Wikipedia:Reference desk/Archives/Science/2009 September 4

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September 4[edit]

Containment of Rust[edit]

In principle, if I cover something metal that already shows a degree of rust with a clear sealant, will that clear sealant stop the rust from progessing? (I have a sculpture that has an element that is wrought-iron bulrushes. I am stripping the sculpture of old paint that has started to crack, and am scouring off the rust. However, I like the look of the rusted bulrush heads and would like to leave them as they are. I don't want them to rust further.) If the answer is no, is there any other way of stopping the rust at just this point? If the answer is yes, what type of clear sealant would be recommended? The sculpture sits outdoors in the Canadian climate all year round and is in direct sun. Everything else on the sculpture I am painting with a Tremclad primer and then a rustproofing paint for the top coat. Thanks // BL \\ (talk) 00:49, 4 September 2009 (UTC)

"Canadian climate"? Where in Canada? It's a huge place. Rusting is heavily dependent on local humidity, which is different throughout the country. --‭ݣ 02:16, 4 September 2009 (UTC)
Southern Ontario, in a wetlands valley area, but not on a lake or near salt water. // BL \\ (talk) 03:19, 4 September 2009 (UTC)
Here we use stop-rust-converter, which is phosphoric acid. It turns the rust a grey colour though. Graeme Bartlett (talk) 03:24, 4 September 2009 (UTC)
Lacquer and Varnish are your friends here - make sure you get an outdoor type. (talk) 11:34, 4 September 2009 (UTC)
There will be thousands of products to choose from [1] [2] I can't make any recommendations - except to say that if you get a uv cured varnish it might be longer lasting. (talk) 11:39, 4 September 2009 (UTC)

I would heat the thing pretty hot to make sure that all of the water has been driven off the surface - then - when it's cool again, apply a decent coat of some kind of varnish. If the varnish can exclude the air and water from the metal - then I don't see how the rust could spread. Rusting is the combining of oxygen with the metal - no more oxygen therefore means no more rust. SteveBaker (talk) 16:35, 4 September 2009 (UTC)

Hard to heat a 4-foot tall sculpture, unless you mean just to leave it in the sun. (We do have sun this week for the first time since about May.) Thanks for all the ideas. // BL \\ (talk) 23:20, 4 September 2009 (UTC)

Toxicity of lead(II) nitrate[edit]

Is lead(II) nitrate toxic enough that skin exposure to a single small drop of its solution, washed off after only 1 or 2 seconds, will cause fatal poisoning? -- (talk) 00:53, 4 September 2009 (UTC)

Probably not lethal, per the compound's MSDS, if there's no cut, etc, and it's pure skin contact. However, we do not offer, and are not qualified to offer, medical advice, and it is advisable to seek proper advice from a doctor asap. Tim Song (talk) 01:03, 4 September 2009 (UTC)
How soon after exposure do the symptoms typically appear? I couldn't find that in the article you linked to. Also, the solution was 1 molar, if that matters.-- (talk) 01:12, 4 September 2009 (UTC)
These are medical questions that we are not qualified to, and will not, answer. Please seek medical advice from a medical professional. Tim Song (talk) 01:22, 4 September 2009 (UTC)
This is verging perilously close to seeking medical advice, which we can't give here. If you were handling the substance, you should have first read its Material Safety Data Sheet. If you don't have access to that, you can link to it here:[3]
You will note that in the section relevant to skin exposure, it instructs you to seek medical advice (it means face-to-face, from a qualified Medic, although it doesn't explicitly state that). Unless your question was indeed purely hypothetical, please do so. (Addendum: I swear those earlier answers weren't there when I posted mine.) (talk) 02:41, 4 September 2009 (UTC)
No. It wasn't. The guy was probably dissatisfied w/ my response, so he rewrote the question & removed the response. Then you responded; then someone else undid the rewrite/removal. Hence the mess. Tim Song (talk) 03:10, 4 September 2009 (UTC)
Phew! That's one proof that I'm going mad eliminated, then. Too bad about all the others. (talk) 21:58, 4 September 2009 (UTC)
No, because lead nitrate is not a fatal poison like cyanide, it causes damage by chronic exposure (definition:[4]) , the LD50 in animals is ~100mg/kg , so for a 100kg person that would be 10g. (talk) 11:30, 4 September 2009 (UTC)
Also see Lead poisoning83.100.250.79 (talk) 11:32, 4 September 2009 (UTC)

green leaf mulch - metabalism or decay?[edit]

I have a truckload of mulch which is part mulched branches and about half mulched green leaves. It rained a little and I noticed vapor coming off the pile. When I dug beneith the surface I was shocked to find a large amount of heat coming from the pile. Is the heat due to continued metabolism of the leaves? I can not imagine they have had time to start the process of decay sufficient to produce as much heat as is coming off the pile and besides they are still green. -- Taxa (talk) 01:18, 4 September 2009 (UTC)

  • How long has it been there? I found this in Composting: "If the pile is built in a short period, and has a good mix of materials (C:N) and a coarse structure, with about 50% moisture ("like a squeezed out sponge"), the temperature should rise within days to as high as 60 °C (140 °F)." Looks like decay can begin pretty quickly. You might also check Decomposition. Makeemlighter (talk) 04:00, 4 September 2009 (UTC)
Yes, its the decay caused by the action of the bacteria which the material no longer has metabolism to prevent according to the article. Thanks for the links. -- Taxa (talk) 05:56, 4 September 2009 (UTC)

Mustard stains turn pink?[edit]

So being the slob I am, I just got mustard all over my grey track pants. I went to the bathroom and sprayed a variety of household cleaners on my pants -- I figured I didn't care much if they had bleach stains; I just didn't want them to be yellow. Something even weirder happened: The mustard stains turned pink when I sprayed them with a particular foaming cleaner (containing, among other things, ammonium chloride). What's going on? --‭ݣ 02:10, 4 September 2009 (UTC)

Most yellow mustard contains tumeric as a coloration agent (it gives it its bright yellow color). Tumeric is also a good acid-base indicator, in that it turns a brilliant vermillion in the presence of a strong base. Usually, there is enough acid (vinegar) in the mustard to keep the tumeric in its yellow form; but if you overwhelm the acid with enough soap, it will turn a bright red. My guess is that the ammonium chloride is of a high enough pH to turn the tumeric red. --Jayron32 03:16, 4 September 2009 (UTC)
The only problem is that ammonium chloride solution is acidic. And per this, you need a pretty strong base to turn it red. However, per Curcumin, if your cleaner contains borates, that can cause the formation of a red compound. Tim Song (talk) 03:53, 4 September 2009 (UTC)
Yes, in particular, borax (sodium borate) is widely used in detergents. Does that foaming cleanser happen to contain borax, by any chance? Red Act (talk) 04:12, 4 September 2009 (UTC)
Many strong cleaners are very basic, especially the ones for floors, toilets etc. The indicator idea is right for turmeric (don't know about mustard)- to get the colour to change back soak in orange juice or something. To get rid of the stain is very difficult. (talk) 11:20, 4 September 2009 (UTC)
Problem is, if it contains ammonium chloride, it's probably not basic. Tim Song (talk) 11:23, 4 September 2009 (UTC)
Yes you're right, just woken up. (talk) 11:25, 4 September 2009 (UTC)
Unless it contains both ammonium chloride and, say, sodium hydroxide. Such bi-phase cleaners are a common way to keep ammonium around, since acid-ammonium compounds aren't volatile at all. However, once the two phases are mixed in the presence of a liquid, the whole mess is basic. It would be entirely appropriate for the ingredients label to list ammonium chloride if that was what they added to the mess to generate ammonia in situ, even if the actual cleaning agent is basic ammonia, which is what I suspect here. I should have been clearer; nearly ALL industrial cleaning agents (even if they list ammonium chloride as one ingredient) will have a very high pH. Prepared yellow hot dog mustard almost always contains tumeric as a coloring agent. Tumeric + strong base = bright red color. That is exactly where his pink came from. --Jayron32 17:56, 4 September 2009 (UTC)
The 'borax-turmeric' complex is also convincing - and I suspect will be far more difficult to get rid (stable?) than just adding a bit of grapefruit juice. If the original questioner is reading this they should check for the presence of "boric acid" or "borate(s)" in their cleaner.
As an aside I think washing the clothes (using clothes washing powder) does eventually remove turmeric stains, though not always on the first wash. (talk) 18:13, 4 September 2009 (UTC)
The only thing I've ever found to remove turmeric stains is bleach unfortunately. --TammyMoet (talk) 19:12, 4 September 2009 (UTC)

two neutrons[edit]

