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October 27

At the time of when Islam was first arose...

Did we know of any other planets in the solar system? ScienceApe (talk) 02:55, 27 October 2011 (UTC)

That would depend on who you talked to. Nevard (talk) 03:17, 27 October 2011 (UTC)

The existence of five other planets has been known since at least ancient times, if not prehistoric, by pretty much everyone everywhere--at the very least Venus, Mars, Jupiter, and, I would think, Saturn. Mercury might have been harder to notice by prehistoric peoples everywhere, I'm not sure. I have never knowingly seen Mercury, but then I've always lived with urban light pollution. Anyway, see History of astronomy, Venus#Historic understanding, Mars#Historical observations, Jupiter#Ancient mythology, Saturn#Ancient observations, and Mercury (planet)#Ancient astronomers. Islam first arose in the early 600s AD, of course. What prehistoric and ancient people thought these planets were and why they moved through the sky the way they did is a different question. Pfly (talk) 04:11, 27 October 2011 (UTC)

It should probably be mentioned here that the dawn of Islamic astronomy marked a real advance on earlier knowledge - an emphasis on empirical observation had long-lasting effects on the development of astronomy as a science. One should note that even today, many of the visible stars have names of Arabic origin: e.g. Aldebran, Deneb, Rigel, and all the other stars found in our List of Arabic star names. AndyTheGrump (talk) 04:25, 27 October 2011 (UTC)

See classical planet - the Babylonians knew the planets and called them by sort of the same meanings under different names (i.e. Ishtar was Venus, Marduk was Jupiter, Nabu was Mercury, Nergal was Mars, Ninib was Saturn. I don't know how many of the correspondences in the roles of the deities with those of the Romans were invented or exaggerated after the fact by commentators. Wnt (talk) 16:47, 27 October 2011 (UTC)

If a proton were the size of our sun...

How big would an electron be approximately? And if it were just one electron, about how far out would its probability cloud be if the proton were where the sun is? Just to be clear I'm aware that the bohr model isn't accurate. ScienceApe (talk) 02:58, 27 October 2011 (UTC)

An electron is a point particle, so it's unclear what is meant by the phrase "how big would an electron be". However, I can give an idea of some of the relative sizes involved. Expressing everything in the same units (picometers) for easier comparison, in increasing size, the charge radius of a proton is about 0.000877 pm, the classical electron radius (which isn't really the radius of an electron) is about 0.00282 pm, the Compton wavelength of an electron is 2.4 pm, and the Bohr radius is 53 pm. Multiplying those four numbers by the same constant gives 1 solar radius, 3.2 solar radii, 2,700 solar radii, and 60,000 solar radii, respectively. In comparison, 1 astronomical unit is about 215 solar radii, so divide those four numbers by 215 if you'd prefer to measure everything in AU instead of solar radii. Red Act (talk) 07:12, 27 October 2011 (UTC)

The proton article gives a proton radius of 1.6 to 1.7 femtometers. The Bohr radius is 53 picometers. So we'd put the electron at 32000 solar diameters out. The solar diameter is 1392000 km, so that's 44 700 000 000 km = 299 astronomical units. Which oddly enough is close to Red Act's 280 despite the apparent difference in derivation. Wnt (talk) 17:01, 27 October 2011 (UTC)

There's nothing particularly odd about it. The proton article gives the proton's diameter as 1.6-1.7 femtometers, which is roughly consistent with the 0.000877 picometer charge radius that I used, which is why our answers are roughly consistent. Despite your misspeaking above, you did actually use the 1.6-1.7 femtometers as a diameter in your calculation, not a radius, so that didn't create a discrepancy between our answers. Red Act (talk) 17:50, 27 October 2011 (UTC)

Thanks for catching that. I've been trying to do a very low calorie diet recently and for some reason these wrong word substitutions keep cropping up all over the place, despite a relative lack of other mental effects. Wnt (talk) 15:13, 28 October 2011 (UTC)

See Electron#Fundamental properties. I don't pretend to know what it means, but after describing it as a point particle, it gives an "upper limit" of the electron radius as 10^-22 meters. —Akrabbim^talk 15:26, 28 October 2011 (UTC)

That "upper limit" just means that with all experiments performed to date, it can be determined for sure that r < 10^-22m. Thus, experiment is consistent with the theoretical value of r = 0, since r = 0 and r < 10^-22m can both be true simultaneously. On the other hand, if an experiment some day were to find a strictly positive experimental lower limit to the electron's radius, that would be an inconsistency with the theoretical value of r = 0. Red Act (talk) 17:29, 28 October 2011 (UTC)

Rods and cones in the male/female eye

I've noticed that my brother and I can usually see quite well in the dark, whereas many women I know have to strain their eyes to see things at night (like mountains) that I can see easily. This set me wondering, do females have less cones than males? If so, do they have more rods? And are the effects of this noticeable? Can females differentiate between colours better than males? Thanks, --T H F S W (T · C · E) 03:00, 27 October 2011 (UTC)

I'm not sure all of the specifics, but one key difference is that males are 16 times more likely to be colorblind than females, see Color_blindness#Genetics. My understanding is that a lot of color perception genetic coding is on the X-chromosome and consists mostly of dominant genes. In females, with two X-chromosomes, the presense of the recessive "color blindness" gene can be masked by the dominant gene on the second X chromosome. Males, with only one X-chromosome, don't have that second gene, so if they have the color blindness gene, it always manifests itself. I'm not sure what this means for general (non-defective) vision differences between males and females, but there may be something there. --Jayron32 03:42, 27 October 2011 (UTC)

You appear to be stating your question backwards of how you're intending it. Rod cells are the ones responsible for night vision, and cone cells are responsible for color vision.

Number of rod cells would be only one potential difference that might affect night vision.

This study, at least, would seem to suggest that women might if anything tend to have better low-luminance visual acuity than men. Red Act (talk) 04:57, 27 October 2011 (UTC)

I think this would be a hard comparison to make, because it takes a long time for night vision to reach maximum sensitivity. You would have to be sure that you were comparing males and females who had both been in the dark for equally long. Looie496 (talk) 05:00, 27 October 2011 (UTC)

Night vision may depend on eye colour. I believe I have read that people with blue eyes have better night vision than those with brown eyes. Some women are tetrachromatic, and do have superior colour discrimination.--Srleffler (talk) 17:20, 27 October 2011 (UTC)

(edit conflict) Sorry, got the rods and cones mixed up in my original question. I read the study, but since the youngest participant was 56 I think the results could have been because females' eye's don't go bad as fast as males' or something similar. And when I noticed this both the males and females had been in the dark for the same amount of time. --T H F S W (T · C · E) 17:25, 27 October 2011 (UTC)

I would expect women to have better colour discrimination since I'm guessing they have more cones and less rods. But I'm wondering is if having better night vision probably means having worse colour discrimination, and vice versa. --T H F S W (T · C · E) 17:27, 27 October 2011 (UTC)

Color vision also depends on the way you were raised, the language you speak etc. Count Iblis (talk) 00:09, 28 October 2011 (UTC)

I looked for published papers about Himba color perception and found this one, which is linked from the Himba people article. Those researchers found that their Himba subjects' ability to recall colors was correlated with their color vocabulary (not just the basic color terms of the language they spoke, but each individual subject's vocabulary). I don't find that very surprising. If you're shown a color and later asked to pick it out of a lineup, you're more likely to succeed if you habitually use words like "magenta" and "violet". But if you're asked to match a color against a set of others, all presented together, your success rate isn't going to be any higher than someone who calls them all "purple", assuming you both have normal color vision.

The phenomenon shown in that BBC documentary, on the other hand, would be extraordinary and revolutionary if true, not to mention apparently at odds with the results of Roberson et al (all of whose subjects tested normal for color vision). Yet I didn't find a single paper about it. Serge Caparos seems to be a real researcher who has worked with the Himba, but his research seems to have nothing to do with color perception. That section of the "Himba people" article is marked [citation needed]. If you can find a published description of the experimental procedure and results, I'll read it. Otherwise I'm going to chalk this up to creative editing on the filmmakers' part. The Great Eskimo Vocabulary Hoax is a good read. -- BenRG (talk) 04:56, 28 October 2011 (UTC)

Laws of Physics

Is there any law of advanced physics that says that a body may travel from point A to B without actually having to cross the actual distance between these two points ( or any other possible path )?  Jon Ascton  (talk) 04:30, 27 October 2011 (UTC)

There are several features of quantum mechanics that pertain to your question. For one thing, at extremely small scales, objects don't really take any specific path from A to B, so much as take all possible paths from A to B; see Double-slit experiment. Also, objects can go from A to B by going through a region where the object would classically be prohibited from going due to energy considerations; see Quantum tunneling. Also, a qubit can be transmitted from A to B, without being transmitted through the intervening space; see Quantum teleportation. Red Act (talk) 05:24, 27 October 2011 (UTC)

That all only applies to quantum particles. For macroscopic objects, you're probably out of luck. Wormholes are probably your best hope. --Goodbye Galaxy (talk) 13:26, 27 October 2011 (UTC)

There might be some scope in Brane cosmology#Brane and bulk if your body can exit the brane and travel through the bulk before reappearing in the brane. That, at least, is one possible (if unlikely) explanation for the rather speedy neutrons we've been hearing about recently. --Tagishsimon (talk) 13:36, 27 October 2011 (UTC)

You're only probably out of luck with macroscopic objects. Such objects obey the same physics as "quantum particles". There is a chance that they will tunnel or otherwise exhibit non-classical behaviour. That chance is simply extraordinarily small; small enough that events like that are not likely to occur even over the whole lifetime of the universe.--Srleffler (talk)

There are a lot of ways to interpret this question, but I think it's best to say no. Continuity and locality are extremely important principles of modern physics, "even" quantum mechanics. There's no relationship between distinct points A and B that doesn't involve points in between them. -- BenRG (talk) 20:13, 27 October 2011 (UTC)

The Heisenberg uncertainty principle dictates that the position and momentum of a small particle such as an electron cannot be simultaneously measured. Thus an observer cannot find the actual precise path, though this is different from having no path. ~AH1 ^(discuss!) 20:16, 29 October 2011 (UTC)

Night vision

Do people from the Far North tend to have better night vision than average? Seems to me that this would be highly advantageous, considering that it's dark for six months up there... 67.169.177.176 (talk) 06:08, 27 October 2011 (UTC)

This paper suggests that the high vitamin A content of Inuit diets improves night vision. The downside is that over-consumption of vitamin A can lead to some pretty nasty effects, including death in extreme cases. See Hypervitaminosis A and also Piblokto. SpinningSpark 11:14, 27 October 2011 (UTC) and 11:24, 27 October 2011 (UTC)

The six months of Polar night is a common mistake. For example here in Cambridge Bay the polar night lasts from 1 December to the middle of January but there is a period of twilight, at least 4+ hours, each day. On the other hand somewhere like Alert, Nunavut, much further north than Inuit live, the sun does not rise from 15 October until 27 February and there is no twilight from 29 October to 13 February, just over three months of darkness.

