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June 27

Tsunami physics

The tsunami article alleges that a tsunami's wavelength is on the order of hundreds of kilometers long. But if a tsunami is caused by an earthquake, an event which lasts no more than a few minutes, then the tsunami's period cannot exceed a few minutes either. How then does a tsunami have such a long wavelength?

Also, I remember learning that a tsunami's long wavelength was somehow responsible for its large destructive powers. I don't remember why (something to do with energy), could someone help fill in the gap?

Finally, how does a tsunami not die out after travelling such large distances? 74.15.137.221 (talk) 01:56, 27 June 2013 (UTC)

My understanding is that a tsunami does not have a single wavelength, but rather a range of wavelengths, as it is originally produced by a disturbance that is rather localized in space and time. Because of the dispersion relation of the ocean waves, the waves of different wavelength have different velocity (that is, different phase velocity and different group velocity). As a result, the tsunami becomes progressively broader as it travels away from where the earthquake has happened. Also, if I remember correctly, deep-water waves of shorter wavelengths dissipate faster than the longer ones. --Dr Dima (talk) 02:43, 27 June 2013 (UTC)

Imagine that you whack a pendulum to make it start oscillating. The pendulum may have a period of several seconds, even though your hand was only in contact with the pendulum for a tiny fraction of a second. That's because the pendulum's period is determined by its physical characteristics--specifically its moment of inertia and center of mass--and not by your initial whack. Similarly, a tsunami's wavelength is determined by the physical characteristics of the ocean, not by the earthquake that caused it.

A tsunami's long wavelength means that when a leading trough first hits a shore, the shoreline recedes for a while before the peak hits (see Tsunami#Drawback). That doesn't make the tsunami more destructive, but it does mean that lots of people will be out collecting seashells in the newly exposed sand, unaware that they're about to drown. --50.125.28.190 (talk) 06:15, 27 June 2013 (UTC)

The pendulum analogy is nice but unfortunately incorrect. A pendulum - a simple harmonic oscillator, technically - possesses only a single mode of oscillation. Deep water, on the other hand, can have propagating surface waves of any frequency, with wavelength as a function of frequency being given by the deep-water wave dispersion relation, see Dispersion relation#Deep water waves and Dispersion_(water_waves). --Dr Dima (talk) 08:03, 27 June 2013 (UTC)

In an earthquake, the ground on one side of the fault line might suddenly drop or jump upwards by several feet - spread over an area measured in square miles. The mass of water that this displaces is spectacular - a 1 meter sea level change over one square kilometer is a million metric tons of water set in motion. In terms of waves - you get surface waves with wavelengths from a few centimeters to kilometers in length - propagating outwards as speeds that are proportional to the square root of their wavelength - so the longest waves arrive first as huge volumes of water moving at crazy speeds. But in deep water, these waves are extremely shallow - a tsunami wave can go past a boat (in deep water) without anyone even noticing - the boat might be lifted a few feet over the course of a minute and then lowered just as gently. Nobody would notice the tsunami going past them! As the water gets shallower, the math of their propagation speed and amplitude changes and refraction makes the wave turn to be roughly parallel with the shoreline and all of that long, slow vertical motion builds up in height from tens of centimeters to tens of meters.

Losses due to viscosity of the water and air resistance obviously do gradually sap energy from the waves - but there isn't much energy loss and a million tons of water packs a heck of a punch. These waves can circumnavigate the earth and still be measurable.

SteveBaker (talk) 13:37, 27 June 2013 (UTC)

Thank you. 74.15.137.221 (talk) 23:40, 28 June 2013 (UTC)

Plausibility of leaving message for police with bare finger?

In season 2 episode 4 "By the Book" of the crime procedural television series White Collar, a kidnapping victim, as she is being taken from her home, uses her bare finger (it is not dipped in ink or any other marking or sticky substance) to invisibly rub/spell out a word on the surface of her non-dusty (so she was not spelling out a message in dust) dresser without her kidnappers knowing. Later, when the FBI dust the crime scene for fingerprints, their dusting reveals the word she left, which the FBI uses as a vital clue that enables them to track down her kidnappers and her location and rescue her. Is this actually plausible, that the bare finger secretes enough liquids that, just by rubbing your bare finger on a surface, you can leave messages that the police will then be able to find? —SeekingAnswers (reply) 04:26, 27 June 2013 (UTC)

I haven't tried the experiment because I don't have any aluminium powder, but it sounds perfectly plausible. The cleaner the original surface, the more likely the oils from the skin will leave an invisible trace detectable by fine-powder dusting. (Advice to kidnappers: polish all surfaces before you leave!) Dbfirs 06:19, 27 June 2013 (UTC)

You can try it yourself without powders by doing it on a window or mirror, the writing is clearly visible - unless you've just washed your hands - I tried and directly after washing my finger left only a few faint marks. (Yes it's OR but easily replicatable.) Roger (Dodger67) (talk) 06:47, 27 June 2013 (UTC)

Also, what constitutes a "clean" surface? If it's a piece of polished wooden furniture, then there are who-knows-what waxes and oils on the surface that could be disturbed by dragging on them with a clean finger. But it's pretty obvious that if you can detect a fingerprint, you can detect a finger-smear. It seems entirely plausible. SteveBaker (talk) 13:15, 27 June 2013 (UTC)

Remarkable claim about handaxes

I was doing research on the handaxe and found these remarkable claims from this page:

"Handaxes were known to the ancient Greeks, who believed them to be the thunderbolts thrown down by Zeus, the Tree-splitter. They were held to be sacred and were put on display in the temples, such as the Temple of Apollo at Delphi, which had two of them."

I'm highly skeptical because I haven't seen these claims in any other source. Can anyone substantiate or refute them? --50.125.28.190 (talk) 05:58, 27 June 2013 (UTC)

See Labrys. --Dr Dima (talk) 06:02, 27 June 2013 (UTC)

Interesting article, but the Labrys is a bronze tool used by a Bronze Age civilization. The handaxe is associated with the Acheulean industry, 1.6 million to 0.2 million years ago, and was mostly replaced by better tools by 40,000 years ago. It would be remarkable if the ancient Greeks preserved some memory of this distant past. --50.125.28.190 (talk) 06:32, 27 June 2013 (UTC)

Surely the "Ancient Greeks" were just as capable as we are of finding hand axes and then concocting an explanation for them. Roger (Dodger67) (talk) 06:54, 27 June 2013 (UTC)

I highly doubt that. They had no army of trained archeologists who spend their lives finding prehistoric artifacts, and have decades of experience on where to look. Consider that the first Acheulean site was only found at St. Acheuls in 1847 (hence the name). I also don't think the handaxe looks remarkable or distinctive enough to have required a superstitious explanation. --50.125.28.190 (talk) 07:15, 27 June 2013 (UTC)

1847 was the first time they were intentionally and systematically studied but merely finding such objects is way easier and more common than that. In a ten minute random walk in certain parts of my father's farm one could easily find several stone tools just lying on the ground - finding them does require scientific knowlege about them. Ground up dinosoar fossils have been part of traditional Chinese medicine for centuries - long before anyone knew what they really were. Roger (Dodger67) (talk) 07:51, 27 June 2013 (UTC)

In this PhD thesis [1], on page 16, there's a short discussion and references. Please let us know if that's what you were looking for. --Dr Dima (talk) 07:35, 27 June 2013 (UTC)

Good find! From the thesis, I see the claim: "From the Temple of Apollo over two millennia ago, to the more modern era of bible-centric Creationist ‘science’ the presence of handaxes was conventionally explained as the physical manifestation of thunderbolts. In Ancient Greece, these were attributed to the gods (Montelius, 1910), and later on to nature, fitting into the notion that the world had existed since its Creation by God, in 4004 BC."

Montelius 1910 is "The Sun-God's Axe and the Thor's Hammer", available here on Wikisource. It seems that this article talks about the double-axe (shaped like the Labrys). None of the photos look anything like a handaxe, and although I haven't read the whole thing, I don't see any description that clearly matches the handaxe. Still, it was an interesting read. --50.47.81.232 (talk) 09:43, 29 June 2013 (UTC)

• The association does indeed exist. Even the words acme, heaven, Himmel and hammer, as well as the Slavic kamen, "stone" have the same root; see *ak in Calvert Watkins' dictionary. I don't recall the source, but stone battle axes were considered to have religious importance in pre-historic northern European cultures. μηδείς (talk) 19:29, 27 June 2013 (UTC)

See our article on Thor's hammer. μηδείς (talk) 20:00, 27 June 2013 (UTC)

TREES & SOIL WATER

Which plant takes more water than all other plants? — Preceding unsigned comment added by 112.79.37.226 (talk) 06:13, 27 June 2013 (UTC)

An aspen grove - a clonal colony - may well be a single plant (a single organism). If that's your definition of "plant", this may be the answer. If not, please let us know what you mean. --Dr Dima (talk) 07:46, 27 June 2013 (UTC)

Looking at both these questions together, you might find that the same species can both take up large amounts of water from the soil during rains, and take up little or no water during droughts. Cacti and succulents are two examples. This is similar to how animals in places with inconsistent water availability, like camels, can take up lots when available, and little or none during droughts. Other plants in places with a more regular water supply may lack the ability to store water in this volume, so must take up water from the ground more consistently. StuRat (talk) 06:37, 29 June 2013 (UTC)

SOIL WATER

Which plant takes less water than all other plants? — Preceding unsigned comment added by 112.79.37.226 (talk) 06:16, 27 June 2013 (UTC)

I'm not sure, but that would be some desert plant (maybe a cactus, or a creosote bush?) 24.23.196.85 (talk) 07:13, 27 June 2013 (UTC)

I LOVE SCREAMING! Plasmic Physics (talk) 10:32, 27 June 2013 (UTC)

It's hard to find a reference - but I'd put my money on some kind of lichen. Some species can live on a rock (not much scope for roots!) in a dry desert and take thousands of years to grow to an inch or two in diameter - when there is no water present at all, they can shut down their biochemistry and lie dormant for extended periods - using no water at all.

The problem with this question (and the previous one) is that plants can lie dormant for extended periods using no water at all. So should we consider dormant plant seeds? Those have been found in sealed stone jars, 2,000 years old - and have been planted and watered - then germinated and grown. If we take an average water consumption over the entire life of the plant - it's almost zero...but when it starts growing it may need quite a bit of water. We need a better definition of what the questioner actually needs to know.

Generally, knowing why the questioner needs this answer would help (eg: If you're a farmer in a dry part of the world, then ask us which crop needs the most to get a good yield - but if you're a NASA scientist planning to take plants on a trip to the moon to test them, or someone who doesn't like to water their back yard yet still have it look nice - then the answer is very different!

Probably, this is just general curiosity (which is a perfectly reasonable purpose for asking a question here on the science desk!) - in which case you're going to get a range of often conflicting answers - but you'll probably learn something interesting!