Suppose I shoot two neutrons out of two neutron cannons at the same time and speed so that they traveled almost parallel but get closer and closer becasue of the slight angle of the cannons. As the neutrons got closer and closer what will they do when they touch? -- Taxa (talk) 02:20, 4 September 2009 (UTC)

Neutronium and Dineutron cover your topic if you would like to take read. Graeme Bartlett (talk) 03:21, 4 September 2009 (UTC)
Neutrons do not repel each other with the electrostatic force, but they do repel each other according to the Pauli exclusion principle. As above, the only relevant way to describe their collisional interaction is quantum-mechanically. Nimur (talk) 03:59, 4 September 2009 (UTC)
Since neither of the above directly answer your question, I'll try. I believe the answer is that, depending on random quantum details, there are various possibilities. They either glide right through each other, bounce off each other, or briefly stick together and then keep going their separate ways. (talk) 04:48, 4 September 2009 (UTC)
It should be noted that this situation is identical to sending two neutrons slowly toward each other (just in a different inertial reference frame). Rckrone (talk) 06:40, 4 September 2009 (UTC)
There are other possibilities besides the ones already mensioned. They could stick and form deuterium releasing an electon, an anti-neutrino and energy, or one of them or both could decay before collision. Dauto (talk) 15:21, 4 September 2009 (UTC)
Exactly the same thing that would happen if you shot them directly towards each other at a much lower speed. — DanielLC 16:32, 5 September 2009 (UTC)

Born with feet the wrong way round?[edit]

My uncle on my mother's side was born with his feet facing completely the wrong way round, along with webbed toes. He also suffers from some minor mental handicaps, though my family suspect this is the result of the extensive and painful treatment he had to undergo to reverse the position of his feet.

I've searched everywhere and can find no reference to this disorder - my main question is; what is it, and is it hereditary in any way (e.g. is there any chance my or my sister's children could suffer the same fate)? —Preceding unsigned comment added by (talkcontribs)

The best person to answer such a question is a physician. We can't advise whether the condition you described is hereditary. It sounds like your description is not quite correct, either; there are a wide variety of possible physical aberrations which might be close to what you have described, such as club foot, but "feet facing completely the wrong way round" sounds like an implausible scenario. Again, you should ask a physician about this, since we can't diagnose what the actual condition was. Nimur (talk) 04:00, 4 September 2009 (UTC)
It does happen.[5] Red Act (talk) 04:15, 4 September 2009 (UTC)
It's not implausible at all. The genes that control development operate in a hierarchical way, and there are many cases of mutation of a high-level laterality-controlling gene leading to things of that sort. A quick scan of Pubmed didn't show any easily findable descriptions of a syndrome, though. Looie496 (talk) 04:20, 4 September 2009 (UTC)
Well, I understand if it's something you can't comment on. I'm not looking to sue wikipedia over some hysterical self-diagnosis though - I just wanted to know if those symptoms are similar to any kind of recognised disorder, and if they are, whether that same disorder can be passed along.
We can't diagnose this condition - we're not allowed to. We'd have to say that if someone was born this way - it would have to have been something that developed quite early on in the womb - but whether that was caused genetically - or perhaps due to some unfortunate chemical that the mother was exposed to - would require such a diagnosis. It seems to me that this would likely have happened so early in the developmental process that it would almost certainly be genetic - but then things like Thalidomide have cause non-genetic birth defects that early it's possible that it was an environmental rather than a genetic cause. SteveBaker (talk) 16:25, 4 September 2009 (UTC)

Magnise Steel[edit]

What % of magnise should be available in Mn steel.

K C GUPTA Sr. Manager Mech. HINDUSTAN COPPER LTD —Preceding unsigned comment added by (talk) 05:01, 4 September 2009 (UTC)

The Steel article states "...manganese steel contains 12–14% manganese...". -- Tcncv (talk) 05:14, 4 September 2009 (UTC)
I missed it at first, but "manganese steel" redirects to the Mangalloy article, which may have additional information of interest. -- Tcncv (talk) 05:33, 4 September 2009 (UTC)

Reviving an extinct common ancestor of two taxa[edit]

Let's say there's an hypothetical species that branches into two distinct lineages. After a while, the original species is extinct, but the two diverging lineages survive and diversify as each lineage adds new features and adaptations that weren't found in the common ancestor. You could infer that the features that are unique to both lineages developed after the split, but the ones they share in common are ones that were present before the split.

Would it be possible, using genetic engineering, to remove only the genes that are unique to each lineage, but keep the genes that are common to both of them and reproduce the genome of the extinct ancestor?

My guess would be that it would work better for simpler organisms and especially for ones that have a lot of different descendant species, but would it be possible to try it on more complex species that have been diverging for millions of years? (talk) 05:54, 4 September 2009 (UTC)

In the situation where a gene changed in one of the two lines, how would you be able to tell which of the two is the original version and which is the one that changed? If a certain gene has changed in both lines, so that the original version of the gene no longer exists in either line how would you recreate it assuming you could somehow find out it was missing? Rckrone (talk) 06:19, 4 September 2009 (UTC)
You may be better off also comparing an out group not descended but still related to see if its gene is the same or equivalent to one of the decedents. There may also be totally deleted genes that you not recover at all. Graeme Bartlett (talk) 06:47, 4 September 2009 (UTC)
Even if you can reconstruct the ancestral genome from an information-theoretic point of view, you're still a long way from being able to revive an ancient beastie. --Sean 15:09, 4 September 2009 (UTC)
Taking the question as it is worded literally, if you removed the genes that were unique to each 'new' lineage and only used the genes that were common to both to recreate the ancestor organism, you would end up with an incomplete organism. Might be fun to look at but it wouldn't be the same as the original. --KageTora - (영호 (影虎)) (talk) 15:02, 5 September 2009 (UTC)


Do any particles of matter not have a half-life? -- Taxa (talk) 06:54, 4 September 2009 (UTC)

Maybe. See Proton#Stability. They certainly have a half life that is really really REALLY long. --Stephan Schulz (talk) 07:27, 4 September 2009 (UTC)

short half-life and fusion[edit]

There appears to be a correlation between the shortness of an end product's half-life and how easy it is to create the product by fusion. Is this correlation imaginary or real? -- Taxa (talk) 07:07, 4 September 2009 (UTC)

And perhaps more importantly, is it coincidental or causal? Vimescarrot (talk) 07:39, 4 September 2009 (UTC)

nuclear reactions[edit]

Palladium 109 has a half life of only 13.427 hours and decays to silver 105 with a half-life of 41.29 days which decays to palladium 105 which is stable. Can the decay of pd 109 or ag 105 immersed in a container of deuterium produce traces of tritium? -- Taxa (talk) 07:46, 4 September 2009 (UTC)

