Wikipedia:Reference desk/Archives/Science/2011 September 29

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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 Wikipedia. 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)