gauge fixing...)  There should be no higher orders, because there are no interactions. --Reuben 18:19, 24 May 2007 (UTC)


 * Fair enough, there are no interactions for free particles, but the QED lagrangian also contains the terms for a free electromagnetic field, which wouldn't be covered by the Dirac equation. I don't know if there is a simple K-G like equation for spin-1 particles (photon, gluon) or if the field tensor contraction as in the Lagrangians simply covers that? Cyta 18:49, 24 May 2007 (UTC)


 * The Klein-Gordon equation works at least for free, massless vector bosons. I think it's OK for free, massive vector bosons too.  The four-vector components act the same as independent scalar fields.  This does require the correct gauge choice, Lorenz guage.  Of course, the strong and weak bosons never act like free particles, given electroweak symmetry breaking and color confinement.  So it's not a very good model in practice for anything but the photon.  --Reuben 18:55, 24 May 2007 (UTC)