SteveBaker (talk) 13:05, 27 June 2013 (UTC)

Lichen aren't exactly plants, for what it's worth. They are fungus-alga symbionts (or in some cases, fungus-cyanobacteria symbionts). The alga or cyanobacteria provide the photosynthesis but the fungus provides the "body", to so speak. Their water needs differ from regular plants as a result. Just saying. Pfly (talk) 05:14, 28 June 2013 (UTC)

Since this question is about plants that don't take up much water from the soil, perhaps we should look at plants which capture water from water vapor in the air, rain, or suck it out of other plants and animals. There are also floating plants, like the water lily, and they presumably get their water directly from there. StuRat (talk) 06:49, 29 June 2013 (UTC)

Human Subspecies

LINK Can anyone inform me on the validity of this work? Thanks. --OptionalCommune (talk) 10:44, 27 June 2013 (UTC)

Perhaps others will answer, but I suggest that you take the time to summarize the points of interest, and ask a specific question. Simply providing a link to a blog demonstrates scant effort, and the volunteers who answer questions here should not be expected to show more. -- Scray (talk) 11:04, 27 June 2013 (UTC)

Sorry, the summary provided is as thus:

"The term race is a traditional synonym for subspecies, however it is frequently asserted that Homo sapiens is monotypic and that what are termed races are nothing more than biological illusions. In this manuscript a case is made for the hypothesis that H. sapiens is polytypic, and in this way is no different from other species exhibiting similar levels of genetic and morphological diversity. First it is demonstrated that the four major definitions of race/subspecies can be shown to be synonymous within the context of the framework of race as a correlation structure of traits. Next the issue of taxonomic classification is considered where it is demonstrated that H. sapiens possesses high levels morphological diversity, genetic heterozygosity and differentiation (FST) compared to many species that are acknowledged to be polytypic with respect to subspecies. Racial variation is then evaluated in light of the phylogenetic species concept, where it is suggested that the least inclusive monophyletic units exist below the level of species within H. sapiens indicating the existence of a number of potential human phylogenetic species; and the biological species concept, where it is determined that racial variation is too small to represent differentiation at the level of biological species. Finally the implications of this are discussed in the context of anthropology where an accurate picture of the sequence and timing of events during the evolution of human taxa are required for a complete picture of human evolution, and medicine, where a greater appreciation of the role played by human taxonomic differences in disease susceptibility and treatment responsiveness will save lives in the future."

--OptionalCommune (talk) 11:46, 27 June 2013 (UTC)

I'm thinking troll... no, not you, gentle OP, I mean Woodley. To begin with, I can think of no two words that give a greater impression that an otherwise clever-sounding idea may be totally wack than "Medical Hypotheses". Also, his suggestion that there is a "Homo africanus" seems bizarre - if you believe there's one subspecies in Africa, you have to believe there are three or more. Last but not least, his claim that Victorians were smarter because they had a faster reaction time [2] which is based on a weak correlation. From our article it would appear chewing gum makes you smarter also. Plus, the idea there that weakened natural selection is making us all dumber has a creepy vibe along with this that makes me think that the ghost of Spencer is seriously begging for a dose of salt and burn. (To be fair, the sort of epigenetic Lysenkoism I'm more open-minded toward doubtless has its own creepy vibes...) All that said, though --- trolls have their purpose. It is hard to define subspecies, and for various cultural reasons it is difficult to do so, and the most interesting cases seem little researched and worthy of a bit more attention. It does seem like "Pygmy" groups like the Twa are interesting, in part due to some degree of reproductive isolation. History tells us again and again that new species of humans burst forth onto the world out of Africa, and I am partial to the notion that they will be next: futurists often speak of descendants of man with giant heads, but small bodies are an evolutionarily easier route to greater efficiency for space colonization. Because Pygmies can presumably write just as much code and run just as many robots as anyone else, they should enjoy a small but exponential advantage that will lead to their predominance in the universe. Wnt (talk) 11:51, 27 June 2013 (UTC)

This certainly appears to be junk. The problem is that when you talk about genetically distinct sub-groups (which is what that fancy words "polytypic" (having more than one sub-group) and "phylogenetic" (grouping determined by gene sequencing) means), you have to ask what set of genes you're talking about. The author clearly wants to get back to old-school racism by picking the set of genes that determine skin color. However, that's only one way to slice the pie. Why pick that set of genes rather than the ones that determine (say) lactose intolerance, color blindness, musical ability or finger length?

The key to thinking about this is a term called "the fixation index" - which basically asks: How much of the genetic variation present in the entire species is found between your proposed sub-groups? So if (for example) you found a group of organisms who were genetically much more similar to each other than they are to other individuals in their species - then you might identify them as a different sub-species - but if you find that there is almost as much variation within that sub-group than in the species as a whole, then that division makes no logical sense.

When you do that with humans you find that no matter how you group people (eg by skin color, lactose-tolerance, color blindness or whatever) 85% of the variation measured across all humans on earth is found within individuals of that group. That is to say that two randomly selected Inuit people exhibit 85% as many genetic differences as (say) an Inuit and an Australian Aborigine...and two randomly selected color-blind people also exhibit about 85% as many genetic differences as color-blind and not-color-blind people selected at random. So the basis of splitting them into different sub-species is very narrow indeed. It's very likely that an Inuit with lactose intolerance is more genetically similar to an Aborigine with lactose intolerance than he is to his next door neighbor.

Put another way: Skin color tells us that changes in just three or four genes is enough to produce the difference between dark and light skin. Lactose intolerance says that mutations in two genes produces that effect. Color blindness involves more than fifty different genes. So genetically, skin color (as way to determine a sub-group of humans) falls somewhere between lactose intolerance and color blindness as a determining factor. If you try to take a wider view and group more genes together to define a particular race, then you get more and more variations between individuals of that race and drawing a genetic map becomes harder and harder.

So if you're going to define genetically dissimilar sub-species, then perhaps it's better to split our world into two races - the lactose intolerant and the rest. The trouble with that is that there are a hell of a lot of ways to slice the pie - and there is no obvious way to pick which one...unless of course your some kind of evil racist who thinks skin color is the determining factor just because it's where some inner historical hatred lies...and that's not science.

You can define race by ethnicity or by historical migration patterns - but you just can't do it with genetics.

SteveBaker (talk) 12:50, 27 June 2013 (UTC)

There's a little more to it than that - our article on Fixation index cites rates up to .19 for Yorubans (didn't check but presumably from here, and our rivals at Metapedia (a site to be seen to be believed - check out their collections on "sexual Bolshevism"...) do point usefully at [3] illustrating that the threshold for subspecies is a bit low in some hands. Everybody loves a chance to name something... :) But the difference to Homo neanderthalensis, nominally a whole different species, isn't that great, and there are differing degrees of admixture of this species in contemporary populations for that matter. I should note I didn't find Fst analysis for the Twa or other Pygmy groups (which are apparently quite divergent from one another) and remain curious. Bottom line: I don't think we can rule out finding a few nominal human subspecies somewhere, at least not under all possible semantics and given the fairly limited amount of sampling we've done in Africa. Wnt (talk) 13:27, 27 June 2013 (UTC)

100 ml rule

Is there any scientific reason behind the 100 ml carry on limit for liquids on planes (other than selling more water in airport shops)? Main question: Why liquids? Why 100 ml? bamse (talk) 14:14, 27 June 2013 (UTC)

That restriction was instituted in the wake of the 2006 transatlantic aircraft plot, which involved liquid explosives. — Lomn 14:19, 27 June 2013 (UTC)

Sure: it's the science of operations research, the scientifically-founded engineering discipline of making an operation work smoothly. Blanket bans on all suspicious items makes the security check faster, and therefore more efficient. In the U.S., if you're travelling on a commercial airline and you're willing to spend lots of time before and during travel, you can file lots of paper work to get permission for all sorts of "special items", as long as you comply with federal regulations and your airline policy. But at the checkpoint, the objective is to screen all passengers as efficiently as possible; the rules are set up to keep dangerous items out of the secure area without requiring a lengthy and invasive search of every single item.

For all the bad press the TSA receives, it's worth reminding the world at large: this week, like each and every week, millions of travelers are mildly inconvenienced about their bottled water and a few dozen loaded handguns are caught at the checkpoint. This happens every week. I would propose, from the standpoint of applying the scientific method, that the current method of screening - including blanket bans on apparently-benign items like bottled water - is a more effective method for keeping the handguns off the aircraft. Unfortunately, like most social sciences, it is impractical to conduct a control experiment. Nimur (talk) 17:03, 27 June 2013 (UTC)

Actually, Nimur, the more relevant link is to Security theater. The airline industry, and the U.S. Government, can do very little to stop a properly determined, trained, and equipped person from causing massive havoc. If we knew this, we wouldn't fly. So, they institute a series of (entirely ineffectual from a security standpoint) measures designed to give the impression that they are doing something, so we're more likely to spend money buying plane tickets. All arbitrary and restrictive security rules that seem outwardly benign (such as restrictions against bottles of water and requiring passengers to take off their shoes in security lines) fall into this security theater categorization. There are some security measures (such as restricting the use of actual explosives and firearms on planes) which are probably actually effective, but the types of measures the OP is noting are not among them. --Jayron32 17:12, 27 June 2013 (UTC)

Security theater, yes; but I prefer to think of it as a different stage-trick altogether. While everybody is focusing on bottled water, to which the TSA draws your attention through theatrics and loud public debate about civil-liberties; behind the scenes the TSA and its law enforcement partners are bagging fifty gun-toting airline passengers a week, and all without frightening the air-travelling public. Perhaps I ascribe too much competence to the Government's ability to keep quiet about its actual policing activity; ironically, my theory is frighteningly more Orwellian than yours. Nimur (talk) 17:32, 27 June 2013 (UTC)

I'm not sure it's that ironic, and I'm also not sure that you're theory is one iota different than mine. --Jayron32 17:39, 27 June 2013 (UTC)

We're getting off topic, but I would like to point out that guns were caught pre-TSA as well. Metal detectors and x-ray systems were already in place as standard security. — Preceding unsigned comment added by 209.131.76.183 (talk) 17:51, 27 June 2013 (UTC)

Hm, so you are saying the size of 100 ml is completely arbitrary!? It is not related to any maximal-achievable-explosion/damage with this amount of of explosive? bamse (talk) 18:46, 27 June 2013 (UTC)

I don't think it's completely arbitrary. However, I also don't think there's been enough information released by the TSA, etc, to conclude that it's completely objective, either. Various critics have noted, for example, that even if the personal limits on liquids (because it's not "100 ml"; it's however many 100 ml bottles you can fit in a 1-quart bag) is small enough to prevent an incident, it doesn't protect against 5 people each carrying the personal limit and then pooling their stuff after the security checkpoint. As with all countermeasures, then, it is someone's attempt to create a reasonable standard. How successful that attempt has been is, as you can see above, a matter of some debate. — Lomn 19:06, 27 June 2013 (UTC)

• This is pretty obvious. Laws have to be written objectively, and if a limit is given a reasonable round number that fits the concerns will be chosen. IT is like picking 18 or 21 for the drinking age. If they are going to pick some number then they have to chose some arbitrary number. The point is that we don't give a drinking age of 5 or 55, but somewhere near physical adulthood, and we don't put a limit of 1ml or 1 cubic meter on carry-on liquids because were are looking at a threshold size for effective but hideable explosives. Of course a pint would have been a much more reasonable measure, but that's a separate question. μηδείς (talk) 22:27, 27 June 2013 (UTC)

