Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

November 25

Odd hummingbird aggression

Recently I saw an Allen's Hummingbird in my backyard, chasing a Lesser Goldfinch. It was clearly deliberate, since the finch would flutter from tree to tree, and the hummingbird would follow it and hover around until it left, several times until they both left the yard. The hummingbird in question is an adult male and appears to have declared my yard his territory (there's also a female of the same species in the front yard). I have never seen a hummingbird attack a goldfinch; in my experience they mostly show aggression toward other hummies, and occasionally squirrels. What could account for this unusual aggressive behavior? 75.4.21.125 (talk) 01:06, 25 November 2014 (UTC)

I'm not a hummingbird expert, but I was once a member of a bird forum where hummingbirds were a common topic of discussion. I seem to recall people saying that hummers could be quite scrappy little things, when the urge arose - even though they don't look like much. --Kurt Shaped Box (talk) 01:31, 25 November 2014 (UTC)

They sure are fierce! What seemed odd to me is that this one was attacking a creature that was neither a competitor (goldfinches, as far as I know, don't drink nectar or eat insects) nor a potential threat. And it only went after one goldfinch, ignoring all the others and the house finches, doves, jays, etc that were around75.4.21.125 (talk) 03:56, 25 November 2014 (UTC)

Birds as a clade are just territorial creatures in general and there are all manner of complex relationships between species that can lead to behaviours that at first seem counter-intuitive (and in some cases in fact are). But if you're capable of differentiating and sexing these species, you probably already know that. In this case, it's worth noting that when smaller birds, hummingbirds included, harass larger birds it often has more to do with protecting a nest or territory associated with a potential mate than general aggression prompted over feeding territory and other resources, and that seems to fit the bill (hah!) with the situation you describe, except this isn't really the season where aggression associated with mating is strongest, unless you are in a particularly warm latitude. Hummingbirds are also intensely curious creatures and have been known to follow other birds, creatures and objects around for a time, especially if they exhibit strong colors. Was the hummingbird making a racket or taking dives at the finch? Both are common when they are significantly agitated. Snow talk 05:04, 25 November 2014 (UTC)

I'm in Southern California and apparently some hummingbirds build nests in winter (I saw an Anna's Hummingbird doing so last January). And the hummingbird didn't dive (as Allen's often do when aggressive), but it did hover near the finch and seemed to have its feathers fluffed. 75.4.21.125 (talk) 14:40, 25 November 2014 (UTC)

Yes, hummingbirds whose territories extend into the tropics or otherwise warm habitats are known to mate year round, but even tropical and subtropical climates, October and November are the least likely months for nesting. On the whole, I'm inclined to assume this was just a mild territorial tiff on the part of the hummingbird. Though as to whether it has anything to do with the neighboring female, I wouldn't venture to guess in this case. My previous caveat that aggression towards larger species usually has something to do with nesting or mating not withstanding, hummingbirds are known to sometimes zealously guard a feeder, sometimes wasting a hours or even days chasing away all comers that it can get away with harassing even if it only has need to feed a handful of times itself. Conventional wisdom has it that they do with when preparing for migration, and though at first I assumed your little scraper wouldn't have much need to move much farther south (and would already be down there if he did), our article on the species says that it winters on the central coast of Mexico, so it's quite possible he's stockpiling nutrients from some source in your yard and was not going to risk any of it going to no damn finch, not when everyone knows those guys are yellow-bellied. Bwahaha! Snow talk 03:25, 26 November 2014 (UTC)

I'd agree with general territorial defensive behavior. A few other things: goldfinches don't sip much nectar but they will eat buds. So technically there could be some competition in the sense that a bud eaten by a finch will not be able to later produce nectar for the hummingbird. I'm not familiar with Allen's but the common ruby-throated is very curious, and will check out many brightly colored things. So it may have just been interested and not really attacking/defending. SemanticMantis (talk) 15:40, 25 November 2014 (UTC)

• As I have long warned, if hummingbirds had mouths like great whites', rather than beaks designed for stabbing they'd rule the world. μηδείς (talk) 17:41, 25 November 2014 (UTC)

Tip-of-the-pen phenomenon?

I know that there is this phenomenon called tip-of-the-pen, which is very similar to tip-of-the-tongue, but it occurs in cultures where the writing is not phonetic and more logogrammatic. A person knows the word and can say it, but just forgets how many brushstrokes there are in the single logogram/character and how to put it together meaningfully. I think "tip of the pen" is the official name for it, because I do remember a brief mention about it in a textbook. The brief mention was that the relatively new phenomenon is not well studied, but that may mean there are some insights into it, right? How many studies have been done on tip-of-the-pen up to this date, and are there any in English? 71.79.234.132 (talk) 02:14, 25 November 2014 (UTC)

It's unlikely to be a phenomenon in English because you can always rite yor wurds fonetikly. People make spelling mistakes in the process - I find that I sometimes get stuck on the correct spelling of a word - but never that same complete inability to write the word at all.

Another interesting (and perhaps related) phenomenon in English is almost the opposite. My wife will ask me to spell a word that she doesn't know - and the only way I can spell it for her is to first write it down and then read back what I wrote.

SteveBaker (talk) 03:12, 25 November 2014 (UTC)

Ack, I meant RESEARCH PAPERS in English. 71.79.234.132 (talk) 05:13, 25 November 2014 (UTC)

As Steve notes, it is highly unlikely for the phenomena to manifest in English as produced by a developmentally mature and fully literate person, owing to the fact that the entire writing system is comprised of a 26-character alphabet and couple dozen forms of punctuation. The tip-of-the-tongue phenomena is in large part owed to the vast (and increasingly large with each successive modern generation) stock of words a person learns over the course of their life, many of which may not be used regularly, leading to that typically rare, but vexing phenomena where you've half formed the linguistic representation of a concept and know basically the meaning of the word you are trying to conjure (note that we all almost always respond to this frustrating event with vague invocations of the definition: "It's almost synonymous with term X, but you only use it context Y and it's less absolute-sounding than word Z!") but are stuck as the language centers of your brain try to apply fuzzy logic to all the various phonetic, syntactic and semantic associations that might lead you to the proper form. The small sample of letters are used routinely and besides which are largely processed by different regions of the language centers of your brain. Tip-of-the-pen is similar in that there are large number of similar phenomena (logograms or pictograms) which may need to be recalled, though they too use still different, if somewhat overlapping, brain regions from those employed with an alphabet or syllabary.

That being said, there are extreme cases where English speakers and other practitioners of written languages that employ phonetic (rather than logographic) characters may have difficulty recalling or producing the appropriate characters, such as with the conditions agraphia, alexia, apraxia, and, depending on your definition, some forms of aphasia. These sometimes debilitating conditions usually occur as the result of stroke, head trauma or other neurological damage and, combined with modern imaging have actually been immensely helpful in helping to chart which parts of the language centers of the brain regulate which parts of language perception, conceptualization, and production, so in that sense there are actually is a significant body of work which treats the phenomena of the inability to produce usually easily recalled and produced characters in English (and a significant number of other languages). If you have access to JSTOR or another major academic database, I recommend plugging the above terms into it. Failing that, Google scholar will probably give you no shortage of hits, some of them open-content. If neither points you towards the information you need, however, or if you are having difficulty parsing what will largely be highly technical linguistic and neurological terminology, post a follow up comment and I'll see if I can't isolate some more germane and readily-accessible works. Snow talk 04:37, 25 November 2014 (UTC)

I think there is a complete misunderstanding of my request. When I said "English", I was referring to research papers written in English about the tip-of-the-pen phenomenon. But now that two people have misunderstood it, I think my original statement was written in a non-intentionally misleading way. 71.79.234.132 (talk) 05:18, 25 November 2014 (UTC)

I also have a neuroscience background (BS) in RL, so I at least have college-level knowledge of terms and anatomy. So, the real barrier is language. I can only read articles in English. 71.79.234.132 (talk) 05:20, 25 November 2014 (UTC)

Ah, ok, I see. Well, unfortunately I have less guidance to give in finding articles about the phenomena in neurologically healthy individuals speaking languages that employ a logographic writing system. :( A Google scholar search turns up these abstracts: 1, 2, 3, none of which I have access to just at the moment, but which all contain reference to "tip-of-the-pen" or "tip-of-the-brush", but which might be using them in a more literal sense than the figurative use you are seeking. In any event they seem more concerned with second-language acquisition than language cognition. This paper does treat the exact phenomena you are looking into, but not in significant detail. Unfortunately, I think you're going to find that this particular subject will not have much treatment in English, as it is a foreign concept to most English speakers. Sorry I couldn't be of more help with regard to the exact concept. If however you are looking at the phenomena under the lens of cognitive-/neuro-science, I still think looking at the above-mentioned conditions will give you a great deal of insight in the way the brain processes symbolism associated with linguistic processes. Best of luck! My formal background is also largely in cognitive science, and my first degree was in linguistics and thus the intersection of the two is always of fascination to me, so if this line of inquiry leads to other questions, don't hesitate to return here or contact me on my talk page. :) Snow talk 06:17, 25 November 2014 (UTC)

FWIW, this was recently (within the last month) discussed at the Language Log blog in the context of Chinese, where it was referred to as "character amnesia". {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:49, 25 November 2014 (UTC)

In logographic writing systems, it's completely normal to know exactly how to pronounce a character and what it means, but have no idea how to write it. There's nothing surprising or psychologically interesting about that--if words in English consisted of random letters arranged in a random order, with no relation whatsoever to their pronunciation, you'd often forget how to spell a word. --Bowlhover (talk) 17:02, 25 November 2014 (UTC)

Ehh, no real need to talk down to the OP or dismiss his interest in this subject. Everyone who's participated in this thread thus far seems perfectly aware of the nature of the phenomena and is unsurprised that it occurs. Tip-of-the-tongue is a perfectly familiar and not altogether surprising phenomena as well and yet has been found to be immensely "psychologically interesting" to academics in neuro- and psycholinguistics who feel it provides a lot of insight into how the brain organizes conceptual phenomena, matches them to representative morphemes and handles associations between related semantic and phonemic classes, to just begin to list its implication. Suffice to say, whatever the nature of the interest, the OP is intrigued by this similar phenomenon and is looking for research upon it and our job here is to detail such resources, or at least point him towards them -- not condescendingly tell him what he clearly already knows and imply that there is no intellectual merit to his interest beyond that simple overview. Especially when there is in fact immense merit; there's no surprise as to why children make syntactic and morphological errors when learning language either, but studying the nature of those errors and the particulars of how they occur led to arguably the single greatest development in the history of linguistics with massive implications that reshaped the cognitive sciences and our understanding of how the human mind operates and generates some of the qualities that are most unique to our species. Snow talk 20:57, 25 November 2014 (UTC)

I wasn't trying to be condescending at all. I'm sorry if I appeared that way. I just thought that the OP might not know how normal it is to forget a character in logographic systems. It's more similar to forgetting a phone number than tip-of-the-tongue, because the characters often have no relation to how they're pronounced or what they mean.

Also, I'm a native Chinese speaker, so I have no idea how much a typical English speakers knows about logographic writing systems. I wasn't assuming the OP is stupid, since I don't think everyone should be expected to know about all the different types of languages in the world. --Bowlhover (talk) 21:31, 25 November 2014 (UTC)

Fair enough! It just seemed a little pointy, is all, and suggestive that the inquiry was about a superficial and uninteresting topic. But certainly I take you at your word that it was not nearly your intent; hopefully you'll take me at mine when I say my own response was meant only to defend against a perceived judgement of the value of the topic and the OP's interest and that the kindly tone you used to clarify the matter is well appreciated. :) Snow talk 22:21, 25 November 2014 (UTC)

Some native Chinese speakers grow up in China and are given a formal education in the Chinese language. Some Chinese speakers grow up overseas, usually in places where Mandarin is not the dominant language. The latter may be able to speak Chinese, but may not be able to read/write it unless given a formal education in Chinese writing. I am part of the latter population. I was raised mostly in the United States, and there was one year in my childhood where I got the opportunity to take a Chinese class and a piano class before I moved to a different state where the Chinese population seemed even smaller. Suffice it to say, I usually use Yabla Chinese and my knowledge of pinyin to decode my parents' speech and use of idioms. It's not a perfect method, because my parents speak Mandarin with a regional accent, but my pinyin approximations usually get me the right Chinese word most of the time. I can't speak for the normalcy of not being able to read/write Chinese characters. TBH, my dad uses a program to input pinyin and output the correct character, while my mom does not use pinyin at all. (They never learned pinyin in their childhood.) Luckily for her, there is a search engine that allows her to scribble brushstrokes onto the computer screen and find the right Chinese logogram. The time when they actually ask each other for help on a specific character is extremely rare. 71.79.234.132 (talk) 02:37, 26 November 2014 (UTC)

Interesting - so, is your interest on the phenomena of tip-of-the-pen purely a matter of curiosity about the occurrence itself or are you looking for learning/work around strategies for more practical purposes? Because I actually came across a number of sources on the latter topic when first responding, which I dismissed at the time as not germane to what you were looking for. Snow talk 03:02, 26 November 2014 (UTC)

Out of curiosity about the occurrence. As previously stated, I am just curious, because it's briefly mentioned in a now-sold textbook. The brief mention was really a caption to a picture on the side of the main text, and it basically said that the tip-of-the-pen phenomenon is one that is not well studied. But its nature is very similar to tip-of-the-tongue. So, what are the sources you found? 71.79.234.132 (talk) 05:34, 26 November 2014 (UTC)

Inserts in injection molding process

When Injection molding products made of liquid silicone rubber is it possible to have a set of inserts prepositioned inside the mold so that once silicone is injected they would be secured in it? Its just that I cant see any other way to secure metal parts within silicone body due to the inertness of silicone rubber. If it is possible, is it a common practise for the industrial scale production? Also how would you position such an insert in a way that is entirely covered with rubber from all the sides? Because in this case the insert can not have any connection points with the mould for it's prepositioning.195.94.247.199 (talk) 11:17, 25 November 2014 (UTC)

The easy way to do this is to create the moulding in two halves (or more layers), with the inserts placed at the edge of the first moulding, then sealed by the second moulding. The trick of using fine rigid wires is probably too fiddly for mass-production. Both methods leave a trace. Dbfirs 21:14, 25 November 2014 (UTC)

You can always fabricate difficult products in one step if if you allow a high percentage of waste/failed results but reliable results are usually only achived by splitting up the process into multiple steps. --Kharon (talk) 02:23, 26 November 2014 (UTC)

I suppose the positioning wires could be made out of something that will slowly dissolve, perhaps using a bit of solvent mixed in with the silicone. StuRat (talk) 15:58, 26 November 2014 (UTC)

Dry juice

Is it possible to dry juice or other drink in a powder ??

