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September 29

Criteria for mountain pass

Is there some sort of defined criterion or criteria for what does and doesn't constitute a mountain pass? Our article on the topic says that there are precisely 42 passes in the 5300-km-long border between Argentina and Chile; it would seem that some sort is necessary in order to say that most low spots between mountains aren't truly passes. Is there perhaps a minimum amount of topographic prominence for the mountains on each side of the pass? Nyttend (talk) 01:11, 29 September 2011 (UTC)

There could be within some limited context, but not in general. For a very non-pass-looking-pass, take a look at Deadhorse Pass, File:CupLakeDeadhorsePass.jpg—it's the dip on the right side of the photo. I wonder about the claim of "precisely 42 passes" on the Argentina-Chile border. Seems fishy. Perhaps there is some context, like "named passes" (although I would think there are many more than 42), or some arbitrary cutoff prominence. Or perhaps Chile and Argentina have some official standard they abide by for whatever the term would be in Spanish... Pfly (talk) 01:33, 29 September 2011 (UTC)

I would think that one criterion -- maybe the only one -- is that at least a few people have actually used it to get from one side to the other. Looie496 (talk) 01:41, 29 September 2011 (UTC)

That doesn't work. Someone could cross a mountain by going over the top, but that doesn't make the peak a pass! APL (talk) 02:15, 29 September 2011 (UTC)

According to [1] there are more than 42 official border crossings, all named "paso" such-and-such. Pfly (talk) 01:47, 29 September 2011 (UTC)

The full quote from mountain pass is

"For passes with roads, it is also customary to have a small roadside sign giving the name of the pass and its elevation above mean sea level. An example of this is Argentina and Chile that share the world's third longest international border, 5,300 kilometres (3,300 mi) long, running from north to the south through the Andes mountains, having a total of 42 mountain passes between them"

--emphasis mine. I think the article is saying that there are 42 passes with roads, each of which has a sign with a name and elevation. I have no idea if that's true, but it does seem to imply how the count was arrived at. SemanticMantis (talk) 01:55, 29 September 2011 (UTC)

mental excercise

What mental exercises ramp up the burning of calories to the max such that a person who is wheel chair bound can burn off as many calories as possible? --DeeperQA (talk) 02:12, 29 September 2011 (UTC)

Serious question? Plasmic Physics (talk) 02:34, 29 September 2011 (UTC)

CT scans are said to be used to find places in the brain where activity has increased as the result of seeing an appealing human form which have been said to cause excitement. The method I am told relies on the places in the brain where the greater activity is related to increased cerebral metabolism, i.e., the burning of calories. --DeeperQA (talk) 03:41, 29 September 2011 (UTC)

Perhaps playing a musical instrument ? Dealing with music seems to be a global process in the brain and presumably burns slightly more glucose. The movements involved in playing it probably burns more calories though I suppose. Sean.hoyland - talk 04:05, 29 September 2011 (UTC)

I'm pretty sure that the brain is like a TV, at least in that what's on the screen doesn't really influence how much power it uses.. Overall, your brain consumes about 20% of the oxygen you inhale, I've never heard of anyone "puffing them selves out" on a particularly strenuous mental activity. Vespine (talk) 04:13, 29 September 2011 (UTC)

I'm not so sure. Try doing something which is likely to use as many different parts of your brain as possible: translate this article Polynesian navigation into medieval French (or whatever obscure language you prefer) while balancing a spinning plate on a stick held in your mouth - none of this will involve a great deal of physical effort, but your brain will probably tire rather quickly. If Vespine has never 'puffed himself out' from mental activity, he has either been exceptionally lucky, or has more mental grunt than the rest of us. AndyTheGrump (talk) 04:27, 29 September 2011 (UTC)

Have a look at this table from here.

The following lists the amount of energy used during various activities in kJ/kg/h. (Sorry it's not in calories. We're metric here.)

Sitting quietly 1.7

Writing 1.7

Standing relaxed 2.1

Driving a car 3.8

Vacuuming 11.3

Walking rapidly 14.2

Running 29.3

Swimming (4km/hour) 33

Rowing in a race 67

It's the fourth line that's important - Driving a car. We do that while sitting down. Many wheelchair users drive. We all know we get tired after driving for a long time. Obviously it uses more energy than just sitting there. HiLo48 (talk) 04:35, 29 September 2011 (UTC)

I'd say you can just as easily claim that the second line is critical; presumably writing takes more creative thought than sitting quietly. Driving, on the other hand, requires near-constant use of major muscle groups. "While sitting" and "just sitting" are very different things. — Lomn 13:05, 29 September 2011 (UTC)

Yes, there clearly is a relationship between what the brain is doing and the amount of energy it uses because you can see it for yourself on a PET scan although the activity specific changes seem to be in the <= 5% range according to this source in Brain#Brain_energy_consumption. Sean.hoyland - talk 04:56, 29 September 2011 (UTC)

Paraplegic or Quadriplegic? In either case, singing along out loud to and dancing (to whatever extent is possible) with some fast paced music. The soundtrack to Saturday Night Fever is excellent. It gets the whole body in motion, including the brainwaves. μηδείς (talk) 19:11, 29 September 2011 (UTC)

The metabolic rate and the blood flow to different brain regions varies when they are active or inactive, as a function of the task, and the harder a part of the brain is working, the more glucose it metabolizes, just as a given muscle does: [2], [3]. I would be expect that that the overall metabolic activity of the brain, and the energy it uses, and the waste heat it produces, less when one is sitting with the eyes closed and the mind blank. or in a dreamless sleep, than when doing difficult mental activity such as memorizing, learning a complex task, designing something, doing mental arithmetic, or taking a difficult math test. I would even expect that brain metabolism varies during the various stages of sleep, since some dreams represent incredibly complex creativity. One reason for this is that the faster a neuron fires, the more energy is required to repolarize it. How hard the brain is working, and at what type of task, causes less variation in the eneregy consumption than for muscles, since the brain is never really inactive. Even when "idling," it consumes a huge amount of energy. It is about 2% of the body's mass and consumes about 20% of the energy:[4]. Edison (talk) 20:09, 29 September 2011 (UTC)

I disagree with one of the above comments about driving, there's a bigdifference between getting "tired" and actually doing meaningful exercise; sitting on a couch doing nothing for 3 hours can be very tiring. Similarly, in reply to Andy's comment: If Vespine has never 'puffed himself out' from mental activity, I wasn't talking figuratively, I meant literally puff yourself out, like you would after running around the block. Yes a chess grandmaster might need a rest after playing a challenging game because they are mentally exhausted, but that is a very different kind of exhausted to someone who has just skipped a rope for 20 minutes. I doubt very much that you burn (EDIT: significantly) more calories playing a challenging game of chess compared to relaxing and reading a book, and if you do, it's probably more due to things like heightened stress rather then actual mental activity. Vespine (talk) 22:53, 29 September 2011 (UTC)

What kind of books do you read that don't require mental activity? Is it something written by Rush Limbaugh? Googlemeister (talk) 13:13, 30 September 2011 (UTC)

Vespine, that's actually an important difference here. If you found that the game of chess burned more calories than relaxing due to heightened stress, then that would be an answer to OP's question. He or she doesn't ask anything about the brain, he asks specifically about burning calories. – b_jonas 17:29, 30 September 2011 (UTC)

A double planet that shares an atmosphere?

Let's say there were two planets that were both identical to our earth. The only difference is that they were close enough that their exospheres touched (The shortest distance between the two planets' surfaces would be 1 megameter). Let's assume everything else is the same as far as our earth is, except that this double planet shares a single moon which orbits the two earths' center of mass. Now, obviously they would be tidally locked to each other. But how stable would this configuration be? How fast would they be rotating around their center of gravity? Would humans or any life forms be able to survive on this double planet? Assuming that they could, what would be the physics behind traveling from one planet to the other? In other words, given our current technology, how feasible would it be to design aircraft (or would it be spacecraft?) that would be able to fly from one planet to another?

Thanks. --70.122.116.118 (talk) 04:55, 29 September 2011 (UTC)

If each planet were Earth size and Earth mass, I think tidal forces would rip both planets apart, and when the dust settled, there would be one large spherical planet. Gandalf61 (talk) 08:17, 29 September 2011 (UTC)

I'm not really sure how best to calculate it. I'm not sure the usual formulae in Roche limit are going to hold in this case. If I've done the calculations right (somebody please check!), then the tidal acceleration on a loose object sitting on the surface of one of the planets (assuming the planets are solid, rigid objects) is 5.2m/s². That is less than the 9.8m/s² gravitational acceleration at the Earth's surface, so it would not be lifted away from the planet it is sitting on. Even if the two planets were touching each other, the tidal acceleration would only be 7.3m/s². My assumption that the planets are completely rigid isn't true, of course, and it is possible that, if deformation were taken into account, I would get a different conclusion. --Tango (talk) 12:41, 29 September 2011 (UTC)

Think of it this way. Imagine a spherical boulder sitting in the middle of a flat desrt. How big do you think the boulder could be before it collapsed under its own weight ? The size of a large skyscraper ? The size of a mountain, maybe ? Certainly a boulder the size of the Moon would just crumble. Now imagine a boulder the size of the Earth ... Gandalf61 (talk) 14:54, 29 September 2011 (UTC)

It's in orbit, so it's weightless. That means it can't collapse under its own weight. In order to be ripped apart, you need tidal forces to be greater than its self-gravitation (and its structural strength). The bigger (strictly speaking, denser, but big tends to mean dense) the object is, the less likely it is to be ripped apart, not more. --Tango (talk) 17:06, 29 September 2011 (UTC)

Gandalf61's thought experiment is close enough to be perfectly illustrative. An object in orbit is not so much weightless as in free fall--but it is entirely subject to gravity and the tidal forces it generates. Two earths approaching 1000km apart (no such orbit would be stable, it's well below the Roche limit) both would crumble into each other just as Gandalf61's thought experiment implies as well as be spinning around each other at terrific speed.μηδείς (talk) 17:35, 29 September 2011 (UTC)

There is no one "Roche limit", it depends on the object. For an object with as much self-gravity as the Earth, it's much closer than for, say, a comet. Unless my calculations above are in error (which is possible), then the planets could touch before getting past their Roche limit. --Tango (talk) 20:06, 29 September 2011 (UTC)

Who said there was "one" Roche limit? And yeah, your calculations are wrong. The Earth-moon Roche Limit is just under 10,000km. See http://en.wikipedia.org/wiki/Roche_limit#Roche_limits_for_selected_examples μηδείς (talk) 20:18, 29 September 2011 (UTC)

You did, and you've just done it again. We're not talking about Earth-Moon. We're talking about Earth-Earth. The Earth is a lot denser than the Moon, so the Earth-Earth Roche limit will be much closer than the Earth-Moon one. Suggesting that the Earth-Moon Roche limit is relevant to a discussion about the Earth-Earth Roche limit suggests you don't understand that there are different Roche limits for different objects. My calculations are just based on Newton's law of universal gravitation, so you can easily check them yourself. --Tango (talk) 23:05, 29 September 2011 (UTC)

Whether an airplane (something requiring air) could fly between them would depend on the shape of their atmospheres - it's certain that the atmosphere of each would bulge towards the other, and it's possible that sufficient air would be pulled in between them to form a column that a plane could fly through - I'm not sure how likely this would be, since it would probably result in thinner air at the ground. Rockets would be fine - the space shuttle could get 600km above the earth, and you only need to go 500km to reach the midpoint and begin your descent. Assuming the planets are tidally locked, it may also be possible to build a 1000km tether to bridge the gap - see space tether. --Colapeninsula (talk) 11:33, 29 September 2011 (UTC)

Such a situation was portrayed fictionally by Bob Shaw in his Land and Overland trilogy, whose second volume was called The Wooden Spaceships. In conversation, he used to say that this scenario would be possible given a different value of pi, but if pressed on what value, he would mutter "Whatever it takes to make my planets work." {The poster formerly known as 87.81.230.195} 90.197.66.236 (talk) 14:11, 29 September 2011 (UTC)

If this atmosphere stuff interests you you might want to read Larry Niven's The Integral Trees. μηδείς (talk) 17:38, 29 September 2011 (UTC)

Can intermediate or stellar mass black holes be detectable gravitational lenses?

Could an ordinary black hole or an intermediate mass black hole (say less than 50,000 stellar masses) produce detectable gravitational lensing? I ask because [5] says "Micro-lensing shows no change in the lensed object's shape, just in brightness." 69.171.160.131 (talk) 05:54, 29 September 2011 (UTC)

Gravitational lensing cannot tell what the focussing object is, but it can give an idea of the mass and how fast it is moving. Stellar mass blackholes should be possible candidates to observe this way. The main issue will be the probability that one crosses in front of a distant star. There should be quite a number of large mass stars that have collapsed into blackholes, but still they would be much less common than white dwarfs or red dwarfs. A 50000 solar mass back hole is probably very very infrequent, even if it does have a bigger sphere of influence, there would be a slimmer chance of detection. Graeme Bartlett (talk) 10:52, 29 September 2011 (UTC)

TLC versus GC

1. What's one advantage and one disadvantage of thin layer chromatography when compared with gas chromatography.

2. List two examples of poor spotting techniques in TLC.

3. How is the Rf value similar to the retention time value in GC? --98.88.80.117 (talk) 06:52, 29 September 2011 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. Roger (talk) 07:30, 29 September 2011 (UTC)

2. I carried out TLC a couple of days ago. I don't really know how to verbalize poor spotting techinques in TLC. I held my TLC paper under UV light and cirecled what seemed like the center of the mobile phase.--98.88.80.117 (talk) 07:46, 29 September 2011 (UTC)

TLC is not well suited for quantitative analysis, or even very good qualitative analysis, because it has really bad resolution. Your spotting technique will affect your resolution; if your spot is too small, you won't see the components as they get carried up the TLC matrix. If your spot is too large, then it tends to spread out too much and you will get bad resolution, as the spots won't seperate well and won't travel well, and will instead tend to merely "smear out". --Jayron32 19:20, 29 September 2011 (UTC)

How to include more ordinary people in Wikipedia

Aside from the lack of attention to the REAL WORLD KNOWLEDGE of your contributors, the great problem with Wikipedia is that it doesn't provide a REDUCTIONIST option. Nearly everything you reflexively present is "expansionist," branching out into endless NEXT LINKS, with no focus on a universal (fixed) reference point: mine is SCIENTIFICALLY VALIDATED INFORMATION, by people who know a lot about the BIG VIEW in the particular subject being discussed.

I'd prefer to always be given a link to a REDUCTIONIST version of what the article is about. For example, I'd like to have a reductionist version of the Diagnostic Statistics Manual, in which the states of the human mind are reduced in a way that ordinary people can easily grasp what the text is saying. Instead of listing endless speculative categories, I'd prefer your presentation of information to be FOCUSED ON THE REDUCED ESSENCE of the subject being discussed. I'm a PhD psychologist (and an Aspergian), frustrated with the atomization of everything, and wanting to reduce discourse to its core elements. For instance, I'd like to hear from the psychologists who regard the human animal (all animals) in terms of POSITIVE AND NEGATIVE (equivalent to WANTING AND NOT-WANTING) neural systems (limbic structures) that deterministically cause-force-allow humans to approach or avoid cognitive events in the external world and within their own selves.

This is a big subject. Ring me on [redacted], or send a reaction to [redacted].

Thanks, Peter Norris PhD (really) — Preceding unsigned comment added by Peter Scott Norris (talk • contribs) 08:00, 29 September 2011 (UTC)

I think you have a perfectly valid viewpoint. You might with to discuss that on the talk/discussion page for that specific article. Killiondude (talk) 08:04, 29 September 2011 (UTC)

OP's personal information removed per instructions at top of page: "Do not provide your contact information. E-mail or home addresses, or telephone numbers, will be removed. You must return to this page to get your answer." AndrewWTaylor (talk) 10:12, 29 September 2011 (UTC)

And please do not shout at us, we haven't done you any wrong that is worth being shouted at. Surely a guy with a PhD has had enough exposure to the internet that he can understand that words in capital letters is the equivalent of shouting?--Lgriot (talk) 14:20, 29 September 2011 (UTC)

Reductionist? I do not think that word means what you think it means. I get the gist, though, and recognize the common frustration of being led into clicking through a series (or worse, a branching tree) of links to different articles, in the course of trying to understand some unfamiliar subject area. It's difficult to fix, because: although it's desirable, from the point of view of any individual reader, to reduce an article to only its core elements, each reader will have a different idea of what those core elements are. (I use italics instead capitals, they don't seem to upset anyone.) Articles on important subjects have a lot of links because they are important in a lot of different contexts. The core information is the information germane to a particular context. So not much can be done to make such an article better, beyond a certain point, all though all kinds of spurious information could be added to make it worse.  Card Zero  (talk) 14:59, 29 September 2011 (UTC)

That's a topic for the Village Pump, not for any article talk page or for the ref. desk. Quest09 (talk) 14:54, 29 September 2011 (UTC)

Whether you like Wikipedia or not, you are under no obligation to use it. Would you like help finding other resources that are not as expansive? Wikipedia is the largest encyclopedia in the world. If you would like an encyclopedia with a little less content, you might find one by at the List of encyclopedias, which is ironically an expansive list that links to several other expansive lists. I highly recommend the World Book Encyclopedia, but I recognize at least a few shortcomings (it's geared toward a primary- or secondary-school level of knowledge for most subjects, with a clear bias of coverage toward American topics). Nonetheless, the quality of content and the editorial control are very good. Nimur (talk) 16:58, 29 September 2011 (UTC)

You might try creating more "introductory" articles. For instance, we have introduction to special relativity and introduction to quantum mechanics. However, since the opposite of reductionism might be something similar to holism in terms of the project and the focus on determinism is likely not a certainty in psychology, a conflict of opinion may result. Regards, ~AH1 ^(discuss!) 01:42, 4 October 2011 (UTC)

SMILES

According to simplified molecular input line entry specification procedures, a double bond is "=", a triple bond is "#", a quadruple bond is "$", and a bond and a half fraction is ":". What is the character for half a fraction bond? Plasmic Physics (talk) 10:17, 29 September 2011 (UTC)

Where do those occur? Can they be implied with % ring closure notation? SMILES has no provision for explicit intermolecular bonds like hydrogenation, for example, which limits its usefulness for many minerals. 69.171.160.237 (talk) 19:34, 29 September 2011 (UTC)

They occur in molecules like H⁺
₂ (one ½ bond), or AuCl
₃ (three ⅔ bonds). Plasmic Physics (talk) 19:58, 29 September 2011 (UTC)

I think H⁺
₂ is [H][H+] and while AuCl
₃ is actually Au
₂Cl
₆, its article says the empirical/ion formula is [Cl-].[Cl-].[Cl-].[Au+3] which can't be right; I'd say [Cl-]1.[Cl-]2.[Cl-]([Au+3]1)2. 69.171.160.237 (talk) 21:25, 29 September 2011 (UTC)

H⁺
₂ is [H]-[H+] only in Lewis structure (valence bond theory) which requires that elements have whole number formal charge and that bonds must always exist as pairs of electrons. Real molecules are better described by molecular orbital theory which more accurately represents things like fractional bond ordder. Take H⁺
₂ for example: In reality, why would one H atom have a greater affinity for the electron than the other would? The electron density should be uniform across the molecule. An even better example of where lewis structures really have problems is with diborane. Now, SMILES is based on Lewis theory, so it may have the same sort of problems with properly dealing with fractional bond order as drawing Lewis diagrams on paper does. --Jayron32 21:45, 29 September 2011 (UTC)

In the AuCl
₃ monomer, there are three ⅔ bonds however, in the dimer there are eight ½ bonds. In diborane, there are four single bonds and four ½ bonds. Plasmic Physics (talk) 22:53, 29 September 2011 (UTC)

There is a misconception, the AuCl
₃ monomer is not Gold(III) trichloride, but Gold(I) trichloride(-⅓). Plasmic Physics (talk) 23:08, 29 September 2011 (UTC)

You say: "It may have the same sort of problems with properly dealing with fractional bond order as drawing Lewis diagrams on paper does." Although there is a SMILES representation for fractional bonds - for bond orders between 1 and 2, there is ":". Bonds that lie between 1 and 2, are represented in Lewis theory as a double line, one solid, the other dashed. Therefore a bond that lies between 0 and 1 should be represented by a single dashed line in Lewis theory. Plasmic Physics (talk) 01:59, 30 September 2011 (UTC)