This rule was actually devised and adopted by the International Civil Aviation Organisation. You can see the state letter here. 202.155.85.18 (talk) 04:07, 28 June 2013 (UTC)

Why don't we have an Atomexpo page?

http://www.presstv.ir/detail/2013/06/18/309646/iran-invited-to-attend-atomexpo-2013/

Is it the lack of coverage in the western press? (I predict that's not going to be a problem in say 48 hours.) Hcobb (talk) 15:28, 27 June 2013 (UTC)

Because Wikipedia is an encyclopedia, not an indiscriminate collection of information; and/or because nobody has made the article yet (which bears somewhat on the conference's notability). Items need to be encyclopedic to merit inclusion. For comparative examples of energy technology conferences, we have an article on Offshore Technology Conference, but as of this writing, we do not have North American Petroleum Expo, even though NAPE is probably almost as big an event as OTC. (Well, by number of attendees it's much smaller, raising another issue - how does one measure notability and importance of an Expo?) Would an encyclopedia article on such a conference add any value to our encyclopedia? If so, please take the initiative and start the article. Here is the official English webpage for the 2013 Atom Expo, sponsored by Rosatom. Nimur (talk) 16:30, 27 June 2013 (UTC)

The way we should measure notability is by having multiple sources about something, and it shouldn't be a high bar - most Wikipedia articles haven't been written yet. That said, there's a lot of politicking and out-and-out PR work about it nowadays. If you look at Portal:Featured_content you'll see that much of Wikipedia's "best" work amounts to ads about very obscure people and events who have something to sell today. We have featured articles about individual wrestling pay-per-view matches, and vast numbers of people who will staunchly defend that a few industry magazines amount to comprehensive secondary-source coverage. Meanwhile anything someone finds offensive (often for personal reasons) or which potentially competes with news wire services is proposed for deletion. There's nothing rational about it - there is no policy, not really - it's naked power politics. Wnt (talk) 23:55, 28 June 2013 (UTC)

Quantum chaos

Here's my question: Does the lack of chaos in a quantum system explain evolution within biology perhaps? I scoured the internet and didn't find much information about it. I found a slight reference to it on Scholarpedia.org (the article named Quantum chaos). You may put complex math equations but don't expect me to understand; math is the exact opposite of what I'm good at (I am a spirituo-creative.). Thanks. Lighthead ^þ 18:56, 27 June 2013 (UTC)

(We have our own quantum chaos article BTW). Evolution isn't much of a quantum-level thing. All it requires to operate is some means by which an organism can hand on it's genetic code to it's offspring - and for there to be occasional random errors in that information along the way. If quantum effects were large enough to significantly change that then we probably wouldn't have stars and planets, let alone living things! SteveBaker (talk) 19:14, 27 June 2013 (UTC)

Actually, I meant the whole origin of life. I'm sorry if I was unclear. Because from what I understand the fact that life even exists flies in the face of traditional chaos theory. Life seems to be heading towards low entropy (according to the theory of evolution as I understand it) as opposed to high entropy as chaos theory predicts. Sorry for the slow response; I completely forgot that I posted this. Lighthead ^þ 00:12, 29 June 2013 (UTC)

Also, that article is impossible to understand for the layman. I, surprisingly, found the article on scholarpedia much easier to understand. Lighthead ^þ 00:18, 29 June 2013 (UTC)

Chaos and entropy are not that strongly linked, so I think the premise of original question was not strong. The notion of life as conflicting with the second law of thermodynamics is oversimplified, because the second law addresses the entropy in an isolated system, so one would have to consider macromolecules, respiration - many components in a very complex dance. As is often the case, we have an article on that: Entropy and life. -- Scray (talk) 01:10, 29 June 2013 (UTC)

Thanks for the article. I will read it. Lighthead ^þ 03:36, 29 June 2013 (UTC)

I read most of the article. Pretty interesting. It really led me to make some interesting conclusions. I still have to think about how it relates to my original question, but at least for right now, it's an interesting aside. Thanks again. Lighthead ^þ 03:58, 29 June 2013 (UTC)

How scientist calculates how stars evolves

When sun expands to maximum size I thought scientist exactly knows how bright the sun will get when reaches RGB tip in 7.6 billion years of between 2000 and 3000 times current luminosity is this possible there are other answers than that. I have navigated through many websites I don't know if I paid attention to their luminosity variables although some websites don't mention how much will sun cools of by the time it reaches gigantic orbs. It is not going to be over 10,000 times the current luminosity, and also do we know exactly how much will the sun cools off?, is this possible there is wide range of answers, impossible to hit the correct pin? I remember Schroeder and Smith and Once and Future of Sun definitely use computer simulation to do the calculations, I just learned computer simulations isn't more accurate than natural calculations. Do scientist build a powerful telescopes to imitate foreign stars what life cycle they have gone through will the solar system? Will space telescopes how can they make predictions, or is it just once scientist build stronger telescopes, they always come up with better answers because they can track more details.--69.233.254.115 (talk) 20:30, 27 June 2013 (UTC)

A lot of this is done simply by looking at what kind of stars exist now in what quantities and figuring out how certain classes of star observed could evolve into other types. It's like taking a picture of a herd of antelope on one day in summer and figuring out that if half the antelope are yearlings, and the rest are aged adults, that most of the yearlings are going to have to die, or the population would be skewed. You don't actually have to watch the babies get eaten to figure out a reasonable population model for the whole herd. Astronomers come up with models to fit the populations of stars e see. We have resident astronomers, so hopefully someone can say something more detailed and intelligent. μηδείς (talk) 02:03, 28 June 2013 (UTC)

The article titled Stellar evolution is a good place to start researching this topic. --Jayron32 05:40, 28 June 2013 (UTC)

Evolution

Are today's chimpanzees, or other great apes, just humans in waiting? Will they eventually inherit human genes/DNA or will they evolve into a separate, distinct species? I'm just curious if evolution results in the extinction of one species; for example, if humans will evolve into something else and chimpanzees will evolve into humans, and if that would continue in a cycle? --Andrew 22:06, 27 June 2013 (UTC)

This is a pretty standard "intelligent design" or anti-evolutionist question. Organisms simply evolve according to immediate circumatsnaces, not some goal. Here are various responses. The Livescience one is recent and reliable. The underlying fallacy is the assumtion that humans are something that exists prior to and outside evolution and that the goal of evolution is to move toward humanity. That's based on an unscientific view of evolution and the idea that one's own personal existence is some part of a plan. See anthropocentrism, as wel as Mediocrity principle and Copernican principle. μηδείς (talk) 22:18, 27 June 2013 (UTC)

Let's look at the probable chain of events leading to human intelligence, and see which might apply to other primates:

1) First our ancestors lived in trees, and this arboreal environment led to the opposable thumb, which is useful for holding onto branches. All primates share this feature.

2) Our ancestors then moved to living on the plains, which meant that bipedal motion was of value for seeing above tall grasses. Most primates still live in the trees. There are some primates which live on the plains, like baboons, but so far they don't seem to have developed full time bipedal motion. I'm not quite sure why, though.

3) This combo of opposable thumbs and bipedal motion freed up our hands for tool use (probably just using rocks as weapons to start with). Some primates (and other animals) have used tools, but they always seem to be temporary tools which are discarded as soon as the task is completed. Perhaps the lack of free hands accounts for this, as there's no easy way to carry them.

4) Permanent tool users then can benefit from increased intelligence, in order to perfect each tool. The ability to pass down this knowledge also requires communication, which also requires increased intelligence.

So, it seems to me that the lack of bipedal motion is the stopping point for other primates. This might be partially due to humans being in control of this niche, so there really isn't room for many other primates to move into plains and develop bipedal motion. So, if humans were all gone, it's possible that other primates might well move into the niches occupied by humans, potentially leading to increased intelligence in the same way. Certainly it's not guaranteed that evolution would point that way, though.StuRat (talk) 06:26, 29 June 2013 (UTC)

Since we're talking about evolution...

My understanding of natural selection is that it's based on tiny natural mutations over many generations that occasionally favours individuals who then manage to pass on their advantageous genes. So... why isn't intelligence more widespread? Since insects have a zillion generations a year, for example, and any increased intelligence or awareness would presumably favour an individual, why are we not surrounded by super-intelligent houseflies? (NB, I am not pursuing an agenda here, I am just interested in the scientific answer which I'm sure someone will quickly furnish me with) FreeMorpheme (talk) 22:35, 27 June 2013 (UTC)

Intelligence requires computation, and computation is expensive. An insect with a three pound brain (like a human has) wouldn't do very well, regardless of how smart it was. Insects actually get quite an extraordinary amount of intelligence out of their tiny little brains. Looie496 (talk) 22:53, 27 June 2013 (UTC)

Yeah, brains are very expensive in terms of energy consumption. For example, although the human brain comprises only about 2% of a human's body weight, it consumes up to 20% of the energy used by a human. See Human brain#Metabolism. Smarter isn't necessarily an advantage if the larger brain can make you more likely to starve to death. Red Act (talk) 23:13, 27 June 2013 (UTC)

Whatever works survives. Insects do well with their tiny brains and short-life circles, that's enough to reproduce before they die. Evolution doesn't go in the direction of 'better' or more capable species, sometimes it even simplifies things. Some species have lost their eyes or legs. OsmanRF34 (talk) 23:00, 27 June 2013 (UTC)

• Intelligence is widespread (there are no macroscopic land animals without brains) and the trend is toward greater intelligence the more derived a clade is among mammals. For example, the most derived even-toed hoofed mammals are whales, and the most derived birds are the higher land birds, especially parrots and songbirds (think crows). μηδείς (talk) 01:52, 28 June 2013 (UTC)

You could think of it this way as well, what sort of human type intelligence do you think would benefit a housefly. Remember, it is still a housefly, it doesn't have coached reasoning skills, knowledge, any of that stuff, it basically has what a chimp has in a fly body. It can't see any better, it can't judge what it is naturally attracted to or repulsed by any better. What humans have which sets them apart is not only, and not even more significantly, confined to the brain. Dolphins neurology is more developed than humans, and the only thing they seem to benefit from that is bravery and compassion. They don't even have the most developed speech in the wild, even though they are very responsive to human training. Any tricky little things they do naturally can be quite encouraging, but not extraordinarily amazing compared to all other animals. A human with basic knowledge of toolmanship, is not only a clever creature, but is a deadly dangerous one. Humans are fast runners, great climbers (humans are slower climbers than goats but can climb things even goats cannot climb), and if you'd nothing else to do but swing around in trees for fifty years or climb rocks, you'd have an iron solid gymnastic strength, with heavily padded hands and feet and nails like wood. Today we think that our brains are what we had going for us in the natural world but in fact we are domesticated and domesticated creatures resemble creatures which are not very healthy, bald, pallid, skinny, and weak. The question is not, does it make sense that houseflies exist without human intelligence, it is, how do humans survive WITH their intelligence! If you want to know what creature is amazing, it's not one with big brains, it's the shark. The shark is the most amazing organic machine there is. But don't forget, you are not a lion or a shark. If a shark met a lion, it would say hello by sinking its teeth in, and if a lion met a shark... yep. ~ R.T.G 21:22, 28 June 2013 (UTC)