Why not? Ruslik_Zero

Yes, for various methods please see Drying (food).--Shantavira|^{feed me} 13:05, 25 November 2014 (UTC)

Milk and eggs are available dried. For fruit juice, it is normally concentrated, and then the water is re-added either by the consumer, or the packager. The latter is normally done for juices that are transported large distances by sea. CS Miller (talk) 13:23, 25 November 2014 (UTC)

I dunno, but I suspect that fruit juices contain live plant cells and drying them would kill the calls, at which point rehydration would produce something, but probably not what you would call juice. Which is why juices are typically concentrated, not dried. 50.126.104.156 (talk) 15:41, 25 November 2014 (UTC)

I have seen dried orange and lemon juices before, if that helps. --Kurt Shaped Box (talk) 18:26, 25 November 2014 (UTC)

See Drink mix for our (fairly limited) article on the subject, although I'm not sure something made from powder could be legally described as "juice" (rather than "fruit flavoured juice drink" or similar). Powdered fruit juice is a common component of field rations, and was part of the Apollo astronauts' daily diet. Tevildo (talk) 19:13, 25 November 2014 (UTC)

For example, if you tried to dry grape juice and reconstitute it, I suspect you'd get something raisin juice, instead. StuRat (talk) 16:01, 26 November 2014 (UTC)

Climate Change Explanation

I've been hearing about Climate Change for years, but I've never come across a good, solid explanation of the phenomena. I just saw a story in IEEE Spectrum that "Climate scientists have definitively shown that the buildup of carbon dioxide in the atmosphere poses a looming danger.", but when I follow the link I only find more of the same kind of stuff I have been seeing.

What I would like to see would include, at the minimum,

- an explanation of how much radiation is reflected/absorbed depending on the level of CO2 in the atmosphere,

- a historical record of global temperatures going back 100,000 years along with an estimate of how accurate those temperatures are, and

- a summary of CO2 sources and sinks and their relative size.

Oh, and without all the political claptrap that seems to the largest part of any story about climate change. Is that too much to ask? 50.126.104.156 (talk) 15:37, 25 November 2014 (UTC)

No, it's too little. The politics is crucial, since that determines whether we are going to see major cities worldwide abandoned to flooding in our own lifetimes, and mass migration due to crop failure. AlexTiefling (talk) 17:04, 25 November 2014 (UTC)

One problem is that everything you are asking for involves multiple layers of assumptions, models, indirect measurements, proxies, extrapolation and averaging. Even the historical temperature record is derived from indirect measurements once you go back beyond human record keeping. And, inevitably, the selection of relevant data, analysis methods and models involves a degree of subjectivity. Gandalf61 (talk) 17:32, 25 November 2014 (UTC)

The points above are apt, but to actually provide a good data source -- The place to go is the IPCC - they are an international body of scientists who have been examining the causes and impacts of climate change for quite a while now. Here is their front page [1]. They issue lots of separate reports, on things like impacts on water or forest systems. Here is their synthesis report, which ties together all of the reports made for the 5th assesment report (AR5) [2] It has all kinds of data, including a nice summary graphic on p.37 that goes back to 1850. There are many other IPCC documents that will go into more detail on the reconstructions we have for climate ~10k years ago, and others that will go into sources and sinks. There are still other sections/reports covering models and assumptions, as well as analysis of political actions and mitigation. But I think the synthesis summary is a good place to start for scientific consensus and apolitical reporting.

In my experience, anyone who claims the IPCC is politically biased or unreliable can be safely disregarded as a crackpot. They are the preeminent world body of experts and they will provide you with exactly what you ask for, if you are willing to look around a bit and read long documents. SemanticMantis (talk)

I think it is disingenuous to put forth the IPCC as the metaphorical spokesman for scientific consensus. The IPCC is one organization, and it happens to be a highly politicized organization; and while they do try to provide a survey of the state of knowledge, they are not the official headquarters-division to whom all of climate-scientists report!

I have read several of IPCC's reports in entirety; and I have read several more in brief. I recommend that anybody who wants to inform their opinion also read the IPCC reports. You can find them online at no cost.

You can read about the different types of report produced by the IPCC. I have found the Assessment Reports to be rather unpleasant; they are not laid out as well as a good textbook, but they are not as brief or to the point as a journal publication. When summarized into a sound-bite for the popular press, the important details (like which parts of a report are novel, and which parts are uncertain) are glossed over. However, that's not really so much the fault of the IPCC as it is the fault of an incompetent journalist!

I much prefer to read factual scientific information in peer-reviewed scientific journals. For example: Journal of Geophysical Research and Geophysical Research Letters are two excellent sources of information on geophysics, including planetary-scale climate. For summary reports, Eos is an excellent magazine-format that is very accessible to less-technical readers. You might also enjoy the oft-feisty "AGU Blogosphere" blog.

But, the IPCC is widely-cited, and is, at its core, a literature review of other peer-reviewed research. So, to directly address the original questions: Grab the 2007 IPCC Assessment Report (2007 is the most current complete report, though a new report Climate Change AR5 will be forthcoming in the next few weeks). Among many thousands of pages of background material, it contains, in direct answer to the OP's specific asks:

• "a historical record of global temperatures going back 100,000 years along with an estimate of how accurate those temperatures are":
  • Chapter 05: Information from Paleoclimate Archives
  • Figure 5.3, Orbital parameters and proxy records over the past 800 kyr (including a sea surface temperature model)
• "an explanation of how much radiation is reflected/absorbed depending on the level of CO2 in the atmosphere":
  • Box 1, Figure 5.1, schematic illustration of multiple interactions between ice sheets, solid earth and the climate system which can drive internal variability and affect the coupled ice sheet–climate response to external forcings on time scales of months to millions of years
  • Chapter 07: Clouds and Aerosols.
  • Chapter 08: Anthropogenic and Natural Radiative Forcing.
  • Figure 8.1, Calculation Methodology cartoon; and in fact, this entire chapter.
• "a summary of CO2 sources and sinks and their relative size.":
  • Chapter 8.2.1, "Introduction" to atmospheric chemistry. Anthropogenic and natural inputs are considered.

Do we want to nitpick at any of these findings? Of course. Some of us are formally-trained geophysicists! But before we can nitpick, we have to first educate and inform ourselves.

I am inclined to believe that the role of atmospheric carbon dioxide - specifically, anthropogenic carbon dioxide - is greatly overstated by the popular press. But, that's not really the fault of the IPCC, or any of the other hard-working scientists who are seeking to elevate the discussion about climate-policy using factual evidence. Heck, the IPCC publishes a thousand-page scientific textbook that pretty much explains everything that we know - except that it's written at a level that is accessible only to physicists and chemists and climate scientists! Most people aren't quite autistic enough to spend a few days reading about the real science; for most people, it's much more fun to brand ones-self an "activist" and form an angry protest mob, because physics and chemistry are difficult!

If you're really new to the field of climate and meteorology, and you are looking for a very introductory textbook to meteorology, I can think of no better book than Aviation Weather. This entire textbook is available at no cost online as FAA Advisory Circular 00-6A. It has an excellent introduction to the Earth's atmosphere, its structure, and its dynamic processes, and it's written at the level of a very introductory university course.

Nimur (talk) 19:59, 25 November 2014 (UTC)

You say the IPCC reports are too long and hard for most people to read, but then you say you prefer primary literature? Certainly most non-scientists/can't won't read the primary literature, and I think the executive summaries from the IPCC are fairly accessible to an educated lay person. You can't really have it both ways- primary literature is too technical and popular press is low on content and high on politics. IPCC is certainly closer to the former than the latter, but it depends on the document in question. As for being a metaphorical spokesperson - there really isn't one as you know, but I was absolutely no being disingenuous -- the IPCC's broad conclusions are largely the scientific consensus. Virtually all the top names for each subfield are tapped to review and criticize IPCC reports. Each chapter had dozens of named reviewers, who had hundreds of helpers, and there was also an open comment period. There is no general finding reported by the IPCC that does not report the consensus of most of the top experts in each subfield. Of course experts will debate smaller details (model assumptions, exact year of a bad benchmark being hit, etc.), but IPCC is the closest thing we have to an official consensus on causes and effects of climate change. (Disclosure: I helped review a chapter of AR5). Surely it is better to offer the publications of a consortium of international experts than to tell the average joe to go read the primary literature. SemanticMantis (talk) 20:50, 25 November 2014 (UTC)

1) Carbon dioxide (CO2) enhances the greenhouse effect, causing more radiative energy to be trapped near the surface of the earth. Ultimately, nearly all energy in the atmosphere derives from the sun, and the sun's input isn't changing significantly, but the CO2 holds that energy closer to the surface. The analogy that is often used is something like putting on a winter coat. The coat itself doesn't generate any heat, but it holds in the heat allowing the person inside to stay warmer. For convenience, scientists often use a simplified description of CO2 impacts on radiation, wherein they equate the radiative impact of CO2 changes with an equivalent amount of excess sunlight at the top of the atmosphere. That is to say, if the sun increased by X then that's about the same as CO2 increasing by Y. This is an over simplification for a number of reasons, but it is a convenient framework for thinking about the problem of greenhouse gases, so it is widely used. For CO2, the equivalent top of atmosphere radiative forcing is

$\Delta F\approx 5.35\times \ln {C \over C_{0}}~\mathrm {W} ~\mathrm {m} ^{-2}\,$

where C is the current CO2 concentration and C₀ is the preindustrial concentration (280 ppm). The logarithm comes about because the wings of the CO2 absorption band are approximately exponential. So, to give some concrete numbers. Today's CO2 level is about 400 ppm. So that is roughly the same as $\Delta F\approx 5.35\times \ln {400 \over 280}=1.9~\mathrm {W} ~\mathrm {m} ^{-2}\,$. Averaged over the whole Earth, the sunlight at the top of the atmosphere is about 340 W/m², so the impact of CO2 thus far is equivalent to about a 0.55% increase in sunlight. Now, 0.55% doesn't sound like a lot, but the average temperature of the Earth is presently about 288 Kelvin (15 Celsius / 60 Fahrenheit), and without the sun we'd be near 0 Kelvin (-273 C / -460 F). 0.55% of 288 K is still about 1.5 degrees C (2.7 degrees F) of warming. That's a very oversimplified way of looking at it, but still gets about the right magnitude of effect. A more sophisticated way is to introduce the notion of a climate sensitivity, which is just a fancy way of saying how much will the temperature change for a given amount of radiative forcing. Unfortunately, the climate sensitivity still has large uncertainties, but recent estimates suggest the equilibrium climate sensitivity is roughly 2 to 4.5 degrees C per doubled CO2 (= 0.5 to 1.2 degrees C per W/m² radiative forcing equivalent). Using the present 400 ppm of CO2, that would lead to an estimate of 1.0 to 2.3 degrees C (1.7 to 4.1 degrees F) at equilibrium, i.e. allowing that CO2 levels stayed approximately constant for long enough for the oceans to reach a steady temperature. Observed warming since 1850 is about 1.0 C (1.8 F), at the low end of the predicted range, but the oceans are still absorbing heat and even if CO2 levels stopped increasing we would have a long time to go before temperatures stabilized. Dragons flight (talk) 20:12, 25 November 2014 (UTC)

For clarity: the IPCC uses and endorses the concepts of radiative forcing and climate sensitivity that User:Dragons flight described. These equations are essentially linearized models of perturbations to the thermodynamic balance. If one is so inclined, one can find more complicated models of planetary energy balance; but it's almost tautological that if we use a more complex model, that lends itself to more complex predictions that are subsequently more difficult to validate with observational evidence. After all, the modern theory of complex systems evolved out of a famous scientist's computational climate model! Nimur (talk) 20:25, 25 November 2014 (UTC)

And if you're not willing to read long documents (I'll be honest--I'm not), here are a few links to get the OP started.

Carbon cycle has a good chart showing the major carbon sinks/sources, along with how much they release/absorb per year. It doesn't have percentages, but you can compute them yourself.