Yeah, but that sort of representation is a sort-of "workaround" for Lewis structures, just like "bond resonance" is. Its a somewhat inelegent solution (for example, the "line w/ dash": What fraction does it represent? How does it distinguish between a 3/2 bond order and a 4/3 bond order?). Lewis structures are useful, to a point, once you understand their limitation. --Jayron32 02:20, 30 September 2011 (UTC)

From my knowledge, its representative fraction is usually implied by the valencies of the adjoined atoms. Plasmic Physics (talk) 02:56, 30 September 2011 (UTC)

Well, of course, but then again if you are using the valencies of the surrounding atoms, a single line would do equally as well. In general, the standard practice when working in Lewis structures is to write all possible resonance forms, like this: [6]. The dashed-line thing is a later innovation to save time from having to write out all of the contributing resonance forms. That practice is common, but not part of the "standard" rules for working with lewis structures. --Jayron32 03:10, 30 September 2011 (UTC)

A single line doesn't make sense, because it always depicts a unity bond order. That kind of resonance doesn't exist, you should know that. At all times are there three 1 ⅓ bonds. The bonds, don't alternate between 1 and 2 as is depicted in Lewis structures. As far as I know resonance structures was the norm before anyone actually knew what really happens, like the deferent and epicycle theory in Ptolemaic astronomy, before the heliocentric nature of the solar system was known. The single line approach for fractional bonds doesn't make sense in diborane, it would imply that hydrogen is somehow sharing two electrons. Plasmic Physics (talk) 03:43, 30 September 2011 (UTC)

Well of course, resonance is not a real thing. That's the shortcoming of Lewis Structures. I believe I already said that. There are workarounds to deal with the problems, but they are still workarounds and not part of the actual rules for working with lewis structurs. That's the whole problem Restating my words back at me doesn't mean I didn't already say them in the first place. There is not an adequate, elegant method for handling fractional bond order in Lewis structures. You can invent concepts (resonance, the dashed line thingy, etc) which attempt to deal with the problem. Those workarounds don't get at the fundemental problem, which is that Lewis structures aren't well designed to deal with fractional bond order, and sometimes (as with dioxygen) they just get it completely wrong in ways that cannot be fixed. "All models are wrong. Some models are useful..." --Jayron32 03:52, 30 September 2011 (UTC)

So we should accept that some compounds simply don't have SMILES. Plasmic Physics (talk) 10:44, 30 September 2011 (UTC)

Sure, like graphite. 69.171.160.198 (talk) 03:46, 2 October 2011 (UTC)

What do you mean? Plasmic Physics (talk) 11:36, 2 October 2011 (UTC)

You can't code graphite in SMILES. 69.171.160.45 (talk) 08:51, 3 October 2011 (UTC)

That can be said concerning any polymer. Plasmic Physics (talk) 09:37, 3 October 2011 (UTC)

Some monomers or multiples thereof can be coded in such a way that the polymer is explicit, but graphite is the simplest example where that is not possible. 69.171.160.201 (talk) 20:09, 4 October 2011 (UTC)

Try this, [c]123[c]45[c]67[c]89[c]%10%11[c]1([C]2468%10)[C]3579%11. Plasmic Physics (talk) 22:43, 4 October 2011 (UTC)

Beetle or Bug Identification

Not much to go on, but any suggestions would be welcome. Seen today in ancient woodland, just north of London in south-east England. Apparently a beetle with wing-cases that appeared to fully cover the wings, but similar size and shape to a shield bug, or maybe a little smaller. Its back was silver-grey and rough, so that it resembled a piece of lichen. Sorry, no photograph. Any ideas anyone? Alansplodge (talk) 12:55, 29 September 2011 (UTC)

Without a picture it's impossible. One thing to remember though: true bugs (Hemiptera) have four membranous wings. Their "wing cases" (the scutellum) also do not split down the middle. If this is the case and the scutellum more or less covers the abdomen entirely, then it is a jewel bug/shield-backed bug (Scutelleridae, the hemipterans which resemble beetles most closely).

True beetles (Coleoptera), on the other hand only have one pair of membranous wings. Their "wing cases" (the elytra), are actually hardened forewings. So unlike scutellerids, it does split down the middle. Another thing to look at is mouthparts. Hemipterans will invariably have sucking needle-like mouthparts (a rostrum) while beetles will have chewing or biting mandibles (although in some cases, like weevils, they may be so greatly modified or small, it's hard to recognize them).-- Obsidi♠n Soul 13:09, 29 September 2011 (UTC)

Need more information on the nature of the woodland, but initial enquiries lead me to suggest either a Hawthorn Shieldbug or a Parent Bug. --TammyMoet (talk) 13:50, 29 September 2011 (UTC)

It's a really diverse woodland that was enclosed into a park about 150 years ago. Dominant species are oak, hornbeam, sycamore and alder with a mid-layer of hazel, hawthorn, elder, sallow; plus old specemins of spruce, beech and sweet chestnut. Easily 20 species in about 5 acres. Not much help huh? Alansplodge (talk) 16:59, 29 September 2011 (UTC)

At least point out a picture which most resembles the animal in shape and characteristics? Wild guess, it may be a sunn pest.-- Obsidi♠n Soul 17:27, 29 September 2011 (UTC)

Luckily for us, we don't appear to have sunn pests in England. Alansplodge (talk) 10:36, 30 September 2011 (UTC)

Thanks for the description Alan, I was curious to know whether it was chalk woods. Any of them on here? --TammyMoet (talk) 17:37, 29 September 2011 (UTC)

No, it sits on London clay and Reading Beds which is a sandwich of sand, clay and pebbles. I scoured the internet and some general guidebooks before posting, but couldn't see anything like it. It was found by a 9 year old from a primary school class and I said that I'd find out what it was. I was hoping that the lichen-like appearance would ring a bell with someone. Alansplodge (talk) 09:44, 30 September 2011 (UTC)

Me again; after another web search, I think I might have got it. The Fungus weevil seems to fit the bill. "...a very strange one. It looks like it is covered in fungi and it even has small brushes of hairs growing on top... They are closely related to the ordinary weevils, only their snout is large and flat."[7]. The lack of a weevil-type nose stopped me from looking in that department before. The picture doesn't look exactly like mine, but there are many species. Many thanks for all your efforts, and apologies that I led you up the "shield bug" path, but it was the nearest thing I could think of. Alansplodge (talk) 10:28, 30 September 2011 (UTC)

This seems to be the one; Platystomos albinus. Maybe mine was a little lighter in colour, but close enough. Alansplodge (talk) 12:17, 30 September 2011 (UTC)

Resolved

"True bugs"

The previous question brought up another one for me: why is Hemiptera the order of "true bugs"? I mean, what's special about about them that they get to claim to be the only "true" bugs, and everyone else is just a misnomer?

The OED says that the word "bug" has been used generically to mean any miscellaneous insect as early as the 17th century. It's not clear from it (to me) when the specific usage of "bug" for only Hemiptera became important. The use of "bug" in the context of "bed bugs" seems to go back very far, but it's not clear to me why that term would then be generalized to that specific order (as opposed to their family).

Anyone have any real insight on this, or is this just some silly scientific custom? I've always found it very strange to insist, "oh, that's not a true bug..." --Mr.98 (talk) 14:51, 29 September 2011 (UTC)

First of all, it's not a scientific custom at all, it's a silly laypeople custom. Biological sciences themselves do not rely on common names. The reason for the ambiguity is because in everyday language, names for organisms are very very arbitrary (also why I always prefer to create taxonomical articles with their scientific names unless they have an unambiguous common name widely understood).

Oh, and bed bugs are also hemipterans. And I'm not sure what you mean by "generalized to that specific order (as opposed to their family)"... bedbugs were not the first insects called 'bugs'. Obvious in the way it requires a modifier - 'bed'.

Though "bug" certainly had more widely applicable etymons, there was a certain time when they begin to be applied specifically to certain kinds of insects (though I do not know when), which turned out to be hemipterans. People back then weren't exactly discriminating when it comes to which is which in such things. Another example is 'hornet', which was once applied to any large noisy flying insect in Old English. If someone calls a beetle a 'hornet' now, would you also think it silly if someone says "oh, that's not a hornet..."? What about if someone calls a marmoset an "ape", a dolphin as a "fish", a harvestman a "spider", a hyena a "dog" etc.? Adapting common names to point to an exact taxon minimizes confusion.

In taxonomy, they are simply hemipterans and coleopterans. That's it. No ambiguity whatsoever despite their superficial similarity to a layman.-- Obsidi♠n Soul 15:31, 29 September 2011 (UTC)

My understanding from the OED is that bed bugs were called "bugges" well before the "bed" got added. Apparently that goes back to the 17th century as well. Anyway, the above doesn't really explain anything other than saying, "it's arbitrary and I don't know when it started." --Mr.98 (talk) 16:16, 29 September 2011 (UTC)

Go back further than that and it was used to refer to beetles, grubs, and lice. Its application to bedbugs in M.E. may have influenced later usage specifically for rounded large insects which have sucking mouthparts. It's really common sense isn't it? Biological taxa have very specific delineations where one organism can not be a member of another, and hemipterans and coleopterans are quite distantly related, despite both being insects. Unless you're quite adamant with the "science is silly" thing, then discussion is irrelevant.

Like mentioned, dolphins and whales were also "fish" just a few centuries ago. In some languages today, they still are. Should we go back to that and also call them fish, and call people who insist that they are not "true fish" silly? There's a reason why mere morphology is not used for classifying organisms. Otherwise, we wouldn't have bats or birds, we'd have mouseflies and featherflies.-- Obsidi♠n Soul 16:40, 29 September 2011 (UTC)

(Like Die Fledermaus, you mean?) 75.41.110.200 (talk) 17:21, 29 September 2011 (UTC)

I only know the short from Disney. :P -- Obsidi♠n Soul 17:30, 29 September 2011 (UTC)

I'm asking a historical question — when "true bug" became a meaningful distinction. I'm not saying "science is silly". I'm asking when it started. You don't seem to know and don't seem to have the means to find out. I am not looking for a lecture in generic taxonomy. I know what taxonomy is and how it works. --Mr.98 (talk) 18:55, 29 September 2011 (UTC)

Then this should be in language shouldn't it? If you're wondering why I feel obliged to answer when I don't think there even is an answer is that I was the poster who replied with the "oh, that's not a true bug". And your OP makes it feel like I had no basis in doing so, which is more than a little insulting. Also 'generic taxonomy' refers to genus-level taxonomy. I'm sure that wasn't what you meant, since we aren't exactly talking about genera here.

Anyway, when Linnaeus separated Insecta into different groups, he based his classification on wing form. He established Coleoptera and Hemiptera ('sheath wing' and 'half wing' respectively) in the 10th edition of his Systema Naturae (1758 - 1759). When you look at the insects he separated (see 1806 English translation), you realize that members of the first group tend to have common names in English that end in beetle (particularly those known to bite - rove beetles for example). Also see William Fordyce Mavor's The elements of natural history (1806) and Oliver Goldsmith in A history of the earth, and animated nature (1804).

It's not a stretch to imagine that Hemiptera became 'true bugs' to distinguish them from 'false bugs'. Including the beetles, which during that time were still lumped together with the term 'bugs' (cf. ladybugs, june bugs, horn bugs). When the 'false bugs' have been stripped out, you really are left with a group that is mostly composed of hemipterans - hence true bugs. And like I said earlier, it's M.E. application for bedbugs may have influenced subsequent adoption as a group name for Hemiptera since bedbugs were the best known of the insects already called bugs as well. And they exhibit a number of distinctive features shared by all Hemipterans - piercing mouthpart, shape, smell - which are so evident even from cursory inspection by a layman that they probably became the diagnostic criteria for the group. Other group common names have originated in similar ways.

What else is there anyway? All I know is that calling beetles 'bugs' as if they belong to the same insect group is confusing and wrong. Like calling a panda a 'bear'. -- Obsidi♠n Soul 21:54, 29 September 2011 (UTC)

Actually, the Panda is a bear, or at least the sister clade to the true bears. μηδείς (talk) 04:00, 30 September 2011 (UTC)

Ooh. Pointless snide digging aside, this is new to me. They finally made a decision, eh? Rest of it still stands. -- Obsidi♠n Soul 10:53, 30 September 2011 (UTC)

Some know-it-all declaring that only this type of bug is really a "bug" is reminiscent of the half-educated person declaring that "classical music" was only composed from 1750 to 1830, and that Baroque or romantic music is not "classical." Broadly speaking, classical music is classical music, and bugs are bugs. I listen to one on the classical music FM station, and I squash the other. (Figuring out which is left as an exercise for the reader). Edison (talk) 06:00, 30 September 2011 (UTC)

Go ahead and call anything that crawls a 'bug'. You sound very educated and doesn't-know-it-all-ish when you do so, broadly speaking. Next time someone asks for an ID of an insect here, just say "that's a bug, squash it". In fact, let's just reinvent taxonomy altogether. I propose we start calling Arthropoda "creepy crawlies"; Insecta as "bugs"; Coleoptera "fat bugs"; Lepidoptera "pretty bugs" (adult), "fugly bug" (larva); Hymenoptera "run away from this bug"; Orthoptera "noisy bugs"; Diptera "annoying bugs"; Odonata "bigass bugs"; etc. After that, we all dump our biology classes (if you haven't already) and just listen to FM to get our full dose of edumacationz. -- Obsidi♠n Soul 10:53, 30 September 2011 (UTC)

Look at all these half-educated people. Amazing what they teach our children nowadays eh? I wager they don't have FM.-- Obsidi♠n Soul 11:22, 30 September 2011 (UTC)

"Worry the bottle mama, it's grapefruit wine..." --Trovatore (talk) 18:22, 30 September 2011 (UTC)

In England, people say sometimes say "bug", but they generally know that it's American slang. In general parlance, most people say "insect", or "creepy-crawley" for anything else that obviously isn't an insect but is in that general class of creature. It often comes as a surprise to laymen to find that there are things that can properly be called "bugs". Alansplodge (talk) 11:56, 30 September 2011 (UTC)

Can it be said that ethanol is an energy carrier rather than an energy source?

If this is true, would the energy source be, sunlight and dead organic material? 198.151.130.145 (talk) 14:54, 29 September 2011 (UTC)

It can certainly be said. It could then be debated, but it seems reasonable on the surface. Note, however, that "dead organic material" will then reduce to "sunlight". — Lomn 14:59, 29 September 2011 (UTC)

So if that's the case, then what is more efficient: making ethanol, or using solar panels and storing the energy in a battery? 198.151.130.145 (talk) 15:01, 29 September 2011 (UTC)

It probably depends on what you mean by "efficient" (particularly, how far back in the manufacturing process are you looking, how far forward are you willing to look for future gains, and what are you optimizing?) Note also that, for portable fuels, energy density is a particularly relevant value. Per our chart, batteries are particularly bad, ethanol is middle-of-the-road, and gasoline/diesel quite useful. Hydrogen is an interesting case in that it's exceptional on a per-mass basis but handicapped per-volume since you can't conveniently store it as a liquid. — Lomn 15:17, 29 September 2011 (UTC)

Faster-than-light travel

Why would an object traveling faster than the speed of light arrive at its destination before it leaves? --Melab±1 ☎ 15:43, 29 September 2011 (UTC)

It wouldn't. Googlemeister (talk) 15:50, 29 September 2011 (UTC)

Depends on the observer. Some observers would indeed see that happening. Dauto (talk)

To understand that you have to understand Lorentz transformation and velocity addition. Dauto (talk) 16:53, 29 September 2011 (UTC)

The article, Relativity of simultaneity, is also a good introduction to this conceptual idea. The trouble is, "the moment of departure" is not a universal "moment." It is a coordinate - an (x,y,z,t) coordinate for a specific position and time. One of the first things you need to know about relativity is that coordinates are relative to an observer's frame of reference. The Lorentz transform provides the most simple method to calculate a coordinate transform between two observers. However you want to look at this: if an object moves faster than light, either causality is violated, or the equations we currently model spacetime with are violated. The most succinct way I can think to state this: for v > c, proper time is poorly-defined (it is the square root of a negative number). Nimur (talk) 17:12, 29 September 2011 (UTC)

I can imagine there are perhaps methods to restrict or restore causality using strings?... and there appears to be possible extensions to the Standard model, but I am not familiar with them. What I am familiar with though is a model that I've been working on which directly and succinctly addresses this whole topic, and you guys just might like, :-), what I have when you get to see it because I plan to blog on it, although I am not sure yet what date I'll start posting. But when I do I'll put a link, to my blog, on my Wikipedia user page. I almost never update that page thus if you watch it and it eventually turns up in your watchlist, its because I either added the link or, alternatively, I'm giving some lame excuse for not following though with this. --Modocc (talk) 20:54, 29 September 2011 (UTC)

I don't think this question can be sensibly answered. There's a standard answer that assumes Lorentz invariance, but the very existence of faster-than-light propagation would seem to be strong evidence that Lorentz invariance is wrong. The traditional idea of tachyons from the early days of special relativity (1910s, 1920s) just isn't relevant any more. In modern field theory, everything propagates at light speed, even "tachyons". (See this page, particularly the part about unit propagation velocity.) In the wake of the OPERA paper I've heard people suggest that neutrinos could take a "shortcut through extra dimensions", but as far as I know this is simply a way of breaking Lorentz invariance—the shape of the extra dimensions violates the symmetry. Likewise I've heard people say that loop quantum gravity allows for different maximum propagation speeds for different particles, but again LQG breaks Lorentz invariance. The principle of causality, that "things can't arrive before they leave", seems much more likely to survive a shakeup of physics than the principle of Lorentz invariance. Assuming, of course, that the neutrinos really are superluminal, which they almost certainly aren't. Even the OPERA team thinks it's a measurement error. -- BenRG (talk) 20:22, 29 September 2011 (UTC)

Personally if true tachyons were found, I think it is much easier to accept that causality and time as we experience it are merely an illusion, then to suggest that some version of Lorentz invariance (or at least a close approximation thereof) isn't true. There are ways to cheat by adding extra dimensions and making small modifications to Lorentz invariance, but you can't change it very much without diverging from lots of experimental results. On the other hand, most of physics can be understood just fine without invoking any notion of causation. In that sense, I personally think that causation is more peripheral and superfluous to physics than Lorentz invariance is. Dragons flight (talk) 21:24, 29 September 2011 (UTC)

Causality is extremely important to physics theories. Without it physics as a science loses the power of predictability since things could happen for no reason at all. That would be a serious departure from centuries of physics dogma. Lorentz invariance violation could possibly be accommodated, but it wouldn't be easy. Dauto (talk) 21:56, 29 September 2011 (UTC)

No, most physics is deterministic not causal. To give simple examples, Newton's laws "predict" the time evolution of a system as time evolves. However, those laws are completely time invariant. One can say that the future state must be X because the past state was Y, but one can just as easily say that the past state must be Y because the future state is X. The direction of time is irrelevant and no notion of X causes Y or Y causes X is actually needed. Most (though not all) of physics is deterministic in principle, though in practice chaos and the impracticality of measurement make many time evolutions impossible to predict either forward or backward very far. There are of course exceptions, especially in quantum mechanics, that appear to be non-deterministic or not time-invariant, but that could be because we don't really understand the way they are determined. And of course some things that appear non-deterministic are still not causal (e.g. when a quantum entangled state decays it isn't actually meaningful to say that measuring one end caused the other end to decay). Dragons flight (talk) 23:43, 29 September 2011 (UTC)

If causality is violated then determinism goes with it (and that's the problem) because at any time non-causal unpredictable information might come come from no-where and influence physical states. Dauto (talk) 00:45, 30 September 2011 (UTC)

No. You can have a deterministic universe that is non-causal, it depends on the nature of the causality violation. If tachyons exist, for example, then the universe is non-causal because events can by influenced by other events separated from them by space-like intervals (and asking which event precedes or follows the other is an arbitrary matter of perspective). However the universe can still be deterministic if all observers would agree on the set of events that must occur (up to changes of reference frame and disagreements about event ordering) assuming those observers are also granted global rather than local knowledge of the system. Dragons flight (talk) 01:10, 30 September 2011 (UTC)

As BenRG explains below, a non-causal theory has causal loops which introduce unpredictability in the theory because there is no way to tell the state of those loops from previous or future events since those loops are caused by themselves, nothing else. Those unpredictable loops can affect other events of the theory making it non-deterministic. Dauto (talk) 02:41, 30 September 2011 (UTC)

To me causality just means the absence of closed causal loops, and I have trouble understanding what it would mean for a theory to have closed causal loops. It seems akin to ill-founded induction or a set theory that suffers from Russell's paradox. It's not a property a theory can have so much as it's a proof that you don't actually have a theory. On the other hand I have no trouble imagining consistent theories that are approximately but not exactly Lorentz invariant (such as a luminiferous aether!). That's not to say that I "want" Lorentz symmetry to be violated, and of course right now there's no evidence that it is. -- BenRG (talk) 01:01, 30 September 2011 (UTC)

the abillity to differentiate

in RGB how many points do I need to move for a human viewer to differentiate between color A to color B? example: I differentiate between the color blue and the color pale blue. Exx8 (talk) —Preceding undated comment added 18:06, 29 September 2011 (UTC).