Chimps are orders of magnitude more intelligent than flies, including the ability to reason out the solution to problems (relatively simple problems compared to what humans can solve, of course). StuRat (talk) 06:00, 29 June 2013 (UTC)

It is interesting to consider the effects of rapid environmental change. Humans might well have originated in regions of Africa with huge yearly changes in conditions - vast areas of flooding that turn to wildfires and desert over the course of a year. Now humans seem like the ultimate invasive species, and that seems largely due to high intelligence. But as the global climate changes over and over, not merely from ice ages but from global warming, deforestation, and above all transshipment of species around the world, as species hybridize and achieve greater genetic diversity under these conditions... I wonder how many other species have been pushed roughly onto the road to intelligence, and how long it will take? Wnt (talk) 23:49, 28 June 2013 (UTC)

The remarkable thing about human intelligence is that we are born knowing almost nothing. For example, look at walking. While many other animals are born with the instinct to walk, and are up on their feet in minutes, it takes humans months or even years to learn to walk. This is because it's vastly more efficient to be born already having instincts to do such things than to have to learn them from scratch. The advantage of learning so much is that it allows us to be far more flexible, and survive in many more environments. For example, we aren't designed just to eat one type of food. We can adapt to many different kinds of food, even those which are poisonous until we cook them, etc. On the other hand, if you transported a polar bear to Polynesia, it wouldn't be likely to figure out how to eat coconuts. StuRat (talk) 06:08, 29 June 2013 (UTC)

Well, I didn't find video, but if a polar bear failed to manage to eat coconuts when available I would be very disappointed in it. Only experiment can resolve questions like that. :) Wnt (talk) 17:29, 29 June 2013 (UTC)

Some scientists would argue that the advantage of being born *prematurely* compared to the other apes, is that compassion and community become essential. If you don't pick a human baby up it will not survive for instance whereas a chimp baby will cling on for itself. ~ R.T.G 21:03, 29 June 2013 (UTC)

I would suggest though Stu, we might be born without ability rather than knowledge. A new born baby can cling hard enough to be lifted off the ground, though I wouldn't encourage you to try that, and apparently new born babies can hold their breath and even swim. There is certain mechanical aspects to everything perhaps. Humans do not just think we are smart, we think we are special smart, and there's a bit of a dumb feel to that. ~ R.T.G 21:06, 29 June 2013 (UTC)

Privately towing a car with the handbrake engaged

Can you tow, with a private car (140 HP), another car (more or less same weight) which has the handbrake engaged? OsmanRF34 (talk) 22:37, 27 June 2013 (UTC)

If you're asking whether it is possible to make the second car move, that would depend on the quality of the handbrake. as well as the weight and gearing of the two cars. This is a strangely bizarre question for you, Osman. Looie496 (talk) 22:49, 27 June 2013 (UTC)

I don't find it bizarre. Every now and then some guy (the same) parks in my parking space. That would be the fast and dirty solution. I don't mean to tow him away some miles, just some feet. OsmanRF34 (talk) 22:54, 27 June 2013 (UTC)

Well, from a technical point of view, you can almost certainly tow him if only the handbrake is engaged. But if a gear is engaged (or, for an automatic, if the car is in "P"), this will be much harder, and, even if it succeeds, may cause significant damage to the drive train. --Stephan Schulz (talk) 00:05, 28 June 2013 (UTC)

But, if a gear is engaged and you tow in the 'right' direction, would it still cause damage?

Another point, is it only possible to move it if the wheels spin? In a real-life scenario, can't you just drag a car, with the wheels blocked? OsmanRF34 (talk)

• Seriously, Osman, do you expect us to have an encyclopedic source that will tell us whether your dad can beat up the other guy's d....I mean, whether your peni....I mean whether your car can tow his car even if braked? μηδείς (talk) 01:57, 28 June 2013 (UTC)

Sure. It's a physics problem. Given the weight, the HP, the friction, is it possible? OsmanRF34 (talk) 08:17, 28 June 2013 (UTC)

Yes, it will almost certainly be "possible" (I've been tempted to do it myself!) but that doesn't mean that it's advisable, because the owner of the towed vehicle is likely to make a claim for damage (real or imagined). Dbfirs 08:13, 28 June 2013 (UTC)

I used to work in a vehicle auction house. Basically this consisted of 18 months spent reverse-parking cars and vans in varying states of repair. Because many of the vehicles had been standing around for 6 weeks or more, flat batteries and binding brakes were an almost daily part of the fun and games to be had. What follows are my personal reflections and recollections. I do not make any comment on the legality or advisability of moving a car that is not your own.

If the car to be towed is in neutral with the handbrake off, it should be easy to move, either with another vehicle or even a hefty push by hand. Note, however, that if the steering lock is engaged, you will have no say on the direction it goes in. You also won't be able to stop it easily once it begins rolling - you may need someone to tug on the underneath of the rear bumper (fender) to bring it to a halt. Whatever you do, don't be tempted to stand in front of the moving vehicle and stop it by pushing in the opposite direction.

If the handbrake is on (or if the brakes are off but binding), but the vehicle is in neutral, you should still be able to move it. A slightly larger and more powerful towing vehicle than you describe would be preferable (ideally a diesel engined manual with 200+ bhp) but it's still worth a try. Attach a tow rope to the towing eye of your vehicle and the vehicle to be towed. Make sure it is securely attached and that it's not attached to the bodywork - you WILL rip off a bumper otherwise. Gently roll forwards in your car until the rope is tight. Then engage first gear, bring the revs up to about 2000 and slowly lift the clutch. Again, remember that your brakes only stop your own vehicle - the towed car will keep moving once rolling. If you keep the speed low, it should come to a gentle rest against your rear bumper, but again a friend to slow it down would be a bonus.

If the car is in gear (or in park in an automatic) - do not attempt to tow it or push it. You won't go anywhere and could cause damage. In this situation we would usually 'bounce' the car out of the way. You need at least two people, and what you do is position yourselves on opposite sides of the rear of the vehicle, push sharply down on the bodywork above the rear wheels and release. Keep doing this a few times in rhythm and the car should start to bounce, with the rear wheels briefly leaving the ground. Once this starts, keep bouncing, but exert gentle pressure in the direction you want the car to go.

I'll note that none of these options are likely to be discreet. Someone is almost certain to spot you doing it, and the car's owner will definitely turn out to be 6'7" tall and built like a brick outhouse. You might want to keep your engine running for a speedy getaway. - Cucumber Mike (talk) 08:47, 28 June 2013 (UTC)

Have you mentioned the issue to the property manager? Or if there are phone numbers posted in the lot for a towing company that enforces the parking rules, you could call them directly. They'll tow the car off to their lot and charge the owner a decent fee to get the car back, which hopefully will convince them not to park there again. 209.131.76.183 (talk) 11:30, 28 June 2013 (UTC)

I'll also add that it is probably a bad idea for you to mess with the car yourself. You don't want to be liable for any damage you accidentally cause. The tow company has insurance for that, you don't. 209.131.76.183 (talk) 11:31, 28 June 2013 (UTC)

Definitely a bad idea to dink with someone else's car. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:44, 28 June 2013 (UTC)

If you do that, for stopping a car in movement, put something below the wheels, a plank or something. Trying to push is a very bad idea, trying to pull not so bad, but ineffective, unless the floor is flat. 80.58.250.84 (talk) 17:40, 28 June 2013 (UTC)

• Think the OP has got too emotionally involved to think in basics. Look at this from the others point of view: They have parked there several time without complaint so (to s/he or its point of view) it must be OK with the PS owner. So, just place a note on his windshield to the effect... I have noticed you have parked here several times before, so I have made a note of your licence plate. Should you need to park around this area because you need to make an emergency call to one of my neighbours who's space is already taken up, then please phone me on my mobile xxxxxxxx and let me know. Thanks. Don't add further details about the inconvenience , frustration etc., that it is causing you – if the driver is reasonable that should be enough for him to get the hint. After all, the driver may turn out to be a really nice guy and useful to get to know. Think serendipity.--Aspro (talk) 18:18, 28 June 2013 (UTC)

If this were my problem, I'd be looking at using a set of wheel skates [4]...or better still...[5]. Maybe you could rent a set someplace? Anyway, the latter kind fit around the wheels then tighten up to lift the car slightly off the ground onto a bunch of little caster wheels. Then you can easily move the car around with just one person pushing it - no matter whether the car is in gear, in park or has the brakes locked on. So long as the ground is smooth - it should roll very easily. No towing required! SteveBaker (talk) 20:42, 28 June 2013 (UTC)

Anyone advising the OP to mess with someone else's car may be advising them to break the law and/or to invite very serious trouble. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:41, 28 June 2013 (UTC)

I should point out that a normal tow truck routinely used by business owners avoids the costly consequences of messing with a car on an amateur basis. The way I understand it, predatory towing remains a lucrative industry in many places, so I wonder if it's really so difficult to work out an arrangement with some company provided you have at least a nominal right to claim the space. I would assume that going along with the established racket has the added benefit of sticking the victim with a huge bill rather than leaving yourself in legal jeopardy. Wnt (talk) 23:44, 28 June 2013 (UTC)

Yes, as with the infamous Lincoln Park Pirates in Chicago. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:38, 29 June 2013 (UTC)

"Eryngium heterophyllum"

Hello,

I am trying to find out information about an herb called "Eryngium heterophyllum" . There is a page in the Spanish Wikipedia on the subject, but I couldn't find anything in English. The everyday term in Spanish is "Hierba del Sapo" or roughly translated in English: "Toad herb". I have no idea what the everyday term would be exactly in English. My doctor here in Mexico prescribed it to lower cholesterol and there are some studies (in Spanish on Wikipedia) that vouch for results. I would like to collaborate this information with something in English. Can anyone help?

Thank you for your time, David Ryan Oaxaca, Mexico — Preceding unsigned comment added by 187.212.162.40 (talk) 23:45, 27 June 2013 (UTC)

We don't answer requests for medical advice. Sorry. AndyTheGrump (talk) 23:50, 27 June 2013 (UTC)

Right, no medical advice, but I can direct you to search google scholar for the latin species name. The top 4 hits are all english-language journal articles that mention the species and its uses. SemanticMantis (talk) 02:59, 28 June 2013 (UTC)

June 28

Gamma ray bursts and extraterrestial civilizations

Could short duration gamma ray bursts be from nuclear pulse propulsion vehicles piloted by extraterrestrials? 202.155.85.18 (talk) 01:33, 28 June 2013 (UTC)

Do the arithmetic — look up nuclear weapon to get the gamma-ray flux from an explosion of that size. Then apply the inverse square law to figure out how much of it we'd see at the distance from here to the closest star system (Alpha Centauri, I think). Then compare with the brightness described in gamma ray burst and let us know. --Trovatore (talk) 01:37, 28 June 2013 (UTC)

I can't find any values for the gamma ray flux from nuclear devices, and "that size" is highly variable as the devices could be very compact anti-matter or antimatter catalysed explosives, or large Teller-Ulam thermonuclear explosives, or something else entirely. 202.155.85.18 (talk) 01:44, 28 June 2013 (UTC)

OK then, work backwards. Consider it a Fermi problem. What's the order of magnitude of gamma-ray flux that might be needed for us to detect a gamma-ray burst? What's the order of magnitude of the size of the detector? What solid angle does that detector subtend, at the distance of Alpha Centauri? Multiply the minimal detectable flux by 4π divided by that solid angle, and get the total flux you'd need at the source. You can throw in a fudge factor for the fact that it's not expanding uniformly in all directions.