How does Palladium turn into silver? The number of nucleons decreases by 4, yet the atomic number changes from 46 to 47, are you sure you have your question correct? Graeme Bartlett (talk) 11:54, 4 September 2009 (UTC)
The Wikipedia article lists only the "most" stable isotopes of palladium without showing the decay chain. Pd (46)109 is not included in the chart so I can not check it out there. Elsewhere the decay product of pd (46)109 is listed as ag (47)105 and the product of ag (47)105 as pd (46)105. -- Taxa (talk) 12:54, 4 September 2009 (UTC)
Another site shows pd 109 ==> ag 109 via -beta decay so the pd 109 to ag 105 on the other site may be in error. -- Taxa (talk) 13:31, 4 September 2009 (UTC)
Yes, if you look at [6] it tells me beta decay, going to Ag109. Ag109 is stable. At [7] you can see Ag105 giving out positrons or eating electrons. So to consider the next part of your question, can high speed electrons (or positrons?) and gamma rays interacting with deuterium produce tritium? Graeme Bartlett (talk) 13:40, 4 September 2009 (UTC)
I am using pd 109 as an example because of the relatively short half-life of 13 hours but I mean to include all of the unstable isotopes of palladium. So would any of these decays result in the production of tritium if occurred in a container of deuterium? -- Taxa (talk) 14:30, 4 September 2009 (UTC)
No, you can't produce tritium that way. Dauto (talk) 15:11, 4 September 2009 (UTC)
What about if the deuterium were nitrogen? -- Taxa (talk) 15:28, 4 September 2009 (UTC)
Nitrogen certainly isn't going to change into tritium, why would it? Perhaps you should explain what you actually want to know and we can then work out what the information you need it. --Tango (talk) 17:41, 4 September 2009 (UTC)
It does when hit by cosmic rays. Cosmic_ray#Interaction_with_the_Earth.27s_atmosphere-- Taxa (talk) 17:58, 4 September 2009 (UTC)
But this reaction: 14N(n, 3H)12C needs high energy neutrons. Graeme Bartlett (talk) 22:39, 4 September 2009 (UTC)
Actually you mean proton. However, all you need say is that nothing any isotope does when it decays can change deuterium into tritium, regardless of what the isotope is. -- Taxa (talk) 19:00, 5 September 2009 (UTC)
You aren't making sense. Deuterium and tritium are isotopes. Why would one isotope decaying change another isotope? --Tango (talk) 22:31, 5 September 2009 (UTC)
My interest is with palladium decay chain and products and in particular what they do in a Deuterium environment but by the same token other isotope decay chains and products may spawn reactions or serve as catalysts. Whether they may do so to the extent of fusion or fission is the question. -- Taxa (talk) 11:32, 6 September 2009 (UTC)
And I wouldn't describe that as nitrogen turning into tritium, it is nitrogen turning into carbon with tritium as a by-product. --Tango (talk) 23:14, 4 September 2009 (UTC)
That is the great news about such interactions - they leave a uni-directional trail. So if I wake up in the morning with tritium in my bottle of deuterium I can speculate that maybe there was some nitrogen in there that got hit by a cosmic ray. Likewise, if I had some palladium in there I might ask if any of the unstable isotopes of palladium were in there as well which decayed resulting in a similar thing. Unfortunately, I have not been able to find any papers exploring or even speculating on any possible explanation except that tritium was probably already in there to begin with. -- Taxa (talk) 23:25, 4 September 2009 (UTC)
The n meant neutron, but it was produced in other high energy reactions involving cosmic rays, which are mostly protons. You conclusion is quite likely, that natural deuterium will likely contain tritium, unless it is especially aged to let it decay away. Graeme Bartlett (talk) 22:29, 5 September 2009 (UTC)

The question sis whether any of the decay products of the isotopes of palladium could cause fusion in an environment of Deuterium reslting in the presence of Tritium. The need for high temp and high presure or extreme temp, however, seems to prohibit this possibility. -- Taxa (talk) 12:04, 6 September 2009 (UTC)


Is there anywhere I could see a list of 20th/21st century inventions not invented in America? Am I mistaken in thinking most inventions are made in the US? TheFutureAwaits (talk) 07:57, 4 September 2009 (UTC)

I'm sure USA are near the top of the list, being one of the worlds leading developed countries, but I imagine Japan and several European countries are worthy competitors. Googling phrases like 'latest recent inventions' comes up with heaps of sites about recent technological advancements. I imagine that there are new things being invented all around the world, it's just you more likely get to hear about the succesful ones that are relevent to you and your life. (talk) 08:10, 4 September 2009 (UTC)
Off the cuff I would say that you are almost certainly misled in believeing most invetions begin in the US. The main problem here is that "invented" is a fairly subjective term, the closest possible thing I could think of that one could quantatively measure is patent applications and patents granted. But this should be treated with caution as one "invention" could be covered by one patent, whereas another could be covered by thousands. Patents granted 2005 Patent applications 2005 These would suggest that japan leads the way with about 30% of granted patents, US following with 22%. Despite this it could be argued that patent applications may be a better measure of the competition in technological indstry, rather than its level of innovation.—Preceding unsigned comment added by (talkcontribs)
I think this will be very hard to measure. Many inventions are quite useless. To be honest, many patents are quite useless - if you start to use the number of patents or of patent applications as an indicator of success, smart people will start to generate a large number of patents or patent applications. Researchers at public institutions often do not apply for patents for inventions that would be patented if developed in a large company. But look at some of the biggies. Radar and computers are (mostly) British. Rockets are (mostly) German and Russian. Much of current software technology is from the US (but MP3 is German). Lasers are mostly US. CDs are Dutch/Japanese. Penicillin is British. Assembly lines are (mostly) US. --Stephan Schulz (talk) 09:59, 4 September 2009 (UTC)
It depends how you define "inventions". You can definitely get statistics on patents approved, but whether these count as legitimate "inventions" is problematic. Additionally tons of "inventions" that we think of as being American have been, in their present forms, developed outside of the US. So modern solar cells were developed in the US in the 1950s, though a far more efficient model was worked out by the USSR in the 1970s, though most solar cells today are developed by Germany. Similarly, Americans may have invented the first microwave but it's likely that the patents that cover your current microwave are held by the Japanese (ditto your television and many other digital things).
The US does have a strong tradition of invention dating back to the 19th century, and the research labs of the post-WWII period certainly contributed a lot. It's not incorrect to say that the US has a disproportionate amount of inventing and innovation, though it is an exaggeration to be sure to suggest that all of the important inventions of the modern time came out of the US. -- (talk) 13:38, 4 September 2009 (UTC)

A further point that complicates the matter is that something protected by a US patent is not necessarily invented in the US, nor by a US citizen. --Quest09 (talk) 15:49, 4 September 2009 (UTC)

And worse still, the existence of a patent doesn't prove that there is a novel invention behind it - many MANY patents are just junk. Until a patent is challenged in court and actually survives that challenge - you have no idea whether it's a truly novel and non-obvious invention or just some schmuck trying to make a quick buck. There are more patents in the US because there are more people patenting junk - laws that allow things like "business methods" and software algorithms to be patented - too few patent clerks to check each patent in sufficient detail - and a legal system that allows big companies to patent things that smaller companies invented and then suing them years later with a 'submarine patent'. The cause of the large number of patents is not some amazing national tendency to inventiveness - it's a sucky patent system! SteveBaker (talk) 16:15, 4 September 2009 (UTC)