I've never noticed that anyone has better night vision up here, in other words they may have lost the ability. However, that could be down to most people living in houses with electric lighting and street lighting the same as anywhere else in the Western World. Also today the diet includes a lot more Western food than in years gone by coupled with a reduction in traditional diets. Also there is the period from 20 May to 25 July (Cambridge Bay) when the sun does not set at which point the night vision wouldn't help. CambridgeBayWeather (talk) 03:48, 28 October 2011 (UTC)

Thanks, but I was thinking more along the lines of genetic/congenital predisposition to better night vision. This is from my own personal experience -- I am originally from the Far North (although not that far north, where I used to live we didn't really have polar night in the winter) and when driving at night with only a crescent moon I can still see objects well beyond the range of my headlights (far enough that I can drive the daytime speed limit with complete safety, even on the freeway). But now I've been living in California for several years, and what I observe is that as soon as it gets dark everyone just starts driving so %#$@ing slow that it's downright maddening. What I was thinking about is whether there may be a link between the latitude of your birthplace and the ability to see well at night. But then again, maybe it's just me having the right genes for night vision? (BTW, I can also see just a tiny bit into the near infrared, which I found out when I first used a spectroscope in my high school chemistry class. Could there be a link between this and my night vision?) 67.169.177.176 (talk) 06:05, 28 October 2011 (UTC)

Didn't explain it too well but that is what I meant. I couldn't find the exact quote but I did find this where hunters who should not and traditionally were not, dependant on the time of day were complaining about the lack of light. Of course they may have had better night vision in the past and the modern lack of it could be down to the change in diet and lack of vitamin A. See this and this. CambridgeBayWeather (talk) 01:36, 30 October 2011 (UTC)

Thanks for the info. So, my being able to see by the light of a crescent moon might simply be a matter of eating lots of carrots? 67.169.177.176 (talk) 02:09, 30 October 2011 (UTC)

And in our case more liver. That second link to the "Age differences in vitamin A intake among Canadian Inuit." is correct in that younger people (I'm 55) don't eat liver much any more. CambridgeBayWeather (talk) 07:32, 30 October 2011 (UTC)

How much heat can Asbestos withstand?

Pure or mixed with concrete or other materials. By withstand, I mean both how hot till it burns and how hot till whatever it's protecting gets significantly hotter. Thank you. Cliko (talk) 07:09, 27 October 2011 (UTC)

Asbestos will not burn under any conditions, it will just melt if it gets hot enough. As for the second part, a sufficiently heavy layer of asbestos can protect human tissue against burns at temperatures of up to 1100 C or so (at least, that's what I've found so far). 67.169.177.176 (talk) 06:09, 28 October 2011 (UTC)

Oh, asbestos can burn, alright. Just introduce it to a sufficiently Lovecraftian chemical and stand well back! --Link ^(t•c•m) 07:28, 28 October 2011 (UTC)

I was thinking more along the lines of a "normal" fire (oxygen as oxidizer), not ClF₃ or other suchlike exotica. (I presume that this was also the OP's intent, since he/she was asking about heat alone -- am I correct?) 67.169.177.176 (talk) 22:31, 28 October 2011 (UTC)

The melting point of asbestos varies considerably depending on the type of asbestos, but can be above 1200C.[1] There are too many unspecified variables for the second part of the question to be answerable; about all that can be said is that the thermal conductivity of asbestos is about 0.126 W/(mK).[2] Red Act (talk) 07:58, 28 October 2011 (UTC)

Egyptian battery powered lamp

Some time ago this year, I watched a program on Discovery channel and observed an Egyptian tablet that was discovered with various figures and signs on it. The one of very interest to me , is the one figure, if it is the correct term, was one indicating a light globe, showing light and connected to something that looked like a power source, can it be a ‘battery’? It will be very interesting if you can verify if it was a burning light? Jack Koopman Pretoria South Africa. [email address removed]— Preceding unsigned comment added by 41.135.62.33 (talk) 13:38, 27 October 2011 (UTC)

Are you thinking of the Baghdad Battery? The closest thing to expert consensus is that it may have been used for electroplating, but probably not for light. SemanticMantis (talk) 14:18, 27 October 2011 (UTC)

There's also the Dendera light, which most experts believe is not depicting an electric light source, but which does bear a striking resemblance to modern light bulbs. Buddy431 (talk) 14:55, 27 October 2011 (UTC)

Hmmm, seems to bear a more striking resemblance to a surfboard, complete with the little cord keeping it connected to the surfer's ankle. A snake makes a cool decorative motif for a surfboard, but a lousy filament. Wnt (talk) 17:35, 27 October 2011 (UTC)

not a science question, but...

Is the mathematics taught in Thomas' calculus enough to understand concepts presented in "principles of physics" (by Haliday)?--Irrational number (talk) 15:01, 27 October 2011 (UTC)

By "Haliday" I presume you mean Halliday, Resnick, and Walker. My recollection is that the book is designed to be used by students who have completed a basic calculus course such as Thomas. There might be some use of differential equations in Halliday, I don't remember for sure, but in any case I think you would be okay. Looie496 (talk) 16:48, 27 October 2011 (UTC)

The old edition of Thomas I have, at least, does briefly cover ordinary differential equations, although not partial differential equations. Red Act (talk) 17:11, 27 October 2011 (UTC)

I think so. I don't actually have the Halliday book, but Thomas should be adequate as a mathematical prerequisite for pretty much any undergrad level physics textbook. You will need more math than what is in Thomas to understand all of undergrad level physics, but the additional math needed is in general presented within physics textbooks as it is needed. Not having actually looked at Halliday, I don't know for sure that that's the case with Halliday, but I would presume so just from the thoroughness suggested by the page count. Red Act (talk) 16:50, 27 October 2011 (UTC)

Human pheromone, sextual attractant

A QUESTION TO WIKIPEDIA:

THIS EMAIL IS MEANT TO BE SENT MAINLY TO WIKIPEDIA FOR INFORMATION ABOUT TRUE RELIABLE STRONG HUMAN PHEROMONE SEXUAL ATTRACTANT. ALSO ANY HELP OR CONTRIBUTION TO ANSWER FROM KIND ; READERS IS HIGHLY RESPECTED; THANKS FOR EVERY ONE. PLEASE READ BELOW. PLEASE RESPPOND BY EMAIL: <email removed>

Sir/Madam; DEAR WILIPEDIA; My question is about: True -not gemmics- RELIABLE sexual attractant for both sexes, THAT REALLY WORKS.

In particular; I do kindly seek correct information about HUMAN PHEROMONE:

1- IS THERE A REAL TRUE HUMAN PHEROMONE THAT DO REALLY WORKS IN ATTRACTING OPPOSITE SEX? ATTRACTING FEMALES AND/OR MALES? PLEASE KINDLY RESPOND AND PLEASE STATE IF ANY TRUE PHEROMONE EXISTS AND DOES WORK TO ATTRACT FEMAL/MALE SEXES TO EACH OTHERS. IF ANY, PLEASE TO ADVISE OF THE BRANDS IN THE MARKET AND OR ANY PERFUME THAT HAS IN ITS STRUCTURE PHEROMONE SEX ATTRACTANTS FOR HUMAN. (I did have read the articles in wikipedia but eventually could not make an idea if there is any or how it is made or of any brand to buy.

2- Please to advise of how human sex attractant is prepared/made. please to advise of the steps and the ingredients and the sources; whether plants, animals, amino acids, wastes, sweat, urine.....................etc. PLEASE TO ADVISE OF THE SITES OR WIKIPEDIA PAGES - OR KINDLY TO PROVIDE ADDITIONAL INFORMATION- OF HOW TO EXTRACT IT IN STEPS. 2- PLEASE TO ADVISE ABOUT THE MOST REIALBE VERSIONS/BRANDS OF THE HUMAN SEXUAL PHEROMONE THAT ARE AT PRESENT EXISTING IN THE MARKETS FOR SALE. WHETHER BLENDED IN PERFUME/S OR BY ITSELF; OR IN LOTIONS, CREAM, SPRAYS, DRINKS, FOOD, PAPER TISSUES, HAIR PRODUCTS OR BLENDED IN CLOTHES MAKING AND OTHER HUMAN ITEMS.

3- RE THE ABOVE REQUESTS, PLEASE EIHTER 2 PROVIDE THE SOURCE/s for THE SPECIFIC REQUESTED INFORMATION; WHETHER IN WIKIPEDIA pages ( but please to be addressing specifcally the requested information, and not general information), and/OR FROM OTHER SITES OR FROM ANY OTEHR SOURECES ACCESSIBLE BY NAVIGAGTING MAINLY THE INTERNET; OR BOOKS,SELLERS, MAKERS....ETC IN ADDTION, PLEASE TO HELP TO ADDRESS SPECIFICALLY THE REQUESTED INFROMATION REGRDIING: MAIN RESOURCES INITIAL PRODUCTS TO EXTRACT/PREPARE, HOW TO EXTRACT AND/OR PREPARE IT, WHERE TO FIND IT, BEST REPUTED SELLERS, BEST BRANDS IN THE MARKET THAT TRULY WORKING FOR HUMAN, AND WHICH BRAND THAT WAS TRIED AND/OR TESTED AND HAS REPUTAION THAT IT IS TURLY WORKING, IN ADDITION TO THE FORUMS>( THE (CUSTOMERS USED IT; BUT NOT SELLERS AND PROMOTERS), WHO TRIED IT AND HAAPPY ABOUT THE RESULTS AND THEIR FEEDBACKS AND RECOMMENDATIONS, IF ANY.

SIR/MADAM;

I AM SEEKING WIKIPEDIA TO GET RELIABLE TRUE OBJECTIVE SCEINTIFIC INFORMATION. IN MY VIEWS, WIKIPEDIA IS THE ONLY SOURCE THAT WOULD PROVIDE RELIABE, BOJECTIVE, SCIENTIFIC UNBIASED INFOMATION REGARDING ITS TOPICS. BUT THE INTRNET AND SELLERS' WEBSITES SEARCH IS NOT THE BEST APPROACH TO FIND RELIABLE INFORMATION RE THE REQUESTED PRODUCTS. THIS IS BECAUSE MOSTLY ANY PRODUCT INFORMATION USUALLY FOCUSSING ON ADVERTISEMENTS AND FOR MARKETING AND PROMOTIONS TO MAKE SALES. ANY INFORMATION WIKIPEDIA MAY PROVIDE RE THE ABOVE IS HIGHLY RESPECTED AND VALUED. THANKS FOR UR PROMPT RESPONSE

ADAM

PLEASE CC EMAIL TO: <email removed> <email removed>

cheers

ps: Sorry for any POSSIBLE semantic, grammatical and/or spelling mistake/s; if any. I am from a non-English speaking background. what can I do? NOT MY MISTAKE....... SORRY. — Preceding unsigned comment added by 49.2.26.145 (talk) 15:55, 27 October 2011 (UTC)

I've removed the e-mail addresses, which will only be used by spammer. We don't reply by e-mail on this board; if there is an answer, it will appear in the space below. --Mr.98 (talk) 16:19, 27 October 2011 (UTC)

I removed the hatnote - capital letters are unusual but not a crime - some of us grew up in an age of the Apple ][. I've added some extra linebreaks, because in Wiki formatting they're ignored if there's only one, unless the line begins with one or more colons. If the capital letters are that hard on your eyes feel free to lowercase the text. Wnt (talk) 17:06, 27 October 2011 (UTC)

In response to the question, the existence of pheromones seems to be a bit of a mystery - see [3] for an approachable reference. The best study I've seen is described in lay terms here [4].