Now, is that a plausible value for a spaceship? --Trovatore (talk) 01:49, 28 June 2013 (UTC)

Ok, so according to [6] the detection limit for the x-ray telescope is 2x10^-14 erg/cm^2/s which is 2x10^-21 J/cm^2/s. I'm going to assume the x-ray equipment is more sensitive than the gamma ray equipment, since no LLD is quoted for that. Short GRBs last for less than 2 seconds so that's 4x10^-21 J/cm^2. Alpha centuri is 4.37 lightyears away, or ~4.1x10^16 m. A sphere of that radius has a surface area of 2.1x10^34 m^2 or 2.1x10^38 cm^2. That gives a total of 8.4x10^17 J of gamma rays. According to [7] a nuclear weapon released 0.13% of its yield as gamma rays, using that factor, the total yield for our device would need to be 6.5x10^20 J to be detected. That's the same as 155 gigatonnes of TNT. Sounds implausible, but in a Medusa type craft the main source of propulsion is from radiation pressure. If the explosives were tuned to give say 50% of their yield as gamma rays, the gross yield could be as low as 400 megatons, just to be barely detected. Ok, sounds like it's not possible. 202.155.85.18 (talk) 02:56, 28 June 2013 (UTC)

Nice! I was pretty sure that was going to be the answer (at interstellar distances, such a craft would be too dim to see), but I didn't feel like doing the work myself. (I have not, BTW, checked your work.) --Trovatore (talk) 03:45, 28 June 2013 (UTC)

GRB signatures

• It would be awfully strange if it just happened to be the case that every gamma-ray burst we've seen that was a spaceship happened to have the same signature we'd expect from a stellar-size explosion.

μηδείς (talk) 01:54, 28 June 2013 (UTC)

The signatures of GRB are highly variable (File:GRB_BATSE_12lightcurves.png), and the low-red shift short GRB may be closer and weaker than they would be if they were stellar sized. 202.155.85.18 (talk) 02:05, 28 June 2013 (UTC)

I am entirely disposed to accept your claim. But how does one interpret the chart you linked to, and which signature is the most relevant? Thanks. μηδείς (talk) 03:05, 28 June 2013 (UTC)

They're all equally relevant. The point is that GRB can only be broadly categorized into short and long. There doesn't seem to be much of a pattern to the rest of the signatures. 202.155.85.18 (talk) 03:22, 28 June 2013 (UTC)

(OR ahead) If nuclear pulse propulsion was the major source of GRBs, we'd be looking at both red-shifted and blue-shifted pulses, sometimes from spacecraft during acceleration, and sometimes during deceleration.

I'd think that a small source like a glorified H bomb cools quite quickly due to its rapid expansion, while a more massive source (say, several solar masses) would expand more slowly.

Thrid, I always had the idea that accelerated ejecta (i.e. gas and plasma), not the particles and rays from the nuclear explosion would push the NPP spacecraft. The Medusa seems even more particle-driven ejecta-driven, since (caution: WILD WP:OR ahead) a "sail" would not capture as many gamma rays as Orion's pusher plate. - ¡Ouch! (^{hurt me} / _{more pain}) 12:36, 28 June 2013 (UTC)

(Very tangential contibution ahead) It looks like the Orion is the big ship of the family, while the Medusa is the small ship -- it scales down much better thanks to its long tether, so you don't have to resort to lots of inefficient micro-nukes for small ships. - ¡Ouch! (^{hurt me} / _{more pain}) 17:00, 29 June 2013 (UTC)

Yeah, that's a good point. Radiation pressure from gamma rays would be insignificant on a thin sail. 39.215.55.222 (talk) 01:17, 2 July 2013 (UTC)

I am amused to read this discussion. We have no idea what an ET would use as a propulsion source. With all due respect, to assume that their technology would follow the profile of our nuclear bombs or any of our theoretical propulsion systems is half-baked. (Although we have to start somewhere!) We do know that at least 17 billion extrasolar planets exist in our galaxy. If there are any space-faring civilizations among them, then we can expect their technology to leave some sort of mysterious mark in the cosmos. Kortoso (talk) 22:19, 3 July 2013 (UTC)

STD

A condom can give us 100% protection against sexual terminating disease or not? — Preceding unsigned comment added by 112.79.36.180 (talk) 01:58, 28 June 2013 (UTC)

No. See Condom#Effectiveness for a breakdown of how successful it is in preventing pregnancy and in preventing the transmission of various diseases. --Jayron32 02:03, 28 June 2013 (UTC)

side discussion that does not provide any references to help the OP answer their direct question
The following discussion has been closed. Please do not modify it.
The only truly "safe" sex is to abstain. However, condom with spermicidal foam is regarded as highly effective. [Apparently NOT - see below] ←Baseball Bugs What's up, Doc? carrots→ 03:12, 28 June 2013 (UTC) Any reason for including spermicidal foam in a discussion of STD prevention? I think you'll find there is scant evidence for efficacy in preventing infection. Some might try to argue that some pregnancies resemble infections, but that's unfair -- Scray (talk) 05:55, 28 June 2013 (UTC) If I recall correctly, nonoxynol-9 used to be recommended as helpful in preventing HIV transmission, presumably on the grounds that it killed the virus in vitro, but then when they actually followed up and checked, it turned out that it made transmission more likely, perhaps by irritating the mucous membranes. This is just my vague recollection and no one should rely on it. --Trovatore (talk) 08:51, 28 June 2013 (UTC) Interesting point, and my information was old. The condom + foam should still be nearly 100 percent for pregnancy prevention, but that wasn't the OP's question. ←Baseball Bugs What's up, Doc? carrots→ 13:34, 28 June 2013 (UTC) Actually, as per the OP's question, this discussion is about sexual terminating disease. 202.155.85.18 (talk) 06:30, 28 June 2013 (UTC) There's no such term. STD stands for sexually transmitted disease. Jayron's link leads to information about condoms and STDs. If the OP wants to know about something called 'sexual terminating' disease, s/he will have to come back and explain. - Karenjc 07:01, 28 June 2013 (UTC) If "abstention"abstinence is safe is entirely open to debate. It will make it very unlikely to contract an STD (you can still pick up diseases classified as STDs via other ways of transmission - toilet seats ;-), needles, ...). But it might have other detrimental effects on your health, both physical and mental. --Stephan Schulz (talk) 08:46, 28 June 2013 (UTC) That wasn't the OP's question. And if you get it from some inanimate source, it's technically not "sexually transmitted" (not directly, anyway) - not that that makes any difference to the microbes. ←Baseball Bugs What's up, Doc? carrots→ 13:30, 28 June 2013 (UTC) Stephan, your English is normally impeccable, but "abstention" is the noun form of "abstain" in the sense of not voting. When you're abstaining from something fun, especially sex, it's usually called "abstinence". --Trovatore (talk) 08:55, 28 June 2013 (UTC) Thanks. I was under the impression that one was the verb form (actively not doing it), the other the noun (the state of not doing it), and was not aware of a difference in usage. Fixed above. Probably not fixed in my mind. Expect more embarrassing errors in the future ;-). --Stephan Schulz (talk) 09:40, 28 June 2013 (UTC) Safety is less debatable than efficacy. "Abstinence", like all methods of contraception or STD prevention, has a failure rate. See [8], which estimates the use effectiveness rate at about 50%, lower than most other forms of contraception. A theoretical rate of 100%—assuming perfect use by perfect practitioners—is a useless figure in terms of real world decisions. Studies have demonstrated that teenagers, at least, who pledge abstinence, have sex as frequently as those that have not made such a pledge. -Nunh-huh 09:06, 28 June 2013 (UTC) A "pledge" of abstinence does not equate to actual abstinence. I'm talking about actual abstinence. ←Baseball Bugs What's up, Doc? carrots→ 13:32, 28 June 2013 (UTC) But then you have to apply the same criterion to other means of prevention. Does "actual use of a condom" exclude those cases where it was not properly put on, or of the contraceptive pill mean only when it is taken exactly as prescribed? These figures will all be real-world figures, not some theoretical ideal. Besides, "actual abstinence" is also fuzzy: where does the boundary lie – when no direct physical contact takes place at all, ever? — Quondum 14:44, 28 June 2013 (UTC) Yes, lack of contact is actual abstinence. A "pledge" is meaningless - unless you live up to it. ←Baseball Bugs What's up, Doc? carrots→ 14:57, 28 June 2013 (UTC) As interesting as this discussion is, it does not provide any additional reading for the OP to go read to directly answer their question. --Jayron32 15:11, 28 June 2013 (UTC)

Neutrinos that go toward neutron stars

What fraction of the flux of neutrinos that go into a neutron star get "stopped"? Do some of them end up orbiting the star? There's the famous 50 light years of lead claim, true or not, but neutron stars are way different from lead. Thanks.76.218.104.120 (talk) 09:37, 28 June 2013 (UTC)

A quick calculation using that 50 lightyear figure for lead and the density ratios yields that the fraction that get scattered will be of order 1. If we consider cosmic background neutrinos then the coherence length will be large, of the order of 0.1 millimeters and you'll have a huge number of nucleons within the radius of one coherence length in a neutron star, making the probability of scattering a lot larger than what you would expect using the ratio of densities. Count Iblis (talk) 13:05, 28 June 2013 (UTC)

Yes, the density of a neutron star being in the order of 5×10¹⁶ times that of lead, and a light-year being about 10¹⁶ m would lead to the same level of neutrino absorption or scattering for 50 ly of lead occurring in 10 m of neutron star material. Would the coherence length of the neutrinos not potentially make the neutron star material more neutrino-transparent just as glasses and liquids are to light (not more opaque as as you suggest)? As to whether scattered neutrinos might end up orbiting the neutron star (and one would want to include repeated scattering of suborbital neutrinos in this), this would not be the case with a normal neutron star: its material would be at such a high temperature that the typical scattering event would impart too much kinetic energy to the scattered neutrino. Incidentally, a Google search finds "A fairly common qualitative statement in physics texts is that the mean free path of a neutrino is about a light-year of lead", which is echoed in more place. I suspect that lead is used precisely because its density is about right to produce this easy-to-remember figure. This would make the mean free path of a neutrino in a neutron star (coherency and any energy-dependency ignored) about 0.2 m. — Quondum 16:49, 29 June 2013 (UTC)

So could these scatterings be important to the evolution of a neutron star, given all the zillions of neutrinos, almost all of which apparently scatter within the star? Thanks again.76.218.104.120 (talk) 20:50, 29 June 2013 (UTC)

I'm definitely no expert. The bulk of the significant neutrinos would be generated and radiated as it is becoming a neutron star and soon afterwards, at which stage they are very important: they carry away the bulk of the thermal energy, cooling the interior (or so I gather from Neutron star). If the density of incident neutrinos (e.g. the neutrino remnant from after the big bang) is sufficient, this scattering could serve as a way of cooling the neutron star faster than otherwise, but I really have no idea whether the incident neutrino rate is sufficient to be significant in this regard. I do not expect other neutrino mechanisms (absorption) for low-energy neutrinos to be significant. — Quondum 20:58, 30 June 2013 (UTC)

Are you guys sure you can use all three dimensions of density for your calculation? Certainly the cube root of 1E16, for the depth, I can believe, but do adjacent nucleons(not directly in the path) coming in closer actually matter? It seems counterintuitive to me that the neutron star would impede a neutrino so vastly much more than the same star unpacked, but then again, my intuition is worthless here. :) Wnt (talk) 17:21, 1 July 2013 (UTC)

What is the name of this toy?