According to the International Commission on Illumination, an average human can identify around 2.4 million shades of red/green/blue combinations. By "points", I think you mean points on a 0-255 scale. Then, it would be about 7 points for an average human across the entire scale. A single human tested could be higher or lower. Further, sensitivity to red, green, or blue shades should be very different within the individual. -- kainaw™ 18:13, 29 September 2011 (UTC)

It would also depend on what colour and how you're changing it, since different cones are responsibly for different colours. So, for example, one individual might perceive changes in the red range of colours more easily than changes in the green range. --Goodbye Galaxy (talk) 18:30, 29 September 2011 (UTC)

It also depends on gender, context, and culture. See color psychology.Smallman12q (talk) 19:17, 29 September 2011 (UTC)

It is not quite true that "different cones are responsible for different colors." That implies a different cone type for each discernable hue. Instead, each type of cone has a certain spectral sensitivity function, the curves overlapping, and hue discrimination require comparison by the nervous system of the differential responses by the different types of cones. Edison (talk) 19:48, 29 September 2011 (UTC)

You might be interested in reading about the Weber–Fechner law - similar rules apply whether we are differentiating colours, masses or sounds. SmartSE (talk) 21:37, 29 September 2011 (UTC)

one individual might perceive changes in the red range of colours more easily than changes in the green range. I know that was just an example and would be true for at least "one individual" ;) however just out of interest, in general, people can differentiate more shades of green then any other color. Vespine (talk) 22:33, 29 September 2011 (UTC)

YABIDR (Yet Another Bug ID Request)

This critter was stuck quite firmly to my car window a few weeks ago. Central NC, USA. It was about an inch long. Anyone know what it is? --Sean 19:43, 29 September 2011 (UTC)

Likely some sort of scale insect. SemanticMantis (talk) 19:51, 29 September 2011 (UTC)

Hmm. It looks like scale insects only range up to 1/2" long (Magnolia scale), and this thing was easily double that. --Sean 20:05, 29 September 2011 (UTC)

Looks like some sort of caterpillar—what did the legs look like? μηδείς (talk) 20:14, 29 September 2011 (UTC)

I'm afraid I didn't get a good look at them. I was thinking caterpillar, too, based on the horns. I looked all over the "what's that bug" and "bug guide" sites but didn't see anything similar. --Sean 20:28, 29 September 2011 (UTC)

Its an Isa textula or "Crowned slug moth caterpiller". For the record, I typed "fuzzy green caterpillar" into google images and got the answer that way. Google is still awesome. See [8]. --Jayron32 21:49, 29 September 2011 (UTC)

Awesome, thanks! -- Sean --66.57.60.56 (talk) 22:10, 29 September 2011 (UTC)

Sea salt

Is sea salt healthier than regular salt? --75.60.12.227 (talk) 20:22, 29 September 2011 (UTC)

Depends on the purification method. Salt is salt, any differences is due entirely to impurities not removed by the respective purification method. Plasmic Physics (talk) 20:26, 29 September 2011 (UTC)

(EC with below) Not exactly. Sea salt generally lacks any fortifications like iodine that may be present in more ordinary table salt where you live. Such fortifications are usually considered beneficial for a significant proportion of people hence why health authorities and governments mandate them and sea salt (and other unfortified salts) don't tend to naturally have them in significant amounts. I'm not aware any of the additional minerals/impurities present in sea salt are considered particularly beneficial in the quantities present. So it's probably fair to say sea salt may be less healthy for a significant number of people in some places. Nil Einne (talk) 21:04, 29 September 2011 (UTC)

Meaning, the salt in question is only as healthy as the additives contributed to it which, brings us back to the point: any differences in health, is due to what has been left, or added in. Plasmic Physics (talk) 22:59, 29 September 2011 (UTC)

Have you considered reading sea salt#health? Plasmic Physics (talk) 20:29, 29 September 2011 (UTC)

I have a tangential question. Which parts of the world obtain their salt mainly from mining, and which parts by evaporation of sea water. I get the distinct impression from both this thread and the Sea salt article that there is some distorted view that "normal" salt does not come from the sea. That may be the case where a lot of our editors live (USA? UK?), but is not the case everywhere. I also note that "Sea salt" is a trendy fashion item in modern western cooking. When something is associated with fashion, logic (and often, knowledge) regarding its best use goes out the window. HiLo48 (talk) 23:14, 29 September 2011 (UTC)

Virtually all salt in California, at least, comes from evaporation of ocean water. Nevertheless "sea salt" is sold in stores. It's a marketing thing. Notionally I think "sea salt" is supposed to be less processed than "regular salt", but I don't know whether it actually is less processed. --Trovatore (talk) 23:34, 29 September 2011 (UTC)

Hmm, it's possible I had a misimpression on this. There are large salt ponds near where I live, but they seem to be operated by Cargill, which is not a brand that I see much. The most recognized table salt brand around here is Morton Salt. I don't know where they get their salt. --Trovatore (talk) 00:17, 30 September 2011 (UTC)

From the Bahamas -- and yes, that is sea salt too. 67.169.177.176 (talk) 00:40, 30 September 2011 (UTC)

I can't speak for the USA, but given the size of the place and the distance of most of it from an ocean coastline I'd hazard that a large amount of salt in the USA is mined, not gently evaporated from limpid salt pools beside the dreamy ocean. Same in the UK - we have great big salt mines in Britain. See for instance Salt in Cheshire and Droitwich Spa, from where salt has been extracted since prehistoric times. Droitwich is pretty much as far from the sea as you can get in the UK. Tonywalton ^Talk 23:47, 29 September 2011 (UTC)

Yes, I didn't want to sound rude, but I couldn't imagine that the climate of the UK would be all that conducive to evaporating sea water. ;-) HiLo48 (talk) 00:31, 30 September 2011 (UTC)

Essex was the place for sea salt manufacture in the UK.[9][10]. Alansplodge (talk) 09:24, 30 September 2011 (UTC)

Actually, most of our salt (especially that intended for food consumption) is indeed evaporated from the ocean, mostly in California and along the Gulf Coast, as well as on the southern Atlantic seaboard. (Not all of it, however, is evaporated "from limpid salt pools beside the dreamy ocean" -- some of it (most notably in Tampa, FL) is produced by flash distillation in desalination plants.) There are numerous salt mines in the Midwest, but these produce salt mainly for industrial use (especially for the production of chlorine and sodium hydroxide). As for climate, please note that in Russia, some of the salt is (used to be, at any rate) produced from the water of the White Sea (near Arkangel!), not by solar evaporation, but by fractional freezing followed by hot distillation of the resulting concentrated brine. 67.169.177.176 (talk) 00:58, 30 September 2011 (UTC)

Salt is a bulk good that is not all that difficult to haul around, so it wouldn't be very surprising for primarily sea salt to be used thousands of miles from the coast. Googlemeister (talk) 13:10, 30 September 2011 (UTC)

The Salt Institute seems to have the opposite opinion that because it is a low cost high weight bulk item it is most economic when consumed near where it is produced. However their FAQs [11] are heavily weighted to industry, pointing out that the large majority of U.S. industrially-used salt is produced by solution mining wells (not sea salt or rock salt). But they don't answer the question of how much of edible salt is sea salt versus rock salt. 75.41.110.200 (talk) 16:16, 30 September 2011 (UTC)

Do consider that table salt is probably not the main consumer of salt in the US. I expect more is used for road maintenance in winter, for chemical production or for the raising of livestock, then is eaten by humans. Googlemeister (talk) 18:56, 30 September 2011 (UTC)

Both Mayo Clinic [12] and Massachusetts Department of Public Health [13] say that table salt is rock salt. ("Table salt is generally sold in very small grains, and is mined from underground salt deposits. ... It is commonly used in salt shakers and during cooking and baking.") do we have any sources for 67.169.177.176's claim that most U.S. table salt is sea salt? 75.41.110.200 (talk) 16:28, 30 September 2011 (UTC)

Morton has a nice page that explains that they get salt from more than one source. -- kainaw™ 16:39, 30 September 2011 (UTC)

It may also be worth noting that nearly all rock salt also ultimately formed by the evaporation of sea water, except that the evaporation happened naturally when a pool of ocean water got cutoff from the ocean, possibly many millions of years ago. Creating salt from sea water evaporation today is a more controlled and arguably cleaner process than what happened to form natural evaporite deposits, but the starting material is the same. Dragons flight (talk) 19:09, 30 September 2011 (UTC)

Cleaner, perhaps, but not necessarily better. It probably is not part of the human evolutionary heritage to ingest seawater, and definitely not to ingest purified sodium chloride - "salt", such as it was, would have been from deposits on land containing a range of ions. Note that potassium compounds have some activities which counter the increase in blood pressure from sodium chloride, and are nutrients less likely to be taken in sufficient amounts. The idea that salt is sodium chloride is one of those core myths people learn in school which they need to unlearn. Wnt (talk) 21:28, 1 October 2011 (UTC)

It is part of the human evolutionary heritage to ingest fish from the sea that contains high levels of sodium, and in fact before salt was discovered, peoples whose diet was deficient in sodium used a variety of salt substitutes, such as ashes of plants high in sodium, or even dried animal blood. Anyway, the human body needs both sodium and potassium, and while sodium deficiency is rare these days, it used to be a serious problem in the ancient times. 67.169.177.176 (talk) 01:21, 2 October 2011 (UTC)

Wasp behavior and oak trees

A mutated acorn. Inside this is the wasp larva.-- Obsidi♠n Soul 23:32, 29 September 2011 (UTC)

For many years (5-10) an oak tree in my house's front yard would be infested with wasps, which caused a fair amount of terror for me in the years I had to mow the yard while they were there. My family never found a wasp nest (although that's not saying that one wasn't there), they just seemed to really like that tree (and that tree only, given that no other trees in the neighborhood had wasps)...enough so that they would remain there after we would spray the tree with wasp killer. The wasps just randomly didn't come back after winter one year, which kinda surprised me, and since then the tree has gradually (for the first time I can remember) started producing acorns. My two questions are:

1. Why did these wasps seem to have a liking for this oak tree?
2. I've frequently heard from people an oft repeated saying about wasps and bees that "if you don't bother them, they won't bother you" whenever I get freaked out when there are any around, usually said as a rationale for me to just ignore them and not leave the area as quickly as possible. I find this very dubious based on the fact that, to me, they seem to be "bothered" by my very presence anywhere near them (they won't leave me alone) despite the fact I'm not doing anything that these people would consider "bothering them". Is there truth in the phrase "if you don't bother them, they won't bother you" when it comes to wasps and bees, and if so, what constitutes "not bothering them" given that they don't leave me alone whenever I'm near them?

For reference about species, my location that these questions are based off of is Salina, Kansas for the former and both Salina and Norman, Oklahoma for the latter. I don't know the species of the oak tree, but it appears to be about 25–35 feet (7.6–10.7 m) tall, at most 20 feet (6.1 m) wide and I'm pretty sure it's been there since at least 1995 (the earliest I can remember). Thanks in advance, Ks0stm ^{(T•C•G•E)} 22:40, 29 September 2011 (UTC)

Wasps are more aggressively territorial than bees, because stinging doesn't kill them. Generally neither will attack without provocation though, but a noisy lawnmower could have easily resulted in accidental provocation. I suspect that the tree was diseased, allowing the wasps to build a nest inside it, and then the nest became abandoned and the tree was able to recover. 69.171.160.237 (talk) 23:09, 29 September 2011 (UTC)

What kind of wasps? Oak trees are actually one of the most favorite trees for gall-making wasps, and they have hundreds of species, most preferring oak. You will not find a wasp nest because the wasps themselves are solitary and nest in the oak tissue. It's actually fascinating stuff, a kind of natural genetic engineering.

Wasps inject something into developing acorns, mutating it into something quite unlike an acorn (probably the reason why you've never come across a 'normal' acorn until that year they weren't around). Hard and perfect for developing wasp larva. Other species develop galls in other parts of the plant. Leaf buds, for example, result instead in what is known as oak apples. Still others produce galls on the roots, which are then called oak potatoes. See gall wasp. -- Obsidi♠n Soul 23:31, 29 September 2011 (UTC)

Oh, and like most solitary wasps, they are not aggressive so don't worry. As long as you don't swat one or cuddle one or something, heh. Social wasps, like yellowjackets, which build colonies are the ones to watch out for.-- Obsidi♠n Soul 23:36, 29 September 2011 (UTC)

What a great vespine question :) . Most of this was news to me, I chose my name because I like the word and I like wasps, not because i know particularly much about them. Vespine (talk) 01:08, 30 September 2011 (UTC)

My experience with yellowjackets is that they buzz around a lot and go for intimidation, but rarely sting. I don't guarantee that that will be anyone else's experience. --Trovatore (talk) 01:11, 30 September 2011 (UTC)

Gall wasps, which, where I live, mostly infest twigs and leaves, are solitary, and extremely small, like midges. (As for yellow jackets, I have been stung by them more often than by honeybees.) μηδείς (talk) 03:57, 30 September 2011 (UTC)

Growth of the Universe

Human growth is done by the mitosis of cells. The universe is growing at an infinite rate, but it isn't made of cells. The only real thing that can grow the universe is atoms, but how do atoms grow the universe? These atoms can't just appear, right? 64.229.181.189 (talk) 23:50, 29 September 2011 (UTC)

The existing atoms are just moving further apart from one another, taking up more space. Oh, and the rate of growth is quite measurable. It's not infinite. HiLo48 (talk) 00:28, 30 September 2011 (UTC)

Think of the universe as a rubber band. Stretching a rubber band doesn't mean that all of a sudden you have more rubber than before. Everyone would agree that is a silly conclusion, otherwise the band would get heavier. (It does somewhat, but that is due to a different reason.) Plasmic Physics (talk) 00:40, 30 September 2011 (UTC)

In theory, it sort of can just appear. See false vacuum and cosmic inflation; also [14] for example. The idea being that the universe, by expanding, reaches a lower energy state, with the excess energy turning up as mass + the energy we see. (note a certain philosophical similarity between the chaotic inflation theory and the steady state theory as described in the latter article...) Wnt (talk) 01:18, 30 September 2011 (UTC)

Yeah, but that is not the reason that the universe is growing. Infact, the word "growing" isn't even applicable here. The universe is stretching. It's not gaining net energy/mass (mass-energy equivalence) as what growing involves, it's simply redistributing itself. Plasmic Physics (talk) 01:50, 30 September 2011 (UTC)

Recently, we had a similiar user ask a relevant question - he thought that the universe grows by the contineual injection of more space. Plasmic Physics (talk) 01:52, 30 September 2011 (UTC)

HiLo48 is correct that the rate is measurable and not infinite, but atoms per se are not moving apart. For example, the atoms in your body are not moving apart. They are electrostatically bound, just as the stars within galaxies are gravitically bound. It is the universe as a whole which is expanding (stretching and growing have implications which make those words less than ideal) and the space between gravitically non-bound galaxies is increasing. But there are plenty of galaxies which are actually moving towards each other, such as ours and the Andromeda galaxy. μηδείς (talk) 03:52, 30 September 2011 (UTC)

Historically, the supposed spontaneous creation of new atoms indeed formed part of the Steady State theory (aka Continuous Creation), which was formulated (by several leading astrophysicists of the day) to explain the then-recently observed expansion of the Universe together with the inferred maintenance of its density over deep time. The atoms' creation could be viewed as a further consequence of the driving force behind the expansion, or - in some interpretations - as the actual cause of it. Subsequently accumulated observational evidence has of course favoured the rival Big Bang theory, and Steady State, despite corrective modifications by its proponents, has largely fallen out of favour. {The poster formerly known as 87.81.230.195} 90.197.66.221 (talk) 14:18, 30 September 2011 (UTC)

September 30

biochemistry

what colour could be observed if glucose solution is added to hydrochloric acid + iodine solution — Preceding unsigned comment added by 41.78.77.246 (talk) 07:27, 30 September 2011 (UTC)

I don't know. When you added glucose to a mixture of hydrochloric acid and iodine in your chemistry lab, what happened for you? --Jayron32 19:09, 30 September 2011 (UTC)

You may wish to read Iodine test and Benedict's reagent. Graeme Bartlett (talk) 08:21, 2 October 2011 (UTC)

second moment of area

hi, how can we visualise second moment of area ? i men, its easy to visualise normal moment of inertia, but i am having difficult in physical visualisation of second moment of area — Preceding unsigned comment added by 117.192.193.0 (talk) 13:09, 30 September 2011 (UTC)

There is a COMSOL Multiphysics demo which shows this, in a beam strength and stress simulation. They will give you a free 30 day demo CD and key if you ask. 69.171.160.77 (talk) 18:09, 30 September 2011 (UTC)

Radio frequency intervals

Warning: the topic below will require some basic knowledge of music theory, physics of sound harmonics and radio astronomy.

Hi. Last night, I was experimenting with my radio. It was on the AM radio dial, and at approximately 600 AM (probably a bit lower), an ambient humming sound filled the room. I found that the beat frequency was almost exactly 0.5 Hertz, and that the pitch was at an E natural, more than two octaves higher than middle C. At frequencies of both 640 and 680 AM, I detected a near-monotome, static buzzing hovering at B flat, just below middle C. Experimenting further on my electric keyboard, I found that the distance between these two notes was two octaves plus six semitones. Thus, I found the note between these two, as well as another note of a lower pitch at the same frequency. The chord formed by these four notes is a G-diminished 7th.

My question is: what causes these specific channels to produce these ambient buzzing and humming sounds, even in the lack of clear channel reception? What is the Hertz interval between the two main notes mentioned (B flat below middle C and E natural 2 octaves above)? Moreover, what actually caused the 0.5 Hertz beat? Thanks. ~AH1 ^(discuss!) 14:15, 30 September 2011 (UTC)

You are probably hearing intermodulation distortion (tone injection) due to complicated interference between the transmitter's carrier frequency and some other frequency (possibly your local oscillator, or some other frequency in your radio). Do you know what type of radio you have? Do you know what type of signal you're tuning? (If it's commercial AM radio in the United States, it's probably DSB-SC; but you can still get intermodulation distortion even without a tonal carrier, it's just harder to describe in simple terms).

Also, to convert musical-note to numeric frequency, you only need to know this equation:

$f=f_{0}2^{n/12}$

...where n is the number of half-tones above f₀. For example, Middle C is three half-tones above A₄₄₀ - so f = 440 Hz × 2^0.25 or about 523 Hz.

Finally: to diagnose the root-cause of a 0.5 Hz beat, we'll... need some more technical information. How much do you know about your radio? Does your receiver have a built-in frequency auto-tuner? AGC? ... Can you hook a spectrum analyzer up and see what else is going on? If you can't answer those more precisely, we probably can't say any more than "it's probably interference from something." These kinds of questions are better probed with the sort of equipment you find in a HAM base station, rather than an off-the-shelf AM radio. Nimur (talk) 18:25, 30 September 2011 (UTC)

If the sounds stays around the same pitch, but the buzzing changes every few seconds, then that can be interferences from a television. Buzzing that drifts in frequency can be switchmode power supply. A very clean n x 1kHz whistle could be interferences from different radio station carriers, including those from overseas using different band plans. Computers are also great at interfering with AM radio making a a bunch of whistles and "sssh" blocks of white noise. Have a look at Note to work out your frequencies in Hz. Graeme Bartlett (talk) 08:41, 2 October 2011 (UTC)

What is the average size of human tonsils?