Temperature of the Earth, with multiple sources for the past 100,000 years: [3] --Bowlhover (talk) 21:21, 25 November 2014 (UTC)

3) Carbon in the Earth system can roughly be divided into four groups: atmosphere, biosphere on land (including both living and recently deceased plants/animals), oceans, and near-surface geosphere (carbon bound in rocks). Each of these pools include very large quantities of carbon and except for the geosphere fluxes between pools are also large. Environmental carbon is usually expressed as gigatons of carbon (GtC) equal to 10¹² kg of carbon, and only the carbon content is counted regardless of if it is bound to oxygen (as CO2) or some more complex organic form. Using the numbers in carbon cycle, the four pools of carbon contain roughly the following at present: atmosphere 720 GtC, biosphere on land 2,000 GtC, oceans 38,400 GtC, geosphere 75,000,000 GtC. As one can see the atmospheric piece is actually the smallest, while the geosphere pool is huge. A small fraction of the geosphere pool consists of exploitable fossil fuels, about 4000 to 6000 GtC. The fluxes between the pools are also large, except for those involving the geosphere. In addition, most of the exchanges are roughly symmetrical. For example, nearly the same amount of carbon moves from ocean to air as from air to ocean each year, about 90 GtC/yr, with an estimated net flux of only about 2 GtC/yr from atmosphere to ocean. Similarly from atmosphere to biosphere and from biosphere to atmosphere, the flux each way is about 120 GtC/yr, with a net flux towards the biosphere estimated at about 3 GtC/yr. With exchanges this large (e.g. 120 GtC/yr), the atmosphere and biosphere take only about 15 years to equilibrate, so for long-term purposes they can be imagined as a single pool. The ocean carbon pool is much larger, so it can take hundreds of years to equilibrate. The natural flux from the geosphere to the atmosphere and ocean is small, ~0.5 GtC/yr, and mostly due to a combination of weathering of rocks and volcanic activity. The net flux into the geosphere is even smaller at present, ~0.1 GtC/yr. By contrast, the carbon we are adding to the atmosphere by intentionally extracting and burning fossil fuels is about 8 GtC/yr. As we add this carbon to the atmosphere, it shifts into the biosphere and ocean. This redistribution is important to us as it presently offsets about half of what we emit. If we could magically stop burning fossil fuels tomorrow, then the atmospheric levels would decline for a long time as carbon dioxide continued to move out of the atmosphere and into the ocean and land. However, because the flux into the geosphere is so low, it will take many thousands of years, to move carbon out of the land/air/ocean system and return it to the ground.

Related to this, the ability of the ocean to take up carbon is also rather complicated. Though it contains 38,000 GtC, only about 1% of that exists as CO2. Most of the remainder is either bicarbonate (HCO3^-) or carbonate ions (CO4^-2). The balance between the ocean and the atmosphere happens when the partial pressure of dissolved CO2 in the surface water is equal to the partial pressure of CO2 in the overlying air, which sets the boundary condition; however, the transformation from CO2 to carbonate and bicarbonate is also influenced by the pH of the ocean and the abundance of cations (e.g. Ca⁺²). The influences of these factors are expressed through the Revelle factor, which expresses the change in total ocean carbon as a function of changing CO2 levels. In rough terms, a 100% increase in atmospheric CO2 equilibrates with about an 8% increase in ocean total carbon content. The consequence of this is that even though the ocean is a huge carbon pool, it can only capture about 50% of our fossil fuel emissions. The land captures another 35%, leaving ~15% of the emissions to linger in the atmosphere for thousands of years. Dragons flight (talk) 05:37, 27 November 2014 (UTC)

The fundamentals first. The laughable attempts to pass off CO2 sensitivity estimates based on the temperature record since 1850 should be regarded as stabs in the dark, as the error bounds associated with a temeperature reconstruction such as HADCRUT4 are large and ever increasing, once we go back beyond 30 odd years ago. Greglocock (talk) 21:44, 25 November 2014 (UTC)

Svante Arrhenius computed an approximate climate sensitivity from first principles around 1900. Since we are fairly far from climate equilibrium, it's indeed non-trivial to derive climate sensitivity directly from the recent temperature and CO₂ record. But then I don't think that is a major method used. --Stephan Schulz (talk) 16:16, 27 November 2014 (UTC)

it is a difficult subject. In absolute terms the changes are quite small, temperature is relative to absolute zero at -273°C so a change of 2°C is less than a single percent - and yet it means a huge change for us. It is difficult to get within a factor of 2 about the probable change, a lot of work has been done and the estimates and error bounds are the best that can be done at the moment. At the end of the day it comes down to whether you think all those scientists are actually doing their best to come up with a good estimate or whether you think they are practically all deluded or involved in a giant conspiracy. As to acting on what they say the question is rather like going to the doctor and being told you have cancer. Of course a lot of people will just deny anything is wrong with them, and sometimes nothing bad does happen as the outcome isn't definite, but is it a rational way of dealing with bad news? Dmcq (talk) 23:36, 25 November 2014 (UTC)

The effects of global warming on the human world is hard to predict, but the OP is asking for more definite information. The sizes of carbon sources/sinks and how much radiation CO2 absorbs are both measurable, the latter to a very high precision. --Bowlhover (talk) 00:24, 26 November 2014 (UTC)

I was explaining that what they were asking for was too much to ask for which is what they asked. Dmcq (talk) 08:44, 26 November 2014 (UTC)

• Read After the Ice Age by Canadian scientist E. C. Pielou who mentions the fact that the interglacial period we are enjoying (with its temperature maxima long over) has already begun it's next ice age cycle. μηδείς (talk) 03:53, 26 November 2014 (UTC)

• CO2 as a forcing is fairly easy to find in IPCC. I believe the total increase of CO2 from 1750 to present (50% increase) is equivalent to 1.5 W*m² (the total from the sun is on average around 1500 W*m²). Annual, seasonal, and daily fluctuations of CO2 are pretty large. Solar activity variation is on this order of magnitude. The larger concern isn't what's happened so far as it's not particularly significant (or even attributable to CO2), but the lifetime and accumulation of CO2 makes the 50 and 100 year projection significant. Also, it's not clear what happens to other GHG's such as water vapor so while the forcing of CO2 might be known, how it affects other forcings (i.e. how sensitive the climate is to CO2) is still being researched.
• There's nothing that will compare to the recent record. Even since 1850, natural variations have swamped the global warming signature. For example, glaciers that are in retreat since 1850 had periods of growth such as from 1950 to 1970. To see global wrming effects directly requires pulling a very small signal from data that naturally varies. It's also not understood why most of the surface warming is arctic with little tropical warming and antarctic cooling. It was only recently discovered that a lot of measured sea level rise in Greenland and even the landfall of Sandy was due to a teeter-totter effect of melting glaciers (land rises under the glacier, sinks in another place).
• Carbon cycle [4] shows some of the numbers. Human contributions are mostly fossil fuel combustion and cement. It is a relatively small contribution and some of the sinks have actually adapted (i.e. oceans have absorbed about half of all human emissions which changes the pH of the oceans, also a warming ocean will start returning CO to the atmosphere). One of the difficulties in assessing the ultimate effect of global warming is that the contributions year over year are very small. Much smaller than natural variation which is why climate change must be studied over decades. It's also why weather variations cannot be attributed to climate change. --DHeyward (talk) 07:33, 26 November 2014 (UTC)

There is no "good, solid explanation" but we clearly see "good and solid" evidence that something is seriously going wrong(like rapidly melting glaciers). Additionally it is absurdly strange that every producer has to prove his products can cause no harm and that they are foolprove reliable but in the climatechange debate this seems turned around and made near impossible that way that even clear evidence is not enough to prove massive pollution is causing seriouse harm. --Kharon (talk) 16:04, 26 November 2014 (UTC)

Since we are coming out of an Ice Age wouldn't it be a bit odd if the glaciers weren't melting? Greglocock (talk) 19:39, 26 November 2014 (UTC)

The ice age cycle is approximately 100,000 years long. You would indeed not expect any noticeable changes after only 100 years, which is 0.1% of the cycle, but drastic changes have been observed in the past few decades. Look at the data and convince yourself that the ice age temperature changes are orders of magnitude too small to explain the recent warming. Also notice in that graph that we're already near the peak of the cycle, where natural warming rates are expected to slow down or reverse. --Bowlhover (talk) 20:17, 26 November 2014 (UTC)

You are assuming some sort of gradualism argument. Since the climate is chaotic there is no reason to assume that all changes should be slow. Greglocock (talk)

Unsourced Opinion
The following discussion has been closed. Please do not modify it.
(1) The IPCC is a political body, and its article is the most highly policed one at WP, as far as I am aware. Try changing, for instance, the statement that it is scientifically tasked to a bureaucratically tasked entity, and see what happens. (2) We have only been measuring glacier expansion and retreat for the last century or so. Across the globe some are retreating and some are expanding. (3) Natural sources of CO2, such as volcanoes so swamp human emissions as to make the latter negligible in overall effect. (4) It is well known that there have been higher concentrations of CO2 with lower global temperature and (5) that the warm periods of 6,000 BC, the Roman era, and the late Middle ages make our period a cold snap in comparison, and (6) that no panicked advocacy of climate change is made without the implicit political claim that economic expansion (carbon footprint) is evil, and draconian redistributive schemes are called for. (7) The coming ice age of the 70's was of course also taken as proof that economic expansion (reflective smoke) is evil, and draconian redistributive schemes are called for. (8) So, just ignore the facts, since they are claptrap, and accept that economic expansion is evil, and draconian redistributive schemes are called for. μηδείς (talk) 20:39, 26 November 2014 (UTC) Short Brigade Harvester Boris (talk) 23:46, 26 November 2014 (UTC) The real claptrap are your unreferenced and long-debunked statements that have everything to do with politics--even though the OP specifically said "without all the political claptrap"--and nothing to do with reality. In the end, it's the OP's choice whether to trust the scientific consensus given in the references, or a random stranger making unreferenced claims on the Internet. --Bowlhover (talk) 02:01, 27 November 2014 (UTC)

Here is a graph of temperature change over the last 450,000 years [5]. This is part of a series of graphs of global temperature over different time scales. Each page links to the next longer and shorter time scales. The next shorter time scale is 12,000 years, which has estimates by several different methodologies plotted on the same graph, and can give you an idea of the inherent error in the estimations. Given that glaciation cycles last about 100,000 years, I find it useful to look at the 5 million year time frame (the next longer time scale). At some point continental drift comes into play, so time scales longer than a few million years are probably not useful in separating the anthropogenic component from the natural short-term baseline. It is still instructive to look at the 65 million year plot to see how much cooler it's gotten since the dinosaurs went extinct. Ice age gives a pretty good overview of natural temperature cycles, and includes the 450,000 and 5 million year plots I've mentioned (click on them to see the bigger version). I hope you're still reading in spite of the political diatribes.--Wikimedes (talk) 07:48, 27 November 2014 (UTC)

Image blurring

Is it possible to blur a printed image by layering something on it? Placing a mate film over it will not do as in this case blur effect comes at a price of desaturation? Can some kind of polarised film or flat lens do the trick?176.14.253.145 (talk) 21:03, 25 November 2014 (UTC)

Seeing imagery through slightly wavy but otherwise clear glass seems to do this. Also, seeing imagery through clear water but with a degree of disturbance at its surface seems to do this as well. Bus stop (talk) 01:35, 26 November 2014 (UTC)

They used to smear vaseline on the lenses of camera to make a soft focus effect. Not sure if it will work, but you could put glass over the image and see how it works on the glass. 217.158.236.14 (talk) 11:32, 26 November 2014 (UTC)

There exist soft focus lenses that use spherical aberration to create a soft focus effect. Diffusion filters can also be used for soft focus; thin nylon or silk fabric is sometimes tried, or one could buy a professional filter. Motion blur is a third way to blur an image. --Mark viking (talk) 11:56, 26 November 2014 (UTC)

November 26

Current in two circuits

Hello. I have a question from McMaster University's Physics Contest, which can be found here. For that last question, #10, I assumed that the current follows conventional current and that the "electrons" from the positive side of the left battery would flow in a counterclockwise direction through the bottom light bulb, up to the top light bulb, and to the negative side of the battery. Thus, the resistance in the first circuit would be greater than the second, and since the voltage is the same for both circuits, since V=IR, if resistance (two bulbs vs. one) increases, the current decreases, so I2 should be greater than I1. The answers, however, state that no current flows through the top light bulb at all! Can someone shed some light on this? Thanks! 74.15.5.210 (talk) 04:28, 26 November 2014 (UTC)

The classic way to solve these problems is to calculate the voltage at each junction, and the extrapolate current using Ohm's law. When a wire splits, voltage is identical. Let's say the batteries are at 5 V. If you look at that top bulb, that means the voltage on one side of that bulb = +5V, and the voltage on the other side of that bulb = +5V. If the voltage on one side = voltage on the other side, there is no potential difference, no EMF, so no current. Now, in BOTH circuits, the voltage at the top juncture = +5V, while the voltage at the bottom of each circuit is 0V. That's a voltage difference, so that means the bulb has a current. Since that voltage difference is the same in both pictures, the two currents have to be identical as long as they have identical bulbs. Don't try to figure out how electrons "move" or "flow". Just find voltage across every component and use ohm's law to find the current. --Jayron32 04:46, 26 November 2014 (UTC)

Assuming they are perfect batteries, the bottom picture is very straight forward and I₂ = V/R. Looking at the top picture, the same voltage is applied to the vertical light bulb by the perfect source on the right so I₁ = V/R. This means the currents are equal. When working through these types of problems, there are forced voltages with the battery. What's also identifiable is that the voltage across the second (horizontal) lightbulb in Figure 1 is 0 so this means the current through that bulb is 0. The difference is that in the bottom circuit, both batteries split the load while in the top circuit, only the right battery supplies current (assuming ideal sources). The answer is C). I1=I2≠0 --DHeyward (talk) 08:00, 26 November 2014 (UTC)

Confirm: C is correct. To understand it: If the left battery nears empty, the right will particially backup, but only up to a quarter of energy on each bulb. The lower bulb well emit less light by time, the upper bulb more until euqual. It is a quarter on energy on each bulb. The bulbs are in line. This halves the resistive load (doubles the ohms Ω walue) on the right battery causes half current. Half voltage and half current is a quarter of energy per bulb, see Ohm's law. --Hans Haase (talk) 10:42, 26 November 2014 (UTC)

Work hardening

I've read your article on work hardening and dislocations etc but how do you see this on a stress visualisation animation which changes as load is applied to a material over time. The visualisation is limited to a maximum of the materials yield stress. 194.66.246.125 (talk) 10:34, 26 November 2014 (UTC)

Diagramms are always limited and these are not much more that an example. Might even been put in there so the article isnt just text ;) Material science is a highly underestimaten and very complicate field. This starts with the fact that "stress" is not an uniform unit or measurement (shear-, bend-, swing-, notch impact-, torrision-, tension-, weight-"stress" etc..) and thus you would have to add a lot more diagramms. Additionally this all does change with each material, and even with each alloy. So what example would you like more? --Kharon (talk) 15:41, 26 November 2014 (UTC)

Rescue dog awareness of selection and rejection?