I should add that I once worked around a colony of breeding mice now and then, and found the effect of their pheromones to be extremely distracting. They seemed to affect only female attractiveness, and particularly a sort of vaginal fixation which to me is quite atypical. Even women who were 100% not attractive to me were affected. I actually think that such pheromones might have a therapeutic function, because at the time I had had, for 30 years, the perception that women with east-Asian features were completely unattractive, but the pheromone made women like this attractive, and seemed to open my mind toward them permanently. I would love to see someone test these pheromones on pedophiles and see if they could be used to make them at least expand their preferences regarding age. Wnt (talk) 17:17, 27 October 2011 (UTC)

Human sexual response to odors generally varies vastly more in proportion to the respondent's predisposition, mood, attitude, other emotional factors, other sensory input (e.g. appearance of stimuli) and for females, estrous cycle state, than the odor itself. The human olfactory system has about 1,000 separate receptor types, all of which attenuate. There are very few bona fide hormones released by human males or females, and those that are do not have a substantial effect on sexual response of the opposite sex. Whether general body odor is attractive depends also on nationality, upbringing, etc.; the same can be said for perfumes and colognes. Dualus (talk) 20:10, 27 October 2011 (UTC)

metric system

Hello

I am not familiar with your community, so please excuse my foolish question, that for sure was asked many times before.

For example Parasaurolophus like many other articles contains a lot of redundant information about length an weight in metric system and in short tons, feet etc.. That is disturbing by reading this article.

Why do you not use the metric system alone? You could display information in any other system by using javascript via mousing over a value. (small box by mouse over)

Please do not let me be misunderstood. I am in respect for short tons and feed and inch and miles and landmiles and gallons. But please understand in metric system every value has a strong logic relation to an other value. For example 1 kg Water is 1 liter and needs a cube of 1 dm. (Stone has a factor approximately by 2,1 no big deal)

So if I read about a bone 1 m and 25 kg, I can imagine a good picture about other values like density (in stone) or stability. Even if this values are not provided I can make myself a good estimation about the Object that you like explain to me. :-)

Further more it seems to me a question of writing style. Providing values in many systems is like a over-decoration in regards of "political correctness". But the whole world cannot understand it ...

2.213.212.216 (talk) 17:27, 27 October 2011 (UTC)

This is the English Wikipedia. The US is a major English-speaking country, too big to ignore. Many people in the US don't understand metric units very well. Forcing the adoption of metric units is impossible, because whenever it is attempted, corporations make large campaign contributions to Congress critters, and the legislation is promptly watered down so that nothing happens. Jc3s5h (talk) 17:35, 27 October 2011 (UTC)

I understand your point. Whats about the javascript-solution that I proposed?

By the way, Wikipedia is not even a small entity. :-) YOU are in many aspects the unchallenged leading platform in science education in the world. Thats a responsibility I know. But it is also a chance to define standards. 2.213.212.216 (talk) 17:42, 27 October 2011 (UTC)

This isn't really a refdesk question, rather a WP:Village Pump kind of thing, but... It's not a matter of logic, but usefulness to the reader. For example, the air conditioners I've seen in the U.S. are rated in terms of BTUs. People who use them have their opinions about exactly how many BTUs they want to cool a given room. If you give a figure in watts, they won't be able to compare it to an advertisement or a product on the shelf - no approximate mental calculation is enough, they need the exact number. If they're going to need to make that mental calculation, it's only reasonable for them to post the results of it to the article in consideration of the next person. Wnt (talk) 17:45, 27 October 2011 (UTC)

OK, good point. :-) acclimatization. But it is also possible to acclimate to an other system. 2.213.212.216 (talk) 18:09, 27 October 2011 (UTC)

If you'd think logically for a second, 2.213.212.216, it would be easier if you could acclimatize to the wikipedia convention that units tend to be specified in metric and imperial, than that you seek to get all those who prefer imperial to acclimatize to metric. Your reservations concerning style and readability pale into insignificance with the more important objective of immediate access to immediately comprehensible material and without javascript accessibility no-nos. You see? --Tagishsimon (talk) 18:35, 27 October 2011 (UTC)

Its not about the question "How much is it in inch". It is about the Question "Can I make myself a scientific imagination of a described object using a logic toolbox." In other words: "Can I provide a writing style that makes indulgence, enjoyment and scientific stringence at the same time".

Lets make a thought-experiment: What would be if Wikipedia would say: "We always use the metric system in all languages, starting 2012!" Just for imagination, what would happen? I really want to know your opinions. :-)) 2.213.212.216 (talk) 18:03, 27 October 2011 (UTC)

If that was made a hard rule I think most Americans would stop using and contributing to Wikipedia, and seeing as Americans constitute the majority of users, editors and also donors, that would be the end of Wikipedia. Roger (talk) 18:16, 27 October 2011 (UTC)

Hm ... Maybe you are right.

That's ridiculous. For science-related articles, the metric system is already predominant. Anyone with a scientific or technical background is likely to be competent in the metric system and aware of its advantages. The bulk of those who find it annoying are those who specialize in entirely non-quantitative subjects, i.e. humanities people like me. But that's soft opposition. As for honest-to-god ideological metrication-haters, they're already more likely to spend their time huddled together at Conservapedia, Fox News Nation, World Net Daily, etc. Most ordinary people wouldn't care, and would get used to whatever standard. LANTZY^TALK 18:40, 27 October 2011 (UTC)

The advantages are somewhat overstated. The decimal stuff is useful for mental arithmetic in simple cases, but (i) other systems aren't that much harder, you just have to remember a few constants and (ii) most people don't do mental arithmetic anyway. For non-simple cases there's really no difference. Other advantages are things like not having to ask "now, is that a gram Avoirdupois or a gram Troy?" but those are somewhat marginal cases.

But the most important point is Wnt's below — Wikipedia is not a tool for reform. It's not anti-reform, just neutral. --Trovatore (talk) 18:54, 27 October 2011 (UTC)

I don't know if I'd entirely agree. I think anyone with a resonable education and knowledge of metric will know say 1680g is 1.68kg or 412 cm is 4.12m and these sort of things come instantly or very close to it and I don't think they are as rare as you suggest. Even if you're used to US customary or imperial, I'm guessing for most people if you ask them how much 22 ounces is it takes longer to figure out it's 1 pound and 6 ounces and even longer to figure out it's 1.375 pounds. Ditto if I ask about 53 inches. Nil Einne (talk) 15:59, 28 October 2011 (UTC)

Me thinks the People are loving this baby with all its peculiarity. :-)) *gg* But I am speaking as a german. People here would probably say "OK. If it is given as a hard rule we accept it. Enough for talking, lets go back to the workbench." 2.213.212.216 (talk) 18:35, 27 October 2011 (UTC)

I am not quite sure if I understand your points. But I am absolutely sure that this WP is not only the best collection of information. Your system of work is the future of science and education. You are not only collectors. Just wait 20 years of manpower and development. You will become a very important voice in history and thats ... for right. 2.213.212.216 (talk) 19:13, 27 October 2011 (UTC)

The rule would be reverted after vigorous protests. I think, 2.213.212.216, you have seen too few of wikipedia's holy wars if you estimate that the gnomes would simply shrug and get on with their work. --Tagishsimon (talk) 18:39, 27 October 2011 (UTC)

You are probably right. As I said I am not familiar with the indoor climate of Wikipedia.

But whats with small steps? The javascript-solution? Its fine. It makes things easy to editors ... every value is calculated automatically. And users can see how much is it in inch. 2.213.212.216 (talk) 18:48, 27 October 2011 (UTC)

Unlikely to work well or smoothly with screen readers. See Wikipedia:Manual_of_Style/Accessibility#Styles_and_markup_options We already have templates which convert one unit into another and display both, so that advantages is already catered for. --Tagishsimon (talk) 19:19, 27 October 2011 (UTC)

I think if a usable solution is desired, someone will appear to realize it. :-)) If you only want it. Do you want to go a small step in this direction? Imperial (and others) as a additional Information provided via javascript. In every case a unit is used. Thats a benefit for many articles. 2.213.212.216 (talk) 19:40, 27 October 2011 (UTC)

We try not to engage in magical thinking. We're content to follow screen reader technology, not provoke its extension. Really, this enthusiasm of yours is going nowhere. --Tagishsimon (talk) 19:46, 27 October 2011 (UTC)

The main thing is, Wikipedia doesn't have the purpose of improving how people measure things. It just prints what is known, as people know it. Get people to stop using non-metric units and Wikipedia articles will follow. Wnt (talk) 18:43, 27 October 2011 (UTC)

YOU are the most powerful entity in education. In my point of view there is absolute not reason to underestimate yourself. If you think something should be chanced by good reasons, you are the people who can do it. Nobody else could do it like explained above. Am I wrong with that? 2.213.212.216 (talk) 18:56, 27 October 2011 (UTC)

You are wrong. The most easy thing would be for you to acclimatize yourself to wikipedias valid use of the metric (imperial) convention, than for you to seek to get wikipedia to acclimatize the views of millions of people who have one or other first preference. We are not here to proselytize your view of what would be best and don't agree the supposed benefit is worth the inconvenience to users. --Tagishsimon (talk) 19:22, 27 October 2011 (UTC)

It bothers me that our IP editor is being pushed in a certain direction because it would be the easiest path. Sometimes it's better to do the hard thing now to make the world a better place in the long term. Most of the world that was imperial successfully converted to metric during the last century by talking a long term view. Sadly, modern politics is built on the short memories of voters, so the USA probably won't metricate any time soon, but it's disappointing to see "take the easy path" becoming dogma in the world's most popular science resource. HiLo48 (talk) 19:51, 27 October 2011 (UTC)

It's not about easy. We're not supposed to do it, period. This is part of WP:NPOV and is an absolute fundamental idea of the project. --Trovatore (talk) 20:02, 27 October 2011 (UTC)

If wikipedia were to decide to use metrics-only, it could trigger the mother of all edit wars. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:44, 27 October 2011 (UTC)