I've read the WP article on tonsils including the passage "Tonsils tend to reach their largest size near puberty, and they gradually undergo atrophy thereafter. However, they are largest relative to the diameter of the throat in young children." So what is that largest size, on average? I don't have a medical encyclopedia handy but an initial G-search proved fruitless. §everal⇒|Times 19:03, 30 September 2011 (UTC)

What measure are you looking for? This paper PMID 20304270 reports tonsil size (in terms of height, width, thickness, and weight) in overweight and normal-weight children who have problems with breathing during sleep. If that does not answer your question, perhaps you could provide a more specific question. -- Scray (talk) 12:16, 1 October 2011 (UTC)

I was looking for a statistic of diameter or of volume. I'm aware that there's often no true "average" size of any particular human body part and that any such measurement is subject to differences in age, weight, diet, etc. When medical WP articles discuss the size of certain parts relative to others, however, it's useful to have some specific numbers involved in the discussion. The paper you provided is helpful (though I suspect that tonsilar volume may be related to incidence of sleep disorders and/or breathing difficulties, so it's not quite what I was looking for). Thanks! §everal⇒|Times 17:06, 3 October 2011 (UTC)

Why exactly does the enthalpy of vaporization fall to zero at the critical point?

Is it because the heat capacity of the gas ends up increasing much faster than the liquid? If so, this qualitative explanation doesn't appear to be included in our critical point (thermodynamics) article, though it delves into derivatives. And if so, why does this overtaking trend accelerate ? I note that 10 degrees Celsius below the critical point, the heat of vaporization is still considerable, but at the critical point, this disappears completely. elle _{vécut heureuse} ^{à jamais} (be free) 19:43, 30 September 2011 (UTC)

The reason is actually tautological. At the critical point, the substance becomes a Supercritical fluid, for which there is no distinction between a gas and a liquid. The fact that the enthalpy of vaporization at this point drops to zero is because vaporization has no meaning above the critical point. The two statements (enthalpy of vaporization = zero, distinction between liquid phase and vapor phase doesn't exist) are simply two statements of the same fact; which is the critical point of the substance. That is what the critical point is. --Jayron32 19:48, 30 September 2011 (UTC)

Well yes, but I was looking for a more quantitative explanation. This doesn't really solve problems of the heap: what's the difference in enthalpy of vaporization for a substance 0.000001 K below the critical point versus at the critical point? Surely we cannot resolve problems of analysing a quantitative trend by merely using hand-waving definitions. AFAIK, the two distinct phases don't exist because Hvap is zero, not the other way round. The two phases disappearing is a result of this fact. So I want to know -- what causes this fact? elle _{vécut heureuse} ^{à jamais} (be free) 20:00, 30 September 2011 (UTC)

What causes the critical point? The article Critical point (thermodynamics) covers that rather well, I thought. The reason that the critical point exists is that the kinetic energy of the molecules overcomes the energy holding the molecules together in the condensed phase. After you exceed that temperature, no amount of compression will cause the molecules to condense. In some ways, you can think of the enthalphy of vaporization as related to this energy difference. In one perspective, you can think of the enthalpy of vaporization as the extra energy needed for that fraction of molecules not yet in the vapor phase to get into the vapor phase. The closer you get to the critical point, the greater proportion of molecules have that necessary energy, so the less extra energy you'd have to supply to get there. The article Enthalpy of vaporization has a very nice graphy which shows that the enthalpy of vaporization decreases until it reaches zero. The difference between the critical temperature and an arbitrary temperature below that is that, at the lower temperature enough molecules have a low enough kinetic energy that they cannot overcome the intermolecular forces holding them together, if there is enough pressure. At the critical temperature, this number of molecules functionally drops to zero. --Jayron32 20:56, 30 September 2011 (UTC)

Yes, but that's all nice and qualitative. I guess I want a semi-quantitative explanation (e.g. a relation like dG/dT = -S) for why heat of vaporization should accelerate to zero near the critical point. What exactly is going on? Why does it accelerate? elle _{vécut heureuse} ^{à jamais} (be free) 21:51, 30 September 2011 (UTC)

Oh. In that case I think you want to look at the Clausius–Clapeyron relation for a general mathematical treatment of phase changes. This page discusses some of the mathematics involved at the critical point. This page here represents some early research on the topic, and discusses the derivation of the relationship between heat of vaporization and critical temperature. --Jayron32 23:34, 30 September 2011 (UTC)

Unidentified bird in France

What is this?

Does anyone know what kind of bird this is? I thought it was some sort of finch, and then I realized, hey, I don't know anything about birds (and even if it is a finch, I have no idea what kind). If it helps, this was taken in Nantes, France. Apologies for the rather inadequate photo. Adam Bishop (talk) 20:44, 30 September 2011 (UTC)

Looks like a wagtail, perhaps an immature white wagtail. Mikenorton (talk) 20:55, 30 September 2011 (UTC)

Thanks! Adam Bishop (talk) 18:39, 1 October 2011 (UTC)

How would you calculate the change in freezing point (with increasing pressure) without the Clausius-Clapeyron equation?

At first if am only given density difference, difference in pressures, and the freezing point at one temperature. If I assume the change in entropy of vaporization is constant -- +22.014 J/(K*mol) and I know the change in volume per mol is +217.05 cc/mol (yup this is water). Then the difference in atmospheric work between 10 MPa and 1 atm is 2.0785 kJ/mol.

ΔS = ΔH/T T = ΔH / ΔS

then our new temperature point = ΔH/ΔS = (6.01 kJ/mol - 2.0785 kJ/mol) / +22.014 J/K = 178.6 K = -94.6 C

This is a very large change in the melting point of the ice.

But if I use Clausius-Clapeyron engineering equation (which I don't think I'm supposed to do):

T2 = 0C

ln(1 atm / 10 MPa ) = 6.01 kJ/mol / R * (1/T1- 1/(273.15 K) )

R * ln(1 atm / 10 MPa ) / 6.01 kJ/mol = (1/T1 - 1/273.15 K)

R * -4.592 / 6.01 kJ/mol + 1/273.15 K = 1/T1

Which brings me below absolute zero (if I flip this -- I get 98.35 C)

If I use the slope equation mentioned in the Clausius-Clapeyron article I get ΔT = ΔP * T * ΔV / L = (10 MPa - 1 atm) * 273 K * 0.875 cc/mol / 8.68 kJ/mol = -0.272 Kelvin

Which is wayyy less than the ~100K drop predicted before.

What is the cause of the discrepancy? Is it just me? elle _{vécut heureuse} ^{à jamais} (be free) 22:25, 30 September 2011 (UTC)

[The heading “Freezing point change calculation” is adequately brief and adequately informative.

—Wavelength (talk) 23:18, 30 September 2011 (UTC)]

Earnshaw's Theorem

Just trying to comprehend something the teacher said in class. So if I have 8 identical point charges (protons let's say) positioned at the corners of a cube (like a physical octopole except all charges have the same polarity), then if I place a positive test charge at the center of the cube, the test charge will be in equilibrium, right? From what I understand of Earnshaw's theorem, the test charge will be in equilibrium but it won't be in a stable equilibrium so if I perturb the test charge slightly (just push it in any one direction), the test charge will fly away as fast it possibly can. My teacher sounded like as if there is no equilibrium and no matter what (even theoretically) the charge just won't stay at the center. I was like how can this be. If I put a charge dead center it will stay there. All of the components of the force vectors should cancel. In the real world of course, I understand its impossible to confine a single charge like this let alone plasma or something. Am I right?128.138.138.122 (talk) 22:38, 30 September 2011 (UTC)

That isn't quite an accurate description. Instability means that if you push the charge away from the center, it will start to move farther away. It does not necessarily mean that it will move quickly -- and in fact it won't. If you only move it a small distance, it will move very slowly. The point is which direction it moves: away from the center. Looie496 (talk) 22:52, 30 September 2011 (UTC)

A stable equilibrium will return to the equilibrium point when perturbed (in chemistry, this is called Le Chatelier's principle, but the concept applies to any stable equilibrium system). An unstable equilibrium (usually termed metastable) will drift away from the equilibrium point when perturbed. --Jayron32 23:09, 30 September 2011 (UTC)

Note that Earnshaw's theorem implies that there are no completely unstable equilibria either, because any such point would be a stable equilibrium for a test particle of the opposite charge. So the center point in your example must be stable against perturbations in some directions and unstable against perturbations in other directions. -- BenRG (talk) 23:39, 30 September 2011 (UTC)

As expected, we have an article for Earnshaw's Theorem. I wouldn't say it's an accessible article or that helps understand the topic well:( DMacks (talk) 19:36, 1 October 2011 (UTC)

October 1

Garfasil DNA contamination

I was reading a few articles about it and I was wondering what the possible risks can be since I have gotten the first two shots. — Preceding unsigned comment added by 76.87.48.142 (talk) 03:04, 1 October 2011 (UTC)

I suspect you mean Gardasil; you can find the patient product information here and the prescribing information here - Nunh-huh 03:16, 1 October 2011 (UTC)

I guess you could argue that since the antigenic material in the vaccine is influencing the prevalence of certain configurations of genes in the adaptive immune system it is "contaminating" but that would be a major stretch. Viruses like HPV are much messier when it comes to "contaminating" DNA, and there has been some speculation that a substantial percentage of human DNA (i.e. Introns) is nothing more than "contamination" by inactive viruses, though that's largely speculation. In short, if you want to preserve your genetic cleanliness (whatever the heck that means), getting vaccinated against viral infections is a good thing because the viruses will cause a lot more genetic damage than a little bit of the adaptive immune system doing what it's supposed to do. SDY (talk) 07:43, 1 October 2011 (UTC)

I didn't want to mention this per our policy on medical advice but I think it's likely the OP is thinking of the bullshit certain people and sites are spreading that is debunked here [15] not anything to do with effects on the adaptive immune system. Nil Einne (talk) 16:57, 1 October 2011 (UTC)

World after 100 years

Will industrial civilization, as we know today, collapse after 100 years due to peak oil? --DinoXYZ (talk) 06:07, 1 October 2011 (UTC)

No. HiLo48 (talk) 06:09, 1 October 2011 (UTC)

If capitalism is still the dominant economic system, then yes. →Σ ⚑  ☭  06:14, 1 October 2011 (UTC)

In many parts of the world large efforts are going into the development of alternative technologies for supply of energy. As oil prices rise, these will become viable options. HiLo48 (talk) 06:31, 1 October 2011 (UTC)

That's correct -- nuclear energy in particular appears promising, as well as coal-to-liquids technology and (to a lesser extent) wind energy. 67.169.177.176 (talk) 06:36, 1 October 2011 (UTC)

"to a lesser extent"? You might want to review Wind power#Cost trends: Wind is trouncing everything, including coal which used to be the least expensive, and is growing faster than ever. 75.71.64.74 (talk) 19:57, 1 October 2011 (UTC)

This does not take into account the maximum amount of wind power that can realistically be generated, which is still less than the the total level of energy consumption. So while wind power is a promising part of the mix, it cannot by itself meet our country's energy needs. 67.169.177.176 (talk) 00:46, 2 October 2011 (UTC)

Yes, it does. 69.171.160.45 (talk) 07:15, 3 October 2011 (UTC)

Boy, there's some POV on show here today, isn't there? ;-) I may have compiled a different list (nuclear is experiencing a bit of a hiccup in some areas right now), but the point is still valid. HiLo48 (talk) 06:41, 1 October 2011 (UTC)

If the amount of oil decreases significantly, the price of energy will probably go up, at least in the short term. The demand for energy will probably also go up. The ways around this are that if the price rises significantly, certain technologies which do produce energy today, but are not competitive with oil, will suddenly become competitive economically. Additionally, if the price of using energy goes up, then there will be additional incentive for using less of it. So in the end it is actually not that awful a thing for the oil to run out. Oil is addictive — it's cheap and bad for you (as a planet). There are lots of alternatives. They are not as cheap as oil (or coal), on the whole, at least in their current iterations. But many/most of them are a lot better for the environment than fossil fuels. (The really stupid but tempting thing to do would be to switch from oil to coal, of course.) Now this kind of transition, if it is very rapid, could cause significant economic disruption, which could cause significant political or social disruption if handled poorly by the powers that be. On the other hand, if the transition is anticipated, and the energy portfolio is diversified, then it's probably only a minor hiccup. I don't see total collapse of industrial civilization as a result in any case, though. This is obviously me gazing into a crystal ball, but it's based on fairly straightforward economic principles (and based on some article I read in Scientific American a long while back). --Mr.98 (talk) 13:30, 1 October 2011 (UTC)

Synthetic fuel is now less expensive than petroleum-derived fuels in some electricity markets (see wind power above) due mostly to improved plating alloys for electrolysis anodes, so expect it to become very much more popular in the next few years. 75.71.64.74 (talk) 19:57, 1 October 2011 (UTC)

Electrolysis? I work in the field of synthetic fuel technology, and while many synthetic fuel production methods involve the use of hydrogen, I don't know of any where the hydrogen is produced by electrolysis. In fact, in most processes that I know of, hydrogen is produced either by the water-gas shift reaction or by steam reforming. Are you sure you didn't mean "improved catalysts"? Or that you didn't actually conflate synthetic fuel production with wind power (where electrolysis is indeed used for energy storage)? 67.169.177.176 (talk) 00:37, 2 October 2011 (UTC)

Yes. See http://windfuels.com 69.171.160.45 (talk) 07:15, 3 October 2011 (UTC)

The future is solar power. When the earth becomes unified and invests resources into creating one of those things where they put millions of satellites with solar panels on them in orbit around the sun (d[a-z]+ spheres, or something, I forgot) solar power will become the principal source of energy. →Σ ⚑  ☭  02:04, 2 October 2011 (UTC)

Wrong again -- solar power is much more expensive than any other kind, and space-based solar is even worse. Besides, switching to exclusively solar power would give an unfair advantage to savages and greatly hurt civilized countries. 67.169.177.176 (talk) 02:12, 2 October 2011 (UTC)

He's referring to futuristic, sci-fi style plans like Dyson spheres Ah, yes, that's what it was called! →Σ ⚑  ☭  02:49, 2 October 2011 (UTC) or rings or bubbles and the like. It's pretty speculative. Anyway, considering the first part of the statement involves a politically unified planet, it's not happening anytime soon by any other indications. (I've also no idea what you're getting at with the idea that solar will help third world countries or something like that. Perhaps you haven't noticed, but oil hasn't exactly propelled the third world into great arenas, despite it being rather plentiful there.) --Mr.98 (talk) 02:20, 2 October 2011 (UTC)

What I'm getting at is that meeting the per-capita energy demand here in the USA with solar power alone would require several HUNDRED square meters of solar panels for EACH AND EVERY PERSON in the country, at prohibitive economic costs, while meeting the energy demand somewhere in Kenya would only require a solar-panel area measured in square decimeters. Does this sound even remotely fair to you, especially considering all the great achievements that the civilized nations have reached due to their use of their energy resources? 67.169.177.176 (talk) 02:31, 2 October 2011 (UTC)

Maybe it would be lower if the USA citizens didn't waste so much energy on supersizing everything rather than aiding the aforementioned nation. →Σ ⚑  ☭  03:13, 2 October 2011 (UTC)

(ec) My sense, not based on any careful analysis, is that the contribution of solar power for the forseeable future will be decentralized, point-of-use photovoltaics. Their price has come down I think quite a lot and should drop still more. Solyndra folded but the basic idea is good, just needs different market conditions that will show up sooner or later. These can make a significant contribution to residential and business power supply; doesn't mean you can cut off ties with your local power company, just that you won't have to buy as much of their product.

Centralized solar I don't think is in the cards. The power density just isn't high enough, you need too much land, and the plant stops delivering power just at the time everyone's turning their lights on.

What I think people need to take on board is that the demand for electricity is going to go way up as electric cars come on line. I don't think solar is going to cut it for that; people are going to want to charge their cars at night. That's one reason I think we're likely to need new nuclear capacity, and quite a lot of it. --Trovatore (talk) 02:42, 2 October 2011 (UTC)

In an earlier post I said about alternative technologies that "THESE will become viable options". Rather than having almost total dependence on what is really one source of energy, fossil fuels, many differnt sources will be developed, as apporopriate to particular needs. The criticisms here of solar are at least partly valid, so we won't depend on solar alone. A combination of new technologies will evolve - solar, wind, tidal, thermal, even cleaner nuclear, etc, etc, etc. Attacking one of these doesn't prove we won't use it. HiLo48 (talk) 02:56, 2 October 2011 (UTC)

I wasn't attacking solar! I just think its main use will be decentralized, not from power plants. One of the best things about solar is that it can be generated in a decentralized fashion. --Trovatore (talk) 06:08, 2 October 2011 (UTC)

The reaction you get, when you try to build one little 10KW thorium reactor for your personal use.... --Trovatore (talk) 06:12, 2 October 2011 (UTC)

Yes, good point. Solar can work right beside where you want to use it. That doesn't apply to many technologies. (It would for your thorium reactor of course.) HiLo48 (talk) 06:30, 2 October 2011 (UTC)

Did I not mention unifying the planet, or did your eyes jump to the glorious and enlightening hammer and sickle in my signature? →Σ ⚑  ☭  03:05, 2 October 2011 (UTC)

Oh-My-God particle & force

1. According to our article on ultra-high-energy cosmic rays, occasionally particles hit the atmosphere at 1.0×10²⁰ eV+, with the vast majority (~99.9995%) of energy in these collisions going to kinetic energy, and the rest going to "interaction with a proton or neutron." Where exactly would the kinetic energy go? As in, which particles, if not protons or neutrons?
2. If this particle were to crash into a sunbather, would it be cancer inducing? My understanding is that most cancer comes from photons in electromagnetic radiation. If the answer to my previous question was "photons", I imagine the answer would be a resounding "yes" because the collision would produce some very high energy gamma rays.

Magog the Ogre (talk) 06:36, 1 October 2011 (UTC)

(1) AFAIK the kinetic energy goes into inducing high-speed movement of air molecules in the ionosphere, as well as their ionization; the other 0.0005% actually goes into transmuting a proton or neutron into any of a whole bunch of exotic particles, along with gamma ray emission.

(2) Yes, any kind of ionizing radiation is potentially cancer-inducing; however, a single cosmic-ray particle would definitely not suffice to cause even one cell to become cancerous. 67.169.177.176 (talk) 06:43, 1 October 2011 (UTC)

Clarification to part 1: the 0.0005% of the energy goes into transmuting the proton or neutron into such exotic particles as mesons and hyperons, while the other 99.9995% goes into propelling said exotic particle at very high speeds through the upper atmosphere while it collides with other protons/neutrons, transmuting them as well. Eventually all the exotic particles formed in this cascade reaction decay back to protons and neutrons, with emission of gamma rays and neutrinos.