Are dogs in rescue centres likely to realise they're being selected and rejected? Are they trying to appeal to be chosen and disappointed when someone walks past or are they likely to have no idea at all what's going on? --78.148.108.62 (talk) 13:01, 26 November 2014 (UTC)

Im not an expert but dogs are mostly focused on their relation to the "leader of the pack". In the case of rescue duty the woman or man they always work with. From that point of view there is likely no difference between a "rescue team" and a "family". But to be certain we would have to ask the dogs. --Kharon (talk) 15:50, 26 November 2014 (UTC)

To clarify, you mean what our article describes as rescue dogs, not search and rescue dogs, right ?

I doubt that the dogs in a the pound know they are facing the gas if they don't get adopted. However, dogs have been bred for thousands of years to appeal to humans, so them acting friendly is the expected behavior, with exceptions for some that are in the pound because they are "defective" in that regard, or perhaps were abused to the point where they now fear all humans.

If the dog pound was full of wolves, instead, which are genetically almost identical to dogs, save the thousands of years of breeding for traits humans find desirable, then very few of them would act in a friendly manner (and those few would be the mutations). StuRat (talk) 16:07, 26 November 2014 (UTC)

Have you ever walked through a place where you can adopt a dog? I think Kharon's right that they will likely already be a bit focused on their caretakers, and Stu's right that they have no concept of death if they are not chosen soon enough. But-- they still are often bored and restless, as the caretakers don't have the manpower to give all the dogs all the time and care they need to have stimulating life. So, some dogs at shelters will indeed perk up and wag their tails, lick hands, or whine in pleasure as people come by. It's not so much that they have a concept of being chosen but I think many of them just want to make friends. If they are chosen and led out by new people, they look extremely happy. Seriously, go check out a dog adoption center. You aren't obligated to take any home, and you'll learn a lot about the variety of dog behavior in that context. SemanticMantis (talk) 18:22, 26 November 2014 (UTC)

I pet the cats at the local humane society whenever I've nothing better to do. (At first I went for at least a couple of hours every week; then I got more work and a pair of cats at home.) (Other volunteers take the dogs for daily exercise.) Most of the dogs seem more alarmed than pleased to see me; maybe they can tell I'm a vampire. —Tamfang (talk) 06:24, 27 November 2014 (UTC)

What are the differences between Thimmamma Marrimanu, Pando, Armillaria solidipes in Oregon, Posidonia oceanica in Mediterranean Sea?

I was reading about the largest organisms and I don't understand how the plants (like those 4 mentioned above) differ from each other. I would like an explanation for a layman as I'm not familiar with the subject.

For example, how is the way the banyan "spreads"/grows different from the aspen? They both seem about the same to me.

Are these plants only considered 1 single large plant because they are physically connected? Can 2 physically disconnected parts of the plant be reconnected again?

Thanks.

138.75.150.164 (talk) 15:29, 26 November 2014 (UTC)

An organism can be defined, very broadly, as a contiguous living system. Of course, in reality this definition is almost invariably restricted to only include contiguous living systems that possess the same or essentially the same genetic material throughout their extent, and/or to only include contiguous living systems where all parts are not just in contact with each-other but actively exchange some resources between them. That is, for example, a flock of sheep huddled together is not a single organism. A pine grove is not a single organism either, as the pines merely grow next to each-other. By contrast, an aspen grove (a clonal colony) constitutes a single organism when all individual trees are interconnected at the roots and can exchange water and chemicals with each other via the interconnected root system. Plants can form interconnected clonal colonies by various means. For example, some plants (like many grasses) send out roots or rhizomes that sprout new plants when they reach the surface. Some plants (like strawberry) send out runners that root at certain intervals. Some plants (like raspberry) produce roots when their branches touch the ground. Some plants (like banyan) send aerial roots down from its branches, and some of these roots with time become secondary trunks. Fungi ("mushrooms"), too, form interconnected clonal colonies by sending out their hyphae (mycelium) and producing new fruiting bodies from them; this often looks like a circle of mushrooms, and can be quite large. Does this answer your question? Please let us know. All the best, --Dr Dima (talk) 19:08, 26 November 2014 (UTC)

To your question on whether 2 physically disconnected parts of the plant be reconnected again, the answer is yes. You can do this experiment yourself, it is called grafting. --Dr Dima (talk) 19:13, 26 November 2014 (UTC)

I think you've explained it pretty well. OP and others may like to read up on ramets and genets, perhaps rhizomes and stolons. The general concept of plants spreading/growing through various non-sexual means is vegetative reproduction - some of those methods can leave the "parent" and "clonal offspring" connected as one organism, some end up separated. In the most confusing cases, whether the clone becomes a distinct organism is often a matter of chance, e.g. in the well-known spider plant. (I also took the liberty of linking the terms in the header for convenience.) SemanticMantis (talk) 20:17, 26 November 2014 (UTC)

Yes it answers my question. Thanks for the help! I have a few related questions: Is it theoretically possible for humans to cultivate/grow an artificial plant/fungi that is even larger than what nature has naturally made? (given sufficient land space) If it were discovered that there was a disconnect/break in the underground roots/mycelium/etc. of the organisms mentioned above (thereby reducing its total size), would grafting them back together make them one organism again? Thanks. — Preceding unsigned comment added by 138.75.128.131 (talk) 15:56, 27 November 2014 (UTC)

Von mises

Von Mises yield criterion (edit | talk | history | protect | delete | links | watch | logs | views)

Does von Mises yield criterion take into account material shape or does it only consider the fact that a particular material with a material shape has a yield stress which is a factor of sqrt3 more than that of the shape in pure shear? — Preceding unsigned comment added by 194.66.246.125 (talk • contribs) 16:05, 26 November 2014 (UTC)

In other words how do you mathematically predict the yield stress of a structure if you only know the material yield stress, Young's modulus and poissons ratio. Am I right in assuming this isn't enough information to predict this? What else do I need?

The von Mises criterion is useful when you have more than one stress acting on a point. For example, if you have tensile stresses acting along both the x and y axes, you might imagine that even with each stress being lower than the yield stress, the 2 acting in combination might be enough to cause yielding. The von Mises criterion gives an estimate of how big the 2 stresses can be before yielding occurs. Before applying the von Mises criterion, you need to find out what stresses are acting on the point in question, and this will require knowledge of the loading and geometry (unless, for example, the stresses are given to you in a class problem).

If you want to find the magnitude of a pure shear stress that will cause yielding, you set sigmav = yield stress (sigmay) and plug the shear stress (e.g. sigma12) into the von Mises criterion (the last equation in the mathematical formulation section of the von Mises article). This gives sigmay = sqrt(3)*sigma12. So the factor of sqrt(3) relating shear stress to the yield stress (tensile) is one case of the von Mises criterion.--Wikimedes (talk) 06:49, 27 November 2014 (UTC)

I'm actually trying to find a way to validate a finite element model of the von mises stresses on a structure with a uniform load applied. I'm trying to do this with theoretical values but I don't know how to produce theoretical values using what I have. 194.66.246.26 (talk) 17:55, 27 November 2014 (UTC)

100 billion coincidence

There are 100-140 billion stars in the Milky Way, probably more than 170 galaxies in the Universe, and about 100 billion neurons in the human body. The similarity of these numbers astonished me. What a coincidence that each of the stars in the galaxy corresponds to a galaxy. It also led me to think about the Anthropic_principle, where the constants of nature are so finely tuned that (apparently) to shift even one would make human life impossible. The fact that there are 100 billion neurons in the human body doesn’t fit into that equation, though, since the number of nerve cells is not a prerequisite to life but rather a part of life. Still, this is a very interesting coincidence. Not a question, I just couldn’t resist putting such an interesting factoid before you to see what you think. --Halcatalyst (talk) 20:12, 26 November 2014 (UTC)

As factoids go, I'd have difficulty accepting that it was 'interesting'. There are many (approximate) numbers one can find in relation to the human body, from the number of heads (one) to the number of electrons (which I will leave someone else to figure out... 2.3*10²⁸ [6]). That one of these numbers is somewhere near the number of stars in the Milky Way is accordingly entirely unsurprising. AndyTheGrump (talk) 20:20, 26 November 2014 (UTC)

Once again, the user per his user contribution s is basically a single purpose account; the purpose being to pose ref desk questions. So long as the OP is suggesting there might be as many as 17o galaxies in the universe, I think a private chuckle is perhaps the best response. μηδείς (talk) 20:23, 26 November 2014 (UTC)

What is with this weird criticism that pops up again and again? There's nothing wrong with using an account to mostly post questions here. To insinuate that that makes someone unwelcome is doing a disservice to the ref desks. I'd rather answer "asking-questions-only" than IPs, if only so I can more easily keep track of who I'm talking to. SemanticMantis (talk) 20:27, 26 November 2014 (UTC)

On top of that, a registered user does not run the risk of exposing their IP. The only policy criterion they seem to flunk is "not here to build an encyclopedia" but this one is a mild example. I'd be more upset about users who insert nonsense into articles.

You can't say that "probably more than 170 galaxies in the Universe" is wrong, either. That probability is a damn high one if you ask me. 217.255.180.86 (talk) 07:29, 1 December 2014 (UTC)

That there are roughly as many galaxies as stars in the milky way is at least an easily remembered heuristic. It's unclear on whether these "mean" anything, but you may wish to read up on pareidolia. Our pattern recognition skills were (and are) crucial to our survival, so it's not too surprising to see that ability produce many false positives. SemanticMantis (talk) 20:27, 26 November 2014 (UTC)

Don't you think it's interesting that the scale is from human to (what could be called) the basic unit of the Universe to the Universe itself? Another interesting factoid is that, starting from one meter (human size), there are about the same number of powers of ten going up to the size of the Universe and down to the size of a neutron. --Halcatalyst (talk) 20:37, 26 November 2014 (UTC)

That could help explain how the Greeks were able to invent the atom. On the other hand, how the article Anthropic principle's size is related to that of Sapience remains undetermined. --Askedonty (talk) 20:49, 26 November 2014 (UTC)

The OP may find the Dirac large numbers hypothesis interesting. Tevildo (talk) 20:52, 26 November 2014 (UTC)

+++ I have never posed a question to the reference desk (though I'm aware the practice stands somewhere between discouraged and forbidden, depending on your taste.). Visitors might appreciate a little courtesy from the reference librarians.

I was looking for intelligent answers, which I generally get to questions I put to Wikipedia. --Halcatalyst (talk) 20:59, 26 November 2014 (UTC)

If Dirac relates "ratios of size scales in the Universe to that of force scales," I guess I can do something of the sort too. BTW, I was just interested in thoughts, not looking for meaning. Thanks for those who have contributed thus far. --Halcatalyst (talk)

You said it yourself: it's a coincidence, nothing more or less. To read about crackpots who read too much meaning into coincidences, see numerology. --Bowlhover (talk) 02:05, 27 November 2014 (UTC)

You may want to check out Benford's law. The apparently disproportionate quantity of ones as the leading digit when measuring items is a much-studied phenomenon and not at all related to numerology or pseudoscience. Matt Deres (talk) 19:33, 27 November 2014 (UTC)

Well the OBVIOUS conclusion is that it's not a coincidence but the universe is in fact a giant brain!! And of course there's only one brain it could be: It's the brain of GOD! Of course I don't I don't believe any such thing, but just demonstrating how easy it is to dive down the rabbit hole. Vespine (talk) 03:50, 28 November 2014 (UTC)

so my fart could be God's brain fart?!66.87.116.95 (talk) 16:09, 28 November 2014 (UTC)

Physicist Richard Feynman has a great quote relevant to such coincidences: "...on the way to the lecture, and I came in through the parking lot. And you won't believe what happened. I saw a car with the license plate ARW 35W. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!"

The joke, of course, is that the probability of this coincidence is in fact very low if it were predicted (pre-observation); but post-observation it ceases to be a probabilistic situation at all.