What is your weight in Newtons? Wikipedia does well enough without trying to be entirely "metric" to be sure. Give then a centimeter and they will take a kilometer, as the adage goes. Collect (talk) 22:56, 27 October 2011 (UTC)

I'm drifting off-topic here, but weight in that sense really means "mass". A person's weight, in the sense of how much force he exerts on what he's sitting on, has always been secondary except to chair-makers and so on; what has always mattered most is the quantity of matter, and this has traditionally been called "weight". Physics teachers somewhat arbitrarily insist on using weight to mean exclusively force, I think mostly to emphasize to their students that the gravitational force and the quantity of matter are not the same thing, but this linguistic distinction has no historical basis. --Trovatore (talk) 00:12, 28 October 2011 (UTC)

The trouble with the thought experiment is it depends entirely on how it happens. If by some magic a consensus is reached to abandon imperial or customary units then I don't think the suggestions above are likely. There may be some opposition and people trying to edit war (likely leading to blocks) and some people will leave but the fact a consensus is reached is going to suggest most Americans aren't going to leave. As for donors, well it's difficult to say but while we may lose some I find it hard to imagine most will stop donating. However the chance of a consensus being reached to abandon imperial or customary as long as it has widespread use in the US is extremely unlikely. On the other hand if it's a foundation issues a directive to abandon imperial or customary it's easy to imagine it will cause quite a few people both from the US and elsewhere to leave, perhaps even a fork, or simply the board being voted out in the next election and the directive abandoned. If the foundation doesn't issue a directive but instead decides to organise a vote where a simple majority is enough to use metric exclusively and presuming the vote comes out yet (which I find hard to believe), again this is likely to be rather controversial and could cause quite a few people to leave. Nil Einne (talk) 16:11, 28 October 2011 (UTC)

Let's stick to God's units. Count Iblis (talk) 23:47, 27 October 2011 (UTC)

Cubits, talents, like that? --Trovatore (talk) 01:09, 28 October 2011 (UTC)

Actually it would be fun to translate everything to the talent–cubit–day system and see how things shake out. What would the unit of capacitance be, for example? The farad is inconveniently large; who knows if this one would come out more reasonable. --Trovatore (talk) 01:12, 28 October 2011 (UTC)

I have an idea: 1 planck length = 1 splinter, 10⁹ splinters = 1 plank, 10⁹ planks = 1 pallet. Plasmic Physics (talk) 02:11, 28 October 2011 (UTC)

Everything is dimensionless, but to make use of this fact one needs to correct for the fact that we've assigned units to quantities in an inconsistent way. Correcting for this amounts to switching to Planck units (up to some arbitrary overall scale factor). Count Iblis (talk) 03:50, 28 October 2011 (UTC)

A megasplinter! Plasmic Physics (talk) 05:28, 28 October 2011 (UTC)

On a more serious note, we really ought to use decimetres more- the centimetre, like its humanistic counterpart, the digit, is not appropriate for most of the uses it is put to. Nevard (talk) 02:37, 28 October 2011 (UTC)

In UK engineering, only metres and millimetres are used, to avoid confusion. BTW it's not just the US that still uses non-metric measure; we Brits still buy milk and beer in pints, have speed limits in MPH and road distances in miles, weigh ourselves in stones and measure our height in feet and inches (unless we're in hospital). Alansplodge (talk) 10:18, 28 October 2011 (UTC)

I know young people who know their weight and height in metric. Also, I think we buy our milk and beer in multiples of 568ml, technically speaking. Grandiose (me, talk, contribs) 10:24, 28 October 2011 (UTC)

The OP said the Parasaurolophus page contains a lot of "redundant information" in terms of metric and imperial measures. But looking at the page, I don't see any measurements except in the "Description" section, and there I count five total measurements in metric/imperial. While I've seen other pages with many more examples, this one doesn't seem so bad. Plus, the abbr=on parameter of the {{Convert}} was used (as it usually should be, I think), which greatly reduces clutter. So I don't see that page as being particularly troublesome, although I know there are other pages where the issue is more obvious. Still, I think it is in most cases helpful to provide measurements in both systems. An exception might be reasonable for very simple cases, like 1 kilometre (0.62 mi) (or the reverse), maybe. I tend to add convert templates to pages that don't display both measure systems, but not as much when it is simple and/or vague (eg, uses words like "about"), like "the waterfall is about a mile downstream from the bridge". Finally, on the idea that metric is superior to imperial, which this thread seems to have touched on--while the metric system has a number of obvious benefits, such as making many kinds of calculation easier, the imperial system is not without some benefits of its own, over metric. The one that has come up for me most often is when one is subdividing lengths into equal portions. There are 12 inches in a foot, and inches are subdivided into quarters, eighths, sixteenths, etc, and these subdivisions are clearly marked on rulers (both physical rulers and rulers in graphics software). The number 12 is highly composite, while 10 is not. And metric rulers do not show "division by two" very well--rather they show "division by ten" and sometimes "by five". In many cases, fractions like 1/4, 1/8, and 1/16 are easier to grasp and manipulate mentally than their metric equivalents, 0.25, 0.125, and...wait let me calculate half of 0.125... See what I mean? Pfly (talk) 10:38, 28 October 2011 (UTC)

Welcome to our world, that's how we feel about imperial. Plasmic Physics (talk) 13:23, 28 October 2011 (UTC)

With metrics, you don't end up with recurring decimals when converting halfs and fifths. Plasmic Physics (talk) 13:40, 28 October 2011 (UTC)

Just try dividing a meter by 3 and get back to me when you reach the last decimal. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:49, 29 October 2011 (UTC)

OK, a different point - 1/2^k m can easily be converted into a decimal in centimetres with mental arithmetic. Plasmic Physics (talk) 05:48, 29 October 2011 (UTC)

True, but it gets harder and harder as k increases, whereas a pound of 16 ounces can be divided with less effort. Dbfirs 12:17, 29 October 2011 (UTC)

Yeah, but yyou end up with the same problem once you convert ounces to pounds. Besides, with metric you don't have to memorise how many increments there are in each unit of measurement. Plasmic Physics (talk) 23:33, 29 October 2011 (UTC)

You'd be surprised how many people don't know how many millimetres there are in one centimetre (not Wikipedia editors, of course). Dbfirs 06:44, 30 October 2011 (UTC)

Metric is good for science, and scientists are comfortable with it. That does not necessarily translate to it being a superior system for the general populace. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:41, 30 October 2011 (UTC)

OK, we can agree on two things - firstly, in common use, neither system is inferior; secondly, in scientific use, metric is superior. Plasmic Physics (talk) 06:22, 31 October 2011 (UTC)

Should not articles accommodate those of us who live by the FFF system? — Michael J 01:58, 1 November 2011 (UTC)

October 28

How do human beings copulate?

On Youtube, I sometimes watch videos of animals mating with each other. I have seen a male dog mate with a female dog. The female dog is standing on all fours. The male dog rests on top of the female dog's back and mates with her. In frog species, the female frog lays hundreds or thousands of eggs in the pond water to prevent desiccation and the male frog fertilizes all the eggs in the water. Different animals have different ways to mate with one another to bring forth the next generation.

Simply put, what is the normal,natural human mating position? I am not sure if the female is turned away from the male or facing toward the male in the mating process. — Preceding unsigned comment added by 75.185.79.52 (talk) 02:00, 28 October 2011 (UTC)

I'd suspect that face-to-face is probably more common, but both work, and it comes down to cultural norms, and to individual preference. I think it is probably both 'normal' and 'natural' to experiment, try a bit of variety, and see what suits the couple concerned. AndyTheGrump (talk) 02:25, 28 October 2011 (UTC)

Humans show a remarkable capacity for play or experimentation into adulthood; they also have a major difference from animals in the form of culture. Humans fuck in different ways for different cultural reasons. Some times these cultural reasons are large, like American television authorising certain ways of negotiating sex. Some times these cultural reasons are small, like peer-to-peer advice, or the private negotiation of personal preference. As far as the wide variety of manners in which people fuck, they do it standing, seated, lying down on their front back or side. They face each other, they turn away, they face each other sideways. If there is one way to characterise human copulation, it is that humans copulate in exhaustively permuted ways. Fifelfoo (talk) 02:33, 28 October 2011 (UTC)

Both; see sex positions. It... is illustrated. Dualus (talk) 02:44, 28 October 2011 (UTC)

How do humans compare with other hominids or apes or monkeys or primates? — Preceding unsigned comment added by 75.185.79.52 (talk) 02:56, 28 October 2011 (UTC)

As far as I'm aware, only Bonobos (pygmy chimpanzees) regularly copulate face-to-face, though apparently Gorillas have been observed doing it occasionally. Bonobos are unusually 'promiscuous' and seem to copulate as a method of communication rather than procreation (but then, so apparently does Homo sapiens)... AndyTheGrump (talk) 03:10, 28 October 2011 (UTC)

I just want to add in, there is no one "normal, natural" position. Every historical record we have points to people in all cultures, at all times, doing it every which way. At certain very extreme times, various cultures have proclaimed one way of doing it to be the only acceptable way by their standards, but there is absolutely no reason to privilege such occasional proclamations over the observed variation. Seeking a "normal, natural" position is a fool's errand at best. You will not find it for it does not exist. To editorialize a bit: that we have such a variety of sexual practices, while much of the animal kingdom has relatively restricted means, is yet another reason it's great to be a human being, and not, say, a dragonfly. Let's not be so quick to embrace the rigid dragonfly as an ideal. --Mr.98 (talk) 11:24, 28 October 2011 (UTC)

Embracing rigid dragonflies may be illegal in many jurisdictions... but, whatever floats your boat... --Jayron32 12:51, 28 October 2011 (UTC)

Molecular bonding II (Repost)

Unresolved

What does the MO diagram for monomeric beryllium hydride look like?