Seeing that for popular inventions such as radio, telephone, computers, planes, etc just about every nation can throw in a somewhat valid claim, you'll find it very hard to get any agreement on that. Can I ask the other way round: Can you name just one invention that is undoubtably solely American? (talk) 22:54, 4 September 2009 (UTC)

Any of the application-specific technology for landing a man on the moon (well, most of that stuff, anyway) is pretty exclusively American. (Though, the engineers who worked on those projects may have had backgrounds or origins from other nations). But I doubt any other country can make a legitimate claim to inventing a Lunar Excursion Module before the USA. They might have hypothesized such an idea, or even built some prototypes, but none were actually functionally invented until Americans actually executed the lunar missions. Nimur (talk) 23:12, 4 September 2009 (UTC)
Could you have any kind of rocket engine without some Russian help? Very few things are invented completely from scratch, they usually build upon the work of others. It is usually difficult, if not impossible, to determine a unique inventor for a device in a way that can't be disputed. Should you credit the person that did the underlying work? The person that came up with the idea for the device? The person that came up with a way of implementing that idea? The person that actually made it work in practice? --Tango (talk) 23:23, 4 September 2009 (UTC)
The aerodynamic roll-control system for airplanes is undoubtedly solely American. (talk) 05:25, 5 September 2009 (UTC)
Well, not according to Aileron#History. Apparently, an aileron system was not only invented, but even patented (by a Brit) nearly 40 years before the Kitty Hawk ever flew. --Stephan Schulz (talk) 07:03, 5 September 2009 (UTC)
He didn't put it on a plane, though, so it doesn't count. According to the same article, it was actually Glenn Curtiss who invented and patented the first SUCCESSFUL aileron control system, and that's what counts -- else it would've been William Samuel Henson who invented the airplane, and not the Wright Brothers. (talk) 09:02, 5 September 2009 (UTC)
Isn't that precisely the point though? You claim it is solely an American invention. Others claim it was just building on earlier inventions. Nil Einne (talk) 01:21, 6 September 2009 (UTC)
Now what on Earth do you mean by that? (talk) 01:47, 6 September 2009 (UTC)
Quoting from above, which you replied to "Very few things are invented completely from scratch, they usually build upon the work of others. It is usually difficult, if not impossible, to determine a unique inventor for a device in a way that can't be disputed. Should you credit the person that did the underlying work? The person that came up with the idea for the device? The person that came up with a way of implementing that idea? The person that actually made it work in practice?". You say, because the aileron wasn't put on a plane, all prior inventions should be ignored, even if the American version was building on earlier inventions. (I don't know if it was.) Others say people made aileron's before that and the Americans were building on earlier inventions, no harm in that, but misleading to call it a solely American invention (perhaps you can call the American version the first successful invention, but that's quite different from calling it a solely American invention.) Another complication is what do you do with independent inventions? In other words, ultimately this discussion is going no where since don't agree on how you define a solely American invention. You are welcome to your opinion, but it's clear quite a number of people don't agree so it's ultimately just random opionions on what is an isn't a solely American invention Nil Einne (talk) 04:37, 6 September 2009 (UTC)
FYI: The method of roll control used on (almost) all the world's airplanes today (namely, the aileron) was first successfully developed and used by Glenn Curtiss as I already mentioned above. His design was based entirely on the Wright Brothers' wing-warping system (the arrangement of the control cables was nearly identical, but they actuated ailerons instead of warping the whole wingtip). The Wright Brothers, on the other hand, designed the wing-warping system completely on their own after watching seagulls fly, and did not build upon any other aileron or wing-warping control systems. Therefore the wing-warping system definitely qualifies as a solely American invention, and so does the aileron, since it was invented by an American inventor and based on another invention that was solely American. (talk) 04:50, 7 September 2009 (UTC)
LK Lander? That it was never used is no slur on its "invention" per se.
And again, we're back to mincing words over what counts as an "invention" - to answer this question at all, we need a really rigorous definition for "invention." Nimur (talk) 17:26, 5 September 2009 (UTC)
I just found a couple more examples of inventions that were solely American: the phonograph was undisputably an all-American invention, and so was the nuclear reactor. Painkiller drugs for surgery were also first developed in the USA. So there were quite a few inventions that were solely the work of our American inventors.
And as for the LK lander -- it was never tested in its intended application (i.e. to land on the Moon), so it doesn't count as an invention either. It's only an invention once it's been tested and found to be useful either in its intended application or in some other application, or else every failed idea and useless gadget in the world would count as an invention, which would take credit away from those (like Thomas Edison or the Wright Brothers) who made their inventions practical. (talk) 00:09, 6 September 2009 (UTC)
Your nuclear reactor example is (Italian) baloney. Chicago Pile-1 was constructed by Enrico Fermi, who was an Italian citizen until several years after it was constructed, based on an outline design that Hungarian Leó Szilárd worked out while living in London. -- Finlay McWalterTalk 00:18, 6 September 2009 (UTC)
I don't understand how nuclear reactions, or even a reaction pile, could possibly be considered as an "invention", I'd prefer a "technological development". The technology was developed by a huge team, not through one single person's idea. But if it's going to be labelled as an invention, then I'd say Lise Meitner was the inventor. Franamax (talk) 01:00, 6 September 2009 (UTC)
To both of you -- your arguments are bullshit. Enrico Fermi was living in the US and designing the reactor for the US government's Manhattan Project -- ain't that enough to make this an American invention? And Leo Szilard's "outline design" was just that, an outline, he never had it made into actual hardware, which is an absolutely necessary requirement for an idea to be considered an invention. And as for Lise Meitner, she only discovered nuclear fission, she never played a part in actually designing the nuclear reactor, so your claim that she was the inventor of the nuclear reactor is bullshit squared. According to your reasoning, then, it would be Leonardo da Vinci who invented the helicopter because he made the first design sketch, even though that design was never built, never tested, never flown, and indeed was incapable of controlled flight? Or it would be Rutherford who invented the TV because he first demonstrated that an electron beam can induce phosphorescence, even though his "TV tube" didn't actually show any pictures, but just glowed in the dark? You don't even know the difference between an "idea" and an "invention", do you? Or do you just not give a hoot about such fine distinctions? (talk) 01:39, 6 September 2009 (UTC)
N.B. Our article implies Enrico Fermi was stateless from 1938 to 1944 (not an Italian citizen). In some ways this may be accurate given the situation at the time. Both of the above did of course take up American citizenship not that long after. But they do highlight another issue. Some inventions are made in another country (usually a developed one, often the US) by citizens of another country (who perhaps got most of their education in their country) and some of these don't choose to take up citizenship of the country were they made the invention (many do of course). Should their inventions be considered inventions of the country where they were when they made the invention (considering they likely had help etc), both countries, or what? Nil Einne (talk) 04:56, 6 September 2009 (UTC)
The pain killer example seems rather odd to me. According to anaesthesia and surgery, opium, alcohol, cannabis, aconitum and others have been used for a long while, by (depending on the combination) the Greeks, Romans, Chinese, Indians, and others long before the US existed. Because of the risks of with unstandard doses, attempts were made to standarise the doses as much as possible given the level of sophisticary at the time. Hanaoka Seishū evidentally is often credited as the first to perform surgery (specifically a masectomy) under general anaesthesia in 1804 albeit his work was not published to the Western world because of the isolation policy of Tokugawa Shogunate until they had already developed their own techniques. Moving on to a different area, inhalant anaesthetics were used by Arabic and Iranian/Persian physicians/surgeons and in Islamic Spain via narcotic soaked sponges (influenced of course particularly by the Greeks). (Some of the earlier anaesthetics were of course inhaled.) Of course it's questionable if there can really be called inventions per se but it's also clear that these were important in the development of later anaethesia methods and drugs. Coming to more modern times, Morphine was first extracted in Germany and we're getting closer and it was an important step forward allowing a great degree of standarisation although the lack of the hypodermic needle hindered its use. Diacetylmorphine (aka heroin) was synthesised in London from morphine albeit didn't become of interest until it was synthesised again in Germany (although I'm not sure if it was ever used much for surgery). Okay I'm getting a bit ahead of things there... The anaesthetic properties of nitrous oxide (itself discovered by a Englishman) was discovered by a Brit albeit first used (that we know of) by an American albeit for dentistry since it's too weak to be used as for general anaethesia (but shouldn't be ignored, since it's seems definite it did have an effect on later developments). Diethyl ether was possibly discovered by a Spainard and first synthesised by a German and its analgesic properties discovered by a Swiss although first used in surgery (that we know of) by Americans. Chloroform was discovered first by an American then independently by a Frenchman and a German, characterised by another Frenchman and its anaesthetic properties discovered by James Young Simpson and first used by him in his England, before spreading to Europe and eventually America (although as it later turned out, the Americans were fortunate they stuck with ether for so long given that chloroform was much more likely to kill the patient and was abandoned). John Snow (physician) from England was evidentally one of the first to study and calculate dosages for ether and chloroform, evidentally learning of ether from the Americans and chloroform of course from his compatriot and as his work was published in 1847/1848 (ether being first publicly demonstrated in the US in 1846), I don't think the Americans were far ahead of him. He was also instrumental in promoting and increasing it's acceptance in Britain from what I can tell I mean he used it on the queen (with her permission) for hecksake. Karl Koller (ophthalmologist) used cocaine as a local anaesthetic (although many of the early drugs/herbal products were used locally partially I guess since they were more likely to kill the patient if given generally because of the dose regulation and other issues) before he moved to the US. Coming to the modern developments Paul Janssen a Belgium appears to be credited as one of the pioneers of modern anaesthesia drugs [8]. There's obviously a fairly big gap between Janssen and morphine/ether/chloroform/nitrous oxide which I haven't looked at, primarily because I didn't come across much discussion of that in my reading but I think I've covered enough. Your broad statement is questionable. My guess is you were planning to claim that Americans were the first to use a form of general anaesthesia (specifically ether) that developed into our modern methods (which is a far more specific claim). This is true. It's clear however as others have emphasised with other examples that 1) These built on (or at least repeated) earlier efforts of using anaesthesia by a large number of people of different cultures and countries. 2) They wouldn't have happened if someone hadn't found ether, and as they were influenced by nitrous oxide if that hadn't been found and the effects of that hadn't be known it's not clear what would have happened either (you might argue someone else would have, but that's like arguing someone else would have used ether for general anaesthesia) 3) What we have today is the result of the efforts of a lot of people, many Americans of course but also a lot of other people 4) We know at least one Japanese person did use general anaesthesia before the Americans, even though his work was not an influence. This is not to belittle the accomplishments of those Americans involved but to acknowledge that their work can't be held as not being influenced by others nor (IMHO anyway) can it be considered the seminal work as although it was important, so was a lot of other things. Nil Einne (talk) 04:27, 6 September 2009 (UTC)
You're correct in saying that my statement should have been more specific. Yes, other nations had in fact used primitive forms of anaesthesia for surgery before we came up with the idea of using ether for that purpose. However, none of the methods you mentioned above could offer complete, relatively safe pain relief: aconitum is highly toxic, and alcohol/cannabis/opium can only numb the sensation of pain, not eliminate it completely. The first truly practical anaesthetic agent was ether, and its use for anaesthesia was pioneered by American surgeons (namely Crawford Long). Cocaine and heroin aren't safe to use for anaesthesia either, by the way. (talk) 05:24, 7 September 2009 (UTC)
I took a look at the article about Hanaoka Seishu -- it says about his "anaesthetic" witches' brew that "The active ingredients in Tsūsensan were scopolamine, hyoscyamine/atropine, aconitine and angelicotoxin" -- which are deadly poisons and would have been extremely dangerous for routine use during surgery. It also says that "His wife, who participated in his experiments as a volunteer, lost her sight due to adverse side effects", which speaks volumes about the safety of his formulation. I for one would surely not wanna take that stuff before getting a broken bone reset -- even chloroform would've been safer, to say nothing of ether. (talk) 03:49, 8 September 2009 (UTC)