It's sort of engineering... what is this toy called? Thank you in advance for your superior knowledge and help. Saudade7 14:45, 28 June 2013 (UTC)

I've not seen this particular toy specifically, but broadly it looks like a type of Mechanical puzzle, like a Disentanglement puzzle, or a something similar. --Jayron32 15:05, 28 June 2013 (UTC)

The article on Trammel of Archimedes suggests at least some call it a Kentucky Do-Nothing. 88.112.41.6 (talk) 16:23, 28 June 2013 (UTC)

Yep, more generally it is a type of linkage_(mechanical). For a fun way to kill some time, try these web applets demonstrating various cool linkages: [9], [10], or just google /linkage applet/. SemanticMantis (talk) 16:47, 28 June 2013 (UTC)

Thanks everyone ! I will check those things out. 64.134.223.233 (talk) 22:20, 28 June 2013 (UTC)

Effectivity of condoms and other anti-conceptives

why do they state the effective of condoms (and others) in the form of percentage of failure/year? Wouldn't it be more accurate to put it as failures/times used? 80.58.250.84 (talk) 17:31, 28 June 2013 (UTC)

It is somewhat arbitrary, but as the failure/use rate is rather small, when picking an arbitrary period over which to express a measurement, the measurement is often picked to keep the number within an easy-to-understand range, basically keeping things within about 2-3 digits on either side of a decimal point. For example, I can express my weight as either 95 kilograms, or 95,000,000 milligrams, or any of a number of other measurements, arbitrarily. The human brain does a better job of processing numbers with a small number of digits to either side of the decimal point, so a scale is chosen to keep that in mind. For example, assuming a 2x per week usage, a condom with a failure rate of 2% per year would be expressed as 0.02% per usage, and it's easier for most people to internalize how much "2" is rather than "0.02" --Jayron32 17:39, 28 June 2013 (UTC)

You mean 0.02 times per usage - not 0.02% per usage. So in your example the failure rate (expressed as a percent of times used) would be 2% - and that seems easy enough to grasp. StewieCartman (talk) 19:39, 28 June 2013 (UTC)

No, Jayron is correct. His approximation is 0.02 times per year / 100 usages per year = 0.0002 times per usage. -- — Preceding unsigned comment added by 177.120.234.75 (talk) 13:18, 29 June 2013 (UTC)

I don't think that that's what he meant. He said a "failure rate of 2% per year". That is not the same as 0.02 times per year / 100 usages per year. StewieCartman (talk) 14:09, 29 June 2013 (UTC)

No, 177 is correct. If something fails 2% per year that's 2/100 chance of failure per year, and at 2 uses per week that's about 100 uses per year, which would be a failure rate of 2/10,000 chance of failure for each usage. --Jayron32 20:15, 29 June 2013 (UTC)

I see. My apologies for the misunderstanding. StewieCartman (talk) 10:27, 1 July 2013 (UTC)

The approximation only works, of course, because 0.02 is a relatively small number. You could not, for instance, take the 85% probability that a sexually active woman will become pregnant in one year and conclude that the chance of getting pregnant from a single instance of intercourse is only 0.85%, because the majority of those woman will become pregnant early in the first year of trying. The actual number appears to be more on the order of 5% per instance. [11] -- 189.71.47.213 (talk) 22:03, 2 July 2013 (UTC)

Yes, but people who have sex 10x/week and people who have sex 1x week will both think: it only goes wrong once every 50 years. Both cannot be correct. If you told me, for each 100 uses, 2x it goes wrong, then everyone would still understand it. And people who have more sex than average would know where they are getting into. 80.58.250.84 (talk) 17:44, 28 June 2013 (UTC)

The failure rate also acts as a disclaimer. If they said 100 percent effective, they would be leaving themselves open to costly complaints. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:21, 28 June 2013 (UTC)

I think you've misinterpreted the question. No one is suggesting that they should say 100 percent effective. StewieCartman (talk) 19:34, 28 June 2013 (UTC)

I didn't look that well at the previous discussion but I know this issue was at least hinted at. Do note that failure rates are complicated. For example, as mentioned in the previous discussion, abstinence has a near 100% success rate at preventing pregnancy or STDs if used perfectly. Similarly condoms alone have a very high success rate. However these figures are often considered misleading or confusing so instead real world failure rates are generally quoted which considers rates when usage is not perfect (in the case of condoms this can lead to slippage or breakage although as with most methods wich require action, simple failure to use is the most common problem as per our article). Determining these rates and what to count is not simple but frequently involves surveys of what people intend to use and in how many cases it failed (as determined by pregnancy, STD transmission etc). (I've heard before of abstinence proponents quoting 100% success for abstinence and so discounting people who were intending to be abstinent but were not, yet if these people were intending to use a condom but didn't including them in the failure rates for condoms. Not that determining rates for perfect usage for condoms in particular is necessarily any easier.) Getting people to estimate how many times they had sex complicates matters (it would likely require more subjects for starters and even then your results may still be more questionable) and the figures could also mislead. While there would be some correlation between failure rate and number of times people have sex, the correlation may not necessarily be that high. Beyond the differences in how effectively the person uses the method, there will also be other confounding factors like how vigiriously the sexual activity is, how long it lasts, the persons susceptibility to the STD etc. In other words, as Jayron32 said, ultimately you have to find some way to meaningfully communicate the info, and it's not clear that a failure rate per usage would be any better than per year in addition to being harder to determine. Nil Einne (talk) 18:23, 28 June 2013 (UTC)

The neuroscience of waking up

To the best of my understanding, we fall asleep because certain neurons in the ventrolateral pre-optic nucleus crave adenosine, and our bodies manufacture it. The adenosine then goes to those synapses and we fall asleep. How do we wake up? — Preceding unsigned comment added by Bobgustafson1 (talk • contribs) 17:44, 28 June 2013 (UTC)

I do believe other neurotransmitters are also involved in out sleep. Take for example melatonin or histamine (involved in wakefulness). 80.58.250.84 (talk) 17:51, 28 June 2013 (UTC)

• The science here is not very solidly established, but according to Cliff Saper, transitions between sleep and waking are controlled by mutually inhibitory interactions between the VLPO and a set of "arousal" centers, which combine to form a sort of "flip-flop" circuit. The VLPO inhibits the arousal centers, but the arousal centers also inhibit the VLPO. The VLPO is activated by adenosine (a sort of "tiredness" signal) but also by other factors, including circadian rhythms. When the VLPO is activated strongly enough to dominate, we fall asleep. By morning, though, adenosine levels have dropped and the phase of our circadian rhythm has shifted, and so the drive to the VLPO decreases. At some point the arousal systems escape from inhibition, and when they come on, they inhibit the VLPO, allowing further increases in arousal -- thus we get a rapid transition from sleep to wakefulness. This story is at best oversimplified, and might turn out to be completely wrong, but it's probably the best story we can tell right now. Looie496 (talk) 18:14, 28 June 2013 (UTC)

(subquestion) - there's one practical aspect of this that continues to intrigue me. Back when I was having trouble with gout (a very painful condition in the legs) sometimes I would awaken, but deliberately maintain sleep paralysis of my legs for up to an hour or so to avoid feeling the pain. For very brief periods it was even possible to move arms, at least a little, without breaking that. I assume this has some relevance to anaesthesia by hypnosis? Somehow I didn't get far trying to figure this out with present sources, but I would wonder even if things as serious as locked-in syndrome could somehow have to do with this weird, seemingly low-level block over motion and sensation. Wnt (talk) 20:04, 28 June 2013 (UTC)

• Firstly, neurons don't "crave" adenosine. There's evidence that adenosine accumulates during sleep deprivation and shifts the brain's sleep-wake circuitry in favour of sleep (see Looie496's "flip-flop" explanation). However it is not the only factor in sleep homeostasis. Circadian rhythms of multiple transmitter/peptide systems cause the brain to shift from wake to sleep and vice versa. A very good, fairly non-technical open-access review in Neuron is available here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3026325/ --Markr4 (talk) 20:22, 28 June 2013 (UTC)

Wind direction and planetary rotation

Hello! I always remember the phrase, "The sun rises in the east and sets in the west," probably because I remember the phrase, "The land of the rising sun," so I know which direction the world rotates, but what I didn't connect with it is, I know which direction the wind flows too, and rather than being dragged along behind the rotation of the planet, it is pushing forward ahead of it! Is there a name for this specific phenomenon? Is it the same for all gaseous bodies? Can anyone recommend some basic info, perhaps online? ~ R.T.G 20:44, 28 June 2013 (UTC)

The prevailing wind direction depends on where you are on the planet, and in some places on the season of the year as well. See prevailing wind for a summary of the main patterns. Looie496 (talk) 20:50, 28 June 2013 (UTC)

I'm not sure I understand you, RTG. Are you asking why the planet's rotation doesn't cause wind? The atmosphere is part of the planet and so rotates along with the rest of it. StewieCartman (talk) 20:55, 28 June 2013 (UTC)

(ec) The Prevailing winds, Trade winds and Hadley cell articles are a good place to start regarding the prevailing wind patterns in lower Earth atmosphere. See Jupiter and Saturn articles for the atmospheric circulation patterns in the gas giants. --Dr Dima (talk) 20:58, 28 June 2013 (UTC)

Actually I may have this mixed up. The portrayal of wind direction in history make it seem that winds prevail in the easterly direction, and the articles I looked at did not dispel this impression, however, the diagram in the Trade winds article does make it appear that the central winds move toward the west more powerfully. Makes me re-evalute some reputable documentaries and historic events concerning human travel. Well, if Columbus presented a theory to the Vatican about the world being round they'd have thought he was a slow learner. I guess there is a lot of that today, humans being so clever and all. Thanks anyways. ~ R.T.G 21:39, 28 June 2013 (UTC)

(Pet hate: Columbus, his crew and the guys in the Vatican all knew that the world was round - (See: Christopher_Columbus#Geographical_considerations) - the problem with his voyages were that the estimate for the radius of the earth was way off. The idea that popular belief in the middle ages was that the world is flat is a myth.) SteveBaker (talk) 04:30, 29 June 2013 (UTC)