This was my idea:

__ __ __  3×2σ*
     __      1σ*
↑↓ __ __  3×2σ = 2p_z¹(Be) + 1s¹(H2)
    ↑↓       1σ = 2s¹(Be) + 1s¹(H1)

    ↑↓       n = 1s²(Be)

This was not my idea:

__ __ __  3×2σ*
__ __ __  3×2σ
    ↑↓       1σ* = 2s¹(Be) + 1s¹(H2)
    ↑↓       1σ = 2s¹(Be) + 1s¹(H1)
    ↑↓       n = 1s²(Be)

This is my idea:

  __     2σ*
__ __  2×1σ*
  __     2σ
↑↓ ↑↓  2×1σ = 2s¹(Be) + 2p_z¹(Be) + 1s¹(H1) + 1s¹(H2)

  ↑↓     n = 1s²(Be)

If this is true, then why is there no sp mixing to allow for the diberyllium molecule? Plasmic Physics (talk) 05:16, 28 October 2011 (UTC)

I have not heard of group theory or SALCs before in any of my chemistry papers. Plasmic Physics (talk) 05:16, 28 October 2011 (UTC)

If you have not heard of it, why not do some reading on the subject. Linear combination of atomic orbitals is a good place to start, and it will take you though some specific Linear combination methods if you follow the links. --Jayron32 11:55, 28 October 2011 (UTC)

I have heard of LCAO. I combined the orbitals according to my understanding of LCAO, which is why I need onfimation. Plasmic Physics (talk) 12:45, 28 October 2011 (UTC)

Try Google: [5]. There's This diagram I found, and there is a youtube video in there titled "MO of BeH2" which may be useful to you. --Jayron32 14:52, 28 October 2011 (UTC)

This is my new idea:

__ __  2×1σ* = 3s⁰(Be) + 3p_z⁰(Be) + 2s⁰(H1) + 2s⁰(H2)
__ __  2×n = 2p_x⁰(Be) + 2p_y⁰(Be)
↑↓ ↑↓  2×1σ = 2s¹(Be) + 2p_z¹(Be) + 1s¹(H1) + 1s¹(H2)

  ↑↓     n = 1s²(Be)

Is this true? Plasmic Physics (talk) 05:55, 29 October 2011 (UTC)

I couldn't get the image to load, but I managed to watch the YouTube clip. This is the new diagram incorporating degeneracy. How about the second question? Plasmic Physics (talk) 04:37, 30 October 2011 (UTC)

Being a chemistry student, I just spent about an hour trying to solve this problem using my textbooks, but I doubt you can find a definite answer without actually calculating the MO`s, as our (German) textbooks only deal with even numbers of atoms in molecules here. And I`m afraid calculating orbitals is currently beyond my abilities... Phebus333 (talk) 19:42, 1 November 2011 (UTC)

Sequentially precipitating certain metal salts out of a solution

I have a vague memory from high school chemistry that we had a table showing that one could precipitate for example copper out of a solution by adding an iron salt (or was it zinc?). The table was in the form of a "sequence": Add A to precipitate B then add C to precipitate B then add D to precipitate C.... I can't remember what the table was called so I can't search for it. Roger (talk) 07:10, 28 October 2011 (UTC)

Ferrous sulfate works, to precipitate metallic copper. Plasmic Physics (talk) 10:10, 28 October 2011 (UTC)

Then what do you use to get the iron out? I'm looking for the entire sequence for all the metals from Li to U. In class we were given a "witches brew" and our task was to identify all the metals in it through a sequence of precipitations. Roger (talk) 10:48, 28 October 2011 (UTC)

Oh, you want all the copper to precipetate out? Well, then you have to use something like sodium hydroxide, then you'll precipitate all of it out. Otherwise it just disproportionates. Plasmic Physics (talk) 12:14, 28 October 2011 (UTC)

Read qualitative inorganic analysis. Graeme Bartlett (talk) 12:15, 28 October 2011 (UTC)

Yay! At last someone groks what I'm looking for. Thanks! Roger (talk) 12:20, 28 October 2011 (UTC)

to find out a pill cant find its use

i have a pill 263 on one side and the other side is the manufacturer mark i believe looks like a wide u with a line above it its oblong and a faint color of blue green i would like to find whats the drug or use found in cabinet i thank you for your time i looked for some images and the markers mark looked like a company named activus elizabeth ? not sure how it was spelled well i hope you can find info thank you — Preceding unsigned comment added by 71.231.228.250 (talk) 08:23, 28 October 2011 (UTC)

If it is just a random pill you found flush it down the toilet and forget about it. If you have a genuine reason to know what it is, take it to a pharmacist. Roger (talk) 08:55, 28 October 2011 (UTC)

Flushing drugs down the toilet is not environmentally friendly. The ideal way to dispose of drugs is to use a community drug take-back program. If no such program is available locally, the recommended procedure for disposing of unidentifiable drugs is to mix them with an undesirable substance such as used coffee grounds or kitty litter, put the mix in a sealable bag, and put the bag in the trash.[6] Red Act (talk) 09:30, 28 October 2011 (UTC)

Drugs.com has a Pill Identifier.

But I agree with the above comments. Even after you identify it you shouldn't actually use it. If nothing else you don't know when its expiration date is. APL (talk) 10:11, 28 October 2011 (UTC)

Red shift due to gravity, where does the energy go?

Lets say you are on a planet with no atmosphere. You shoot a laser out into the sky, and of course the light emitted is red shifted, so the photons lose energy. So where does that energy go? What does it turn up as? ScienceApe (talk) 17:50, 28 October 2011 (UTC)

Gravitational potential energy. Dauto (talk) 18:02, 28 October 2011 (UTC)

So you're saying the gravitational force increases? ScienceApe (talk) 19:44, 28 October 2011 (UTC)

I'm saying the gravitational potential energy increases because the photon has a relativistic mass given by the formula E=mc^2 and therefore it has a gravitational potential energy associated with moving that mass through a gravitational field. See my comment below for a more subtle interpretation (it requires deeper understanding, is harder to comprehend but is much more insightful). Dauto (talk) 20:12, 28 October 2011 (UTC)

I'm not following you. I don't understand either explanation you are giving. In layman's terms, does the gravity field become stronger? ScienceApe (talk) 00:40, 29 October 2011 (UTC)

In layman's terms, no the gravity doesn't change, the gravitational potential energy (read the link) changes. Read Gandalf's comment bellow. If you shoot a cannon ball up in the sky, it slows down as it goes up. Where does the energy go? It turns into gravitational potential energy. Dauto (talk) 14:58, 29 October 2011 (UTC)

Are you basically saying that hypothetically speaking, if the light that was shot out into space was ever deflected and sent back to the planet, it would just be blue shifted, and that's where the energy is conserved? ScienceApe (talk) 01:00, 29 October 2011 (UTC)

I'm saying the energy is always conserved if you also include potential energy along with the kinetic energy (A photons energy is a form of kinetic energy). Dauto (talk) 15:06, 29 October 2011 (UTC)

Ok, but what about when a black hole evaporates due to hawkings radiation? When it finally evaporates, it will release whatever mass it has left as energetic gamma rays. These photons will be redshifted, but there's no more singularity there to increase their gravitational potential energy. ScienceApe (talk) 16:09, 29 October 2011 (UTC)

Why would the last photons be redshifted since, as you said, there's no gravitational well left to redshift them? These last photons won't be redshifted. Dauto (talk) 16:15, 29 October 2011 (UTC)

They would. Or at least some of the photons would be redshifted. ScienceApe (talk) 17:31, 29 October 2011 (UTC)

Here, read more: http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2010_December_11#Mass_Energy_and_Black_Hole_evaporation ScienceApe (talk) 17:40, 29 October 2011 (UTC)

Who are trying to quote from that thread? I hope it's not Ariel since what s/he said makes no sense. Dauto (talk) 13:50, 30 October 2011 (UTC)

Ariel mostly yes. He/she might be wrong though, I'll concede that. Still, light is being radiated away even before the singularity has evaporated completely, so that light is going to be red shifted. After reading that discussion again though, it's possible that the mass of the singularity might exceed the mass of the matter that was actually compressed because the gravitational energy of the matter adds to the mass of the singularity. If all the mass is radiated away as photons, it might still equal the mass of the matter that was compressed in the first place even after being red shifted. This is just my guesswork though. ScienceApe (talk) 23:43, 31 October 2011 (UTC)

Alternatively you can simply realize that gravitational redshift is equivalent to a Doppler redshift in which the photon energy is different depending on the observer because the observers are moving relative to each other. Dauto (talk) 18:24, 28 October 2011 (UTC)

You are on a planet with no atmosphere. You throw a rock into the sky. The rock slows down. Where does it's kinetic energy go ? Same place as the photon's lost energy. Gandalf61 (talk) 09:28, 29 October 2011 (UTC)

What if the best lie detectors only worked on people who haven't been tortured?

What if it were possible to use a fMRI scanner to interrogate uncooperative victims suspects as accurately as cooperative victims, but only if they haven't been tortured by their captors?[7] Would making the suspects think that they have returned to their allies help? Dualus (talk) 20:35, 28 October 2011 (UTC)

What if bosses only paid employees who did bad things? Would punching your boss in the nose earn you a raise? Looie496 (talk) 21:32, 28 October 2011 (UTC)

Is that supposed to be analogous some way? Dualus (talk) 22:40, 28 October 2011 (UTC)

I think he's trying to say, "that's a lot of 'what ifs' you've got there." --Mr.98 (talk) 22:43, 28 October 2011 (UTC)

First sentence: then I guess you wouldn't want to torture them, eh? Second sentence: I don't see why that would follow; you just said they didn't need to be cooperative. If you're not torturing them, then it's gravy no matter what they think, no? --Mr.98 (talk) 22:43, 28 October 2011 (UTC)

I don't know why you included the "if they haven't been tortured" part. And I don't know why victims would be uncooperative. The question is somehow confusing. Anyway, I don't believe any mechanical lie detector works better than experienced interrogators, and I don't believe you can extract more truthful information with torture than without it. Quest09 (talk) 01:18, 29 October 2011 (UTC)

Here's an example of a lie detector that actually works. (More like a truth serum, really...) 67.169.177.176 (talk) 03:54, 29 October 2011 (UTC)

Sorry I screwed up the question. Fixed s/victims/suspects/ Dualus (talk) 09:48, 29 October 2011 (UTC)

No you didn't fixed it completely. Why "cooperative victims"? Quest09 (talk) 10:13, 29 October 2011 (UTC)

There is more than that screwed up about the question. You need to consider what the purpose of interrogation and debriefing actually are, what flavour of information you're expecting to elicit from your "subject" and how you're going to validate and corroborate both your subject and any information you elicit from them.

ALR (talk) 09:52, 29 October 2011 (UTC)

Why is that my job? That's what the criminal justice system is for. Dualus (talk) 18:23, 29 October 2011 (UTC)

Your question displays your own bias.

From a practical perspective there is a difference between debriefing and interrogation, although they are complementary. But the point I'm trying to make is that the purpose of debriefing and interrogation is to elicit information from the subject. To do that one must have an understanding of what type of information one is anticipating and as a result identify the most appropriate tools to elicit that.

Incidentally most of the points that I made apply as much to military debriefing and interrogation as the law enforcement environment.

ALR (talk) 20:12, 29 October 2011 (UTC)

How do you think I am biased? Dualus (talk) 00:26, 31 October 2011 (UTC)

Contact lens + eyeglasses?