If the rough approximation of the order of magnitude of the count of stars did not match, would you have noticed or remarked on its likelihood at all? What about all the other irrelevant cases where some value is approximately equal to a few hundred billion, plus or minus a couple orders of magnitude? Are these coincidences as well? Can you meaningfully compute the probability of such coincidental observations? Nimur (talk) 19:25, 28 November 2014 (UTC)

Freezing temperature for water

When the temperature hits 32 degrees Fahrenheit (or lower), the liquid form of water turns to ice (i.e., it freezes). When I look at my "weather app" on my computer, it always says something like this (for example): "Today, the temperature is 53 degrees, but it feels like 43 degrees." And I believe it is the wind chill factor that makes the temperature "feel" colder than it actually is. So, let's say that on some given day, my weather app says: "Today, the temperature is 38 degrees, but it feels like 28 degrees." What happens to water in that case? Does it not freeze because the temperature is higher than 32 degrees? Or does it freeze because the temperature "feels" like it's less than 32 degrees? Thanks. Joseph A. Spadaro (talk) 23:06, 26 November 2014 (UTC)

Related question: Wikipedia has an article for boiling point, but not for freezing point? Joseph A. Spadaro (talk) 23:11, 26 November 2014 (UTC)

The water would still stay liquid. It feels like 43 degrees to you because you are hot and loose heat quickly when the wind is constantly moving cold air past you. Humans can't actually sense temperature; we sense how quickly heat is being transfered (which is why a block of metal feels colder than a book at the same temperature). To water near 38 degrees, the air isn't that much colder, so it looses heat much more slowly than you (although the wind still makes it cool faster). As for the second question, it's because melting point and freezing point are the same thing. I hope this helps! --T H F S W (T · C · E) 23:44, 26 November 2014 (UTC)

No offense, but your answer actually confused me even more. Joseph A. Spadaro (talk) 00:58, 27 November 2014 (UTC)

Let me try to unconfuse you: 1) Wind chill factor has to do with how quickly heat transfer happens from your skin to the air. The reason why you feel colder when the air is moving is that the moving air carries heat away from your body faster than still air would. Thus, if the weather says "38 degrees F, with a wind chill factor of 28 degrees F", what that means is that your body will lose heat as though it were a windless day at 28 F, though the actual air temperature is 38. The difference is not in actual temperature, the difference is in how fast two bodies of different temperatures equilibrate. When the air moves over the warmer body, it will cool off faster. But it can never cool off to a temperature lower than the ambient temperature. Thus, if the air is at 38 F, the water will never freeze. If the water is at, say, 50 F, it will get down to 38 faster if there is wind than if the air is still, but it can never drop to below the ambient temperature, which is why it will never freeze, no matter WHAT the wind chill factor is. 2) Freezing point and melting point is the exact same thing: the only difference is the direction the temperature is moving. If the temperature is going up, we call the temperature the "melting point". If the temperature is going down, we call it the "freezing point". But the two are identical. --Jayron32 02:17, 27 November 2014 (UTC)

Water can indeed become colder than the ambient temperature, because it loses heat through the latent heat of evaporation and not just by sensible heat. This can be enough to cause the water to freeze when ambient air temperature is above freezing. Peggy LeMone has a nice little article here. Short Brigade Harvester Boris (talk) 03:22, 27 November 2014 (UTC)

Yes, Jayron's usually excellent answers have a glitch here because a wet cloth, or a windscreen, can freeze in a cool breeze that is above 32 F. See Wet-bulb temperature for the technicalities. Dbfirs 13:24, 27 November 2014 (UTC)

• There's no freezing "point" of water unless one looks only at temperature, without regard to the energy of the system. Water at 32F can be liquid, solid or slush. Water requires more energy to be removed from the system to go from liquid at 32F to solid at 32F than it does to drop a degree from 33F to 32F liquid or from 32F solid to 31F. See water and enthalpy of fusion. μηδείς (talk) 22:56, 27 November 2014 (UTC)

Thanks. All the answers were very helpful. Thank you. Joseph A. Spadaro (talk) 16:54, 28 November 2014 (UTC)

November 27

Availability of phase change material fabrics

Are their phase change material fabrics available to the public (in the UK) for use in domestic sewing projects? --78.148.108.62 (talk) 05:55, 27 November 2014 (UTC)

Ebay sells everything. £15 per yard. Plus a ridiculous amount for postage etc.--Aspro (talk) 18:33, 27 November 2014 (UTC)

Von mises

The article on Von Mises is very confusing. Can someone explain simply how you can use it to explain where and when yielding occurs on a material? If for example, I know the pressure on the material, and the material properties, how do I use those values to calculate when and where yielding occurs? — Preceding unsigned comment added by 194.66.246.71 (talk) 19:43, 27 November 2014 (UTC)

That's first year stuff in an engineering degree course, and I must admit it took me two goes to undertsand von mises, and I've now forgotten it again. As such, a post on a forum like this isn't really adequate. Can I recommend that you read JE Gordon's Structures, or things don't fall down? http://www.amazon.com/Structures-Things-Dont-Fall-Down/dp/0306812835 It should be compulsory reading for anyone who is interested in stress analysis. Greglocock (talk) 21:51, 27 November 2014 (UTC)

Amylase Inhibitors

I am inclined to agree with Aspro that this has medical implications and it seems to me that their advice covers the extent of what we can recommend, so I am taking the liberty of hatting. If anyone feels it is excessive, they are welcome to revert. Snow talk 08:20, 28 November 2014 (UTC)

I'm avoiding from eating Beans cause I'm kinda allergic to them... What other foods could serve me as a reasonable resource for natural Amylase Inhibitors? Something that has really lot's of these molecules? thanks. Ben-Natan (talk) 21:24, 27 November 2014 (UTC) Dietary advice is a bit like medical advice and so I decline to say. Also, the FDA has no Indications for this protein group. In other words there is no evidence that it has a beneficial effect in vivo. Better to cut down on starchy foods. Udo Erasmus is a recognized expert on what to eat. From Fat to Fit And how much of each type. Food Pyramid. Then consult your own health care professional.--Aspro (talk) 22:09, 27 November 2014 (UTC)

How does do he take the pure oxygen in the glass in his hands?

I saw in this page a picture of a guy who takes a glass that inside there's oxygen [you can see picture of the same idea (but not with a man who hold it) here in Wikipedia]. According to what I know about the oxygen, the oxygen can not be in the state of matter of liquid when it's up to -183. So I believe in this place it's not -180 degrees (you can understand it according to the wearing of this man). I think it should be broken by the higher level pressure that should created when this oxygen appears such as this temperature (unless the oxygen in a appropriate strong cylinder)5.28.173.111 (talk) 23:22, 27 November 2014 (UTC)

The oxygen is cold so it is liquid. It's warm outside so the liquid is boiling and evaporating, but it takes time to evaporate, so the man has time to check the liquid oxygen. Ariel. (talk) 23:26, 27 November 2014 (UTC)

Sorry to piggyback a question onto this, but this actually made me wonder. I understand the above, but I kind of get where the OP is coming from too. For example, the liquid inside a butane lighter immediately and violently evaporates if exposed to regular pressure, like if the lighter casing is broken, I have witnessed this first hand on several occasions. The boiling point of butane is only -1 °C, the boiling point of oxygen is -183 °C. Why doesn't the butane "boil" away slowly like the oxygen? If you cooled down a lighter below -1 °C, like in a freezer, and THEN broke the lighter would it also boil away slowly like the oxygen? Vespine (talk) 03:38, 28 November 2014 (UTC)

It's the mass-volume, temperature and pressure. Normally, we usually think of the liquid as being room temperature and coming to an equilibrium pressure (like LP gas). Liquid oxygen is not that case, though. It can be chilled while near atmospheric pressure to a liquid. The dewar flask keeps it from absorbing heat and limits the external heat needed to boil it away. The rate at which heat can be exchanged regulates the boil (and pressure). If it's not in a temperature insulated tank, it will be a gas at very high pressure. You can feel the heat exchange process by filling and releasing a compressed gas (expansion feels cold, compression gets hot). --DHeyward (talk) 04:02, 28 November 2014 (UTC)

If you break a container that starts under pressure, the liquid is already well above its boiling point to begin with, and reaching an equilibrium based on pressure tends to be fast and forceful. Cooling the butane lighter should help. However - I would have to look up to know for sure - I am suspicious that butane might have a lower heat capacity in liquid form than oxygen, which would make it evaporate faster (the lower the heat capacity, the more has to evaporate to compensate for the same leakage of heat through the insulation). Still, the rate of heat leakage in a container will be proportional to the temperature difference, so it should still be much slower to boil than oxygen in the same container when they both start off at boiling point and atmospheric pressure. Wnt (talk) 05:37, 28 November 2014 (UTC)

The cryogenic dewar tanks are preferred for supplying heavy users because the tank doesn't have to be purged when it's refilled. Just the glass flask is a poor conductor so most of the heat to boil the oxygen is from air above and that can be controlled somewhat (note the duct tape). The cryogenic storage tank will usually have various ports for high pressure, low pressure and liquid. In a flask, the liquid appears to be boiling until it is gone. For oxygen, it will go from the liquid Dewar flask to an evacuated high-pressure tank. Contaminants and catalysts create hazards in the cylinders (i.e. sea water in emergency O2 scuba rescue dive tank that is filled with pure, high pressure O2 ->salt water reacts with the metal much quicker than atmosphere. Oil from a compressor/concentrator that accumulates in a gas cylinder can be a fire hazard - for those reason, Oxygen compressed air tanks are evacuated before being filled but the liquid storage tanks can be refilled continuously as needed). --DHeyward (talk) 03:48, 28 November 2014 (UTC)

An interesting question. It's worth pointing out this is a high-resolution image. So far as I can tell, the way the man's gloves look makes me think that they are actually above freezing, with just bits of frost from having reached into someplace colder. The oxygen in the container seems to be boiling, as I'd expect. But there isn't very much vapor going around, even though this sure doesn't look like a Dewar flask. So the nature of the material of the container is very much open to question; I have a hard time thinking it is a single layer of glass based on the apparent insulating quality; nor would that seem especially safe... but I don't think many types of plastic would be a good idea... I have a wild guess it might be made out of silicone but certainly am not in a position to know that. Anyway, the loose foil seal at top is a dead giveaway that this is not under pressure, so the rate of boiling of the oxygen directly reflects the insulating quality of the container. Wnt (talk) 05:28, 28 November 2014 (UTC)

It's not hard to fill a standard glass beaker a third or half full of liquid nitrogen and get an effect similar to what's seen here once the glass has cooled down. On initial filling, there is somewhat violent boiling at the liquid/glass interface, but then it settles to a gentle boiloff. Can't keep it for long-term storage, but even simple glass must have enough insulating ability (poor enough thermal transport properties or whatever technical parameter) even without film boiling. DMacks (talk) 06:10, 28 November 2014 (UTC)

If humidity is low, so not much water condenses and freezes on the glass, then it is possible to look like this. It is either glass or quartz glas, because polymer and liquid oxygen together is bad idea. It is not double walled, so it is probably regular beaker glas and after the initial cooling stage (violent boiling) the boiling would be slow and the ice crystals were probably wiped away before the picture was taken. More interesting are the liquid nitrogen YouTube clips of man pouring it to his bare hands. Gergo vassilev (talk) 16:00, 28 November 2014 (UTC)

Leidenfrost effect/film boiling insulates both ways:) LN2 onto your hand is no problem, especially if your hand is not cupped deeply. Dipping your hand into it is more interesting. Or an ALS LN2 Bucket Challenge. Dipping your hand into molten lead is even more-so. Lest you think I'm making all this up, those last two are cited in the article I linked. DMacks (talk) 18:47, 28 November 2014 (UTC)

Ooooh. I just realized that this photo was taken at Eielson Air Force Base in Alaska, where temperatures can drop to 50 below. Even if the room temperature is comfortable, the amount of humidity present might still be less than anything I am used to, so yes, there could be an unexpected lack of water vapor condensation! So yes, it might be plain glass after all... though I'd still think someone might worry about what might get wet with liquid oxygen and explode if it breaks. Wnt (talk) 19:05, 28 November 2014 (UTC)

November 28

Most viewed health topics on Wikipedia

I recently read in a news article that Wikipedia allows free access to its data on the most frequently searched topics. As I understand it, this information can also be broken down according to language (but not to geographical location).

If this is the case, I would like to know which health topics are most commonly viewed on Wikipedia in both English and Arabic. A list of up to about 2,000 topics in each language would be ideal, but otherwise I would settle for a shorter list!

Alternatively, if it’s not possible to stratify according to health topics specifically, I would also be interested in the same lists in a similar category (e.g. medicine, science, biology, etc). — Preceding unsigned comment added by 14.203.101.110 (talk) 00:39, 28 November 2014 (UTC)

The main portal for page stats is http://stats.grok.se/ Which will let you look up individual pages or download count files for all requests. There is a top list but it doesn't seem to have been updated in several months and shows some spurious requests (probably due to bots and other automated web processes). The most visited pages on a month to month basis are often typical issues that are being highlighted in the news (e.g. new movies, celebrities, wars, etc.) As far as medicine goes, I suspect that the Ebola related pages have rated very highly in recent months. As far as I know, there are no preexisting subcategorized lists of page views for medicine or any other topic. In principle one could be created though, either by hand, or by selecting a subset of pages that are already labeled with categories associated with medicine. That would presumably take someone with a bit of programming skill however. Dragons flight (talk) 01:24, 28 November 2014 (UTC)

See Category:Lists of popular pages by WikiProject.

—Wavelength (talk) 03:11, 28 November 2014 (UTC)

You may also want WP:5000; it only gives results per week, not long-term, but since most health topics generally don't get a ton of spikes from news coverage, you'll be able to make a decent guess on "most popular" by checking a few weeks' entries. If you have a bot or a way to scrape content, you can easily amalgamate statistics by months or years. Nyttend (talk) 03:58, 28 November 2014 (UTC)

Using Wavelength's link, you can see a list of the 1000 most popular WikiProject Medicine pages at Wikipedia:WikiProject Medicine/Popular pages. John M Baker (talk) 15:35, 28 November 2014 (UTC)

What's the thickness of a clothing to prevent mosquito bites?

I want to visit South America, and I want to protect myself from mosquito bites. How thick should a clothing be to prevent the piercing of a southern american mosquito? What is the minimum thickness? How deep can southern american mosquitoes pierce into the human skin? 173.33.183.141 (talk) 03:31, 28 November 2014 (UTC)

I don't think it's primarily a question of thickness, but more of the quality and density of the weave. I've never experienced mosquitos biting through a normal dress shirt, but I'd be less sure about a t-shirt, even if technically thicker. If you want to be sure, use something like DEET or Icaridin on the skin and Permethrin on clothing and mosquito nets. Famous brands here in Germany are NoBite and Autan, but international branding seems to vary a lot. --Stephan Schulz (talk) 03:48, 28 November 2014 (UTC)

Thanks. Do southern american mosquitos have longer piercing heads than the north american mosquitos? 173.33.183.141 (talk) 21:30, 29 November 2014 (UTC)

Sublimation and temperature change

Take a quantity of water and evaporate some of it, and the rest cools to an extent. Take a quantity of ice and sublimate some of it; will the rest become colder? Nyttend (talk) 19:25, 28 November 2014 (UTC)

Yes, the ice becomes colder. It is this same phenomena which is used to cool spacesuits. That is why NASA came to over-look the presence of water on the moon during the Apollo era. The H2O that the NASA scientists found in the moon samples, they concluded was just man-made contamination. However, the Soviets knew but the Americans never read their science papers.--Aspro (talk) 20:18, 28 November 2014 (UTC)

Function generator design

Function generators are usualy designed with the primary waveform generated being a triangle wave created by charging a capacitor with a constant current. At higher frequencies than about 3-5 MHz, however, the comparator used has to be very fast and the triangle wave distorted to operate the comparator as fast as possible. I was wondering if there were any function generator designs that used a square wave produced by a voltage controlled oscillator as the primary waveform. Triangles can then be produced by integrators and sine by shaping the triangle as usual. Are ther any problems with this approach and are there any manufacturers using this technique especially for fast (20MHz) generators?--86.157.138.192 (talk) 19:32, 28 November 2014 (UTC)

That might have been true 40 years ago, but any modern function generator will be purely digital, using a DAC to create the waveforms. Apart from the audiophile market (which is more art than engineering), there's very little analog equipment for use at low frequencies available these days. However, I'm sure it would be possible to design an analog function generator along those lines, it just wouldn't be a commercially viable proposition. Tevildo (talk) 21:13, 28 November 2014 (UTC)

20MHz triangle and sine from a DAC??--86.157.138.192 (talk) 21:22, 28 November 2014 (UTC)

120 MHz! It's amazing what they can do these days ("these days" starting in about 1995). Tevildo (talk) 21:42, 28 November 2014 (UTC)

Indeed! Our article is direct digital synthesis. And if you have unlimited budget, you can get direct digital synthesizers deep into microwave bands - arbitrary digital waveform synthesis at tens and hundreds of gigahertz! Such devices are used for satellite communication and microwave RADAR design and test.