Did I forget to mention that the repeating rifle and the six-shooter were solely American inventions? And also the self-loading rifle. (talk) 05:42, 7 September 2009 (UTC)

Oh, and the Gatling gun too... (talk) 23:52, 7 September 2009 (UTC)

Here is a list of stuff invented by Scots. Interestingly set out, too. :) --KageTora - (영호 (影虎)) (talk) 12:06, 7 September 2009 (UTC)

They forgot radar, the magnetron, and penicillin. (talk) 19:52, 7 September 2009 (UTC)
Boy are they lying through their teeth! Quite apart from their rabid anti-Americanism and terrorist sympathies (which alone should have been enough for that site to be banned from the Internet), here's where they're factually wrong: the internal combustion engine was invented by Germans; the telephone was an American invention beyond doubt; the television was the work of a Hungarian, an American and a couple of Russians; and the radio was invented by an Italian who put together two inventions by a German and a Russian inventor! In short, this website is a perfect example of "counterknowledge" in action! Man, those damned Scots are really trying to take credit for inventions that they never even made in the first place! (talk) 00:48, 8 September 2009 (UTC)
Also, the bicycle was developed by a Frenchman and an Englishman, and wire rope was invented by a German -- no Scot had anything to do with any of that! Are they totally out of their goddamned minds, or are they purposely trying to discredit non-Scottish inventors?! (talk) 05:50, 8 September 2009 (UTC)
Oh, and BTW, ultrasound imaging was first developed in Sweden in 1953, not in Scotland in 1958. And finally, insulin was isolated and used medically for the first time by a Canadian and an American -- MacLeod just took the product of their work and claimed it for himself. (talk) 06:40, 8 September 2009 (UTC)
Someone please remind me to never believe what a Scotsman says... (talk) 05:55, 8 September 2009 (UTC)

Telephone was invented by Mr Bell; however due to funding he moved to the US were his idea!! was improved opon and consiquently the US due to funding and improvments of the idea claimed the invention. this is true with regard to many inventions both in the US and Europe as well as China Middle east ECT...a country such as US in mainly made up of Imagrants from Europe south america, unless you are native American indian then you are from Europe or another country around the globe. it is only recently after several genarations you could actually say i am American. Most say i am Irish American African American Mexican American French Amrican or something along those lines. The exAZmple of the telephone was far enough back that it was most likerly a european who had moved to America any way - only recently could you actually claim it was an American invention. Inventions of certain rifles would have been claimed by people like Henry Colt however it was proberly made by somebody working for him who had migrated to the country to the boss goes the spoilsChromagnum (talk) 07:20, 12 September 2009 (UTC)


Is there a maximum possible height for sheer (90 degree) cliffs made of solid rock? I'm asking specifically for Earth gravity although I'm sure on Mars it can be much greater. I think the pressure from the rest of the mountain would cause a cliff of a certain height to collapse? TheFutureAwaits (talk) 10:32, 4 September 2009 (UTC)