Does anyone wear contact lenses and eyeglasses at the same time? For example, if their prescription is -14.50 and the contacts go only up to -12.00, roughly what kind of glasses can they wear to produce the same vision? 66.108.223.179 (talk) 21:26, 28 October 2011 (UTC)

I don't know the specific technical question, but yes, lots of people wear both, especially as they get into late middle age and their near vision starts to deteriorate. My mother wears contacts for her distance vision, but needs reading glasses for her near vision. It's not uncommon in that instance. I've never heard of someone wearing contacts and glasses just to up their prescription in one direction, though, but I've never made a study of it. --Mr.98 (talk) 22:33, 28 October 2011 (UTC)

According to Lens (optics)#Compound lenses, the combined focal length of a pair of thin lenses of focal lengths f₁ and f₂ that are separated in air by a distance d is

${\frac {1}{f}}={\frac {1}{f_{1}}}+{\frac {1}{f_{2}}}-{\frac {d}{f_{1}f_{2}}}.$

The diopters given as a lens prescription is the reciprocal of the focal length of the lens, measured in meters. In the case of eyeglasses, the separation between the cornea and the eyeglasses lens is called the vertex distance, which is usually 14mm. So plugging in -14.5 for 1/f, -12 for 1/f₁, and 0.014 (14mm expressed in meters) for d, and solving for 1/f₂ gives 1/f₂ = -2.14. So to get a total of -14.5 diopters when wearing a contact lens of -12 diopters, the eyeglass lens would need to be -2.14 diopters. Red Act (talk) 23:11, 28 October 2011 (UTC)

Yes, i have a classmate that wears glasses and one contact lense because his glasses would tip to the right because of thickness if he didnt use contacts. Meaning his eyes are so messed up. — Preceding unsigned comment added by 203.112.82.128 (talk) 14:23, 29 October 2011 (UTC)

Yes, until earlier this year I used contact lenses of -6.5 with reading glasses of +2. Nowadays I use disposable varifocal contact lenses, so I don't need to carry reading glasses any more. -- Arwel Parry (talk) 14:35, 29 October 2011 (UTC)

Some people wear contact lenses (with diopters) with tinted sunglasses (without dioptres). I for one have not tried that yet, but I would if I could wear contacts more. Also, I have worn contacts with ski goggles, but that's not the same (I normally wear the ski goggles over glasses). – b_jonas 20:44, 31 October 2011 (UTC)

Chlorine trifluoride

What's the best way to fight a chlorine trifluoride fire? According to the article, sand won't work, CO2 won't work, inert gas won't work, fire blankets will just burn right through, foam won't work, halon won't work, and water will just make things worse. (Kinda makes me glad that we don't have to work with this devil's venom at the refinery.) So if none of these things work, what does? 67.169.177.176 (talk) 22:23, 28 October 2011 (UTC)

The advice from the Occupational Safety and Health Adminsitration is pretty much to let it burn. Unruptured containers can be kept cool with hoses but ones that are already burning will continue to do so unless the fire runs out of fuel, which is unlikely (chlorine triflouride is the oxidizing agent, not the fuel). SpinningSpark 22:48, 28 October 2011 (UTC)

The safety sheet I found says much the same. Rather amusingly, it describes it as "non-flammable" (which is technically true - it takes the role of oxygen, not fuel, in the combustion). It doesn't give a great deal of advice on how to put out fires, but concentrates on how to avoid being killed by them and how to stop them getting worse. I would guess that these fires don't last particularly long - once all the chlorine trifluoride has been used up the fire will either go out or it will just be a normal fire and you can put it out in normal ways. In the first aid section, it says that if you get it on your skin then you should use water to wash it off, but you need to use a hell of a lot of it (and keep going for several hours, unless you have some "iced alcoholic or aqueous zephiran chloride solution or Hyamine 1622 solution" that you can apply, although I'm not sure what that does). --Tango (talk) 23:17, 28 October 2011 (UTC)

Wait a minute... If I get this stuff on my skin, wouldn't it set me on fire? After all, according to the article, ClF3 is "hypergolic with cloth, wood, and test engineers", and I definitely fall into this last category. 67.169.177.176 (talk) 01:51, 29 October 2011 (UTC)

That seems to be a direct quote. It seems to react spectacularly with most organic materials, which presumably includes engineers. I'd not recommend trying it to see if it is true... AndyTheGrump (talk) 02:00, 29 October 2011 (UTC)

Yes, I think that's why it reacting violently with the water you use to wash it off is considered worth it - it's going to be reacting violently with your skin if you don't! --Tango (talk) 02:15, 29 October 2011 (UTC)

And once the ClF3 is used up, the excess water will put out the flames. All the same, third-degree burns are very likely in either case. 67.169.177.176 (talk) 03:52, 29 October 2011 (UTC)

Evidently, the answer to the original question, which was what was "the best way to fight a chlorine trifluoride fire" is probably to run like hell, and let someone else deal with it. For an inanimate substance, it seems to have a great deal of malevolence... AndyTheGrump (talk) 05:11, 29 October 2011 (UTC)

Find an agent that acts as neutralizer to fuel for the fire and thus it will go out — Preceding unsigned comment added by 109.224.25.14 (talk) 08:04, 29 October 2011 (UTC)

What is a neutraliser? Plasmic Physics (talk) 08:53, 29 October 2011 (UTC)

I think he/she meant a reaction inhibitor... 67.169.177.176 (talk) 23:58, 29 October 2011 (UTC)

There would be a few safe gasses that would disperse this, eg carbon tetrafluoride or solids that would not react, such as calcium fluoride, or solids that react to form another solid like slaked lime but it is probably safer to let it burn off as it boils at 12° and so will be very hard to contain. Graeme Bartlett (talk) 11:23, 29 October 2011 (UTC)

Do really want to disperse this? I would definitely want to contain the pillage, instead of creating a disperse cloud of highly corrosive gas. Calcium fluoride would only low down the reation, but would not stop it, it doesn't form an air tight seal. Plasmic Physics (talk) 00:29, 30 October 2011 (UTC)

contact lenses

hello there. my friend has said that since (in our area) contact lens prescriptions are incremented in .5 dioptres whilst glasses prescriptions are by .25, when she wears her contacts she has trouble driving at night in areas she doesn't know because she "can't read the street signs until [she] gets right up to the street". She's told me she has a fairly strong prescription (I don't know specifically but having peeked through her glasses I estimate it is at the absolute most -5 and probably more like -3); but would being undercorrected .25 dioptres really cause such a large difference in how well she can see? Or am I wrong in naively subtracting applied prescription from true prescription to find how someone sees? danke. 196.28.228.254 (talk) 23:45, 28 October 2011 (UTC)

I doubt .25 dioptres would make much difference. Since it only happens at night, I'm guessing it's not a simple issue of myopia. There are various conditions that can affect night vision. She should speak to her optician. --Tango (talk) 00:12, 29 October 2011 (UTC)

She should probably speak to her optometrist (who will diagnose the problem), rather than her optician (who will supply the glasses prescribed by the optometrist). Although admittedly, the terminology may vary by country. Mitch Ames (talk) 23:28, 29 October 2011 (UTC)

This is indeed a simple case of myopia. During the day our pupils contract and make focussing less important, just as reducing the lense aperture on a camera increases depth of field. I have a prescription of -4 dioptre for reading and -6 for distance. But during the day I wear my reading glasses all the time, as I can barely tell the difference. But at night wearing my distance specs for driving is absolutely essential. What is interesting is that at night, things don't look blury, they look darker. — Preceding unsigned comment added by 121.215.50.144 (talk) 02:53, 29 October 2011 (UTC)

I can say for a fact that contact lens prescriptions are incremented by .25 diopters from common U.S. sources (e.g. Wal-Mart). This is of course not a law of science - any manufacturer can make either glasses or contacts with any level of difference between them. There are many potential causes for poor vision and we can't diagnose her particular problem (just for examples - astigmatism, pannus, onset of diabetes, vitamin A deficiency, macular degeneration - and that's by no means a complete list; seriously, it's beyond our powers).

October 29

opposite of attraction for black holes

Was more of a thought than a question; with the attraction or gravitation effect of a Black Hole would there be anything that would act as an opposite of this and be forced away from a black hole? an Anti black hole if you like... — Preceding unsigned comment added by 109.224.25.14 (talk) 07:28, 29 October 2011 (UTC)

black hole are cicle in time and like in the univers gravity get flip in time ,thanks water nosfim — Preceding unsigned comment added by 84.229.88.108 (talk) 08:06, 29 October 2011 (UTC)

If only that reply made sense... The only thing that would be repelled by a black hole would be antimass. Plasmic Physics (talk) 08:51, 29 October 2011 (UTC)

No. There is a theoretical object called a white hole which is the reverse of a black hole in some regards, but it's not what you're looking for. An anti-black-hole like you're looking for would presumably have a negative mass, which doesn't appear to exist. Red Act (talk) 08:57, 29 October 2011 (UTC)

What I said. P.S. 84.229.88.108: Little tree be square in funny of sock, but only on Sundays, please hwgprdy. Plasmic Physics (talk) 09:07, 29 October 2011 (UTC)

What about "tachyons" which, in one theory, have imaginary mass. Would they be attracted or repelled? Dbfirs 12:07, 29 October 2011 (UTC)

1. White hole is most likely just another name for a black hole because of time reversal symmetry
2. Everything is attracted to a black hole, even tachyons or negative mass objects (if they happened to exist which they probably don't). If you have negative mass, an repulsive force results on a attractive acceleration. Dauto (talk) 14:44, 29 October 2011 (UTC)

Indeed. As Galileo showed us, acceleration due to gravity doesn't depend on mass. That's true regardless of what the mass is. If you want a black hole that repels things, then you would need the black hole itself to have negative mass. I'm not quite sure how that would work with relativity, though. --Tango (talk) 15:21, 29 October 2011 (UTC)

Black holes can have an electrical charge, and I believe it is theoretically possible for an oppositely charged object to be repelled from a black hole. Looie496 (talk) 15:22, 29 October 2011 (UTC)

Wouldn't it probably have to be charged but massless? (Which doesn't describe any known particle.) Surely the repulsion of the charge is going to be outweighed by the gravitational forces if not. But I am no physicist, and this is well beyond my ken... --Mr.98 (talk) 16:07, 29 October 2011 (UTC)

Black holes have to have |Q| ≤ M in units where the electromagnetic and gravitational force constants are the same. (Otherwise you get a naked singularity instead of a black hole with an event horizon). This means that two black holes can't repel each other, though in the extremal case (|Q| = M for both) they don't attract each other either. But charged elementary particles dramatically violate that bound—for example, for an electron, |Q| / M ~ 10²¹. So an electron can be repelled from a black hole if the black hole's charge is even 10⁻²¹ of the theoretical maximum. -- BenRG (talk) 22:04, 29 October 2011 (UTC)

Antarctic station

what type of Windows and insulation are in the new Antarctic station — Preceding unsigned comment added by 69.5.89.117 (talk) 13:01, 29 October 2011 (UTC)

Which Antarctic Station are you referring to? Do you mean the new, zero-emmision Princess Elisabeth Base built in 2009? Buddy431 (talk) 15:00, 29 October 2011 (UTC)

I'm interested in any information you can get about any of these buildings as far as their insulation and windows the one I was specifically referring to was the big one that was built about five years ago — Preceding unsigned comment added by 69.5.89.93 (talk) 09:52, 30 October 2011 (UTC)