But we don't even have to look into wacky aerospace and defense technologies to find such circuitry! Chances are high that you've got one of these K-band digital synthesizers - or one like it - built into your home computer!

Nimur (talk) 00:04, 29 November 2014 (UTC)

Universe - universe = 0?

If our universe was created from nothing, and we dont seem to have found much antimatter so far, is it possible that an anti universe was created at the same time as the matter universe? --86.157.138.192 (talk) 21:35, 28 November 2014 (UTC)

But if there was nothing ("0") befor, what created or caused the universe? The theory of an antiuniverse is scientificly as bad (not proven) as the famouse Bigbang theory. Some astrophysists still belive in the theory that this universe has simply always been here. --Kharon (talk) 01:55, 29 November 2014 (UTC)

Mathematically, that notion doesn't work. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:03, 29 November 2014 (UTC)

In fact, the idea that the universe "has always been there", strikes me as the cosmic equivalent of the "Turtles all the way down" story. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:32, 29 November 2014 (UTC)

Well, as explained in the antimatter article, the idea is apparently not totally dead even that antimatter could exist in large amounts somewhere in our observable universe. It is also possible that the observable universe encompasses a large region that is entirely matter, but that there is a variation on a larger scale even than the entire universe we see, so that other regions may be mixed or entirely antimatter (which isn't far from the OP's suggestion really, except the two were once connected as a single region of space but now "you can't get there from here" due to cosmic inflation). But CP violation in baryogenesis is still the more likely looking answer, since there are observed deviations. Wnt (talk) 04:52, 29 November 2014 (UTC)

The concept of a zero-energy universe does not depend on equal amounts of matter and antimatter. -- ToE 16:51, 29 November 2014 (UTC)

Question About the Elimination of Energy

Since energy can be neither created nor destroyed therefore does Einstein’s energy equation equitable with any other forms of energy such as P.E, K.E, Work Done….....?162.157.249.151 (talk) 22:22, 28 November 2014 (UTC)eek

Yes. However, while Einestein's equation says that the total energy of a system remains constant, it does not say that it cannot be converted into other forms of energy. Potential energy is frequently converted into kinetic energy (dropping objects, burning fuel, electrical discharge, etc.) and vice versa. Is this what you are asking? --T H F S W (T · C · E) 23:27, 28 November 2014 (UTC)

By equating, I meant eliminate energy E from E=mc^2 and any other equation of energy of any form. Although physicists don’t agree but here is the example if units are interchangeable in dimensional analyses of the following?

1- Energy, E= mc^2 ----- Eq. (A)

2- E = mv^2 --------Eq. (B) as if “Joule is equal to the energy transferred (or work done) when applying a force of one newton through a distance of one meter (1 newton meter or N·m:)” - [ Wikipedia]. Since, joule = N.m = [(Kg.m)/sec^2].m = Kg.m^2/sec^2 therefore this means Energy; E = mv^2 as L/T is the unit of velocity. We get mv^2 = mc^2 after eliminating “E” from Eq. (A) and (B) and hence v=c unless unit of energy is defined differently in relativity and classical physics

Since you mentioned conversion therefore would the energy released from the burning of 1kg mass (nearly =1lit) of gasoline be = mc^2162.157.249.151 (talk) 04:39, 30 November 2014 (UTC)eek

The answer to your last sentence is "no", because only a very small portion of the mass of gasoline is converted to energy. The combustion products also have mass, which is almost identical to the original mass of the gasoline and oxygen. In nuclear reactions, a much larger portion of the mass is converted to energy, and the decay products have lower mass than the parent product, but even complete radioactive decay of a kilogram of plutonium, for example, will yield much less than 9*10^16J of energy.--Wikimedes (talk) 11:04, 30 November 2014 (UTC)

Ok thankx, I thought E would be different upon changing the mass in e=mc^2. 162.157.249.151 (talk) 16:05, 30 November 2014 (UTC)eek

E=mc^2 can be used to calculate the energy released when mass is converted to energy. In the case of burning gasoline, most of the mass is instead converted to another form of mass (water and carbon dioxide), so the energy released is more easily calculated directly from calorimetry. (A freshman or high school chemistry book might be more useful for understanding basic calorimetry of combustion than the Wikipedia article). E=mc^2 is used to calculate energy released in nuclear reactions, but the mass entered into the equation is not the starting mass, but the difference between the starting and ending mass. In a matter-antimatter reaction, all the mass can be converted to energy, and the use of E=mc^2 is more easily applied.--Wikimedes (talk) 01:58, 1 December 2014 (UTC)

NMR basic problem

I have a relatively basic NMR question, but I am having trouble figuring it out. The chemical formula is C5H10O. The chemical shifts are 1.3 (singlet, integration 2 cm), 1.9 (singlet, integration .3 cm), 5.0 (doublet, .2 cm), 5.2 (doublet, .2 cm), 6.0 (doublet of doublets, .2 cm). The problem also says the peak at 1.9 ppm is solvent and concentration dependent. Does this mean it is -OH? I know there is a C=O. The spin spin splitting is throwing me off. — Preceding unsigned comment added by Pinterc (talk • contribs) 22:34, 28 November 2014 (UTC)

Do you know if that's the molecular formula, or the empirical formula? That is, do you know if the molecular weight is ~86, or could the compound be something like C₁₀H₂₀O₂ or C₁₅H₃₀O₃? (Getting mass spectroscopy results greatly helps NMR determination.) You may want to also double-check your integrations. As written, they sum to 2.9, meaning that each proton should account for ~0.3 (assuming 10 protons) - which means you're getting something like a 6:1:1:1:1 ratio, and a fair amount of error on integration amounts. (Although if you're using an empirical formula, you might be running 30 protons, with possibly more like a 20:2:4:2:2 or 21:2:3:2:2 ratio.) But if the "2 cm" is a typo for "0.2 cm", then you're summing to 1.1, and getting more of a 2:2:2:2:2 ratio. All this, of course, is complicated by the solvent and concentration dependance of the 1.9ppm peak. You may want to figure out what about the peak is concentration/solvent dependent: is it just chemical shift, just integration, or both? You're pretty saturated, though, so that's going to limit you. Do work it out yourself, but I think the carbonyl requirement is going to take up your unsaturation allotment. The splitting pattern itself isn't too hard to accommodate. (You have to remember that if a proton is split, it's going to be splitting another proton in turn, so that constrains how the doublet of doublets and the two doublets are related to each other. Do you have the J values for the coupling constants? In this example it's probably going to be uninteresting, but matching the J values of the coupling constants can be used to figure out which proton is splitting which other proton.) The concern I might have about the split peaks is their shift - ca. 5 ppm and a general lack of unsaturation in the molecule implies some sort of relationship to the oxygen(s). You also have quite a small number of peaks in comparison to the number of protons (especially for larger multiples of an empirical formula) - that usually (but not always) implies a high degree of symmetry in your molecule. -- One suggestion I would make is to break the problem into parts: list a bunch of different molecular fragments which can account for different portions of the data at hand. Then see if you can come up with a way to merging those fragments together to account for all the data. -- 160.129.138.186 (talk) 00:03, 29 November 2014 (UTC)

There's already some confusing idea if C5H10O is the actual molecular formula: the proposed C=O is the oxygen atom, so there's no other oxygen left to be the OH oxygen. DMacks (talk) 05:10, 29 November 2014 (UTC)

Per NMR spectroscopy, "Coupling to additional spins will lead to further splittings of each component of the multiplet e.g. coupling to two different spin ½ nuclei with significantly different coupling constants will lead to a doublet of doublets." This alone implies a CH - CHR - CH structure. I don't see a good table at chemical shift; we should have something like [7]. I fooled around with this for a bit and couldn't think of any ideas; [8] is a useful link but I'm stumped. Someone ought to be able to recommend some searchable NMR database that might come through here. Wnt (talk) 01:47, 29 November 2014 (UTC)

Chemical shift is the general idea, not specifically 1H. For information specific to that, see Proton NMR. But the table there is confusing as hell...seems entirely focused on "what else is attached to the C with the H", making it hard to identify the aldehyde structure as such and except for that case omitting all other H that are not on sp³ C (no vinyl or aryl or OH or NH themselves, just the C_α to it). DMacks (talk) 05:18, 29 November 2014 (UTC)

• You've also got 5 peaks, which implies 5 unique carbons. What are the splitting constants? You can sometimes match neighboring bits by matching splitting constants... --Jayron32 13:32, 29 November 2014 (UTC)

November 29

What are the chances of getting hpv from oral sex?

What are the chances of getting hpv from oral sex, not the chances of oral cancer from hpv? I asked a similar question a few days agoWhereismylunch (talk) 04:28, 29 November 2014 (UTC) ″

Fairly sure the answer will depend on factors like whether any form of barrier protection was used, the sex of the recepient, and whether you're referring to the risk to the receiving or giving/performing partner. Also the presence or absence of open sores or wounds on the mouth of the performing partner, the number of times and whether the people involved have HPV or at high risk of it (e.g. sex workers). The difficulty of seperating these means some figures will be averages of them (for example, I don't think anyone is going to try to come up with a figures for a person who's received oral sex 1x, 2x, 3x, 4x.... during their lives), but I don't think anyone is going to come up with a random single figure for the risk of getting HPV from oral sex. Nil Einne (talk) 13:36, 29 November 2014 (UTC)

But on wikipedia they have a random single figure for aids from anal sex.Whereismylunch (talk) 18:11, 29 November 2014 (UTC)

The question is not from receiving, but from giving oral sex, and I think we can just assume average numbers, not specific risk factors. Basically, the OP seems to be asking, of those who get oral cancer, how many can attribute it to a sexually transmitted HPV infection, not "what are my odds of getting oral cancer if I service a guy wearing a condom", which we wouldn't answer anyway. That being said, my understanding is the risk is measurable, but I have no Idea where I read that, so I am not about to venture a guess. I suspect I read it somewhere that was advocating that not only girls get the HPV vaccine. μηδείς (talk) 03:23, 30 November 2014 (UTC)

Where was it stated it was from receiving not giving oral sex? It wasn't even stated the sex of the receiving partner. And so average numbers for what? I don't get the relevance of most of your later stuff. The point is that the OP hasn't sufficiently defined what they're asking for this to be answered in any meaningful way. (Note also as stated below there are multiple subtypes of HPV and I'm not sure these are always considered together.) In terms of your middle point, this [9] easily found from a simple search says "every year, over 9,000 men are affected by cancers caused by HPV". This includes those affecting "the anus, mouth/throat (oropharyngeal cancer), and penis". I'm sure you could come up with a value for those only affecting the mouth/throat. However it would be silly to assume the HPV always came from sexual contact, and even more flawed to assume that the sexual contact was from giving oral sex. Nil Einne (talk) 04:05, 30 November 2014 (UTC)

Your question is not specific enough. It is better to ask, what are the chances of acquiring a HPV infection of subtype N by the person giving oral sex from the person receiving oral sex provided that the latter person has an active HPV infection with subtype N? The chances are probably high—in the range of tens of percent. However the vast majority of such infection are asymptomatic and will resolve on their own in a few months. Only a very small fraction will become chronic and potentially cancerogenic and only of subtype 16. Ruslik_Zero 03:40, 30 November 2014 (UTC)

If I WP:AGF you are correct, then that should be fixed ASAP. It makes zero sense for any article on wikipedia to say that. For starters, while many people with HIV will eventually get AIDS, it's complicated and can take a while. For this reason, it's far better to talk about the chance of getting HIV not the chance of getting AIDS and few, if any, will talk about the chance of getting AIDS.

Secondly, nearly every single source will differentiate between the receiving or receptive partner and performing or insertive partner when it comes to the risk, as these can vary quite significantly.

Thirdly, the sex of the receiving receiving partner probably may not have a significant effect on the risk for anal sex in the generalised case. In the real world it may have an effect because the person may have a different risk profile and other factors. But actually this would apply to the giving partner in the oral sex case which I didn't mention because I was going to mention the later issues. (In "anal sex" practices where the insertive/giving partner is female like pegging, these normally aren't considered when it comes to anal sex. And female/male here refers to the sexual organs of simple cases. For intersex and other individuals where the partner may have a penis despite being female, I didn't mention that complexity.) In the oral sex case, it's quite important that we differentiate between fellatio and cunnilingus, both are which quite correctly and commonly described as oral sex yet are likely to have difference risk profiles, hence why I said the sex of the receiving partner is significant. (To be fair, anilingus]] may also be included which would include both sexes and isn't something I really mentioned.)