Clarification to part 2: None of the exotic particles formed in the aforementioned cascade reaction ever actually reach the surface -- they all decay in the upper atmosphere, while the gamma rays emitted during the decay process are absorbed by air molecules in the ionosphere, which become ionized in the process and form ozone among other things, as well as re-emitting the absorbed energy as visible light, particularly in the form of Northern lights. 67.169.177.176 (talk) 07:06, 1 October 2011 (UTC)

Or Southern Lights Please try to remember that the earth has two magnetic poles. Roger (talk) 12:34, 1 October 2011 (UTC)

You mean, the Northern hemisphere doesn't have a monopole-y on Aurorae? {The poster formerly known as 87.81.2301.95} 90.197.66.221 (talk) 16:27, 1 October 2011 (UTC)

While most charged particles don't reach Earth, I wonder if a particle at such a high velocity might be going at a quick enough speed to overcome the Earth's magnetic poles. Magog the Ogre (talk) 20:50, 1 October 2011 (UTC)

You can derive this ratio approximately just from special relativity, without knowing anything about particle physics. A high-energy cosmic ray comes in with a (energy, momentum) four-vector of (E, E) relative to the lab frame. The particle it strikes is more or less at rest (relatively speaking), with a four-momentum of (m, 0). In the center-of-momentum frame their four-momenta are (E'/2, E'/2) and (E'/2, −E'/2), where E' is the center-of-mass energy. The dot products of vectors in different coordinate systems (reference frames) are the same. This gives $E'={\sqrt {2Em}}$, which is roughly the geometric mean. In other words, you lose half of the orders of magnitude of the cosmic ray energy in the center-of-momentum frame. Assuming both particles are protons (mass = 10⁹ eV) and the cosmic ray energy is 10²⁰ eV, the interaction energy is only about 10^14.7 eV. The rest, about 1 − 10^5.3 = 99.9995%, is conserved kinetic energy. This is why circular colliders collide beams circulating in opposite directions instead of using a stationary target. This is a purely relativistic phenomenon—in Newtonian physics this ratio never goes above 7550% for like particles, no matter how high the speed. -- BenRG (talk) 21:04, 1 October 2011 (UTC)

Imaging ripples

What is the word to describe the effect whereby the degree to which something like longitudinal or transverse structures in a 3D ripple pattern are visually enhanced (by light and shadow contrasts) depends on the position of the light source ? For example, if you are looking down on a 3D ripple pattern that has superimposed fairly regular londitudinal N-S structures and fairly irregular transverse E-W structures, a light shining from the east will tend to emphasize the regularity of the N-S longitudinal structures and the pattern will look pretty regular whereas a light shining from the north will tend to emphasize the irregularity of the transverse structures and the pattern will look pretty irregular. I get the feeling that this is some obvious word that I should already know but I can't think of it. Here's an example, the same ripple pattern with 1. left image - light shining from the east, and 2. right image - light shining from the north (although there is a very slight horizontal offset between the images). Sean.hoyland - talk 08:33, 1 October 2011 (UTC)

May I ask, are those images created with an emboss function, and were the ripples created algorithmically? --George100 (talk) 08:53, 1 October 2011 (UTC)

Those are real ripples created with sand on a plate that was moved in a water tank by a motor repeatedly to reproduce the effects of a current. Sean.hoyland - talk 09:04, 1 October 2011 (UTC)

I don't know the correct answer, but Anisotropy might figure in it. {The poster formerly known as 87.81.230.195} 90.197.66.221 (talk) 16:31, 1 October 2011 (UTC)

automated blood draw

Is there yet a machine that can draw blood? --DeeperQA (talk) 10:44, 1 October 2011 (UTC)

It is easier to provide a precise answer when the question is specific. What step in blood drawing are you asking about? A pheresis machine draws blood out of people once connected to a catheter that has been inserted into a vein. My guess is that you're asking about venipuncture, and if so I don't think there's a machine that will find and puncture a vein. -- Scray (talk) 12:09, 1 October 2011 (UTC)

If there are machines that can perform surgery then there must be machines that can find and puncture a vein and avoid the many possible mishaps technicians have when taking sample after sample per hour and per day. I have seen many mishaps with needles sliding out for instance and the technician using the wipe to clean blood from the arm rest before wiping the arm to reinsert the needle - a process an automated system would likely not perform no matter how many samples it took a day. --DeeperQA (talk) 19:22, 1 October 2011 (UTC)

There aren't machines that can perform surgery. There are machines that surgeons can use to perform surgery. The surgeon is still in control. --Tango (talk) 19:25, 1 October 2011 (UTC)

No, finding a good vein and walking the patient through the draw is skilled labor requiring human empathy. It's not outside the realm of possibility, but self-service is orders of magnitude easier than automation at this stage. 67.21.131.22 (talk) 21:08, 1 October 2011 (UTC)

Water-added chicken breast

In this week's circular at a local supermarket is chicken breast with 20% added water. Is there a problem of insufficient disclosure in the United States of this added water, or is it well regulated? (If this question belongs in law, please move it.) Thanks. Imagine Reason (talk) 13:16, 1 October 2011 (UTC)

See plumping.--Shantavira|^{feed me} 14:55, 1 October 2011 (UTC)

Why do vegetables cooked quickly in Pressure Cooker

Can anybody pls explain my query -Thanking you Navneeth

Have you read our article pressure cooker, which explains how the increased pressure allows water to boil at a higher temperature? Mikenorton (talk) 15:50, 1 October 2011 (UTC)

It's because of how water boils. If you just have a pot of water at sea level and boil it, no matter how much heat you apply, the water will never get hotter than 100 degrees centigrade. Instead, the water will just boil faster. But if you increase the pressure, the boiling point of water is increased, so you can get the water hotter than 100 degrees, which cooks things a lot faster. Rabuve (talk) 17:23, 1 October 2011 (UTC)

Yes. Essentially, if it were to be at sea level, at 100 degrees, all the heat would go in making steam, rather than cooking the rice. At a higher pressure, the BP is raised, so the heat goes to the rice instead of trying to make steam. Lynch7 17:35, 1 October 2011 (UTC)

(And, magically, vegetables turn into rice :-)

(--DaHorsesMouth (talk) 00:56, 2 October 2011 (UTC))

Rice doesn't come from a plant? News to me! {The poster formerly known as 87.81.2301.95} 90.197.66.70 (talk) 12:48, 2 October 2011 (UTC)

The corollary is that, for similar reasons, you can't make decent tea in the mountains, because the water boils at too low a temperature, because of the lower air pressure. Mitch Ames (talk) 04:27, 2 October 2011 (UTC)

Miller indices and reduction to lowest integers?

In the 8th edition his book "Materials Science and Engineering: An Introduction", Callister states in a footnote on page 64 that "On occasion, index reduction is not carried out (eg., for x-ray diffraction studies that are described in section 3.16); for example, (002) is not reduced to (001). In addition for ceramic materials, the ionic arrangement for a reduced-index plane may be different from that for a nonreduced one."

I am not able to fully understand why this is the case, and hence, would really appreciate it if anyone could provide me with more details about this kind of "special" cases. If anyone has a document that discusses this kind of issues with respect to either x-ray diffraction or ceramics that would be great.

Thank you in advance. — Preceding unsigned comment added by 69.11.30.122 (talk) 16:41, 1 October 2011 (UTC)

Sometimes you can deduce the structure without index reduction, and sometimes index reduction will give you an incorrect structure. You have to check your results with what you know about the composition to make sure it makes sense. 75.71.64.74 (talk) 19:52, 1 October 2011 (UTC)

Reproductive isolation of humans?

If Bushmen man married Fuegian woman, can they have common children?

Their tribes have divided tens (hundreds?) of thousand years ago; they have a lot of different mutations and no gene exchange all this years etc.

I think they can have children, its probably not enough time for real reproductive isolation, but i`m not sure.

Maybe some sort of "weak" reproductive isolation? (For example, hight rates of mortality of infants)

P.S. I'm not a racist. I love Bushmen, Fuegians and all other nations. I'm just curios. - Ewigekrieg (talk) 23:03, 1 October 2011 (UTC)

The human group separated from the rest for the longest period was probably the Australian Aboriginal people. 40,000 years is the widely accepted figure. There have been absolutely no problems with them interbreeding with other humans. HiLo48 (talk) 00:13, 2 October 2011 (UTC)

There are different levels of reproductive isolation - from "no children" to "slightly heightened rates of mortality of infants". We can`t be sure about total absence of problems with interbreeding without data of the health of the "mixed" children - Ewigekrieg (talk) 00:31, 2 October 2011 (UTC)

Why should they marry? Anyway, 40,000 sounds like a lot, but it's not a lot of time in an evolutionary context. We had billions of common evolution before that. Wikiweek (talk) 00:28, 2 October 2011 (UTC)

Twu wuv? -- Obsidi♠n Soul 03:23, 2 October 2011 (UTC)

Geographic isolation doesn't necessarily mean reproductive isolation. While it may have eventually resulted in speciation from genetic drift given enough time; like Wikiweek say, it's simply too short (estimated beginning of human migration out of Africa is 70,000 to 50,000 years ago at the earliest).

The ability to interbreed successfully (produce fertile offspring) is also a plesiomorphic character, and may be retained within closely-related taxa. In Botany such closely related interbreeding groups of "semispecies" are called syngameons. Homo neanderthalensis and Homo sapiens, for example, despite having an evolutionary gap of ~400,000 years, were still not completely reproductively isolated, and were able to hybridize successfully. Modern human non-African populations still have traces of neanderthal genes from contact with them after radiation out of Africa.

It has actually been argued that premodern humans (including H. neanderthalensis) which diverged within around 1 million years ago, should be considered the "true" races (subspecies) of modern humans rather than separate species as they did/can not achieve reproductive isolation yet (Larsen, 2010. A Companion to Biological Anthropology. pp.372–373). The 1-million-year minimum is an approximation based on the average amount of time reproductive isolation/speciation occurs in other similarly-sized eutherian mammals (Cartmill & Smith, 2009. The Human Lineage. p. 412). Neanderthals, after all, did not truly become extinct. They were assimilated into modern humans.

The differences between modern humans even from such geographically isolated populations, in comparison, is exceedingly recent and minor. -- Obsidi♠n Soul 03:23, 2 October 2011 (UTC)

I understand, there is not enough time for complete reproductive isolation. But what about partial reproductive isolation?

For example, almost all species of Bovine can be hybridized. But some hybrids:

1. dying in womb

2. completely sterile and dying in youth

3. completely sterile

4. females are sterile, but not males

5. fertile, but have weak health

6. fertile and have average health

7. fertile and healthy.

Its a whole spectrum of reproductive isolation.

Human-neandertal hybrids can be, for example, at "stage" 4.

Is it enough differences between modern humans for "stage" 5? -Ewigekrieg (talk) 08:06, 2 October 2011 (UTC)

As there are no known cases of any human geographical populations having problems producing offspring together. The answer obviously, is no.

Animal species which show problems producing fertile offspring actually already have achieved reproductive isolation. In rare instances, though, fertile offspring from such unions can go on to create a hybrid species, like the domestic sheep Ovis aries. Your stages 5 to 7 are also subjective. Health of the offspring varies even within populations and is really not a very good indicator of reproductive isolation. Furthermore, what is 'unhealthy' and disadvantageous for one population, may be very advantageous in another. Hereditary diseases can also be passed on whether or not the parents belong to the same population.

It also happens in the opposite direction just as frequently. In hybridization between species and reproduction between differently adapted populations, mixing can result in stronger offspring able to take advantage of other habitats their parents can not, a fact taken advantage of in animal husbandry & horticulture. Modern bananas, for example, are the result of two species - Musa acuminata bear sweet fruits, but can not grow in more adverse conditions; Musa balbisiana is very hardy but produces starchy fruits. Hybridization between the two allowed early human farmers to spread the cultivation of bananas throughout the world. Population bottlenecking on the other hand, can cause inbreeding, which is usually detrimental. Early human cultures took great pains in avoiding this, even resorting to abducting wives from neighboring tribes.

Unless we're talking about obvious genetic defects here, everything else is basically eugenics when applied within a species and driven more by social attitudes as to what characters constitute a 'healthy' or 'acceptable' individual. The basis for genocides. -- Obsidi♠n Soul 09:28, 2 October 2011 (UTC)

Ok, one example. Some of Pygmy peoples have average hight of almost 1 meter. If Pygmy woman married white man, can she give birth without problems? Is her pelvis broad enough? Should she use Caesarean section more often than average?

My mother is Turkish woman and my father is German. I really don't have anything against mixing of nations. I try to understand human evolution. -Ewigekrieg (talk) 10:18, 2 October 2011 (UTC)

She's not exactly going to be giving birth to a six foot baby, heh. In fact, pygmy peoples give birth to newborns of the same average birth weight as that of taller peoples (Average North American birth weight is 7.5 lbs). Here's an account of birth among the Efé people. Besides, the fact that she had gotten pregnant already makes the question of reproductive isolation moot. Pygmy peoples also intermarry with neighboring Bantu peoples, whose heights are similar to European populations. Though it's rather infrequent. AFAIK the only real problems are social/cultural as Mitch Ames also mentions below. And those are not biological per se.-- Obsidi♠n Soul 11:10, 2 October 2011 (UTC)

Yes, I daresay you are right. Thanks for informative discussion -Ewigekrieg (talk) 11:26, 2 October 2011 (UTC)

There may have been "absolutely no biological problems with [Australian Aborigined] interbreeding" with other people, but there were a few social problems - see Half-Caste Act, Stolen Generation. Mitch Ames (talk) 04:24, 2 October 2011 (UTC)

No doubt, but what does that have to do with the biological nature of the original question? Googlemeister (talk) 14:17, 3 October 2011 (UTC)

October 2

Does it hurt getting shot?

I mean, a broken bone will hurt, but what if you get a clean straight shot, only perforating the flesh? Could that be the same case like getting a needle stick by an able med professional, without pain? Wikiweek (talk) 00:06, 2 October 2011 (UTC)

No, because a bullet produces a relatively large permanent cavity and therefore destroys large amounts of tissue, releasing lots of chemicals which stimulate the pain receptors in your arm. A needle is much narrower, produces a much smaller permanent cavity, and produces much lower amounts of chemicals, which translates into much less pain. Also with a needle, much of the small amounts of chemicals that are produced are reabsorbed by non-nervous cells, and never get a chance to stimulate pain receptors. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:20, 2 October 2011 (UTC)

From what I've heard, getting shot feels a lot like getting punched, only worse. 67.169.177.176 (talk) 00:21, 2 October 2011 (UTC)

Getting shot is a combination of multiple types of pain. There is the puncture of the skin, which is a sharp pain. If a bone is hit, there is damage not only the bone, but also to the joints around the bone. Then, just to piss you off, there is a sever burning if the bullet remains near the skin. For an anecdote... I've been shot 3 times. All three times, it hurt a hell of a lot. I've had countless shots and donated blood multiple times each year. I don't flinch when a needle is put in my arm. -- kainaw™ 01:58, 2 October 2011 (UTC)

THREE times?! Ouch! Was it part of an especially nasty wiki-dispute? 67.169.177.176 (talk) 02:06, 2 October 2011 (UTC)

You mean, you were shot three times one bullet or at one occasions three bullets? In the former case you seem to have a pretty bad luck (or good luck of being alive, depending on how you see it). Wikiweek (talk) 02:05, 2 October 2011 (UTC)

Three separate and very different occasions. However, it isn't notable any more than a stupid little anecdote. -- kainaw™ 02:11, 2 October 2011 (UTC)

Adrenalin can override pain. Don't forget about shock. Plasmic Physics (talk) 02:23, 2 October 2011 (UTC)

My obsessive punning brain read that as "admins can override pain". --jpgordon^{::==( o )} 18:47, 2 October 2011 (UTC)

Photon-tachyon interactions

A photon travels directly towards a tachyon moving directly towards it (the photon). They collide. Since the tachyon travels faster than the photon and the photon therefore cannot bounce off it and travel forwards away from the tachyon (because the tachyon will be continuously overtaking it), is the photon destroyed, does it pass through the tachyon, or does it swerve to avoid the tachyon? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:14, 2 October 2011 (UTC)

Tachyons don't exist in real life, so the question has no right answer. 67.169.177.176 (talk) 00:23, 2 October 2011 (UTC)

Absence of evidence≠evidence of absence. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:25, 2 October 2011 (UTC)

Tachyons are purely theoretical. There is no way of knowing how they would interact with other particles. There is a flaw in your logic though. If tachyons behave anything like any other particle one would assume that if it contacted another particle it would be deflected as well. Thus both particles would end up traveling in different directions, avoiding the problem. --Daniel 01:00, 2 October 2011 (UTC)

The tachyon has more momentum than the photon and would therefore overpower it. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:05, 2 October 2011 (UTC)

Good point... maybe. Tachyons lose energy as they speed up so it might depend on speed of the tachyon. From what I understand by reading the article is that to if one calculates a tachyon interacting with a normal particle you end up with imaginary numbers which have no meaning in our universe. --Daniel 01:13, 2 October 2011 (UTC)

I can't see any particular reason why a tachyon would have more momentum that a photon. It's moving faster, but that's not the same thing. In fact, I'm not sure their momenta are even comparable. In some formulations, a tachyon has imaginary mass. Doesn't that mean it would also have imaginary momentum? It doesn't make sense to ask whether a real number or an imaginary number is larger. Even if you are right and the momentum is greater for the tachyon, that doesn't mean it would "overpower" the photon. Typically, they would both be deflected, just the photon would be deflected more. --Tango (talk) 11:55, 2 October 2011 (UTC)

If a train rams a car, the train does not start moving in the other direction. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 14:07, 2 October 2011 (UTC)

But it might well get derailed and go off to the side (if it weren't for the rails, it almost certainly would go off to the side). That's what we mean by "deflect". The collision isn't going to be perfectly head-on, so the particles will each be deflected to opposite sides. If it were a perfect head-on collision, then I think you would just end up with the photon following the tachyon as though the tachyon had gone straight through it. There isn't a problem there before photons don't actually bounce, they are absorbed and then re-emitted. There is nothing to stop the photon being on the other side when it gets re-emitted. (That is all based on some wild guesses about how tachyons behave that come from extrapolating our existing theories to particles that they don't really make sense for, so it should be taken with a very large sack of salt.) --Tango (talk) 17:07, 2 October 2011 (UTC)

A tachyon that couples to the electromagnetic field would emit Cherenkov radiation as it moves through vacuum. The recent OPERA results suggesting that neutrinos move faster than light can be ruled out because of this effect, see here. Count Iblis (talk) 01:14, 2 October 2011 (UTC)

"Tachyon! Duck!" "THAT'S NOT A DUCK! And don't call me Tachyon!" Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:43, 2 October 2011 (UTC)

I don't understand that paper at all. They seem to assume that the neutrinos are straight-up QFT tachyons with E² = p² + m² and m² < 0. But I haven't seen anyone suggest that as an explanation for the OPERA data. QFT tachyons aren't superluminal. The proposed explanations I've seen are quantum gravitational, and I don't think this QFT argument would apply to them, not that I know anything about quantum gravity. -- BenRG (talk) 05:15, 2 October 2011 (UTC)

They assume that you can describe Lorentz invariance violation as is done in this paper. Count Iblis (talk) 22:56, 2 October 2011 (UTC)

Weighing the atom

How much does a single atom weigh? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:15, 2 October 2011 (UTC)

Depends on what kind of atom. See the articles Atomic mass, Chemical element and Isotope for more info. 67.169.177.176 (talk) 00:25, 2 October 2011 (UTC)

Thanks. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:28, 2 October 2011 (UTC)

Bacteriophages as antibiotics?

Would bacteriophages be useful as a practical replacement of chemical antibiotics? Because they produce more of themselves whenever they kill bacteria (and become inactive and are flushed out of the system when all the bacteria are dead), while chemicals require repeated treatments to eliminate the infection, it seems that they'd be much more efficient. --70.250.214.149 (talk) 01:25, 2 October 2011 (UTC)

See the article Bacteriophage therapy. It appears that bacteriophages can indeed be used to treat infectious diseases, but only if the exact strain of the disease-causing bacteria involved is known with certainty. For this reason, it would probably be ineffective against infections that involve a rapidly mutating bacterial strain, or several strains at the same time (as is often the case, e.g. with tuberculosis). 67.169.177.176 (talk) 01:35, 2 October 2011 (UTC)

Terrarium vs. tank

If I'm getting a ball python, is there any advantage of a regular fish tank set-up vs. a glass terrarium set-up? DRosenbach ^{(Talk | Contribs)} 01:30, 2 October 2011 (UTC)

You'd be paying the same for a larger terrarium, right? Go with that and give it a stick to climb. 69.171.160.198 (talk) 03:40, 2 October 2011 (UTC)

AK47 vs. Bulletproof glass

Will bulletproof glass withstand multiple hits at the same point from an AK47? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:39, 2 October 2011 (UTC)

Given enough hits at the exact same point, even the strongest bulletproof glass can eventually be breached. It all depends on how strong is the glass, and how many hits it takes at the same point. 67.169.177.176 (talk) 01:50, 2 October 2011 (UTC)

Hopefully you are not holding an AK47 at this moment... Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:53, 2 October 2011 (UTC)

The question can only be answered with yes, for any material, unless you limit the number of shots. Wikiweek (talk) 02:03, 2 October 2011 (UTC)

Or unless you're shooting at a gravitational singularity... Whoop whoop pull up ^{Bitching Betty | Averted crashes} 02:10, 2 October 2011 (UTC)

Is there any hypothesized method for damaging or altering such a phenomenon? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:29, 2 October 2011 (UTC)

Only hawkings radiation can make it decay, and that would take a long ass time. ScienceApe (talk) 05:13, 2 October 2011 (UTC)

AK-47 shot at bullet proof glass. As the warning at the front states, There is no such thing as 100% "bulletproof glass" - all glass is bullet resistant according to the standards set by the National Institute of Justice and/or the European Committee for Standardization. Buddy431 (talk) 04:59, 2 October 2011 (UTC)

And for the record, there is nothing illegal about owning or holding an AK-47 in many jurisdictions around the world. In the US for example, they are legal in many areas provided they do not have full auto capability. Googlemeister (talk) 14:11, 3 October 2011 (UTC)

Global warming and future

What will the effects, as can be scientifically predicted from present climate scenario, of global warming to human civilization in 2100 and later? Will islands like Mauritius and coastal areas like Sunderbans sink? --DinoXYZ (talk) 05:56, 2 October 2011 (UTC)

Yes. Hence why representatives of the most low-lying island nations were pretty much disgusted at the failure to produce a resolution in the 2009 United Nations Climate Change Conference.