To be even more specific, it was Columbus's estimate of the radius of the Earth that was way off: the mainstream one was pretty good. That's why everyone thought his mission was doomed: he thought he'd get to the Indies in half the actual distance, and everyone was pretty sure he'd actually have to travel the distance we now know that it is. He was just lucky he hit another continent, because he was wrong and everyone else was right. 86.162.68.199 (talk) 18:34, 29 June 2013 (UTC)

Geostrophic wind is also worth having on your list. Dolphin (t) 22:52, 28 June 2013 (UTC)

Yes that one is the sort of thing I was wondering about, thanks again Dolphin  :). ~ R.T.G 23:00, 28 June 2013 (UTC)

You might want to look at some time-lapse videos of the Earth's atmosphere, where you can see clouds moving in different directions at the same time. Of course, the motion of the Earth's atmosphere is only visible when it contains clouds, and there's considerable variation/randomness in wind direction at any spot over time. If you look at a larger planet, like Jupiter, the atmosphere is both more visible and consistent in the directions it moves at each location. I've always wondered if this is just a function of the size of a planet, or if Jupiter's consistency is due to other factors, like distance from the Sun. StuRat (talk) 05:47, 29 June 2013 (UTC)

Actually, realtime satellite videos are great ~ R.T.G 21:08, 29 June 2013 (UTC)

Clouds move mighty slow when viewed at the global scale, so you'd probably want to speed them up to see the patterns. StuRat (talk) 04:16, 30 June 2013 (UTC)

• See: Coriolis_effect#Rotating_sphere It explains it all.--Aspro (talk) 13:20, 29 June 2013 (UTC)

Slugs?

I don't hold the copyright, so I can't upload here, but who are these fellas munching on an earthworm? Evanh2008 ^{(talk|contribs)} 22:23, 28 June 2013 (UTC)

Looks like a Spanish slug, but could be another similar-looking member of the family Arionidae. Looie496 (talk) 22:48, 28 June 2013 (UTC)

Looks too fat to be a Spanish slug. There are plenty of Google Images of slugs, and oddly enough there's one that looks similar[12] - and was likewise posted by someone wondering about it (not this same picture, though). ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:04, 28 June 2013 (UTC)

Possibly Arion ater. This slug belongs to a closely related complex which includes Arion rufus and Arion elater which can only be distinguished by dissection of the genitalia, according to this site. Richard Avery (talk) 07:33, 29 June 2013 (UTC)

June 29

Silly Middle-earth-related question

Is the whole Maedhros-hanging-upon-Thangorodrim episode physically possible to occur as written without invoking magical effects? Double sharp (talk) 16:22, 29 June 2013 (UTC)

If you're asking whether it would be possible in our universe to hang an ordinary human by the right wrist for years without causing death or the loss of the hand, the answer is no. Looie496 (talk) 16:52, 29 June 2013 (UTC)

However, it is possible to keep the arm up voluntarily for years (which, of course, causes severe damage to the arm). You can google Sadhu Amar Bharati for example. --Dr Dima (talk) 19:06, 29 June 2013 (UTC)

The point being, of course, that Maedhros is not an ordinary human, or even an ordinary Elf. While the Valar aren't as interventionist as other gods, it's not unreasonable to regard Maedhros' torment as part of the Curse of Mandos - see Prometheus for an example from Classical mythology. In traditional High Fantasy, the line between "reality" and "magical effects" is necessarily blurred - is the immortality of the elves a magical effect? Is the physical presence and influence of the gods a magical effect? Such questions aren't easy to answer. Tevildo (talk) 20:44, 29 June 2013 (UTC)

(...it's certainly quite fun to rationalize everything in this sort of universe with as few magical effects we don't see IRL as possible...though might turn out somewhat convoluted in some cases...) Double sharp (talk) 13:19, 30 June 2013 (UTC)

And, as this is the Science desk - dehydration would kill a human in this situation before anything else. Assuming he was provided with food and water, cheiralgia paresthetica would then set in, leading to gangrene and death from septicaemia or, indeed, from falling off the cliff face when his hand detached from his arm. Tevildo (talk) 21:23, 29 June 2013 (UTC)

Looking at both articles (and really wishing I'd remembered not to look at wiki medical articles just after lunch...), I can't see how cheiralgia paresthetica would lead to gangrene. From the description, it seems to be mostly just a loss of sensation. MChesterMC (talk) 12:27, 1 July 2013 (UTC)

• The answer to "can a humanoid be hung by the hand" is, in most cases, yes. How long that can be for is a different question. The Maedhros myth has always been one of my favorites. μηδείς (talk) 00:00, 30 June 2013 (UTC)

Mainstream concepts of human race

What is the mainstream view of race in academia today? Is there any difference in such view in nations not in the west? — Preceding unsigned comment added by 174.95.168.157 (talk) 17:03, 29 June 2013 (UTC)

"Human race" is usually understood to mean the human species. Our article human is very extensive, and outlines most of the mainstream academic historical and biological perspectives. SemanticMantis (talk) 17:11, 29 June 2013 (UTC)

And if the question is actually about the concept of human races, our article on race (human classification) gives a very thorough answer. Looie496 (talk) 17:53, 29 June 2013 (UTC)

Fatty acids β-oxidation

Hi, I'm looking for a table that lists different fatty acyl-CoA's and their yield energy (FADH2, NADH and acetyl CoA). [if it includes unsaturated chains as well, it will really help me...] thanks! — Preceding unsigned comment added by 95.86.118.158 (talk) 20:13, 29 June 2013 (UTC)

Notable ancient person whose remains were found

Is there any notable ancient Greek or Roman person except Christian saints whose bone remains, particularly skull, have been found?--93.174.25.12 (talk) 22:24, 29 June 2013 (UTC)

Because of mummys, there are many ancient Egyptian notable people whose remains have been positively identified. --Jayron32 23:14, 29 June 2013 (UTC)

Some of whom were Ptolemaic Greeks, I presume. See also, Philip_II_of_Macedon#Archaeological_findings. μηδείς (talk) 23:58, 29 June 2013 (UTC)

Many notable ancient people were never lost! Many famous and wealthy people were interred in tombs. We have a list of tombs and mausoleums- they are quite numerous. Nimur (talk) 00:13, 30 June 2013 (UTC)

June 30

Plankton

I read on one fact book of mine that plankton makes up 85% of all life on earth. Now that can't be true, right? Or is it? ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 07:17, 30 June 2013 (UTC)

NPR says "Plankton make up 98 percent of the biomass of ocean life", as does this article, so maybe. Clarityfiend (talk) 07:29, 30 June 2013 (UTC)

Check out the article Biomass (ecology). It says most biological carbon is in land life, outweighing sea life by a factor of 50-100, not counting bacteria. There are large unknowns in the distribution of biomass though, bacteria in particular. This all assuming we are talking mass, not number of organisms (I'm guessing bacteria, again, would win a head (sic) count hands (sic) down). 88.112.41.6 (talk) 13:22, 30 June 2013 (UTC)

The table in Biomass_(ecology)#Global_biomass suggests that bacteria win hands-down...but then the commentary afterwards throws doubt in all directions. I think the bottom line is that we don't know. The error bars on all of the stated numbers are huge. The NPR numbers quoted above only tell us what percentage of ocean biomass is plankton - so that doesn't really help.

But the original "fact book" fact is kinda vague. It makes a huge difference whether "making up 85% of all life" means 85% of all individuals, 85% of "wet" biomass, 85% of "dry" biomass, 85% of known species, 85% by volume...it's a very vague term and it's hard to say whether any of those possible meanings are true. It's not impossible that if you pick the right measure - and exclude bacteria or exclude viruses or whatever - that you can make this number come out true - but it seems unlikely.

In all the years I've worked with the Wikipedia reference desk, I've come to believe that anything written in a "fact book" is almost guaranteed to be so vaguely specified as to be meaningless - and most likely, untrue. Those books life and die by having "amazing" facts in them...not boring ones. Hence they cherry-pick the least likely results from the least reliable sources - and write the "facts" in a sufficiently vague manner that it's hard to either prove or discount them. I can't count the number of times people have asked us to fact-check something they read in such books and it's turned out to be nonsense. This one seems to follow that pattern.

SteveBaker (talk) 15:39, 30 June 2013 (UTC)

I always thought fact books were reliable sources... I assumed "all life on earth" to mean out of all living things on earth – fungi, bacteria, animals, plants, etc. ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 08:11, 1 July 2013 (UTC)

Fact books are most certainly not "reliable sources" - we've shown that here many times before. I recall one case where someone posted a couple of dozen "facts" from such a book in a question here - and we gradually found all but a couple of them to be incorrect.

But still, the "fact" doesn't say whether this is 85% by wet mass, by dry mass, by number of individuals, by number of species, etc. So it's just too vague. Also, it's pretty obvious from reading our Biomass_(ecology) article that we really don't have sufficiently good numbers to answer this question definitively. For example, it's only fairly recently that we've discovered extremophile microbes that live inside rocks 1900 feet below the sea floor under 8500 feet of ocean. If those creatures can be found that deep into the earth's crust, then the sheer volume of space that they could possibly occupy would dwarf the thin layer of the surface of the earth that we've explored. The potential for those things to live in such places could easily mean that they are by far the biggest number of individuals, wet and dry mass and number of species...but right now, all that we know is that we don't know. SteveBaker (talk) 14:51, 1 July 2013 (UTC)

Can box turtles crawl in high grasses

On my way home from work I noticed a turtle crawling down the center of the highway (Box Turtle, I think). I have no idea how he didn't get hit, but I decided to pull over and rescue him. I drove a little way down till I found an area that I could put him a safe distance from the road, however, the area had rather thick knee high grass and weeds, which brings me to my question: can turtles pass through this, or is their too much resistance, thus, making them effectively stuck. Honestly, I'd imagine that they would have no problem, but the question crossed my mind while finishing my drive home, I figured I'd ask since it would be a shame to rescue the turtle only to trap it another way! If for some odd reason they can't, I can always go back and retrieve him, Thanks for any help on this seemingly stupid question.Phoenixia1177 (talk) 12:15, 30 June 2013 (UTC)

I don't see how we can help you with sources. But my OR from having kept turtles is that while they wouldn't voluntarily climb in to tall grass (which they don't eat), they should be able to get out. Have you felt the strength of a turtle's legs if you hold one that wants to move or get away? Even if this is a faux pas, don't worry too much. I was getting in the car to leave my waterfront residence on the Great Bay (New Jersey) when an obviously aquatic turtle crawled by my car door. I knew I would pass a lake on the way home, so I put the turtle in a bucket and dropped it off on the side of a nice big freshwater lake about five miles inland. When I got to my apartment in NYC I heard a news story about hundreds of turtles trying to lay eggs on the bayside runways at JFK airport. I looked the animal up and found it was a northern diamondback terrapin, one of the only species of land turtle that prefers salt water. μηδείς (talk) 16:01, 30 June 2013 (UTC)

Agreed. I think the OP is equating slowness with weakness, but this is not the case. The classic example is the weed which pushes up through concrete. StuRat (talk) 13:13, 1 July 2013 (UTC)

eggs in the afternoon

one of my friends told me that eating eggs in the afternoon isn't good for one's health. but, she couldn't elaborate on that. can anyone please tell me whether there are any health risks if i eat eggs in the afternoon?

thanks — Preceding unsigned comment added by 117.197.233.218 (talk) 14:40, 30 June 2013 (UTC)

We're not supposed to give medical advice, but that doesn't make any sense at all. Looie496 (talk) 15:02, 30 June 2013 (UTC)

A google search on "Eating eggs after noon" brings up dozens of hits from health and diet sites saying things like "Healthy Snacks to Beat an Afternoon Energy Slump: A Hard-Boiled Egg"[13]. The trouble is that absolutely anyone can set up a diet/health web site and say just any old nonsense and people will repeat it as if it were scientific truth. So doubtless your friend read it somewhere - and didn't read the other places that say the exact opposite. This is very typical of these kinds of claim.