Since I can't find what you referred to (may be it's already been removed), I'll give a current example. Our HIV/AIDS#Sexual has risks. But it does differentiate between receptive and insertive partner. (And receptive is quite a large range.) It also assumes no barrier protection (condoms) were used. It's also referring to an average per act risk, and exposure to an infected source. And if you read the text, it gives further complications such as whether it's a low or high income country, and the presence of other STIs, and whether commercial sex work including prostitution is involved. This is an example of the complexity involved and why the article you referred to which gave a single figure probably should be changed. Note our article also mentions a value for oral sex (again differentating between receptive and insertive) but makes it clear it's referring to cases where the insertive partner is male. (The high/low income thing is interesting and not something I was aware of although I guess not surprising. Since we're talking about cases where condoms weren't used and the partner has HIV, these obviously aren't the reason. I would guess it's because of how well the HIV is controlled, the relative health of both partners, the number of conurrent STIs, perhaps also stuff like the usage of and type of lubrication and a bunch of other factors.)

Nil Einne (talk) 04:05, 30 November 2014 (UTC)

I will re formulate my question and make it clearer. Just forget what I asked. What are the chances of catching the hpv virus from giving oral sex for men to someone who is infected? I already googled it yesterday and it said in one study it was less than 10 per 1000 person months for healthy men. — Preceding unsigned comment added by Whereismylunch (talk • contribs) 22:00, 30 November 2014 (UTC) Men giving it to women, not men giving it to men.Whereismylunch (talk) 22:07, 30 November 2014 (UTC)

Hydrogen roasting

Molybdenum and tungsten is produced by roasting the oxides under hydrogen gas. What makes the ore of one metal better qualified over the ore of another? Which ores were this technique first applied to, for the purpose of refining the metals? Plasmic Physics (talk) 09:13, 29 November 2014 (UTC)

Metals are smelted from ore using the chemical process of reduction. The material used as a reducing agent depends on the electronegativity of the metal. Some metals (like the ones in your example) have very low electronegativity and require extreme conditions to accomplish ore extraction, such as protecting the entire process within a reducing atmosphere. Mihaister (talk) 07:19, 30 November 2014 (UTC)

Metals are normally smelted, but not always. In hydrogen roasting, hydrogen plays the role of the primary reducing agent, not just the reducing atmosphere. The key difference between smelting and roasting, is that smelting involves a molten phase at some point in the process, whereas roasting does not. An example would be the hydrogen roasting of chalcocite:

Cu
₂S + H
₂ → Cu + H
₂S

Plasmic Physics (talk) 07:42, 30 November 2014 (UTC)

I stand corrected. Mihaister (talk) 07:51, 1 December 2014 (UTC)

If you mean What makes the ore of one metal better qualified over the ore of another – for roasting as opposed to smelting. It would be the melting point of the metal (and to some extent I suppose, the ticklish problem of removing unwanted other elements that occur in the ore, if refining was attempted in the molten state). After all, what would one line the crucible with to stop the crucible from melting? Even ZrO2 Ceramic Properties only go up to 2400°C!!! --Aspro (talk) 02:23, 1 December 2014 (UTC)

OK, thanks. How was the process historically applied? I'm after some light trivia to write into an article where this process is somewhat important in explaining the main topic. Plasmic Physics (talk) 02:32, 1 December 2014 (UTC)

In that case you have come to the right place - I specialize in trivia - whatever its mass happens to be. Have a read of [10] Chapter One, page 1 & [11] page 143. As I vaguely recalled, it appears that the ore needs to be chemically purified before roasting. --Aspro (talk) 06:43, 1 December 2014 (UTC)

Red Bull Stratos

The person might have been burned during re-entry. But he did not. But spacecrafts get fire during re-entry. Please explain why? --IEditEncyclopedia (talk) 10:39, 29 November 2014 (UTC)

See Aerodynamic heating. The guy probably got warm from the friction, but he wasn't going fast enough to cause combustion. The typical "shooting star" comes into the atmosphere at a very high speed and burns quickly. Speed seems to be the key issue. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:27, 29 November 2014 (UTC)

Also, try this: Rub your hands together very fast... Do they get warm? That's why things get hot on re-entry. Friction causes objects to heat up, the faster something is "rubbing" against something else, the more heat is generated. An object such as a meteor or a space craft is moving very fast indeed, and as such, generates a lot of friction with the air of the earth's atmosphere. --Jayron32 13:28, 29 November 2014 (UTC)

Friction is too much of an over simplification when it comes to de-orbiting craft and lumps of comic rock. At these velocities the air stops moving before it gets to the leading surface (called something like the stagnation point). So low flow, low friction! The bulk of the heating comes from compression in this case. The temperature of this air at this point (when it has been turned to plasma) is enough to vaporize all known materials. Fortunately it is not in direct contact with the heat shield (because there is no flow) and so most of the thermal energy radiates away. At lower speeds, the air conducts away much of the heat caused by friction alone, because it is in contact and thus convention is the main method of heat transport. --Aspro (talk) 14:53, 29 November 2014 (UTC)

An important point (not mentioned yet) is that the intrepid Mr Baumgartner only _fell_ to Earth, he was never in orbit. A spacecraft in orbit will be moving much more quickly on re-entry than one which has just been launched straight up, so there's much more energy to dissipate in atmospheric heating on reentry. Tevildo (talk) 15:17, 29 November 2014 (UTC)

Absolutely! That's the huge difference between the two examples. For skydiving from orbit (via an emergency, one man, inflatable reentry device), see MOOSE.-- ToE 16:46, 29 November 2014 (UTC)

I agree. The free fall from a high altitude balloon is much slower than typical orbital speeds. For a somewhat analogous situation see also space elevator. Mihaister (talk) 23:22, 29 November 2014 (UTC)

Snow-resistant buildings

Steeply pitched, gabled roofs in Northern Europe

How can buildings be constructed to be able to support four meters of snow without being damaged?

• New York's Cuomo warns snow-hit Buffalo of risk to roofs—Reuters (November 24, 2014)

—Wavelength (talk) 17:32, 29 November 2014 (UTC) and 19:10, 29 November 2014 (UTC)

Use a steeper roof pitch. Plasmic Physics (talk) 21:36, 29 November 2014 (UTC)

How steep would it have to be to avoid all snow accumulation ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:30, 29 November 2014 (UTC)

Houses built in Northern latitudes typically have steep roofs for this exact purpose. This image is from the main article on roofs. Mihaister (talk) 23:30, 29 November 2014 (UTC)

Perhaps the section heading is misleading. My question is about buildings actually supporting an accumulation of four meters of snow on their roofs, and not about techniques for deliberately avoiding snow accumulation.
—Wavelength (talk) 00:28, 30 November 2014 (UTC)

In snow-bound areas, the solution to building damage from snow accumulation is to build structures where snow does not accumulate. If the snow crushes your roof in, the more sensible problem is to build a roof to allow the snow to slide off, rather than to accumulate. Does that mean that sometimes people in such areas sometimes build structures in an unintelligent way, so that the snow builds up and then caves in the roof? Yes, they do. But the best solution is to avoid letting snow accumulate in the first place. You can build structures to support the weight of the snow, After all, if you can build a bridge to support multi-ton trucks rumbling across them all day, you can apply the same principles to support multiple tons of anything, including snow. Any structure that will support the weight will support the weight. The question is whether such structures are economically sensible, or whether it just makes more sense to pitch your roof so snow doesn't gather. --Jayron32 01:49, 30 November 2014 (UTC)

Just add extra dead load of the said snow while designing the slab thickness if the structure is RCC.162.157.249.151 (talk) 03:54, 30 November 2014 (UTC)EEK

Some of those roofs in the picture don't look very snow resistant. Specifically, the ones that are attached to their neighbours. The snow would accumulate in the valleys and cause a leak problem at thaw time. Richard Avery (talk) 07:50, 30 November 2014 (UTC)

I don't think your concerns are really a problem. Those valleys are supported by load bearing walls and there are clearly visible drainspouts to handle the meltwater. The picture shows a good design for adjoining buildings to handle heavy snow.

I can't really speak for houses, but warehouses and other buildings with large roof areas may simply opt for large support structures that can take the weight. When I toured a DC facility in Owen Sound, for example, there were these thick steel support structures, much larger than anything I'd seen elsewhere for the size of the roof they supported. They weren't visible from the outside, but inside they gave the place something of the appearance of an enormous ribcage. They're not much different than normal columns and OWSJ, just much more robust. Matt Deres (talk) 13:22, 30 November 2014 (UTC)

The method we use here in Finland is that the occupant buys a shovel. 88.112.50.121 (talk) 16:28, 30 November 2014 (UTC)

Yes, that works well when there are upwards of five feet of snow on the roof. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:59, 30 November 2014 (UTC)

It does work, although one would usually not let it get that thick, especially if it is older packed heavy snow. Shoveling a roof is easier than shoveling a similar amount from a driveway, as gravity helps a lot. 88.112.50.121 (talk) 17:20, 30 November 2014 (UTC)

When you get several feet in the space of a few hours, as with Buffalo recently, it's pretty hard to avoid the problem. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:58, 30 November 2014 (UTC)

New snow is pretty light and fluffy, I've never seen a real world problem with it. People have lived here in Finland for 10,000 winters, and the best technology we have for snow on the roof is a shovel. If you come up with a better solution, please do tell. Maybe we can share patent income! Basing all architecture on highly sloped roofs -- thanks but no thanks. 88.112.50.121 (talk) 20:49, 30 November 2014 (UTC)

Read what happened in Buffalo recently. And by the way, there is such a thing as a roof shovel, i.e. a scraper with a very long handle. But the citizens of Buffalo were overwhelmed by it all, and there many reports of collapsed roofs. That's probably what triggered the question here. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:51, 30 November 2014 (UTC)

Just reporting how people who deal with the issue every year handle it, sir. 88.112.50.121 (talk) 00:03, 1 December 2014 (UTC)

Helsinki gets 72 cm of snow a year - Buffalo gets 240 cm on average but in this storm got nearby Cowlesville got 223 cm in 3 days. Rmhermen (talk) 03:49, 1 December 2014 (UTC)

So I suggest getting a shovel and getting busy with it. The alternative of suddenly re-architechting all your buildings to have steep pointy roofs is ...yeah, well, good luck with that.

It is funny to see people struggling with a simple perfectly natural thing. Like someone who discovers he needs to mow his grass, or that dead leaves need to be raked. Memo to all: you got to shovel your snow! 88.112.50.121 (talk) 05:36, 1 December 2014 (UTC)

It seems that it isn't unheard of to have snow guards/snow barriers (and it's a legal requirement in some cases) on roofs in Finland to protect people under the roof from excessive falling snow & make sure the snow accumulates in a safe fashion with respect to the load bearing structures [12] [13] [14] and perhaps also to keep a minimum level of snow for insulation (per our article).

Not from Finland but as an alternative to shoveling [15]. (Although I'm not denying that shoveling is the most common method, albeit sometimes with assitance particularly for commercial buildings File:Snow removed from roof Keljo.jpg File:Snow removed from roof Keljo closeup.jpg & Commons:Category:Snow removal from roofs.)

That said, I think Rmhermen, BB et al do have a point that it's flawed to automatically assume there's something wrong just because people and structures are able to deal with something in one area when it causes greater problems in another area, particularly without considering how similar the situation actually is, the frequency of such events or how out of the ordinary it is, and the reasons such differences in the way things are dealt with might exist. In particular, most places have problems dealing with extremely rare events, I doubt Finland is any different.

Also e.g. [16] [17] (many of the articles relate to snow on roofs) or even our article snow removal has some info on snow on roofs.

It's not like roofs have never collapsed in Finland [18] or there isn't such concern [19]. In fact [20] is designed to provide warnings for when shovelling is necessary and appears to have been developed in Finland [21]. (Although more limited similar ideas may exist [22] [23].)

And there are other risks besides the roof collapsing, as the presence of snow guards illustrate [24] [25] [26]. The shovelling itself obviously caries some risks [27] [28] (the video is from Estonia but the uploader appears to be from Finland). This Finnish person [29] seems to understand that albeit in relation to a different case.

Nil Einne (talk) 13:02, 1 December 2014 (UTC)

Another factor to remember is insulating the ceiling or roof. If the roof gets warm, the snow sticks to it more, and ice forms more. If the roof stays cold, the snow slides off more easily.122.108.177.30 (talk) 07:15, 1 December 2014 (UTC)

Can you mix ants of the same species but of different ant colonies?

If you pick ants from one ant colony and place them in a totally distinct (but of the same species) ant colony, would they come well along? --Senteni (talk) 19:15, 29 November 2014 (UTC)

There has been considerable research on this topic. A Google Scholar search for 'ant colony recognition' will provide a starting point. [30] Ants communicate via scent (notably pheromones), and it seems that each colony (or possibly supercolony [31]) has a distinct scent. AndyTheGrump (talk) 20:30, 29 November 2014 (UTC)

Indeed, but the tolerances and differentiation vary amongst species and this may be a factor in which species form supercolonies and the degree of genetic uniformity within and between separate colonies. Further, there are some parasitic species who will intrude upon a closely-related colony and exist as a distinct genetic population within it without producing their own workers, and in these cases the parasitic species seems to be exploiting the fact that the pheromones employed are (apparently) innately known and universally recognized by the host species. But still other parasitic species will exploit the fact that some species have colonies that establish a scent that falls within certain constraints but varies from population to population, a scent that individuals are fine-tuned to recognize in development and which is therefore in a sense "learned" by the resulting superorganism; parasitic species in this context will sometimes attempt to install their own queen before the first broods are born, in order to either cohabitate with the, to completely leverage their work for themselves, or to simply leave the host colony disorganized until the physical burrows can be captured by a working population developed from their own offspring.