Do you perhaps mean the new Amundsen–Scott South Pole Station? I found this site with lots of information about it, but the only thing I could find about insulation is that it is "insulated to five times the value of the average U.S. residence", which doesn't really mean much. This page mentions that the windows "were tested in CRREL's cold chambers for suitability at Pole's harsh temperatures", but again, that doesn't give much specific information. Buddy431 (talk) 18:59, 30 October 2011 (UTC)

high-rise building

when looking at the large high-rise building like say the twin towers is constructed of mainly glass and steel it does not appear to have any insulation in its walls how is it that they can heat this building in the wintertime without the bills being extremely high and putting a tremendous load on the heating system? Also what type of heating system do they use — Preceding unsigned comment added by 69.5.89.117 (talk) 13:03, 29 October 2011 (UTC)

Actually, a large building will have a smaller surface to volume ratio making it EASIER to climate control. Dauto (talk) 14:15, 29 October 2011 (UTC)

See also insulated glazing. It's pretty much standard these days, at least in cooler climates.--Shantavira|^{feed me} 17:08, 29 October 2011 (UTC)

As noted above, the surface-to-volume ratio of a large building is efficient compared to a smaller structure with a similar percentage of glazed surface, particularly compared to a single-story structure where the roof becomes a major component of heat loss. In most large buildings, even in northern climates, the problem is usually to remove heat from the building in all seasons except deepest winter, due to to presence of people, lights, computers, copiers and other heat sources within. Most large buildings require significant air conditioning in three seasons. The efficiency of insulated glass has steadily improved both in terms of heat retention and solar heat gain rejection. Also, much of the "glazed" area seen in tall buildings is actually opaque spandrel glass concealing structure or above-ceiling space, and is backed by insulation. Wall areas and exterior column surfaces are insulated. Even in the days before significant energy code requirements, insulation was needed to prevent condensation on cold days. Acroterion (talk) 19:30, 29 October 2011 (UTC)

For the purposes of the surface-to-volume ratio, it might be worth defining "large". The shape is as important as the size. A tall skinny building (a "high-rise", per the original question) could well have a higher surface-to-volume ratio than a shorter but more cubically-shaped building. For example, consider a building 100 x 100 x 100 metres. Volume = 1,000,000 m³, surface area of windows (ie excluding floor, ceiling) = 4 x 100 x 100 = 40,000. A high-rise, 50m x 50m base x 300m tall has volume 750,000 but window surface area 4 x 50 x 300 = 60,000. Ie the taller high-rise is smaller in volume but has more surface/window area. Mitch Ames (talk) 23:24, 29 October 2011 (UTC)

Few mid and high-rise office-type buildings (or any other tallish building type) are as deep as 100m; most are more like 30-40m, or 50m at the most for reasons of fire safety, access to light and ventilation, and size of city blocks. Until air conditioning, buildings were cut into smaller sections for light and air, and after air conditioning came into widespread use, few people wanted to be so deep in the interior of a structure. Acroterion (talk) 04:14, 30 October 2011 (UTC)

none of your answers answer my question yes a tall building might be even better than a short glass building I asked specifically about the twin towers there is no insulation in them and the glass is not insulated glazing. Also most buildings used florescent lights which did not produce any heat. In the deepest part of winter which is actually a months long and most northern USA climates do they simply pay tremendous heating costs every month? these buildings have wall to wall glass there is no insulation these are skyscrapers not medium-size office buildings — Preceding unsigned comment added by 69.5.89.93 (talk) 09:38, 30 October 2011 (UTC)

Although it was not obvious from your question that you were specifically interested in the WTC towers, the answers are correct. Although the original WTC did not have insulating glazing (that I'm aware of), their surface-to-volume ratio was still more efficient than an equivalent low-rise structure of similar square footage and construction, and New York is in a climate zone that is somewhat cooling-dominated: additional heating would normally be needed in three months of the year in such a large building in New York. Office buildings generate significant internal heat loads that need to be rejected, and the wall perimeter of any given floor, compared to the floor area, is surprisingly small, particularly for the WTC towers, which had unusually large floors for a tall building. Heating would normally be required only around the perimeter. New York, being a coastal city (and not especially far north), doesn't get extraordinarily cold for long periods, compared to, say, Minneapolis or Toronto. Of course, such large buildings would in fact need a large heating plant, but the cooling plant would be relatively larger. The windows at the WTC were much smaller than might be supposed; they were only 18" wide and there were complaints about their restricted view. The column enclosures (and the columns themselves) were insulated. The WTC's glazing ratio was less than 40%, and probably closer to 20 or 30% when above-ceiling space was accounted for; the columns and their enclosures were much wider than the windows. On a cost-per-square-foot basis, such a large building would probably cost less to heat per square foot than most houses. Since the tenants pay rent per square foot, the heating cost is factored into the rent. Put another way, the 4.5 million square feet of each WTC tower would cost less to heat than the equivalent square footage of 1800 square foot houses with a high surface/volume ratio, which amounts to 2500 houses. Acroterion (talk) 16:58, 30 October 2011 (UTC)

I don't understand why a building constructed of glass and steel would cost the same to heat as a well insulated two-story house — Preceding unsigned comment added by 92.48.194.151 (talk) 16:11, 31 October 2011 (UTC)

If they were of the same size, a well-insulated house to current standards would outperform a structure built to 70s standards without insulating glazing. The point is that they're not the same size: the ratio of surface to volume is radically different. An 1800 sq ft two-story house , square in plan like the WTC, encloses about 16200 cubic feet with a surface area (ignoring attic) of 3060 sf, a ratio of 1.7 (surface area over floor area), or 0.18 (surface area over volume). One tower of the WTC analyzed the same way yields 1,181,440 sf of surface over 4,300,000 sf of floor area for 0.27 surface/floor, and 1,181,440 sf of surface over 59,181,152 cu ft of volume (0.02 surface/volume). 1.7 (house) vs. 0.27 (WTC) for surface/floor area and 0.18 (house) vs. 0.02 (WTC) for surface/volume are almost order-of-magnitude differences. Differences in insulation values attributable to construction methods are more on the order of factors of two or three, not ten. See square-cube law. Add to that the inherently greater efficiency of a large-scale heating plant (for many of the same reasons) over a small-scale residential furnace, and you get comparable or better thermal performance for the larger building. Acroterion (talk) 19:27, 31 October 2011 (UTC)

Car battery

How much stress is the car battery under in this? 86.74.104.61 (talk) 14:18, 29 October 2011 (UTC)

Very little. But if you pressed the wire against the metal continuously, the battery could heat up enough to explode. Looie496 (talk) 15:20, 29 October 2011 (UTC)

Do not try the experiment at home, since the battery might explode or the wire might start a fire. It is difficult to determine the maximum current in the video. It shows two pieces of copper wire, presumably connected to a car battery, being shorted against a piece of iron or steel. What is the wire gauge, and how long are the pieces of wire? That would allow calculation of the resistance of the wire. How is the wire connected to the battery? Wrapping it around the terminal would have greater contact resistance than a proper lug securely connected to the battery, or a solid bolted connection. The bulk resistance of the steel or iron can be ignored, but there will be non-zero contact resistance between the rapidly melting and oxidizing copper wire tip and the iron. While starting a car, the battery is regularly called on to produce a very high current, so a long enough small copper wire with an imperfect contact could limit the current somewhat below that of a solid short across the battery, or even below the "cranking amps" rating of the battery, which might be as high as 600 amps for 30 seconds. Ohm's law says that 12 volts divide by 600 amps implies a resistance of .02 ohms, including the battery internal resistance, the wire, the iron, and contact resistances. Higher total resistance would limit the current to lower. Those little wires shown would likely be quite hot if they had to carry that current very long, but the resistances listed above might limit the current somewhat. It would be a race between the battery overheating and the wire getting too hot to hold. Damage to the battery would be likely in a prolonged short circuit. Edison (talk) 00:50, 30 October 2011 (UTC)

uv400

what does uv400 in sunglass mean? — Preceding unsigned comment added by 92.42.55.187 (talk) 17:23, 29 October 2011 (UTC)

See Sunglasses#Protection for the answer. --Jayron32 17:43, 29 October 2011 (UTC)

how fast is dynamite

If a continuous line of dynamite was laid in a streight line from New york to San Francisco, and then ignited at one end, how much time would the explosion take to reach the other end?190.56.107.76 (talk) 17:30, 29 October 2011 (UTC)

I'm having trouble loading the whole document, but I believe (based on references to it elsewhere on the web) that this document: [8] has linear burn rate data for various explosives; perhaps on page 67? --Jayron32 17:41, 29 October 2011 (UTC)

Based on table of explosive detonation velocities, somewhere between 6 and 9 km/s would be a good guess. Dragons flight (talk) 19:02, 29 October 2011 (UTC)

Note that this of course assumes it actually would propagate linearly down the line. I suspect in real life you'd have the shockwave of earlier parts disturbing later parts and ending the explosive line pretty early on. This is just an intuitive guess, though; I haven't really worked it out. --Mr.98 (talk) 21:10, 29 October 2011 (UTC)

The shockwave/detonation front travels at between two and three times the speed of sound, thus it cannot influence anything ahead of itself. Roger (talk) 21:16, 29 October 2011 (UTC)

I guess my question is whether the detonation front will ignite additional dynamite uniformly, rather than just scattering it. I wouldn't know, but it seems essential to knowing if this would work or not. --Mr.98 (talk) 14:25, 30 October 2011 (UTC)

Dynamite will only explode if it is set off by a blasting cap, otherwise it will just burn. The burn rate of a line of dynamite will vary according to its composition, thickness, the ambient humidity and temperature, etc. In any case it certainly won't be kilometers per second. If you attached a blasting cap to one end, I expect you'd get a localized explosion that would snuff itself out. Looie496 (talk) 23:28, 29 October 2011 (UTC)

Not necessarily -- see detonating cord for an explosive device that propagates the detonation without snuffing it out. 67.169.177.176 (talk) 00:22, 30 October 2011 (UTC)

THIS sounds like a question for Mythbusters! I don't have any personal experience but my thought is that dynamite is a very specific thing which is often confused with TNT. You'd need to define 1st what you meant by "continuous line", do you mean ONE long stick of dynamite? or lots of sticks lined up? or something else? I don't think you could unpack and spill the contents of many sticks of dynamite to make a line and still make it explode, the fact it is compacted and packed in a tube definitely plays a part in the explosion. Similarly to a bullet, if you spill the contents and ignite them they don't go BANG! Vespine (talk) 22:08, 30 October 2011 (UTC)

+1, should be answered by Mythbusters. They don't have those licences for nothing. Dualus (talk) 00:27, 31 October 2011 (UTC)