Based on a documentary about the Grand Canyon, I believe it has less to do with the sheerness of the cliffs and more to do with the angle of the minor fissures in the wall. If the fissures are highest at the face of the cliff and lower inside the rock, gravity pushes rock against rock and nothing much happens. If the fissures are lowest at the face and higher inside the rock, gravity slowly slides the rock above the fissure outwards - eventually causing a collapse. -- kainaw 12:33, 4 September 2009 (UTC)
That would be a factor, and the type of rock also would be. Theoretically, every cliff will eventually collapse, since the earth is constantly changing. But consider Half Dome in Yosemite. That's a long, sheer drop - and that baby has been around a looong time. But I think it's made of granite, which means it is likely to last a lot longer than cliffs of sedimentary rock, such as at the Grand Canyon. Baseball Bugs What's up, Doc? carrots 12:38, 4 September 2009 (UTC)
For a given type of rock, presumably at some point the density times the height of the column will overcome the compressive strength of the stuff at the bottom. My back of the envelope calculation for those factors in granite (density ~.04 lbs per in3, strength ~20,000 psi) gives a column of it a maximum height of around 40,000 feet. I'm sure there are complicating factors, though. --Sean 15:47, 4 September 2009 (UTC)
Your value for the density of granite is too low. If almost 100,000 ft is possible, why, then did I see 7,000 ft somewhere as the upper limit for sheer cliffs? (and interestingly enough, for buildings using 1920s engineering, which are hollow) Sagittarian Milky Way (talk) 23:58, 6 September 2009 (UTC)
And possibly pyramid-shaped? Sagittarian Milky Way (talk) 00:01, 7 September 2009 (UTC)
Not really, no. There wouldn't be a limit. First off, it makes no difference whatsoever if it's a sheer cliff or not - pressure depends only on what's directly above you. On that note, you're currently on top of about 3000 kilometers of solid rock - the Earth's mantle. Whereas it's only 100 km up to space, at which point you're practically weightless. --Pykk (talk) 17:20, 4 September 2009 (UTC)
Crap, that's wrong - I did the math. You're not very weightless at all at 100 km. (the shuttle's just apparently weightless because of its orbit) Anyway, the question would really be if the Earth's core could handle the pressure, I suppose. --Pykk (talk) 17:34, 4 September 2009 (UTC)
A sheer cliff vs. a slanted cliff would matter. It isn't just about pressure, its about distributing the force, and a slanted cliff would be more resistant to slight seismic and thermal disturbances. Of course, there's always the problem of keeping a solid rock "solid"; freeze-thaw cycles and other weathering processes induce cracks and weaknesses on short time scales.
For reference, some of the largest sheer cliffs in the world are actually in the Arctic Cordillera in northern Canada and nearby parts of Greenland; the tallest vertical drop is Mount Thor on Baffin Island. -RunningOnBrains(talk) 22:34, 4 September 2009 (UTC)

New theory or proposal?[edit]

I'm afraid I can't remember where I read about it, but it is like a string theory, m-theory, describing the universe in a statistical method as an encrypted huge information. Can you remind me where this can be read?--Email4mobile (talk) 10:54, 4 September 2009 (UTC)

Maybe Holographic principle (although that's really "the universe is a projection" rather than an encrypted thing). -- Finlay McWalterTalk 11:01, 4 September 2009 (UTC)
You might be right. I don't know how and when I read a context describing the universe as if you have data that contain all characteristic of this universe and that each sub-data with similar characteristics can communicate each other. Perhaps in my dreams (joke).--Email4mobile (talk) 11:34, 4 September 2009 (UTC)
Digital physics, or the See Also section of that article? --Tagishsimon (talk) 11:40, 4 September 2009 (UTC)
Awful thanks for both of you. Wikipedia is a miracle!--Email4mobile (talk) 11:59, 4 September 2009 (UTC)

Virtual Work[edit]

I just had a lecture on Virtual Work in my Applied Mechanics class, and the professor left me with certain basic conceptual doubts. He says the method of virtual Work can be applied to indeterminate systems, and its powerful advantage is that it can generate as many independent equation as one wants. Thus, it can be used to solve situations where Newton's laws fail (indeterminate systems) without losing the assumption of rigidity of the bodies involved. I wasn't convinced with this, and a private conversation after class tells me that this principle of using work (energy) is more fundamental than Newton's Laws, and is more powerful than it. I have several doubts. This principle was derived in my class using the Newton's laws, and no other assumptions. So how can this result in giving more equations than the Newton's Laws themselves? Is Virtual Work really powerful enough to generate as many equations as one wants, and solve indeterminate systems completely ? Is my professor conceptually right? I need solid, authoritative answers on this, and thanks in advance for the help. Rkr1991 (Wanna chat?) 13:06, 4 September 2009 (UTC)

Umm, given that I haven't received too many answers, maybe I can relax those solid, authoritative conditions a bit... Rkr1991 (Wanna chat?) 02:33, 5 September 2009 (UTC)

My understanding of virtual work is that it is just a tool that can be used to solve problems that could otherwise be solved just fine using netwon's laws, but perhaps more with less effort. I didnt think virtual work was taught in most engineering programs. That might be why you didnt get a response. My professor wrote a book that included a lot on the topic. Do you by chance go to the university of arkansas? But, to answer your question virtual work is just an expression of newtonian laws. XM (talk) 05:08, 5 September 2009 (UTC)

I go to the Indian Institute of technology,Madras. We did the theory part quite extensively, and my professor stressed that Virtual Work can indeed be used to obtain as many equations as one wants, which is why I am asking the question here. Rkr1991 (Wanna chat?) 05:41, 5 September 2009 (UTC)

No, VW only allows you to solve problems that could otherwised be solved using convential newtonian methods. You can generate infinate equations, but you could do this in newtonian methods too, but any equations past a point would be surpufolus and wouldnt do any good. That is, you can sum forces about the X, Y, and Z axis, giving you 3 equations, and then put a new axis up and sum forces about x1 y1 and z1 but those 3 new equations dont get you any further. I dont think your professor is communicating VW effectively. There is nothing magical or extra-newtonian about it XM (talk) 10:51, 6 September 2009 (UTC)

Queries about Strong Nuclear Force[edit]

Why the strong nuclear force is many(more than 50) times greater than that of Electrostatic force, if it is only has to overcome the proton-proton repulsion? Also, if it is so then why does it act on neutrons as they are chargeless, hence no repulsion, hence no need for external force? Even considering the revolution of nucleus around itself such high quantity of force may not be required!