To answer the OP's question more directly and succinctly: in rare instances, yes -- one could integrate a migrant ant -- but not in most cases.Snow talk 02:16, 30 November 2014 (UTC)

Two examples: I was told by an entomology professor that an individual worker pharoah ant could be flown from NYC to LA (or Tokyo, etc) and could rejoin a colony there. Also the Argentine ant is thought to be so invasive in the USA because of a founder effect, wherein all invasions are related because they came from the same few queens. So, in their natural range they have small colonies that fight eachother, while in their introduced range different colonies aren't sensed as rivals, and giant supercolonies form. It all really depends on the specific species and how they sense kin/colony relationships. SemanticMantis (talk) 15:44, 30 November 2014 (UTC)

Ants also detect colony mates via signatures of hydrocarbons on the cuticle (which are different from pheremones). Some species will attack a con-colonial worker if she is washed off by humans. SemanticMantis (talk) 16:09, 30 November 2014 (UTC)

Human/Animal Crossbreeds

So, you can cross a horse and a donkey to make an ass or a mule, and a lion and tiger to make a liger, or a dolphin and a false killer whale to make a wolphin. Could humans theoretically mate with orangutans or chimpanzees and produce offspring? Would the offspring be viable? Horatio Snickers (talk) 20:31, 30 November 2014 (UTC)

For starters, we do have some info in our article on humanzee. ---Sluzzelin talk 20:36, 30 November 2014 (UTC)

Here are various facts and theories about how our very great-grandparents may or may not have bred with Neanderthals, Denisovans and their ilk. So there's a glimmer of hope for a chimpboy, but if it were already possible, we'd already have at least enough for a case study in a medical journal somewhere. Humans have been getting halfway there for a long time. InedibleHulk (talk) 23:17, November 30, 2014 (UTC)

Reminds me of when AIDS was first gaining major publicity and it was alleged to have originated in apes. Frank Zappa said, "Why I want to know is, who's screwing those monkeys?" ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:27, 30 November 2014 (UTC)

If this subject disturbs you, do not swim with seals or dolphins. In any case, most reports of humanzees are just the unfortunate sufferers of Gandler-Kreukheim Syndrome. μηδείς (talk) 03:08, 1 December 2014 (UTC)

As we have an article on Next (novel) perhaps this malady is eligible to be added to List of fictional diseases.--Aspro (talk) 03:35, 1 December 2014 (UTC)

Orgasm Weapon (serious)

A few years ago I was looking at weapons or brain waves or electromagnetic radiation articles (something of that nature) and I found an article stating that a potential item exists that could cause females to orgasm from a distance. I am familiar with search operators and advanced search techniques but I can't seem to find the article. Please help. Thanks. Judasschwarz (talk) 22:45, 30 November 2014 (UTC)

Sounds like the plot line of Flesh Gordon. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:47, 30 November 2014 (UTC)

Is this the only response I'll get? — Preceding unsigned comment added by Judasschwarz (talk • contribs) 22:53, 30 November 2014 (UTC)

What have you found in Google so far? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:01, 30 November 2014 (UTC)

A lot of stuff related to porn and a movie title "Orgasmo". I've also used Google to search Wikipedia articles containing terms weapons, electromagnetic, sonic, microwave, directed, energy, orgasm, non-lethal along with the - parameter to remove useless links. I wish I could use "intext" exclusively so that pages with a term in the title (orgasm in this instance) wouldn't come up. I don't know if that's possible or how to do that though.Judasschwarz (talk) 23:09, 30 November 2014 (UTC) edit- combined those search terms in various combinations.

You can do a "-intitle:orgasm" (no quotes). You'll need a separate one for the plural. InedibleHulk (talk) 23:20, November 30, 2014 (UTC)

Thanks I'm looking now with that parameter. I've also considered using The Wayback Machine. I have some experience using it but haven't used it to perform this sort of advanced searching. — Preceding unsigned comment added by Judasschwarz (talk • contribs) 23:54, 30 November 2014 (UTC)

It was the key plot point in Orgazmo. That alone doesn't necessarily mean it's also not real, but it makes it feel that way. InedibleHulk (talk) 23:04, November 30, 2014 (UTC)

A quick Google search on "neurological orgasm weapon" brings up (a) lots of pages (mainly written in primary colours on a black background in ALL CAPS) by people who claim to be victims of them, and (b) references to this 2008 paper (see, for example, this article from the Guardian). The name Robert Galbraith Heath is also a common feature. Make of this what you will. Tevildo (talk) 00:05, 1 December 2014 (UTC)

Thanks. — Preceding unsigned comment added by Judasschwarz (talk • contribs) 00:13, 1 December 2014 (UTC)

Also is this: "(mainly written in primary colours on a black background in ALL CAPS)" a clue to something? I don't understand what that statement was added for. — Preceding unsigned comment added by Judasschwarz (talk • contribs) 00:17, 1 December 2014 (UTC)

Well, that sort of website design is very common among people with unorthodox views of the world. I was just noting that people who believe they have been attacked by the CIA with "neurological weapons" - an unorthodox view by most standards - seem to follow this pattern. Tevildo (talk) 00:55, 1 December 2014 (UTC)

It is a tale told by an idiot, full of sound and fury signifying nothing. At least that's what I grabbed from the hint. Using all-caps is GENERALLY CONSIDERED SHOUTING LIKE A MADMAN!!! And colourful text can uncomfortably distracting. If someone showed up on your doorstep, like a Mormon dressed in a silly pink and white costume with a purportedly true message about orgasms, it's natural to feel skeptical. Same applies to the web. Wikipedia is where it is because we dress the part. (That link was merely at the top for "black white blue suit". Any similarity to Jimmy Wales is a purely eerie coincidence.) InedibleHulk (talk) 01:00, December 1, 2014 (UTC)

Lol, understood. — Preceding unsigned comment added by Judasschwarz (talk • contribs) 01:04, 1 December 2014 (UTC)

The concept exists in science fiction, certainly—in Larry Niven's Known Space books, such a device is called a tasp. (Niven's books also present a wired, non-remote version called a droud.) Direct electrical stimulation of the pleasure centers of the brain is portrayed as potently habit-forming; addicts are sometimes called wireheads. The latter article, interestingly, provides some real-life examples of such stimulation (under controlled conditions); it seems to be just as attractive as science fiction suspected. As far as I know, there is no extant technology for carrying out such stimulation remotely and noninvasively. TenOfAllTrades(talk) 01:19, 1 December 2014 (UTC)

No fair, I was just going to say Tasp. Niven also invented flash crowds. μηδείς (talk) 01:40, 1 December 2014 (UTC)

And one of those stories contains the phrase "a stack of TVs, big ones almost an inch thick." —Tamfang (talk) 08:07, 1 December 2014 (UTC)

That reminds me, it was also in at least one softcore space porn. Can't remember if it was Femalien, Emmanuelle in Space, Andromina: The Pleasure Planet, Veronica 2030 or Femalien II. Pretty sure it wasn't Sex Files: Alien Erotica, but might have been Alien Sex Files 3: Aliens Gone Wild. I'd had enough of the genre by the time that one came out. InedibleHulk (talk) 03:04, December 1, 2014 (UTC)

Are you think of that whore-er movie Barbarella in the Ogasmatron? Whilst on the subject. A beam of photons shone through crystalline carbon can have a funny effect on some people from quite a distance. Just a five carat stone in a jewellers window with a sign announcing Sale Now On is effective along a whole boulevard if the sun shines upon it.--Aspro (talk) 04:02, 1 December 2014 (UTC)

How scientific is economics?

I recently asked an economics question here, and it was moved to the humanities desk. I thought that was odd. I can't see how economics could tell us anything useful if it doesn't follow the scientific method. Is economics a science?--79.97.222.210 (talk) 01:42, 1 December 2014 (UTC)

It depends on who you ask. Our article, definitions of economics, cites several famous historians and economists who use "science" in the definition of economics. The article also cites several textbooks and reviews that categorize economics among other sciences. The very same article lists many more reputable sources who do not use "science" in the definition.

Most accredited universities do not administer the department of economics alongside physical sciences. Some universities administer economics departments alongside the mathematics department. Many universities jointly administer their departments of art and science, blurring the distinction. So, at least among academic circles, there is room for debate about how things should be categorized.

Economics can be approached using the scientific method. This approach is applied less universally to economics than, say, to physics or chemistry.

For the purposes of the Wikipedia:Reference desk, our present categorization places economics within the scope of WP:RDH. This is consistent with the Dewey Decimal System and the Library of Congress Classification: both systems place Economics between Law and Politics, and quite distant from the "Science" category.

Nimur (talk) 02:54, 1 December 2014 (UTC)

I tend to think of economics as a bit of both. In a closed system where currency is based on the value of bullion and there is no borrowings or interest, then it is simple mathematics. As soon as Kings (and later) politicians started to debase the coinage (inflation) and invented new financial tools such as credit/debt, etc., and used these tools to buy popularity, wage war, stimulate the fishing industry to ensure a ready supply of seafarers for the navy to recruit in time of crisis (referring here to Queen Elisabeth I ) things got more complicated and less reality based. Now, Economists (with a capital E) just make it up as they go. Then they try and find reasons why they think they are right and why they think everybody else is wrong. So, today it has become an open dynamic system that is too complicated to model with any certainty. Since as soon as the model gets updated and refined, it is already out of date.--Aspro (talk) 02:57, 1 December 2014 (UTC)

Economics is a social science. Social sciences indeed are sciences, since they employ the scientific method, but when topics are classified (classification = when you put each thing in one basket, and it can't go in more than one) for practical purposes, the social sciences are generally put with the humanities and not with the sciences. This is apparently because of what the social sciences and the humanities study — they're not the same of course, but in general, they're a lot closer to each other than either one is to the hard sciences. If you have different baskets for English literature and chemistry and you're trying to decide which basket gets economics, you'll probably put it with English literature simply because the subjects are a lot more similar: they deal with different aspects of the human experience (neither one would be around without humans), while chemistry is independent of humans, and human biology (being just the human branch of zoology) would be about the same if we didn't have enough intelligence to study human biology. There are still some difficulties (psychology deals with human behavior and the biology of the brain, so where does it go; archaeology is a kind of anthropology, a social science, but it relies heavily on geology and other hard sciences; and is history in the social sciences or the humanities), which you can see reflected in how JSTOR divides its journals by subject, so sometimes we simply have to be a little arbitrary. Nyttend (talk) 04:29, 1 December 2014 (UTC)

Social sciences in general (and economics in particular) is generally characterized by the extreme difficulty in creating and running controlled, reproducible experiments. Economics may make a prediction (factor X will produce economic result Y under conditions Z), but then how does one run a controlled experiment which produces reliable results? You can't create carefully controlled human experiments which can be run over and over and which can reliably produce identical results. That's part of the problem with classifying economics as a science, and why "social sciences" in general get classified with humanities and not other hard sciences. If I want to run an experiment on, say, the way a spring reacts to forces, I can run the experiment as much as I want, get scrupulously reliable results, and then use those results to make predictions about other springs which I can have faith will work as predicted based on past results. Social sciences isn't able to do that. At best we can make rough predictions based on historical results, but conditions are NEVER identical, and forecasts for that reason are quite fuzzy, and only marginally better than dumb luck. --Jayron32 12:25, 1 December 2014 (UTC)

It is getting more scientific and can produce reasonable results. However a lot of the people involved have political ideas that override any scientific detachment or don't understand about motives except for greed and poverty. I think there is still quite a bit of truth in the old joke about the difference between philosophy and economics. In one they ask a different question each year and expect the same answer, for the other they ask the same question each year and expect a different answer. ;-) Dmcq (talk) 13:05, 1 December 2014 (UTC)

The hard science use of Wikipedia

What is the use of Wikipedia as a whole in the context of hard science?

I don't understand the justification of time spent here by intelligent people whom are desperately needed in our society in so many other areas.

I see no logic in purpose as an open and accurate knowledge database of humanity, as noble as founding intent may have been. While much open history of discussion exists and is quite telling for the individual with the time and drive to search through it, there remains a power structure and ability to delete certain data, which always invites corruption and bias at some level.

If someone has a clue, or "theory", please let me know.2601:8:8F00:CA:55CA:998D:E18C:7BC0 (talk) 03:29, 1 December 2014 (UTC)

Are you asking if it's a good use of effort to be maintaining coverage of hard-science topics here? Many of our science experts are professional scientists who edit here in their spare time; if they want to relax by writing about their professional specialties, more power to them. It's the same in other fields, both scientific and not; Doc James is a doctor who writes a lot about medicine (see his biographical article for information relevant to your answer), Arthur Rubin is a mathematician who has written a good deal about mathematical topics (again, see his biography), and Acroterion (there's no article about him) is an architect who writes a lot about architecture. Nyttend (talk) 04:18, 1 December 2014 (UTC)

Err. How do think we the intelligent people (your words not mine) got to be so, if it wasn't for the previous generation of intelligent people taking time out from other worthy pursuits to pass their knowledge and wisdom on to us. Education and access to knowledge is now an essential part of 'our' societal needs. Is that rational not justification enough. Don't you think progress of human-kind would stagnate, if new advancements in technology (like papyrus then paper for writing, printing presses, correspondence courses which took advantage of a reliable postal system, etc., etc.) were ignored? As for a power structure and ability to delete certain data. This has always been the case. Even back when knowledge was passed on by oral tradition only, individuals probable edited out and added stuff to satisfy their on whims and fancies.--Aspro (talk) 04:23, 1 December 2014 (UTC)

Access to information is a key required for development. Yes Wikipedia is not perfect but it is 1) the best we have for a freely accessible general overview 2) is very extensively read Doc James (talk · contribs · email) 04:25, 1 December 2014 (UTC)

Hm. Perhaps Theory X and Theory Y might be an interesting article for you. Lots of people like to be useful. Dmcq (talk) 12:54, 1 December 2014 (UTC)

Meaning of endorse and endorsement in psychiatry

What is the meaning of endorse and endorsement in the following context: "Significance of Endorsement of Psychotic Symptoms by US Latinos. In US regional studies, Latinos frequently endorse psychotic symptoms associated with impairment and mental health service use, yet do not meet criteria for psychotic disorder." I did check endorsement but it didn't help much... Thank you! Lova Falk talk 13:29, 1 December 2014 (UTC)