See Climate change in Tuvalu and Maldives#Environmental Issues. -- Obsidi♠n Soul 06:42, 2 October 2011 (UTC)

Wind instruments

Wind instruments do not have all their notes perfectly in tune with corresponding notes on the piano. There is a chart published indicating the discrepancies with respect to alto and tenor saxophones. It would interesting to have similar charts for, at least the B flat trumpet and the slide trombone. — Preceding unsigned comment added by 82.44.58.70 (talk) 09:01, 2 October 2011 (UTC)

Do you have a question? Plasmic Physics (talk) 11:33, 2 October 2011 (UTC)

No, he doesn't. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 12:15, 2 October 2011 (UTC)

I'll ask it then. Does anyone have a link to a chart for various instruments indicating the discrepancies between their notes and those of a piano? I know that there are many secondary-adjustments sax and clarinet players use, various combinations of keys and tone holes distant from the main ones used for the standard fingering, so would also be useful to know how much this counteracts the discrepancy. Trumpets have a tuning slide that can be kicked in or out while playing to fix certain notes. And a trombonist could just slide a little in or out and match any arbitrary frequency exactly, no? DMacks (talk) 16:16, 2 October 2011 (UTC)

Not unless the trombone is also perfect (i.e. undented). Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:32, 2 October 2011 (UTC)

Comment: "perfectly tuned" is a bit of pseudoscience. Though musicians will adamantly insist that there is such a thing as a true "perfect pitch" - and then furthermore attest that certain humans are "endowed" with a flawless capability to discern exact pitches - anybody with an engineering background will scoff at the idea.

Musical instruments have timbre - they are not monotonal - which means that their frequency spectrum is very complicated. A peak frequency exists (the root note), but it always (always) has a bandwidth. It is physically impossible to construct a real, non-theoretical instrument (including electronic synthesizers) that deliver a pure monotone sine wave. (To do so would require a musical instrument that never started or stopped playing - to have zero bandwidth tone, i.e. "exactly one specific frequency," the extent of the signal must propagate to ±∞ time. Nimur (talk) 18:45, 3 October 2011 (UTC)

Inflation-Adjusted Cost of Electricity?

Is there a way to calculate (or find) the Inflation-Adjusted Cost of Electricity in the US or EU for the past 50 years or so? On a similar note, is there a way to find the inflation-adjusted cost of lighting? --CGPGrey (talk) 10:31, 2 October 2011 (UTC)

You got it. Summary: about 8 cents per kilowatt hour, but recently headed down under 7. 69.171.160.9 (talk) 19:35, 2 October 2011 (UTC)

By which methods and how accurate can we predict the properties of an unknown isotope?

I'm just a bit curious about some sites that claimed like "In case no experimental data is available, trends in the systematics of neighboring nuclides have been used, whenever possible, to derive estimated values"--Inspector (talk) 11:19, 2 October 2011 (UTC)

That kind of guessing is one of the main strengths of the arrangement of the Periodic Table. We've come a long way from Mendelejev and his Eka-aluminum, but the system still pretty much works the same. Take neighboring elements and extrapolate, mainly. I cannot tell you which Algorithms are used in the creation of such data, sadly, but the system in general is pretty sound. I cannot comment of the reliability of any such specific data though. --Abracus (talk) 15:25, 2 October 2011 (UTC)

I depends on the properties you are trying to predict. Look for example at figure 2 here. One can see that while properties across the periodical table are not exactly continuous or obvious, there are trends, so that if you knew some "goalposts", you could try to work backwards to extrapolate the remaining parts. There are other forms of regularity that can be extrapolated ahead of time — e.g. magic numbers. This doesn't mean that these things are understood greatly — there are often surprises (imagine trying to extrapolate the phase diagram of Plutonium only knowing Uranium and Curium, in the aforementioned figure 2) but you can often get a pretty good idea of what the possible and/or likely cases are (in the case of the U and Cm, you'd know that something weird was going to be happening there, because you've got two radically different phase diagrams — Pu, as it turns out, is something of a juncture point in the higher actinides, making it metallurgically quite interesting). Depending on the properties you are investigating, there are probably more or less reliable ways of deducing from other nuclides. --Mr.98 (talk) 17:07, 2 October 2011 (UTC)

For example, the half-lives?--Inspector (talk) 09:14, 3 October 2011 (UTC)

Nuclear half lives fall into the domain of nuclear physics (or "nuclear chemistry"); so the periodic table (which really is a taxonomy of electron behaviors) is sort of inapplicable. To study half-life quantitatively, you need to use a lot of nuclear physics theory, but most of the time, the simple theories can't accurately predict nuclear stability. Loads of experimental correction factors are used, based on known, measured properties. Consider reading: about isotopic stability. Nimur (talk) 18:52, 3 October 2011 (UTC)

future binary solar system?

Given the enormous gravity of Jupiter and the available hydrogen/deuterium in space, how much larger would Jupiter have to be, or how much time would it take, for Jupiter to reach sufficient mass to trigger internal fusion reaction and become a sun/star? Has anybody ever figured this out?, or is this just a stupid question?190.149.154.16 (talk) 12:43, 2 October 2011 (UTC)

It's a perfectly sensible question and has been extensively studied. The article Brown Dwarf should get you started, and will have further relevant links. {The poster formerly known as 87.81.230.195} 90.197.66.70 (talk) 12:56, 2 October 2011 (UTC)

Definitely not time, mass yes. Time has no effect on whether fusion initiates or not. There is a net loss of mass from Jupiter not a net gain, so unless its mass is artificially increased significantly, it will not happen. Plasmic Physics (talk) 12:57, 2 October 2011 (UTC)

Thanks guys. But I'm a little confused about the(Jupiter's mass loss) statement because atmospheric escape indicates that Jupiter's great distance from the sun, It's enormouse magnetic sheild, and large mass/gravity would minimize or eliminate mass loss, even though it doesn't mention jupiter specifically. Now since an enormouse amount of space hydrogen must be attracted by Jupiter's gravity it seems that the mass must be increasing. Please help.190.56.17.233 (talk) 16:00, 2 October 2011 (UTC)

The mass Jupiter is losing is probably very small, but it isn't attracting much either. The inter-planetary medium, especially out as far as Jupiter, is extremely thin. I think Jupiter gains more mass from meteors than the inter-planetary medium, but it will never get anywhere near enough to become a star. It would need to become about 80 times as massive as it is now. There isn't enough matter in the entire the solar system (excluding the Sun) to do that. --Tango (talk) 17:15, 2 October 2011 (UTC)

Is there a reliable source saying that Jupiter is losing mass? μηδείς (talk) 17:27, 2 October 2011 (UTC)

A good point Medeis. I tried several titles but could not find anything indicating Jupiter mass loss. Bearing in mind the enormous gravitational influence of Jupiter, It's clear that it's influence cannot be limited to the space volume within the solar system, and must also effect a large volume of interstelar space, and even though those atoms of hydrogen are widely seperated there must be a lot of matter available to Jupiter. Anybody have anything on that?190.56.17.233 (talk) 18:39, 2 October 2011 (UTC)

P.S. It has been asertained that Jupiter is giving off more heat energy than it gets from the sun, but that's not the same as loosing mass. Or is it?190.56.17.233 (talk) 18:48, 2 October 2011 (UTC)

Antimatter vs. black hole

Would it be possible to destroy a black hole by sending a gigantic lump of antimatter, the same mass as the black hole, into it? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 12:53, 2 October 2011 (UTC)

No. Why should it? Plasmic Physics (talk) 12:57, 2 October 2011 (UTC)

Adding mass to a black hole only makes it stronger. Plasmic Physics (talk) 12:59, 2 October 2011 (UTC)

Adding enough antimatter would annihilate the black hole's singularity, causing the black hole to stop existing. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 13:45, 2 October 2011 (UTC)

Rubbish. Annihilation of matter and antimatter leaves energy, which has the same mass as the original matter and antimatter - see mass-energy equivalence. So you have simply added more mass to the black hole, as Plasmic Physics said. Gandalf61 (talk) 15:04, 2 October 2011 (UTC)

Would the antimatter even make it from the event horizon to the singularity? I thought anything added to a black hole after it forms stays suspended in the infinitely extended spacetime. Or is that just from the antimatter's frame of reference? 69.171.160.9 (talk) 19:33, 2 October 2011 (UTC)

In the frame of reference of the object falling into the black hole, it reaches the singularity within finite time. It is in the frame of reference of an object far away from the black hole that objects falling in seem to become frozen just above the event horizon. --Tango (talk) 22:44, 2 October 2011 (UTC)

Similar question:) HOW to destroy a black hole? -Ewigekrieg (talk) 13:19, 2 October 2011 (UTC)

Add antimass, which has never been proven to exist; or increase the Hawking radiation flux, which there is no known way to accomplish. Plasmic Physics (talk) 13:33, 2 October 2011 (UTC)

Doesn't antimatter HAVE antimass? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 14:32, 2 October 2011 (UTC)

No, anti-matter has normal mass. Dauto (talk) 15:01, 2 October 2011 (UTC)

Can some sort of very strong gravitation waves destroy it? - Ewigekrieg (talk) 13:55, 2 October 2011 (UTC)

No, very strong gravitation waves are produced by coloding black holes, they merge not vanish. Plasmic Physics (talk) 14:00, 2 October 2011 (UTC)

I try to explain. So, we have a bath full of water. We open the plug and create a whirlpool ("black hole"). Now we make really big wave ("gravitation wave"), and the whirlpool collapsed. Can we repeat this with real black hole? -Ewigekrieg (talk) 14:12, 2 October 2011 (UTC)

No. Read my comment below. Dauto (talk) 15:03, 2 October 2011 (UTC)

Anti-matter and gravitational waves both have positive energy and will only make the BH bigger. Note that the singularity is not made of matter. It is a space-time singularity. Think of it as a part of the structure of space-time itself, not as an object located somewhere in space-time. Dauto (talk) 14:18, 2 October 2011 (UTC)

So ram a white hole into it. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 14:43, 2 October 2011 (UTC)

A white hole is just another name for a black hole. read the article you linked (specially the 3rd paragraph) for an explanation. Dauto (talk) 15:10, 2 October 2011 (UTC)

It might be indistinguishable. It might be different though (if it exists). ScienceApe (talk) 15:54, 2 October 2011 (UTC)

See also here. Count Iblis (talk) 15:36, 2 October 2011 (UTC)

Exothermic reactions in warm-blooded creatures

What are the chemical equations of some exothermic reactions that take place in the bodies of some warm-blooded animals? Please use common sense and understand that I am aware that lots of exothermic and endothermic reactions take place in the bodies of both warm-blooded and cold-blooded animals, but by my question I of course am only interested in reactions that are significant enough to be ones relevant in heat output to be one of the reactions that cause the animal to be considered by humans as warm-blooded (and again, yes, I am aware that the term has fallen into disuse; humor me). Peter Michner (talk) 13:42, 2 October 2011 (UTC)

This explains it pretty well. For shivering thermogenesis, it's basically the waste energy released during ATP hydrolysis. In non-shivering thermogenesis, it's the disruption of oxidative phosphorylation (creation of ATP) by UCP-1 which enables the mitochondria to "waste" substrate, generating heat instead of storing them in ATP as it normally would.

I'm sure there are more detailed breakdowns of the reactions mentioned in the linked articles or somewhere else, but you'd probably be better off looking for them yourself. My brain shuts down when I see diagrams of metabolic reactions, I disliked biochem :P -- Obsidi♠n Soul 15:41, 2 October 2011 (UTC)

Newton's laws of motion

Isn't Newton's first law of motion simply a special case of his second law of motion, where f=0? And would massless particles still be affected by the first law, because they have no mass and therefore no force is needed to produce any given acceleration (because $f=0a$, therefore $0=0a$, so any value of a satisfies the equation)? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 14:21, 2 October 2011 (UTC)

1. Yes, the first law is just a special case of the second.
2. No, massless particles also follow the fist law.

Dauto (talk) 14:58, 2 October 2011 (UTC)

I like to think of the "first law" as the definition of inertia, rather than as an equation. The second law is the definition of force in Newtonian physics; and the third law is the formal statement of Newtonian kinematics.

When you compare the "Three Law" statement of Newtonian physics to alternative formulations of classical physics, (i.e., the principle of least action), you see that these three items are explicit. For example, inertia does exist conceptually, when we study Lagrangian physics; but it's not defined so succinctly.

When viewed this way, the shortcomings of Newtonian physics become blatantly obvious: for example, force is defined in terms of mass and acceleration, but mass is never defined. (Nor is acceleration, for that matter!) Newton assumed mass was an innate property of the universe! And he didn't consider wacky spatial geometries where acceleration is poorly defined. Extending the Newtonian definitions to account for these properties leads to general relativity. Nimur (talk) 19:03, 3 October 2011 (UTC)

Infinite Regress and General Relativity

It is often asserted in arguments related to the existence of God that an infinite regress of events is not possible. This to me seems to just be a bare assertion, but I would like a more specific demonstration that an infinite regress is at least theoretically possible to use as a clincher in such arguments. Has someone ever mathematically proved that an infinite regress does not violate General Relativity? Rabuve (talk) 15:00, 2 October 2011 (UTC)

The argument does not refer to an infinite regress of events, but rather to an infinite regress of causes. General Relativity has nothing to say about that. Looie496 (talk) 15:19, 2 October 2011 (UTC)

What I mean is a chain of events each caused by the one before it Rabuve (talk) 16:35, 2 October 2011 (UTC)

In classical theories an infinite regress (in a finite amount of time) is possible. This has been shown rigorously for classical mechanics, and I think in General Relativity there is a similar result. Count Iblis (talk) 15:18, 2 October 2011 (UTC)

What does infinite regress mean in physics?

You have it backwards. The Universe exists because there was nothing to prevent it. μηδείς (talk) 17:24, 2 October 2011 (UTC)

I'm not asking why the universe exists; I'm asking if there is a proof that having an infinitely long string of events casually linked doesn't violate General Relativity. Rabuve (talk) 20:08, 3 October 2011 (UTC)

Worried about eating gnats

So I bought some cinnamon rolls, and I ate one. Then the next day, I see inside the box a whole bunch of flying insects. I was so disgusted, I have no idea how they got in there because the box was closed and in a plastic bag that was wrapped tight. Anyway I got rid of the bugs (They were quite small so I think they were gnats), and considered throwing out the rest. But they tasted really good, and I decided that they were probably harmless so I ate the rest. Now I'm a bit worried (hypochondria?), is there any possibility that they have any parasites in them or diseases? Could they have layed their eggs in the cinnamon rolls? ScienceApe (talk) 15:15, 2 October 2011 (UTC)

We cannot give medical advice here as a general rule. If you are worried about parasites, please ask an appropriately qualified medical professional. --Abracus (talk) 15:27, 2 October 2011 (UTC)

Wow. The question "do gnats carry parasites or transmit disease" is a medical question? --jpgordon^{::==( o )} 15:32, 2 October 2011 (UTC)

Yeah I didn't think this was a medical question lol. If you want, just ignore my little backstory and tell me if there's any danger to consuming gnats or food that gnats were crawling around on. ScienceApe (talk) 15:47, 2 October 2011 (UTC)

See The Food Defect Action Levels by the FDA. [Most unintentionally ingested] insects "pose no inherent hazard to health" except to people who may have allergies to them. -- Obsidi♠n Soul 16:00, 2 October 2011 (UTC)

With this sort of question, the problem is that if we tell you not to bother to seek medical advice and then you get sick, we are partly to blame. So if you are in any doubt it's best you call NHS Direct or the equivalent in your country.--Shantavira|^{feed me} 16:03, 2 October 2011 (UTC)

Like I said, just ignore my backstory dude. :) ScienceApe (talk) 18:58, 2 October 2011 (UTC)

Good point, you reminded me of this article where it says (halfway through) that frozen broccoli is filled with bugs. As the FDA article says there can be more than one aphid/thrip/mite per 2 grams of broccoli. Considering that these are similar to gnats (they feed mostly on plants) it would seem unlikely you'll come to any harm. As the link above shows, you could in fact be a pioneer of entomophagy in the west! (Obviously if you do feel ill go see a doctor). SmartSE (talk) 20:39, 2 October 2011 (UTC)

Insects do not spontaineously generate parasites or other disease causing microbes. They simply convey them from one animal to another. so if those insects do not feed on animals/humans and just like to eat sugar,then that just makes them sweeter.190.56.17.233 (talk) 16:27, 2 October 2011 (UTC)

So, it's secure to eat cockroaches and flies? Quest09 (talk) 16:30, 2 October 2011 (UTC)

As long as they haven't been eating mold, oleander seeds, or something else toxic. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 16:34, 2 October 2011 (UTC)

Cockroaches and flys do feed on animal matter, including feces. And how many orleander seeds do you think a gnat could eat.190.56.17.233 (talk) 16:40, 2 October 2011 (UTC)

Part of one. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 16:44, 2 October 2011 (UTC)

pretty harmless then, Huh?190.56.17.233 (talk) 16:58, 2 October 2011 (UTC)

Do you have ANY idea how toxic oleander is?! Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:21, 2 October 2011 (UTC)

Well our article suggest that it is not that highly toxic. I suppose if you ate a meal of cockroaches, and they had all fed on Oleander seeds, then you might be at risk. Dbfirs 07:38, 3 October 2011 (UTC)

Alcubierre drive vs. black hole

What would happen f you rammed an Alcubierre drive into a black hole? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 16:19, 2 October 2011 (UTC)

The Alcubierre drive is not permitted by the laws of physics and violates causality. When you can violate causality you can do anything, including, I suppose, destroying black holes by preventing their original formation. However, I think that the Alcubierre drive, as usually defined, has no mass, so just tossing one haphazardly into a black hole wouldn't grow or shrink the hole. -- BenRG (talk) 18:23, 2 October 2011 (UTC)

So I was wondering why I had never heard of that drive before, and now I see why. It's a useless piece of non-sense. Dauto (talk) 19:18, 2 October 2011 (UTC)

Wouldn't the expansions and contractions of space-time ahead of and behind the drive yank at the space-time of the black hole enough to seriously perturb it? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:23, 2 October 2011 (UTC)

As BenRG says, the drive can't actually exist (at least, not without some pretty serious changes to our understanding of physics). That means it's meaningless to try and describe how it would work, except as a mathematical exercise. Black holes certainly can be perturbed, in as much as the event horizon won't always be spherical (collisions between black holes are a good example of this), but that won't destroy the black hole. --Tango (talk) 22:50, 2 October 2011 (UTC)

The principle of general covariance implies that the event horizon of a black hole is not fundamentally different from any other place in the universe. An Alcubierre drive would pass through it just like any other region of spacetime. But because it exceeds the speed of light, the usual rule that "what happens inside the event horizon stays inside the event horizon" doesn't necessarily apply any more. Maybe it could shrink the hole by transporting out infalling matter before it hits the singularity. Regardless, the Alcubierre drive requires exotic matter with a negative mass density, and if you've got that you could simply drop some of it into the hole to shrink it, no warp drive required. -- BenRG (talk) 04:29, 3 October 2011 (UTC)

Shot three times

How was User:kainaw shot three times? What are the chances of that happening and the chances of surviving? Quest09 (talk) 16:25, 2 October 2011 (UTC)