Bottom line is that in the absence of any scientific studies where people only ate eggs in the morning and not in the afternoon and vice-versa - with each of them eating "placebo" fake eggs at the other times - then tracked those people's health for months and years afterward, we're unlikely to know for sure. Is it likely that such a study has been done? Hell no! To get any kind of scientific result, they'd have to study a hundred different foods with perhaps a dozen possible time-of-day eating patterns, invent fake "placebo" foods to substitute for each one so people wouldn't know which part of the study they were in ("double-blind") and have hundreds of people in each part of the study and track them for a long time afterwards with detailed health testing. It would be an incredibly difficult and costly exercise - and because there is little expectation of discovering major new health insights, nobody is going to fund such a thing.

So we're left in realms of amateur speculation and so forth. It's really, REALLY, unlikely that what your friend said is true.

May I suggest you ask your friend where they got this piece of information from - let us know the source and we can go an examine how that information was obtained.

SteveBaker (talk) 15:21, 30 June 2013 (UTC)

Maybe if they've been sitting out at room temperature (or worse) since the morning. Otherwise, it's silly. Deviled eggs, for example, are good at any meal. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:20, 30 June 2013 (UTC)

I love the idea of hundreds of research subjects spending years eating either fake eggs or not-fake eggs but not knowing which they are.

Eggs are traditionally a breakfast food, so eating them in the afternoon may be a social mistake but not a medical one. This tabloid source mentions research by the University of Missouri suggesting that eating eggs in the morning has health benefits. It does not suggest that other times of day are bad for eggs. Eggs do contain quite a lot of fat, so eating them when activity levels are higher, rather than lower, may be beneficial.

See also "Go to work on an egg", a 1950s advertising campaign that was banned from being rebroadcast in 2007 because it was felt inappropriate to imply a recommendation to eat an egg every day. --Demiurge1000 (talk) 16:35, 30 June 2013 (UTC)

To elaborate on wanting to eat eggs only when your activity level will be high, it's best to avoid heavy meals, including lots of eggs, right before you go to sleep, since they then tend to be packed onto the body as fat. Now "the afternoon" might be followed by quite a bit of activity for the average person, but for those whose schedule involves going to sleep soon after, then eating eggs in the afternoon could be unhealthy. Of course, eggs aren't particularly healthy at any time. While they do contain protein and lots of other nutrients, they also have a high level of cholesterol. Egg whites lack the cholesterol of the yolks, but also most of the nutrition. StuRat (talk) 13:10, 1 July 2013 (UTC)

Genes and race, what do they code for?

The genes that differentiate the races of two individuals, do they code for the behavioral and temperamental differences between races? E.g. more testosterone in black males and more creativity in whites, analytical thinking in East Asians etc. Can these genetic differences also account for difference in racial IQ and crime rate? — Preceding unsigned comment added by 174.95.168.157 (talk) 18:42, 30 June 2013 (UTC)

No. Virtually all social aspects of "race" are just that - social aspects; genes have little or nothing to do with it. Matt Deres (talk) 20:44, 30 June 2013 (UTC)

Here's a bit of reading: Race and intelligence, Race and crime, Criminal black man stereotype. Matt Deres (talk) 20:46, 30 June 2013 (UTC)

Most of the mass murders in America seem to be committed by youngish white males. The OP/IP should ponder that point for a while before indulging in further hackneyed stereotyping. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:38, 30 June 2013 (UTC)

I don't think we need to assume the OP's question is bigoted any more than we should blame him for geolocating to Canada. But the question does have a false premise--there are no specific genes for specific races themselves. Rather, certain genes tend to cluster statistically in their frequencies among races in whatever sense that word is useful. Genes for higher levels of testosterone might lead to more aggressive behavior, but there are plenty of hyperandrogenic whites and hypoandrogenic blacks. No one would suggest a sensitive black male who likes to crossdress and works in a day care center was actually white or some other race because of that behavior. μηδείς (talk) 21:48, 30 June 2013 (UTC)

Something I was pondering

I was pondering about the nature of reality today and meta-stable states, and thought that given A = "system at local minimum (of energy)" and B = "system in equilibrium", B implies A (or I hope so) and so does A imply B?--Gilderien Chat|List of good deeds 21:13, 30 June 2013 (UTC)

No, there are numerous counterexamples. Unstable equilibrium is a common theme in natural science and in engineering. Our article unstable equilibrium redirects to a general article on equilibrium; and you can also read about stability. There are many instances of a system that is at equilibrium but is not at a minimum energy configuration; and there are many cases where a system is at equilibrium but is not stable with respect to any perturbations from equilibrium. For example, an object orbiting at the L3 point of two other masses is in equilibrium, but is neither stable nor at a local minimum of gravitational potential energy. Nimur (talk) 21:57, 30 June 2013 (UTC)

Would A imply B for all cases then?--Gilderien Chat|List of good deeds 23:16, 30 June 2013 (UTC)

You might have been considering stable equilibria (and I suspect so). Even so, the type of equilibrium remains significant. For example, a system may be in stable thermodynamic equilibrium, but it is plainly not at a local minimum of energy in the sense intended. However, given a purely mechanical system (in which non-zero dynamic properties such as heat are taken as "not in equilibrium"), I suspect that a stable equilibrium (even under perturbations) and local energy minimum might well imply each other. In effect, A would imply B, but then in this interpretation it would also imply a temperature of 0 K. — Quondum 23:28, 30 June 2013 (UTC)

There's more than one definition of equilibrium, but the simplest is that it's a critical point (mathematics) of the potential energy function. Mathematically that can be a local minimum (stable) or a maximum or saddle point (unstable), but in the real world you will never find a system in an unstable equilibrium. So I think A and B are more or less the same. This applies to thermodynamic systems too if properly interpreted (principle of minimum energy). -- BenRG 06:48, 1 July 2013 (UTC)

July 1

Malaria

Does malaria exist in Japan since its common in Asia? Clover345 (talk) 07:40, 1 July 2013 (UTC)

No. Malaria does not occur in Japan. Malaria is spread by mosquitoes and requires a hot tropical climate that supports mosquitoes. Malaria is mainly a problem in tropical jungles that combine high temperatures with plenty of water for mosqitoe larvae to grow in. Japan is too far north of the equator and is thus not a hot tropical jungle region. Malaria cases occured in Japan when soldiers returning from World War 2, having caught it in jungle areas, but as there was no means to efficently spread the disease, once the soldiers recovered, there was no more malaria. See http://idsc.nih.go.jp/iasr/18/213/tpc213.html — Preceding unsigned comment added by 124.178.183.4 (talk) 11:21, 1 July 2013 (UTC)

Thats so gabbled and inaccurate that it does not start to answer the OP's question. There is no indigenous malaria in Japan anymore because the intermediate host (i.e., humans) infected by malaria are too few now to sustain a reservoir of this disease (due to modern anti -malarial drugs). The climate of southern Japan suits the vector (mosquitos) very nicely (as your ankles will witness in the evenings when they come out to bite). --Aspro (talk) 12:01, 1 July 2013 (UTC)

Indeed. Malaria was also endemic to Britain until the 1950s, when land drainage and modern healthcare eradicated it. Britain's climate is similar to Japan's, and the assertion that Malaria "requires a hot tropical climate" is nonsense. ref. -- Finlay McWalterჷTalk 13:26, 1 July 2013 (UTC)

Regarding malaria in Britain, our article on the history of malaria says "Malaria was once common in most of Europe and North America, where it is now for all purposes non-existent ... in the coastal marshes of England, mortality from "marsh fever" or "tertian ague" ("the ague" from Latin "febris acuta") was comparable to that in sub-Saharan Africa today". Gandalf61 (talk) 15:17, 1 July 2013 (UTC)

• There are conflicting accounts regarding Malaria's history in Japan, but the mosquito Anopheles sinensis found in Japan is known to be a vector for Plasmodium vivax (it is apparently refractory to P. falciparum). Malaria is found in many non-tropical areas; for example, it was endemic in much of the United States at one time. -- Scray (talk) 11:38, 1 July 2013 (UTC)

How would certain wikipedians do in the World Quizzing Championship?

Really, some of you show an incredible depth of general knowledge when answering questions... I wonder how some of you would do as quizzers in the World Quizzing Championship? I'm posting this here because I was hoping for a scientific answer. Do these quizzers really have an excellent general knowledge like some of you do, or do they have a different type of brain that is trained to retain bits of trivia? On this matter, it seems to me that some of their quizzing questions are a bit contrived and generally limited to western knowledge rather than true global knowledge... I wonder how these so-called eggheads would do given a random sampling of wikipedia's "did you know" questions? Sandman30s (talk) 14:08, 1 July 2013 (UTC)

Not sure. I participated in academic competitions (in the U.S. called Quiz bowl) of various forms throughout HS and College, such as Granite State Challenge, Academic Competition Federation, College Bowl, National Academic Quiz Tournaments, etc. I have a few trophies. --Jayron32 14:33, 1 July 2013 (UTC)

I suspect that most Ref Desk denizens would fare no better than an average person (although there are exceptions). What we do (or at least, what we're supposed to do) is to use Wikipedia and other online information to find references in order to answer questions - and according to the US WQC site: "The World Quizzing Championship takes the form of a written quiz taken by individuals using no reference materials". Kinda the opposite of what we do. Being good at answering RefDesk questions really requires a broad - but very approximate - base of knowledge, combined with being clever at using search engines in creative ways. SteveBaker (talk) 14:34, 1 July 2013 (UTC)

Two questions about the blood donation or blood test

Hi, I would like to ask two questions about the blood donation or blood test: The first question is: How long after donating blood or blood test that takes the blood to produce the same amount of the blood out of out from the body as I understand it is a process which takes time to create blood cells in the bone marrow and does not ends up by drinking liquids ...

And the second question is: Is there any advantages physiologically in a blood test? (Note, I'm not talking about the importance of the tests themselves but if there is any _ benefits in taking blood out from the body in the case of an ordinary person who is not suffering from polycythemia - Multiple in taking blood). Thank you. מוטיבציה (talk) 15:35, 1 July 2013 (UTC)