Your question seems to presume that the Universe is an elegantly, carefully engineered machine, in which no forces or energy should be 'wasted' in order to achieve certain desirable results. Unfortunately, it doesn't work that way. Physical laws came first, and this Universe is the consequence; the laws weren't designed in advance to produce this particular Universe. (That said, if we wished to play the 'what-if' game, it's worth noting that we probably wouldn't be here if the strong force were weakened. Higher-mass isotopes which are stable in this Universe would tend to be radioactive Fusion reactions – particularly the ones which power our Sun – would have a lower energy yield. There would be a different preponderance of elements in the Universe and on Earth. All in all, a very different place.) TenOfAllTrades(talk) 14:47, 4 September 2009 (UTC)
Why is the proton about 2000 times heavier than an electron? It just is. Why is the strong force stronger than the electromagnetic force? It just is. Dauto (talk) 14:52, 4 September 2009 (UTC)
In such basic questions about the universe, "what" is a question for scientists but "why" is a question for theologians
So the inappropriately 'designed' strong force is proof that there is no god? Cool! SteveBaker (talk) 16:06, 4 September 2009 (UTC)
Lol, only as much as the "well-designed" system of DNA/RNA is proof that there is a god ;-) The Seeker 4 Talk 18:35, 4 September 2009 (UTC)
One could ask whether the theologians really have any more of a clue as to the "whys" than anyone else, really. I've never heard any that did. -- (talk) 20:47, 4 September 2009 (UTC)
The answer to "why is gold yellow?" used to be "it just is" but now it can be explained from relativistic quantum theory. Most physicists think the ratios of the strengths of the fundamental forces will also turn out to have an explanation because they seem too large to happen by accident. -- BenRG (talk) 14:32, 5 September 2009 (UTC)
Perhaps the only thing we have that's close to answering the 'why' question is the Anthropic principle. It basically says that if the universal constants like the strength of the strong force were any different - then in all likelyhood, life would fail to form and there would be nobody here to consider the question. Since we are here to ask the question, these properties must be almost exactly how they are. The strong force is what pulls two hydrogen nuclei together when they get close enough together. If it were weaker, it would be harder for protons to get together like that and we'd probably have no stars...or only much bigger stars or something...which pretty much means no life either. It's an answer - but not a very satisfying one. SteveBaker (talk) 03:07, 5 September 2009 (UTC)
I think you're confusing the strong force that acts on objects with color charge (quarks and gluons) with the residual strong force that acts on color-neutral objects like protons and neutrons. The latter is a lot weaker. I think it's comparable in strength to the electromagnetic force in the nucleus. -- BenRG (talk) 14:32, 5 September 2009 (UTC)
How are you measuring the strength of the forces? If you're referring to force, the strong strong force is sometimes stronger and sometimes weaker than the electrostatic force. Whether it is stronger or weaker depends on the charge, color charge, and distance of the objects the force is acting between. — DanielLC 16:23, 5 September 2009 (UTC)

falling distance[edit]

How high of an object could a person realistically expect to survive jumping off of onto a cement sidewalk, grass covered dirt the deep part of a swimming pool? I understand that this question may not be answerable with the given criteria, but perhaps there is a study that you could push my way that has looked into something kind of like this. Googlemeister (talk) 16:50, 4 September 2009 (UTC)

The nature of the fall (feet-first versus head-first) makes a massive difference - a small difference in HOW you fall makes all the difference in the world to the outcome. So there aren't going to be hard-and-fast answers. Anyway OSHA sets a 'safe fall' limit of 6 feet in most circumstances - without specifying the nature of the surface and says that hundreds of workers in the US die each year as a result of falls from as little at 10 feet. However, there are people who have fallen from airplanes without a (working) parachute who have survived falls from heights that guarantee they reached 'terminal velocity' - which means that it doesn't matter whether they fell from 1,000' or 40,000' - the result would be the same. Vesna Vulović (allegedly) fell 33,000 feet and survived (just) - but there are plenty of well-substantiated accounts of people falling from 20,000 feet and surviving with relatively minor injuries. So the answer is somewhere between 6 feet and 33,000 feet - I don't think that helps much! SteveBaker (talk) 12:36, 5 September 2009 (UTC)
Those really high falls generally have extenuating circumstances. Usually there is something providing them more drag than you would have normally and they usually have something to break their fall. Terminal velocity for a skydiver in the standard position before their parachute opens is about 120mph - I doubt anyone has survived going from 120mph to 0mph in a fraction of a second. --Tango (talk) 12:52, 5 September 2009 (UTC)
Certainly there are extenuating circumstances! That's what I'm trying to say. Check out Nick Alkemade, Ivan Chisov and Alan Magee for example. That's my point - some people die from a 10' fall, others suffer no injury. Other people survive a 33,000' fall. Professor Splash can dive from 40' into one foot of water in a kiddies paddling pool without injury(!) - but if you dive (badly) from just one foot above the water into a swimming pool that's less than ~6' deep, you can whack your head on the bottom and die. Yet Dana Kunze holds the high dive record at 174 feet into water - Kevin Hines who tried to commit suicide by jumping 280 feet from the Golden Gate Bridge and survived although 98% of people who do that don't. It's all about the circumstances...which is what makes answering this question in anything other than the vaguest terms impossible. SteveBaker (talk) 19:18, 5 September 2009 (UTC)

Opal inlays[edit]

Would it be possible to use opal for guitar inlays, instead of pearl? The reason I post here is because I'm interested in the practicality, are there any reasons why such a material could not be used? I gave Google a preliminary search but couldn't find much. Any links to information online would also be appreciated! Thanks. Regards, --—Cyclonenim | Chat  17:00, 4 September 2009 (UTC)

I'd think that a sheet of opal as thin as a soundboard inlay would be very prone to breaking in normal use (never mind Townshendisms), and that broken or cracked opal would be sharp enough to cut fingertips. I guess you could cut a much deeper rebate in the soundboard, allowing for a thicker inlay, but I don't know what that would do to the sound. -- Finlay McWalterTalk 17:15, 4 September 2009 (UTC)
I am pretty certain that actual pearls are not used for inlay work, it is mother-of-pearl, aka abalone that is used. Real pearls would likely not work well. --Jayron32 17:44, 4 September 2009 (UTC)
I'm concerned about the high water content of Opal and how that would affect the wood, if at all. @Jayron, I was aware of that but I always refer to it as pearl for the sake of effort (and I also couldn't remember the proper name!) ;) Regards, --—Cyclonenim | Chat  18:53, 4 September 2009 (UTC)
I don't think it is a problem - opals are not wet, the water is very well bound they do not leach water (the back could be coated anyway), a bigger problem might be the softness of the opal. Also did you mean electric guitar, or acoustic - electric would probably be easier. (talk) 19:01, 4 September 2009 (UTC)
No real preference to be quite honest, I play both, but I only ever have inlays on acoustic, so I suppose that's your answer. Regards, --—Cyclonenim | Chat  23:09, 4 September 2009 (UTC)
Opal is quite heavy - on the body it might not be good - but as frets (is that the right word) it might be ok. I can't see any real issues with it though, except acoustics and possibly it wearing quite quickly. (talk) 23:30, 4 September 2009 (UTC)
I wouldn't be suprised if there are plastic opal simulants available - which would probably have better characteristics than the rock ( a web search confirms such things exist) - probably cheaper too. (talk) 23:44, 4 September 2009 (UTC)

static electricity - clothes[edit]

Is there a simple explanation for why natural fibres (eg cotton) produce far less static electricity than synthetic fibes (eg polyester) when in rubbing contact? (talk) 17:51, 4 September 2009 (UTC)

Natural fibres tend to absorb water due to hydroxyl groups. If conditions are dry, silk and wool can produce static electricity when rubbed. Graeme Bartlett (talk) 22:43, 4 September 2009 (UTC)
I was wondering about that - but does that help conduct the static away - to where? (my shoes insulate) - or does it prevent the static build up in the first place (like a sort of short circuit)? (talk) 23:28, 4 September 2009 (UTC)
In the 18th century Stephen Gray (scientist) learned that some substances conduct electricity well and other poorly. In terms of high voltage, low current static electricity, wood, hemp or cotton drain off a charge. They are sometimes thought of as insulators for low voltages, but when a small charge at high voltage is to be kept from draining to ground, Gray found that silk or glass were superb insulators. He could use a hemp thread as a conductor for static electricity, and insulate it by hanging it from silk threads. So I suggest that natural fibers allow quicker drainage of charge than silk, or synthetics such as polyester or nylon. Fabric softeners or dryer sheets leave a slightly conductive layer of chemical on the clothing to drain off the static charge. Edison (talk) 23:42, 4 September 2009 (UTC)
That's interesting - anyone know (or want to guess) why silk is different from cotton - I know silk is a protein, and cotton a carbohydrate (of sorts) - but both are quite good at hydrogen bond (absorbed water) which was suggested as a cause for the non-static nature of some natural fibres. (talk) 23:48, 4 September 2009 (UTC)
Experiments by 18th century scientists showed that on a slightly damp day, static charge drained away faster than on very dry days. So they would dry the apparatus in front of a fire on a dry winter day for maximum static buildup. Cotton, wood, or hemp still drained off the charge, however dry you made them, but glass or silk insulated even better. I believe the slight conductivity is a characteristic of the fiber and not of the moisture. Maybe at extreme heat some water is driven off, but the fiber would probably lose its normal appearance and properties. If charred, it would probably be somewhat conductive from the carbon, but if reduced to ash it might be an insulator. That would not be recommended for your clothes, however. Edison (talk) 19:36, 5 September 2009 (UTC)