It would depend significantly on what part of your body is hit each time, as well as the calibre and type of bullet and the medical care available (and how near it is). There is no way you can come up with a single number. You could theoretically come up with the number of people who have been shot three times and see what percentage of them survived but I doubt those statistics are easy to come by (and whatever statistics you have are likely to be somewhat flawed anyway, e.g. if you go by hospital visits some people aren't going to go to hospital unless it is severe), and the number it self is fairly meaningless. Nil Einne (talk) 16:47, 2 October 2011 (UTC)

That rather uncouth chap 50 Cent was shot nine times and survived with only minor long term effects so even multiple bullet wounds are survivable. Quintessential British Gentleman (talk) 17:01, 2 October 2011 (UTC)

I realised I forgot to mention how deeply the bullet penetrates will also often have an effect, which will depend on the first 2 I mentioned but also things like the type of gun and distance it was fired from. BTW just to emphasise 'part of the body hit' isn't a simple thing. Obviously a shot which actually penetrates he heart is likely to be fatal and the brain isn't good either but it seems likely you have a greater chance of surviving some shots to the body then a shot whick knicks the Femoral artery. Incidentally I found this very mildly related article [17] Nil Einne (talk) 18:24, 2 October 2011 (UTC)

As Nil Einne states, two of them were small caliber and didn't even break the bone they hit. I grew up playing in woods where hunters were always shooting at anything that moved. The third was a larger caliber, but it was a ricochet into my shoulder. So, it was travelling relatively slow. I know that getting shot isn't common - most people aren't raised around guns - but I don't find this notable. I was raised in an area full of hunters and then I served in the U.S. Marines (they have a few guns too). Now, I work in a hospital, so I have more concerns about infections than guns. -- kainaw™ 17:17, 2 October 2011 (UTC)

Well, as I asked whether being shot hurts, I didn't mean such cases: 2x hitting a bone, 1x ricocheting bullet, and therefore not straight. I thought about a clean high energy straight shot, maybe just hitting your waste fat (only skin and fat), getting in and out. Wikiweek (talk) 19:43, 2 October 2011 (UTC)

I see somene mentioned 50cent. Iremember once in the 1990's reading in a science magazine (or science section of a periodical) that on average there is a 50% chance of death per bullet wound over the general population. Paradoxically, that doesn't mean your chances of survivng one bullet wound is 50%. μηδείς (talk) 17:20, 2 October 2011 (UTC)

This guy survived being "executed" by a firing squad who shot him 9 times including being shot straight in the head - there is a pic here! If you search for "El Fusilado" you'll also find a song telling his story by Chumbawamba _{(much better than a song I can be fairly sure 50 cent will have made about him being shot)}. SmartSE (talk) 20:53, 2 October 2011 (UTC)

Gov Connalley of Texas got shot like 3 times with 1 bullet and lived, if you believe the experts. Googlemeister (talk) 14:00, 3 October 2011 (UTC)

Radar display updating in "real-time"

I watched an episode of Mayday (TV series), and noticed that the airplanes on the Air Traffic Controller's radar display were moving "live", very smoothly. However, there was also the familiar slowly rotating green strike going across the display, indicating the antenna orientation; the motion of the dots just was in no way related to the rotation of the radar. Sometimes the dots even changed direction between the sweeps. Is this how the (modern) radars actually work, or is it just an artist's misconception? I've seen it in numerous other episodes of Mayday, too, and it really sticks out. Thanks! ›mysid (☎✎) 18:55, 2 October 2011 (UTC)

What you see on a radar is called a "track" (well, you see many tracks). Radars rarely work alone. The controlling computers gather information from other radars also. So, you have information even when your radar isn't sweeping an area. Further, the controlling computers predict what will happen between sweeps and show that. When an aircraft behaves in an abnormal manner, it will jump. In reality, it didn't jump. It is just that the computer predicted it would be in one place, but it showed up in another. That isn't as easy as it seems. What if an aircraft dropped chaff to make it look like it is somewhere it isn't? What if it was two aircraft all along and they were real close to one another and then they suddenly separate? All in all, the person at the radar station is seeing the best guess of the computer, not real radar information. -- kainaw™ 19:09, 2 October 2011 (UTC)

Thanks for the info! But what role does the green strike play, then? It was only shown for one radar. (And does this system have a name? Our article on radar tracker doesn't mention one where the dots are moving smoothly) ›mysid (☎✎) 19:25, 2 October 2011 (UTC)

Perhaps the regulations for that kind of a device are old and require it to be there. --145.94.77.43 (talk) 20:12, 2 October 2011 (UTC)

Civilian trackers definitely are not required to display the antenna swipe, at least in Europe. Moreover, in all but the most basic installations, multi-radar tracking is the norm, so there is no single swipe. There are two possible sources for the "stripe". First, if it really was rotating, it may just have been artistic license - they asked a prop man to provide a display, and he programmed a fake. If, on the other hand, the stripe went up (or down), it may just have been interference between the radar screen and the movie camera. --Stephan Schulz (talk) 21:17, 2 October 2011 (UTC)

The green sweep display is just from one radar system of which there are usually several available, and the display is there with controls so that the sweep region can be adjusted or controlled in an emergency. The smooth operational display system displays are multilateration from all the radars that aren't under manual control for the Short Term Conflict Alert, transponders, and communications systems. 69.171.160.45 (talk) 03:35, 3 October 2011 (UTC)

At a non-military control tower, they are mostly looking for the aircraft transponder to tell them where they are, not so much actually bouncing radar beams off of the aircraft. However, they could very well keep that radar system operating in case some doctor is flying his Cessna around without a transponder so mostly the sweep radar is a secondary system. Googlemeister (talk) 13:54, 3 October 2011 (UTC)

Aircraft transponders actively providing position information is ADS-B, a technology that is currently being phased in, but which is not yet supported by all airframes, and rarely used exclusively. Secondary Surveillance Radar uses transponder replies, but still computes the position from the antenna azimuth (i.e. direction ;-) and the signal run time, just as a classical primary radar. The difference is that it take the known latency of the transponder into account (and, of course, the fact that the transponder provides identity and barometric altitude, or, if it is a modern Mode-S transponder queried by a Mode-S Radar, everything from the stock of coffee in the pantry (separated into decaf and regular) to the frequency and duration of the pilot's rest room visits). --Stephan Schulz (talk) 17:55, 3 October 2011 (UTC)

Confining the electron

Would it be possible to confine an electron enough that it is possible to know exactly where it is? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:03, 2 October 2011 (UTC)

No, because of the uncertainty principle. Dauto (talk) 20:04, 2 October 2011 (UTC)

But what if the electron is confined to such a small space that it can only follow one possible track for any given momentum, making it possible to precisely measure both its position and its momentum? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:07, 2 October 2011 (UTC)

can't be done because of the uncertainty principle. An electron is not a tiny little ball that can be confined and will have a track. It is a wave that fills the available space without a clearly defined track. Dauto (talk) 20:13, 2 October 2011 (UTC)

An electron is a PARTICLE. It has diameter and mass. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:14, 2 October 2011 (UTC)

And a wave: wave-particle duality. Any effort to highly constrain an electron must necessarily result in a particle whose momentum is highly uncertain (or more accurately, one whose wavefunction is spread over a very wide range of possible momentum states simultaneously). Dragons flight (talk) 20:31, 2 October 2011 (UTC)

What about an electron that is confined to one single point in space and not allowed to move, thus determining its exact momentum (zero) and its exact position (the position of the point it is confined to)? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 21:08, 2 October 2011 (UTC)

Not possible. Put an electron in a box. Now make that box smaller over time. The smaller you make the box, the more kinetic energy must be transferred to the electron. In the limit that the box contracts to a single point, the kinetic energy of the electron becomes infinite. It is not possible, even in principle, to make a trap that can completely confine an electron to a single point in space. Unlike classical physics, quantum mechanics teaches that a confined electron must have non-zero kinetic energy at all times. Dragons flight (talk) 21:24, 2 October 2011 (UTC)

A diameter ? Sean.hoyland - talk 20:34, 2 October 2011 (UTC)

See quantum tunneling, I'm sure some users here might take issue with this, but for layman's purposes, imagine the electron can teleport through physical walls. So it's impossible to confine in a physical space. At most you can alter its probability cloud with electric fields. ScienceApe (talk) 23:22, 2 October 2011 (UTC)

You can actually measure (and observe) the exact moment when everything classical goes out the window and quantum rules. When you say, "an electron is a particle. it has diameter and mass", you're using a classical language. That can be very effective in some contexts. But when you start talking about sizes of a certain scale, then you have to switch to a fully quantum vocabulary and reasoning. And that means uncertainty. There is a lot of interesting work on physics at that boundary between the classical and the quantum — it turns out to be pretty important in nanoscale engineering. See Mesoscopic physics. Your idea of the box is a classic way to think about it. At a macroscale, you can talk about an electron being "inside" a box, sure. But as you start to shrink it, when you hit the mesoscale, suddenly that language starts to get really problematic, and stops being correct at all. --Mr.98 (talk) 00:23, 3 October 2011 (UTC)

Building "life expectancy"

How long do buildings are expected to last? Excluding things like meteorites, earthquakes and such. Wikiweek (talk) 20:57, 2 October 2011 (UTC)

Often a very long time, look at the Kremlin or the White House. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 21:13, 2 October 2011 (UTC)

That's certainly right, but not the most common case. I was thinking more about concrete office buildings or normal brick and mortar houses. Wikiweek (talk) 21:26, 2 October 2011 (UTC)

For tax purposes, the US convention (since 2010) is to assume that most new construction will have a 50 year useful life. Obviously some buildings continue to be used well beyond that, while others are replaced after much less than 50 years, but 50 years is probably a decent rough estimate. Dragons flight (talk) 21:39, 2 October 2011 (UTC)

So, what about all those pre-war Manhattan buildings? Are they worthless? I suppose that for tax purposes you needed a rule to amortize it. The lawmakers chose 50 years, but could have chosen more or less years. Quest09 (talk) 22:11, 2 October 2011 (UTC)

They're not worthless at all, but they've been renovated at some point, if only to update the systems and the roof, doors and windows. Acroterion (talk) 14:33, 3 October 2011 (UTC)

The White House? It's barely 200 years old... I know Americans think that is old, but it's really not. America doesn't have old buildings. I live in London. You can't walk for 10 minutes here without tripping over buildings far more than 200 years old. --Tango (talk) 23:00, 2 October 2011 (UTC)

You know: 200 years is old in the US, 200 miles is far in Europe. Quest09 (talk) 23:07, 2 October 2011 (UTC)

Very true! --Tango (talk) 00:46, 3 October 2011 (UTC)

There is some distinction that should be made between the 'remains standing' lifetime, the 'still usable' lifetime, and the 'roughly the same, functionally, as new construction' lifetime. While it is certainly the case that buildings 200 years old remain in service, many have limitations which would not be acceptable (or even legal) in new construction. Older buildings (or sometimes just their shells, or even their street-facing facades) are often retained and retrofitted at great cost and inconvenience for the purposes of 'historical preservation' and so forth. I don't dispute that older buildings can have value as works of art and can form an essential part of a street or city's character and be worth retaining on that basis—but by the purely practical measure of cost, it would make more sense to demolish them and replace them with new construction.

Any building older than two or three decades faced much more limited requirements for accessibility by disabled persons. Doorways (and even hallways, if one looks at construction more than a hundred years old, especially in very densely-packed cities) aren't wide enough to admit wheelchairs. Ramps and elevators may be absent or extraordinarily inconvenient. Methods used for heating two hundred years ago were very different from those used today. Retrofitting modern heating, air conditioning, ventilation, elevators, fire containment, fire suppression, electrical supply, lighting, computer networking, handicapped accessibility, and plumbing isn't trivial; building occupants are often forced to make an unpleasant choice between astronomical cost and tolerating inconveniences, discomforts, and hazards—and even if they do spring for the upgrade, it can mean that the building is partly or wholly unusable for months or years of construction anyway. TenOfAllTrades(talk) 11:36, 3 October 2011 (UTC)

If wood-and-masonry buildings can last hundreds of years, I see no reason why steel and concrete buildings wouldn't last longer. So, the answer is very very long, specially if you maintain the building properly and avoid things like water damage. Quest09 (talk) 23:07, 2 October 2011 (UTC)

Indeed. If they are well-maintained, they can last pretty much forever. Such buildings are often demolished when they still have plenty of life left in them in order to be replaced by new buildings. That's far more common that them getting too old (unless they've been abandoned for some time). --Tango (talk) 00:46, 3 October 2011 (UTC)

An interesting book that touches on this topic is How Buildings Learn. Pfly (talk) 04:50, 3 October 2011 (UTC)

European castles made of solid blocks of stone will start decaying in a few decades if unmaintained. The roofs are the weakest part since they are made of more fragile materials. Then the rainwater will flood places that were intended to remain dry. Internal rooms will no longer be protected from very low temperatures, so that water will start freezing inside the cracks of the stone, cracking them even more. Certain stones will crack way sooner than others, if left unrepaired they will damage surrounding stones. Damaged pillars will fall on other stones, cracking them, sometimes adding weight in places not designed for it. Stones in the middle of a wall will debilitate stones above it and will eventually cause the falling of whole wall sections. Usually, the cracks among stones are covered with masonry stuff, which gets destroyed in a couple of decades. If the cracks are kept well covered, stone walls may last millenia. Some stone buildings in Egypt were covered in sand and forgotten, and have been preserved magnificently for 4000 years or so. Now they are been eroded slowly by wind/ice and might last a few centuries if unmaintained. Summary: good frequent maintenance works because it prevents damage to buildings before it happens. Bad unfrequent might repair the most damaged parts but it will not prevent damage to parts that are still in good shape. --Enric Naval (talk) 14:18, 3 October 2011 (UTC)

Any well-constructed building that receives conscientious maintenance should remain standing indefinitely, absent an environmental disaster. That said, the economic life, as calculated by the span between major renovations, can be quite short. For retail buildings, built on the cheap with inexpensive HVAC and roof systems, 15 years is fairly standard. For higher-quality commercial buildings, 30 years may pass before the structure is obsolescent. For public buildings such as schools it may be 40 or 50 years. Bear in mind that most low-slope roofing must be replaced every 15 to 25 years no matter what, and even very durable roof systems rarely go more than 50 years without significant work. Building code requirements or building standards for accessibility, life safety, earthquake or storm resistance, or for energy efficiency may render a building non-competitive in the marketplace or perceived as unsatisfactory. For specialized buildings (again, such as schools) changes in usage requirements may make the building unsatisfactory in a shorter period of time. Technology may affect usage (i.e., air conditioning and artificial lighting may remove requirements for airshafts, or may result in their adaptation for other uses). Few buildings go for more than 50 years without some kind of more-than-routine maintenance. Acroterion (talk) 14:28, 3 October 2011 (UTC)

A couple of cents:

• just because you know some pretty old buildings (+100, +200 or even +300 years) it doesn't mean that buildings on average last that long: you simply don't know how many didn't make it up to our time.
• A life span of 50 for tax purposes doesn't mean the building will probably last 50 years or that it will be worthless in 50 years. It means buildings lose on average 2% value each year, which sounds perfectly normal for me. If you keep repairing that per-war loft, that Quest09 mentions above, it can get even more valuable. For an apartment worth $200,000, you'll have to set aside $4,000/year on average. Just remember that a new HVAC, a new roof, new plumbing, a new elevator, and many other things; all cost some thousand dollar. As the building gets older the costs get higher.

Trustinchaos (talk) 15:58, 3 October 2011 (UTC)

Just on the matter of the White House, other than the outer shell, it is only about 60 years old. See White_House#The_Truman_reconstruction. It's the old problem of the Ship of Theseus paradox; sure, there has been a structure known as The White House for 200 years, but it is constantly renovated and updated (and occasionally almost completely rebuilt from scratch), so what you see now is not, except for some cosmetic bits here and there, really all that old. The same is likely true for many really old buildings.--Jayron32 18:54, 3 October 2011 (UTC)

The White House was burned by our British friends in the war of 1812 and rebuilt about 1820. American sometimes read [18], [19], [20] that it was "white" only because it had to be painted after the burning to hide the soot stains, but in fact it was painted white from the beginning,because of the porousness of the exterior stone, and there was little left to paint after the burning. All that remained of the original building was the foundation and a portion of the south wall. By about 1900 the interior was in danger of collapse and was extensively rebuild. The roof and its support structure was replaced in the 1920s because it was collapsing. By 1948 Truman found it necessary to completely gut it, preserving only the walls and the 1920's roof, and replaced the interior with steel and concrete construction. In each incarnation before the Truman rebuilding, it was ready for condemnation and demolition every several decades, had it not become a national symbol. In the late 1800's its survival as a presidential palace was in doubt, not for structural reasons, but because it was judged obsolete and old fashioned, and there was serious consideration of building a "modern" presidential palace on another site in DC, and converting the building to offices. Edison (talk) 19:51, 3 October 2011 (UTC)

Angle of repose

Does the angle of repose depend on gravity or not ? I thought the consensus was that it doesn't.

I happened to be looking at this digital terrain model of a barchan on Mars today. It's angle of repose seems pretty low, ~20° or less after many avalanches. Puzzled, I had a search and came across this experiment that suggests that perhaps there is a dependency on gravity. Thoughts ? Sean.hoyland - talk 21:34, 2 October 2011 (UTC)

According to this, gravity has an influence. hydnjo (talk) 23:41, 2 October 2011 (UTC)

..yes but the changes in the shear stress and normal stress due to gravity cancel eachother out so the coefficient of friction just depends on the angle for a given material or so the story goes... Sean.hoyland - talk 05:50, 3 October 2011 (UTC)

N-terminal signal sequences in Archaea

I am analysing a protein sequence from from the Archaeon Thermotoga maritima...

MGSDKIHHHHHHMMGLKAHAMVLEKFNQPLVYKEFEISDIPRGSILVEILSAGVCGSDVHMFRGEDPRVPLPIILGHEGAG
RVVEVNGEKRDLNGELLKPGDLIVWNRGITCGECYWCKVSKEPYLCPNRKVYGINRGCSEYPHLRGCYSSHIVLDPETDVLKVSEKD
DLDVLAMAMCSGATAYHAFDEYPESFAGKTVVIQGAGPLGLFGVVIARSLGAENVIVIAGSPNRLKLAEEIGADLTLNRRETSVEER
RKAIMDITHGRGADFILEATGDSRALLEGSELLRRGGFYSVAGVAVPQDPVPFKVYEWLVLKNATFKGIWVSDTSHFVKTVSITSRNY

QLLSKLITHRLPLKEANKALELMESREALKVILYPEG

What's the role of the 6 histidines from AA 7 to 12? It can't be a nuclear localisation sequence can it? I thought Archaea lacked organelles? elle _{vécut heureuse} ^{à jamais} (be free) 23:12, 2 October 2011 (UTC)

Looks suspiciously like a His-tag, used for protein purification. The protein is an alcohol dehydrogenase, the histidines don't appear to be part of the protein. Hzh (talk) 00:31, 3 October 2011 (UTC)

Yup, on checking, pretty sure it is a His-tag, i.e. something artificial added to make protein purification easier. The sequence MGSDKIHHHHHH appears to be called Thio6His6 tag. Hzh (talk) 00:57, 3 October 2011 (UTC)

Definitely an added tag. The record for T. maritima aldehyde dehydrogenase here shows the sequence starting with MMGLK...—which would be right after the His tag. (When in doubt, BLAST it....) TenOfAllTrades(talk) 01:31, 3 October 2011 (UTC)

Probably a bit redundant at this point, but yes.. unquestionably an affinity tag. (+)H₃N-Protein\Chemist-CO₂(-) 16:06, 3 October 2011 (UTC)

October 3

Dark Matter as molecular hydrogren

Regarding the Dark Matter article:

Big Bang theoreticians have made the claim that 80% or so of gravitating matter in the universe must be some unknown kind of non-byronic matter that is as yet undetected and barely interacts with normal matter (or itself). This claim is apparently needed for agreement with Big Bang nuclear synthesis calculations.

I am looking for any firm confirmation that dark matter cannot be large quantities of cold dark H2, the most common molecule in the universe. I understand that at least someone believes that the FUSE satellite data has proved that no large amounts of H2 exist to account for the gravitating mass. However I have been unable so far to deduce such a claim from science reports from the FUSE project that I have seen.

Can anyone enlighten me on this subject?

Moreover in 1999 large amounts of neutral H2 were detected in the edge-on galaxy NGC 891. The reports suggested that enough was found to account for the missing dark matter. Does anyone know if this claim was refuted?

Finally around 1998 through about 2002 several articles appeared discussing Extreme Scattering Events which have been attributed to a large population of extraordinarily small and dense H2 clouds in our galaxy. Has any further progress been made in this research since? Will the Planck mission data be able to shed some light on the existence of such gas clouds?

Thanks for any input.

Carl Hitchon (talk) 00:47, 3 October 2011 (UTC)

Hydrogen and all other atoms and molecules have characteristic absorption and emission spectra including in the < 10 Kelvin blackbody emission region which would be evident if there were massive unmapped clouds of cold dust or gas. There are no such clouds because dark matter is primordial, intermediate mass black holes.[21] We know this because any massive but non-baryonic or weakly-interacting matter would have fallen into black holes billions of years ago.[22] Professor Paul Frampton has been saying this for decades,[23](free at [24]) but the hundreds of astrophysicists who search for WIMPs and axions refuse to listen, because even though there has never been a shred of empirical evidence for such exotic particles (they are merely the hypothetical postulations of supersymmetry, which is not doing so well at the Large Hadron Collider at the moment) there was until very recently no way that anyone had thought of to detect intermediate mass black holes[25][26] so you couldn't get a grant to look for them. Science meets economics and economics wins, sadly. Our Dark matter article is pathetically equivocal on this topic because it's been heavily edited by astrophysicists in favor of their own continued funding, and you can't blame them, really. However, this is not to say that there aren't large unmapped clouds of interstellar hydrogen emitting in the < 10 Kelvin blackbody range; there most certainly are, and they are being detected all the time by, e.g., the Spitzer telescope, but they are orders of magnitude less massive than dark matter. Do you have links for the NGC 891 and scattering observations? 69.171.160.45 (talk) 06:49, 3 October 2011 (UTC)

I've always thought that "dark matter" (and "dark enery") is simply the "here be dragons" of modern astrophysics. Just a convenient label for "everything we can't specifically identify (yet)", thus it could basically be anything (that isn't "glowing" and thus broadcasting it's identity). Roger (talk) 07:52, 3 October 2011 (UTC)

69.171.160.45 is displaying a massive amount of point of view here (PoV). The case for Black holes isn't as strong as he puts it and the case for (WIMPs) isn't as weak as he puts it. There is some good evidence for WIMP's now. Read Dark matter#Direct detection experiments. Dauto (talk) 18:03, 3 October 2011 (UTC)

An event rate modulation which has been unconfirmed since 1986, and 69 detection events from unexplained sources which are therefore theorized as WIMPs? I'm glad you're not picking my investment portfolio. On the other hand, two intermediate mass black holes have been confirmed for years now. Is there anyone supporting WIMPs who isn't in the community depending on grants for looking for them? NASA doesn't. 69.171.160.119 (talk) 20:37, 3 October 2011 (UTC)

Another shower of PoV from 69.171.160.119. The 69 events have no other known explanation while the Black holes might not be primordial. Dauto (talk) 22:46, 3 October 2011 (UTC)

Oh, By the way, the DAMA/LIBRA experiment has collected data as recently as 2009 published in 2010 showing modulation beyond 8.9 sigma confidence limit. Dauto (talk) 23:10, 3 October 2011 (UTC)

Is there a link for that? I seem to remember that wide binary star measurements are consistent with black holes but not WIMPs. Does anyone remember where that was discussed? 67.21.131.22 (talk) 23:53, 3 October 2011 (UTC)

Thanks for everyone's response. I was actually asking more specifically about the search for molecular hydrogen and how much has been found. Here is a link to the 1999 paper about H2 in NCG 891 Here is a link to one of the papers about Extreme Scattering Events probably due to dense H2 clouds: arXiv:astro-ph/9802111v2.

It would appear that very cold clouds of nearly pure H2 would be difficult to detect, so perhaps it still is an unknown, but I'm not sure. Maybe not as exciting as primordial black wholes and WIMPs but seems to me scientist should be looking for horses as well as zebras.

The remark about POV is valid but it seems to be the case in this field that not enough is yet known to have a solid scientific theory that can be agreed upon and highly support by evidence. After all we don't even know what 95% of the Universe is made of.

What kind of worms are these?

They look like they may be pin worms, but I don't think they live in a person's face... http://www.youtube.com/watch?v=GiHtUFuGgSA&NR=1 ScienceApe (talk) 03:12, 3 October 2011 (UTC)

See Psychic surgery. It's a hoax. Introduced while swabbing and does not live on the face.-- Obsidi♠n Soul 05:08, 3 October 2011 (UTC)

Lower size limit on mammals

Are there physical or biological lower limits on the size of mammals? In particular, would it be possible for a cat or dog to evolve to an insect-like or microscopic size (full grown), while retaining its basic cat/dog body shape and characteristics? 69.111.16.7 (talk) 03:48, 3 October 2011 (UTC)

Most mammals (and most birds) are endothermic homeotherms (traditionally, but inaccurately - "warm-blooded"). The smaller the size, the harder it is to maintain acceptable body temperatures for their metabolisms to occur normally. The smallest homeothermic vertebrates (e.g. shrews and hummingbirds), as a consequence have very high metabolic rates. They have to keep eating all the time and require so much oxygen that their heartbeat rates are astonishing (600 to 1320 bpm for the masked shrew).

The other limit, is of course, morphological. This affects poikilotherms and ectothermic homeotherms ("cold-blooded" animals) as well as endothermic homeotherms. A microscopic dog or cat would not have enough space (or cells even) to possess the organ systems necessary to keep functioning. Unless of course, it devolves drastically and manages to find a way to remain alive even after jettisoning most of its organs. Examples of miniaturization achieved by basically giving up the necessities of having to remain alive include anglerfish males which can only survive by becoming embedded parasites of the much larger females (they are basically nothing more than living testes). The males of the fairyfly Dicopomorpha echmepterygis, the smallest insects, also do not have eyes and have no means to feed themselves as adults - they only live to fertilize the females immediately after emerging as adults, then die. Even down to the mm range, there are already constraints as to what can be fitted into a body. In the smallest vertebrate adults, fish of the genus Paedocypris, the skulls have become cartilaginous and roofless, leaving their brains exposed. In the tiny Thorius salamanders, the eyes and the brain have a larger "smallest operational sizes" than other elements of the skull and thus now take up much of the space.

And lastly, smaller sizes means different niches. They have to adapt to different ways of acquiring food, different methods of locomotion, etc. And that means necessarily changing body shape. So no, a microscopic vertebrate is impossible. -- Obsidi♠n Soul 06:53, 3 October 2011 (UTC)

Thanks! That's just about everything I needed to know. 15:28, 3 October 2011 (UTC)69.111.16.7 (talk) 15:29, 3 October 2011 (UTC)

It sure would have made Noah's boat building task a lot easier. HiLo48 (talk) 06:56, 3 October 2011 (UTC)

[The Impossible Voyage of Noah's Ark] mentions miniaturized creatures as a possibility for Noah, tongue-in-cheek. (by the way my captcha is "goatspoke")69.111.16.7 (talk) 15:28, 3 October 2011 (UTC)

He only took two sheep with him for... er... company. Once the flood subsided, evolution did the rest. -- Obsidi♠n Soul 07:07, 3 October 2011 (UTC)

Doesn't anyone read their Bible? He took seven sheep (Genesis 7:2), or fourteen if you believe Wikipedia. Sigh.--Shantavira|^{feed me} 11:50, 3 October 2011 (UTC)

"Or"? Most currently-used English Bibles are pretty clear about it being seven pairs (or seven and their mates) in Genesis 7:2. Direct translation of the Hebrew agrees ("you shall take seven seven man and woman of him") So WP:V wins again. DMacks (talk) 12:00, 3 October 2011 (UTC)

Maybe the scribe stuttered? Oh well... at least we got a rainbow out of it. Antediluvian Earth must have been completely monochromatic.-- Obsidi♠n Soul 12:25, 3 October 2011 (UTC)

Are shrews smaller than marmosets, or are these just young? I guess they are young, since Shrew says, "several are very small, notably the Etruscan Shrew (Suncus etruscus) which at about 3.5 cm and 2 grams is the smallest living terrestrial mammal." Terrestrial? Is there a tiny dolphin or something? 69.171.160.45 (talk) 07:56, 3 October 2011 (UTC)

The larger marmosets in those pictures are (assuming the hand is of an average adult human) at least 10cm long excluding their tails, and by comparison even the smaller younger ones are considerably larger than a typical adult shrew. {The poster formerly known as 87.81.230.195} 90.197.66.215 (talk) 08:33, 3 October 2011 (UTC)

Here is a picture of a Eurasian Pygmy Shrew (Sorex minutus), with another International Standard Sized hand. Alansplodge (talk) 17:57, 3 October 2011 (UTC)

I think that might actually be an Imperial hand, although in the current context its difference from the Metric hand is not great enough to be significant. {The poster formerly known as 87.81.230.195} 90.197.66.215 (talk) 18:10, 3 October 2011 (UTC)

Terrestrial, because a flying mammal - the bumblebee bat - is sometimes regarded as smaller in other criteria. -- Obsidi♠n Soul 09:11, 3 October 2011 (UTC)

Great answer there, Obs.!

Greame Bartlett

I left a note on your user page, but I do not recall how I got there. Please let me know if you received it! Best,91.2.202.173 (talk) 14:07, 3 October 2011 (UTC)

Sorry, obviously I had not logged in before. Khnassmacher 91.2.202.173 (talk) 14:09, 3 October 2011 (UTC)

You want User_talk:Graeme_Bartlett#Political_party_funding. SmartSE (talk) 14:26, 3 October 2011 (UTC)

And if you log in, you should see that he replied on your talk page. SmartSE (talk) 14:29, 3 October 2011 (UTC)

Losing weight

In terms of attempting to lose weight ... why do they say that when you have more muscle, it helps you to burn more fat? What exactly is the relationship between the two? What are the basics of the underlying concepts involved? What is the basic physiology or biology involved with that concept? Thanks! (Joseph A. Spadaro (talk) 15:27, 3 October 2011 (UTC))

Perhaps it's very simple and just means that when you have more muscle you can exercise more strenuously and for longer. And when you exercise you burn calories. Itsmejudith (talk) 16:14, 3 October 2011 (UTC)

I don't believe that's right Judith. More muscle increases the Basal metabolic rate which makes you burn more energy along the day. The energy that you lose through exercise it not very high (despite popular believe that exercise can make you thin). That's why you always have to combine exercise ((muscle building and aerobic) with a diet to lose weight. Trustinchaos (talk) 16:20, 3 October 2011 (UTC)

You lose 100-150 kcal for every mile you walk or run. That translates into 20-30 miles per lb of fat. Most people in reasonable condition could walk/run 3-4 miles a day, which is around 500 kcal. Many people might find it easier to just eat 500kcal less, but doing both is how to lose weight the fastest obviously. Googlemeister (talk) 16:25, 3 October 2011 (UTC)

That implies losing about 3-4 pounds/month, which is not much, but only if you indeed walk 3-4 miles every day, which is more than most people do. Provided that you don't eat more (or more energetic food/drinks), it could work for losing a little bit of weight, but it's highly improbable. Wikiweek (talk) 22:04, 3 October 2011 (UTC)

Just keeping tissue alive (even if you're not moving about or visibly 'exercising') burns a certain number of calories (as noted by others, see basal metabolic rate). This page suggests a burn rate of 7-10 calories per day for every pound of muscle tissue, versus approximately 2-3 calories per day per pound of body fat. So keeping a pound of muscle alive for a year burns about 3000 calories—the amount of energy, coincidentally, stored in a pound of fat.

Of course, you're likely to burn far more calories than that in the activities used to build and maintain that pound of muscle than you ever will relying on its contribution to your basal metabolic rate. (If you start with a pound of muscle and don't use it for a year, it won't still be there at the end of the year, and your body will have used up the material in that muscle (catabolism) as a source of energy.) TenOfAllTrades(talk) 16:53, 3 October 2011 (UTC)

Womans body

Where exactly on a womans body is her minge? — Preceding unsigned comment added by 92.25.96.251 (talk) 16:45, 3 October 2011 (UTC)

See minge. -- kainaw™ 16:46, 3 October 2011 (UTC)

LC strikes again! Here's a hint: Think "south". :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:21, 3 October 2011 (UTC)

Potato fruits

How toxic exactly are the fruits of the potato? Can a person die from eating them? JIP | Talk 18:10, 3 October 2011 (UTC)

Potato#Toxicity has numbers and data. --Jayron32 18:47, 3 October 2011 (UTC)

Petroleum value and chemical uses

I was very surprised to read a statement in Nature News, "Eighty-five percent of the volume of a barrel of oil is used to make fuel, but the chemicals that come from the remaining 15% account for 85% of the barrel's monetary value." I'm skeptical... is there truth to this?[27]

For example, if a barrel of oil cost $100, and this is true, then with petroleum at $100, 55*0.85 = 47 gallons of petroleum destined for fuel should cost $15 - the base cost of the fuel, before refining, should be about $0.33.

More to the point, if this claim were true, then if the technologies discussed in the article, such as biotech isoprene for tires, come to fruition, the base cost of the fuel should be increased. This is because the chemical part of the oil becomes less and less valuable due to competition, whereas the expense of producing it doesn't decrease. (If capitalism even applies to the oil market, which I'm also a bit skeptical about). If that 47 gallons has to produce most of the $100 cost of the petroleum, the base price of the fuel rises $1.66 per gallon to around $2.00.

I suspect what they really mean is that, after the chemicals are worked on, adding value, they become more valuable than bulk fuel, not that those fractions of the oil are more valuable to start? Wnt (talk) 19:21, 3 October 2011 (UTC)

At face value it sounds very fishy to me too. Another possible reading that I could imagine is if "value" were understood as "profit" for refiners. I could easily believe that there isn't much profit margin in gasoline for refiners, and that the profit margins on the less common refined products might be much higher. Dragons flight (talk) 20:00, 3 October 2011 (UTC)

Mean swell wavelength in the open ocean

What is the mean wavelength of swells in the open ocean? E.g. if I placed a large number buoys in the open ocean at random and collected wave data for several years, then looked at just the wavelengths, and averaged them, what length would I get? Standard deviation would be great too! :) — Preceding unsigned comment added by 131.107.0.115 (talk) 20:25, 3 October 2011 (UTC)

The wavelength depends on the speed of the waves and the speed becomes roughly equal to the speed of the wind.[28] Wind wave says

$c={\sqrt {{\frac {g\lambda }{2\pi }}\tanh \left({\frac {2\pi d}{\lambda }}\right)}}$

using the notation in the article. For deep water

$c\approx {\sqrt {\frac {g\lambda }{2\pi }}}$

so λ is approximately (0.8c)² where λ is in metres and c in m/s. Swell tends to continue in this way even after the wind has stopped (all this in Wind wave). I expect you were hoping the weather wouldn't come into things! Thincat (talk) 23:11, 3 October 2011 (UTC)

Thanks for this. I understand that wavelength is a function of wave period and speed; I guess what I'm really asking is what is the actual value? — Preceding unsigned comment added by 131.107.0.95 (talk) 00:01, 4 October 2011 (UTC)

My cat pees on a power socket. Why? How can I stop it?

He's done it three times now! After each incident I've removed the power socket (known as a power point where I am in Australia) and left the wires there (with the live ends suitably covered with insulating tape) while I unstressed myself, cleaned everything up, and figured out how to stop it happening again.

Most recently, some badly stained carpet was completely removed, and the timber flooring and wall panelling thoroughly washed and sealed with two layers of a quality timber finish. The cat stopped showing any interest in the area. The power socket was finally replaced two days ago after a couple of months. First, the cat peed on the floor close by, then peed on the power socket itself, shorting out the power for the house, again!

Why? Any cat psychologists in the house?

How do I stop it? Sensible repellent suggestions welcome, but please don't recommend citronella. That repels me as well. HiLo48 (talk) 20:47, 3 October 2011 (UTC)

Neutering is often successful at stopping male cats from spraying. --Tango (talk) 21:36, 3 October 2011 (UTC)

Thanks for that suggestion. However, he was neutered as a kitten and is now twelve years old. HiLo48 (talk) 22:12, 3 October 2011 (UTC)

Everyone should take care and not pee near Tango's house. Otherwise horrible things could happen to him. 88.8.79.204 (talk) 22:50, 3 October 2011 (UTC)

My father once solved that problem. But it fried the cat. μηδείς (talk) 22:33, 3 October 2011 (UTC)

Should have put four more of them with that one and they could have been content with a network jack. DMacks (talk) 23:11, 3 October 2011 (UTC)

There are passive infrared sensor devices that emit ultrasonic sound and spray gasses or liquids or whatever concoction you enjoy. Some cats are deterred by whatever puts them on alert to possible danger. Even a wind blown CD outdoors will keep them searching for the places they feel safe. --DeeperQA (talk) 23:49, 3 October 2011 (UTC)

Are smart meters evil?

At least, evil regarding the protection (or lack) of private data. Wikiweek (talk) 21:56, 3 October 2011 (UTC)

It seems very difficult to apply a subjective ethical determination like "evil" to a power meter with any real meaning or significance. Issues of data protection certainly exist, but I'm not sure what you're wanting beyond that. — Lomn 22:18, 3 October 2011 (UTC)

They're certainly not popular. Your question is very topical in my neighbourhood. Our local major spreadsheet newspaper (not the more popular Murdoch tabloid) has just published this article with the headline "Smart meters given a fail". HiLo48 (talk) 22:19, 3 October 2011 (UTC)

It depends on how highly you value the confidentiality of your electricity usage. Can you think of any way that the number of kilowatt-hours or whatever could be used against you? ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:20, 3 October 2011 (UTC)

It depends what you use your electricity for. High electricity use seems to be a common way that hydroponic marijuana growing is detected around my part of the world. (Not suggesting that our OP is an indoor gardener.) HiLo48 (talk) 22:27, 3 October 2011 (UTC)

Yes, they could know when I am at home/at the office, and therefore call me offering some junk product or service. And a hacker could break into the system and know exactly when I am at home and more or less what I am doing - they could discover how many appliances I have. A potential employer could discover that I rarely stand up early, but come home late at night many days during the week. The question is not how they could use my private data, the question is that they are my private data. Wikiweek (talk) 22:41, 3 October 2011 (UTC)

Given the meters are individually hackable and regulatable, yes, their mandatory installation is yet another statist evil.μηδείς (talk) 22:31, 3 October 2011 (UTC)

Unless they can be hacked in such a way as to penetrate your bank account, you have much greater cause to worry about the internet than about electricity meters. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:35, 3 October 2011 (UTC)

What is a "statist evil"? Wikiweek (talk) 22:41, 3 October 2011 (UTC)

statism μηδείς (talk) 23:21, 3 October 2011 (UTC)

It is the fact that you are not allowed or provided access to the data that makes them evil. --DeeperQA (talk) 23:30, 3 October 2011 (UTC)

I don't know about you, but my power company gives me access to my smart meter data with 15 minute resolution. Dragons flight (talk) 23:55, 3 October 2011 (UTC)

In NZ there is no regulation or legal requirement for power companies to install smart meters. (Most major power companies here are state owned enterprises which in NZ means they operate more or less as private companies albeit with the government as share holder.) Howevering probably figuring it will be cheaper in the long run, they're doing it anyway but not bothering to make sure their meters have support a home area network to provide any info to the consumer or are compatible with each other [29] [30] [31] [32] [33]. If you want those you'll usually have to install a device yourself whicn connects to the power line since there doesn't seem to be any easy way to get it from the smart meters. Without your seperate power meter you paid for directly, any info on usage needs to come from the power company (if they want to provide it) and at best tends have a day granularity [34] [35]. Some installers have even admitted said there is basically no real benefit to the consumer for the smart meters that are being installed, it's all to the power company. Of course if you don't want an ordinary smart meter, a prepaid one is an easy option, just don't pay your bill on time once [36] Nil Einne (talk) 23:57, 3 October 2011 (UTC)