Are these properties physical or chemical?[edit]

Are taste, magnetism, and solubility in water physical or chemical properties? -- (talk) 21:31, 4 September 2009 (UTC)

I may be wrong, but I think taste is chemical, magnetism is physical, and solubility in water is chemical. Dogposter 21:42, 4 September 2009 (UTC)

Is this homework? Nimur (talk) 21:57, 4 September 2009 (UTC)
Yes. There were 10 properties and I had to say if each one is physical or chemical. All of the other ones were easy properties like melting point or reactivity with acids, but I couldn't figure out those three. -- (talk) 22:26, 4 September 2009 (UTC)
They are a bit tricky - taste is chemical - see taste - though obviously if something is hot (tea) or cold (ice) is a physical property - though that isn't actually a taste. There are chemical receptors on the the tongue...
Both magnetism and solubility are probably physical properties - though both depend on the chemistry - only certain chemicals can be magnetic , but if you are measuring how strong a magnet it that is definately a physical property. (talk) 23:24, 4 September 2009 (UTC)
In the standard High School chemistry text, chemical properties are those which require a "chemical change" to be seen; chemical properties describe how a substance combines with another substance, or decomposes into other substances. What a chemical property describes is how a substance undegoes changes into different substances. If the substance does not change into a new substance while observing the property, it isn't a chemical property. Thus "flammibility" is a chemical property, in that in order to observe if something is flammible, you have to, you know, change it into new stuff. However color is a physical property, because you can observe color by just looking at it. It does not require a change into a new substance to observe somethings color. Using THAT definition, the OP should easily be able to decide which properties are chemical and which are physical, without us having to do his homework for him. --Jayron32 01:26, 5 September 2009 (UTC)
Gah I hated these questions in high school. All they do is confuse students and make them draw arbitrary lines of distinction where none exist. Picking up an object by itself is a chemical reaction (Van der Waals repulsion). Magnetism is chemical (it depends on electron configuration, and you can actually cause changes in it by excitement -- see nuclear magnetic resonance). Melting point in itself is a chemical property, naturally (relying on chemical bonds).
Physical properties would be like the frequency of deformations/defects in a material, how much cold work hardening it has undergone, and these occur on the atomic scale and affect general properties of a material (like tensile strength or ductility). John Riemann Soong (talk) 07:16, 5 September 2009 (UTC)
When I was in the classroom teaching, I tended to glaze over this section as well; the state-mandated End-of-course tests always had some questions on it, so I had to teach it as they expected, but it always left a "bad taste" in my mouth. Still, there is some internal logic to the physical/chemical divide, just not a lot once you really learn chemistry. It is actually a good example of the Lie-to-children, that is the use of inaccurate models for pedagogical purposes; in this case learning to recognize a distinction between irreversable changes where new substances form, verses changes which do not change the type of substance. The same unit usually covers other categorization schemes, which I found much more helpful to later studies in chemistry, such as the distinction between a pure substance and a mixture (you'd be surprised how HARD it is for many students to recognize that Milk is a mixture while water is a pure substance!), or between a homogeneous and heterogeneous mixture (Tyndall effect). The physical/chemical categorization scheme is shitty, but it comes up in class, and will appear on the test, so we should at least make our best attempt to make it work for students when the do have inevitable questions about it. --Jayron32 11:55, 5 September 2009 (UTC)


I know of an edible cactus that is eaten in Mexico. The common name for it is Jacube, however I have not found anything online. Here is a picture. Bewareofdog 21:56, 4 September 2009 (UTC)

Jacube seems to be a name for Hylocereus undatus in at least some areas of Mexico. Try Googling for Hylocereus jacube and Tamaulipas jacube and tasajo jacube. (Tasajo, reina de la noche, and junco tapatío appear to be other names commonly used for the plant in Mexico.) My Spanish isn't quite up to interpreting all the results. Deor (talk) 00:45, 5 September 2009 (UTC)

Stomach to Bladder[edit]

I'm trying to get an estimate of the time, after drinking a bolus of water (say 16 ounces), until it shows up (say 1-2 ounces ) in the bladder. Then, assuming an average adult human how long until 8 ounces and then how long until 14-15 ounces gets to the bladder. I realize that there are many variables that would influence/confound the timing so I'm just looking for a rough generalized estimate. OR with alternative beverage is acceptable ;) Thanks all. hydnjo (talk) 22:03, 4 September 2009 (UTC)

There are so many variables that I don't think we can even give a meaningful estimate. It could vary from a few minutes to a few days (if ever). --Tango (talk) 22:22, 4 September 2009 (UTC)
It's not really a meaningful question. Water doesn't go from the stomach to the bladder. Water goes from the stomach to the bloodstream, if absorbed, or to the colon and from thence elsewhere if not. If absorbed, it affects the state of hydration, and the kidney compensates, if needed, by increasing urine output. But the urine excreted is, if you will, "randomly chosen" from the blood traveling through the kidney, and won't directly correspond to the water just absorbed from the stomach. If the water absorption is going to trigger additional output, it will do so when it's absorbed, it doesn't have to "go" to the kidney to do it. There's no "travel" delay; it will happen right away. - Nunh-huh 22:37, 4 September 2009 (UTC)
An addendum to Nunh-huh's thorough response — urine output from the kidneys is mostly (inversely) tied to the level of vasopressin (also called antidiuretic hormone) in the blood. If the body senses that it has too little water onboard, vasopressin is secreted to trigger its retention. (The regulation of vasopressin is a fairly complex process; our article gives a number of useful pointers.) TenOfAllTrades(talk) 23:30, 4 September 2009 (UTC)

To be more specific, I was trying to understand the body mechanics of one element of a urological exam which involved fasting, voiding, drinking, waiting and voiding again with some ultrasonic imaging of the bladder at various times. No medical advice being sought out, just some musing on my part about the drinking-waiting-voiding part. hydnjo (talk) 01:11, 5 September 2009 (UTC)

I don;t think anyone suggested you were seeking advice, medical or otherwise. In general, you fast before an imaging study (ultrasound or x-ray) to avoid complicating the view with undigested food; then it sounds like you void (to start with an empty bladder), then get imaged as the bladder fills (and is emptied??) What's the test's name? Anyway, it sounds like your question is how long it takes to fill a bladder, and that the answer depends on a lot of factors. Urine output should be on the order of 60 ml/hour. The average urinary bladder holds about 500-600 cc; you start to feel like you want to pee when it contains about 250-300 ml. So, as a ballpark figure, starting with an empty bladder, your bladder will be full enough to make you want to pee in about 5 hours, and be essentially full in about 10 hours. The more you drink, the more you decrease that waiting time. If you really wanted to speed up the process, you could hydrate with an IV. - Nunh-huh 03:49, 5 September 2009 (UTC)
Thanks Nunh-huh - that's the answer to the question that I posed so poorly at the outset. The testing was done to investigate a urine retention issue but I don't know that it has a name. Your explanation has added the context I wanted. Thanks also Tango and Ten for your inputs  :) hydnjo (talk) 11:30, 5 September 2009 (UTC)