My own understanding is that the OP meant either something similar to one long stick of dynamite (i.e. something like explosive cord), or else lots of dynamite sticks daisy-chained together in a single continuous explosive train -- the other possibilities are simply implausible from a practical POV. 67.169.177.176 (talk) 23:14, 30 October 2011 (UTC)

Getting rid of dishwashing liquid smell

This may be more of a misc question than a science question, but I guess a good answer requires a bit of chemistry knowledge, so I decided to try here. Due to an unfortunate shopping accident, I had the insides of my favourite rucksack covered in garlic oil. I tried various methods of getting rid of the stuff and found that soaking the rucksack in dishwashing detergent worked wonderfully - only now I have a rucksack that smells pretty strongly of dishwashing detergent, and it seems impossible to get rid of the smell. I expected the smell to evaporate over time, but the whole affair happened three or four weeks ago, I have aired the rucksack as often as possible by turning it inside-out and leaving it on the balcony over night and have rinsed it with water countless times, and the smell hasn't gotten any weaker. So...is there some commonly available cleaning agent or other chemical that is especially good at breaking down whatever it is that makes the dishwashing liquid smell without damaging the rucksack? The rucksack consists of two layers of Gore-tex with a thin layer of foam padding in between (which I guess is where the smell resides). -- Ferkelparade π 18:34, 29 October 2011 (UTC)

There must be eddies that you can't rinse out. Try soaking it and then rinse it out. Dualus (talk) 18:45, 29 October 2011 (UTC)

Most Goretex products can stand up to a washing machine cycle. Normal laundry detergent will be okay. Do not use fabric softener or bleach. I would wash it first through one cycle using detergent, then wash it a second time using just water. I would not use the dryer, but if you do, use the lowest temperature setting.--108.46.103.88 (talk) 18:50, 29 October 2011 (UTC)

Stainless steel soap? ~AH1 ^(discuss!) 19:39, 29 October 2011 (UTC)

That might work for the garlic, but not for the dishwashing liquid. 67.169.177.176 (talk) 00:06, 30 October 2011 (UTC)

Sometimes household ammonia, acetic acid (vinegar), or table salt solution can cut thorough and naturalizes chemical smells. But I think you need a chemist that can home-in on your particular 'detergent' . Which one was it? Is it the added perfume that is lingering?--Aspro (talk) 20:06, 29 October 2011 (UTC)

There is a bit of perfume added to the liquid, but the smell I mean is that typical dishwashing smell...it's difficult to accurately describe smells, but all the various dishwashing liquids I have ever used have shared that same slightly pungent, thick, oily smell that is only partially masked by the added perfumes, and I (probably slightly naively) assumed their composition is always somewhat similar because they smell and feel so similar. For the record, the one I used on the rucksack says on the label it contains "5-15% anionic and amphoteric surfactants, methylsothiazolinones, benzisothiazolinones", plus perfumes and coloriing agents. -- Ferkelparade π 12:07, 30 October 2011 (UTC)

Anionic surfactants are basic and therefore can be neutralized with vinegar. Just make ABSOLUTELY sure to dilute the vinegar solution in several volumes of water per volume of vinegar, or else your rucksack will start stinking of vinegar and then you'll be back to square one. (And make sure to accurately measure and RECORD the amount of vinegar you used, just in case you have to come back here asking for how to get rid of the vinegar smell.) 67.169.177.176 (talk) 21:32, 30 October 2011 (UTC)

This secret medieval tincture, concocted by that bombastic chemist is a time-honoured panacea for garlicky rucksacks, myopia, tinnitus and rigor mortis. It may also be used to achieve cold fusion, antigravitational levitation of smallish pachyderms and accereates neutrinos to superluminary speeds :) --Incognito.ergo.possum (talk) 07:51, 30 October 2011 (UTC)

PS: If you ever get to Prague, may I recommend a pint of Pilsen´s dark Master Brew (18°). Drooool.

I am not going to waste a good bottle of Augustiner on cleaning my rucksack. That would be a sin. On the other hand, liberally applying a couple bottles to myself instead of the rucksack will make me forget about the smell, but alas, I use that rucksack to carry my reading materials to work, and that's a bit incompatible with your suggestion -- Ferkelparade π 12:07, 30 October 2011 (UTC)

Starlight

I suspect the answer exhibits somewhere obvious, but I seem to be having trouble figuring out the right place to look.

What is the total power in electromagnetic radiation delivered to the Earth by astronomical sources not including the sun or reflections from the moon? I'd prefer an answer that sums over all wavelengths, but an answer for just the visible wavelengths would still be helpful. Dragons flight (talk) 20:08, 29 October 2011 (UTC)

Albedo is a good place to start.--Aspro (talk) 20:11, 29 October 2011 (UTC)

How so? To clarify, I'm not really interested in how much radiation is reflected, just in how much is incident on the Earth from external sources. Dragons flight (talk) 20:32, 29 October 2011 (UTC)

In order to reflect, a body has to receive (unless of cause, one is a vampire whose refection does not appear in a mirror). Then just do a bit a little of math which will provided an answer in approximately the right order of magnitude. Isotope heat generation does not account for much on this level.--Aspro (talk) 20:56, 29 October 2011 (UTC)

Earth's outgoing radiation is dominated by Earth's black body radiation (indirectly created by solar heating) with a small amount of artificial lighting thrown in. I don't see how one could ever measure Earth's reflected power from just astronomical sources, and without that, there is no way to use albedo to connect it to incident radiation. Dragons flight (talk) 21:23, 29 October 2011 (UTC)

I'm not sure but I think you have to add luminosity#In astronomy from the Tully–Fisher relation to the cosmic background radiation, and maybe the blackbody radiation of the interstellar medium if that's not already in there. Good luck! Dualus (talk) 20:43, 29 October 2011 (UTC)

I am not sure what you are trying to tell us but the cosmic backgroud radiation at 2.725 K results in (Stefan-Boltzmann constant)*T⁴ = 3.127*10^-6 W/m² (that's already the correct value: Imagine a ball of 1 m radius in equilibrium with the cosmic background radiation. It will radiate the same amount as it receives, and that is 4*π times the value I gave you, and its surface is 4*π square meters). Comparing with the Sun's irradiation of 1367 W/m² and the Sun's apparent magnitude, that should effectively result in an apparent magnitude of the cosmic background radiation of about -5.14. Adding to that the -5.71 I calculated below, we are at about -6.21 in total. Icek (talk) 14:11, 30 October 2011 (UTC)

You could try looking in some solar power articles. They might have the total available for recovery by solar cells... 71.202.97.70 (talk) 23:02, 29 October 2011 (UTC)

According to apparent magnitude, the total integrated magnitude for the night sky is -6.5. There is no reference for that statement, so I'm not sure how reliable it is and I'm not sure what is included in it. -6.5 corresponds to about 1/370 times the brightness of the full moon. --Tango (talk) 23:44, 29 October 2011 (UTC)

From "adding" the apparent magnitudes in the table in that article (although especially for the brighter magnitudes where there are smaller numbers of stars the actual "average" apparent magnitude is different from the stated magnitude) I get about -5.71, but that's only up to magnitude 10. Icek (talk) 14:00, 30 October 2011 (UTC)

Given the precision we're working to here (different wavelengths, inclusion of planets, etc.), I think it's fair to say those two figures are in agreement. --Tango (talk) 15:58, 30 October 2011 (UTC)

Earth's Energy Resources talks about "extra-solar radiation", but doesn't define it. It gives an average of 121 watts/m² on page 23, plus some mysterious figures in graphs on preceding pages, if that's any help. Clarityfiend (talk) 03:31, 30 October 2011 (UTC)

It also says that all of it is absorbed in the atmosphere and drives wind currents and the ocean temperature gradient (at an abysmally low efficiency, like most energy conversion processes). 67.169.177.176 (talk) 06:33, 30 October 2011 (UTC)

The value of 121 W/m² is obviously far too high, they mean something like the radiation scattered from the atmosphere or whatever. Icek (talk) 13:57, 30 October 2011 (UTC)

There is also this PDF from brillianz.co.uk, which says that starlight is about 0.00005 lux, compared to 32,000 to 100,000 lux for sunlight and 1 lux for moonlight. Lux is a summation of all visible wavelengths, so in conjunction with the solar constant you should be able to work out the power of starlight. --Heron (talk) 09:52, 30 October 2011 (UTC)

So the ratio is about 1.3 billion? Dualus (talk) 23:11, 30 October 2011 (UTC)

Yes, that's the right order of magnitude. --Heron (talk) 10:15, 31 October 2011 (UTC)

Calculating probabilities

Let's say I take a tree, for example, a horse chestnut, with those big dark buds that supposedly look like horses but really don't. Remember those, they'll be important later. Anyway, I get this tree, growing quite happily in a big pot, on a windowsill, inside so it is reasonably warm if not hot or sunny. It's February, let's say the whole first week of the month, so the tree is bare of leaves, just a couple of branches and say a dozen of those big leaf buds.

Now, I look at this tree on February 1st, and I choose out of it two randomly picked leaf buds on the plant, I do nothing to them, I just leave it on the windowsill for a few days. What are the chances that both those two buds, and no others, will be opening with newly grown leaves inside within that week?

Obviously it would not be possibly to work out the exact number, but some sort of rough estimate, an order of magnitude, would it be, for example, 50:1, 10,000:1, 70,000,000:1? Anyone got any sort of idea? Myself, I could not even begin to work out how to calculate this, not without an extensie survey of many trees across the country, but perhaps someone here knows better.

148.197.81.179 (talk) 21:15, 29 October 2011 (UTC)

If you were certain that exactly two buds out of the twelve would open within a week, then the odds against them being exactly the two you chose is 65:1. You need to multiply this 1 in 66 probability (choosing 2 from 12) by the probability that exactly two buds will open within a week. Someone here might know whether horse chestnut is more sensitive to temperature than to length of day. If it is (as for Oak) then the temperature in the room and the amount of sunshine through the window will determine this latter fraction. If light is the main determining factor (as it is for Ash) then the buds are not likely to open until April, so your second fraction is very small and the odds correspondingly large (perhaps a million to one?). If the warmth of your windowsill brings bud-opening forward by a month or two, then perhaps it will begin in one of the eight weeks before April, so the second fraction might be one eighth, giving total odds of 527 to one against (i.e. a probability of 1 in 528). Please note that these figures are not accurate because there are too many variables to make reliable predictions. Dbfirs 22:03, 29 October 2011 (UTC)

You'd be better off in this sort of situation running actual experiments to figure out what the probabilities might be. There are a lot of variables involved, but if you did it was a few hundred plants over a long period of time, you'd probably end up with fairly good "rough" statistics on it. Doing it from first principles is probably the most problematic approach, especially when one doesn't really know for sure what variables actually matter the most. --Mr.98 (talk) 03:28, 30 October 2011 (UTC)

Agreed, and, of course, if you observe the behaviour of your windowsill tree this coming February, you will have a much better chance of making a reasonable estimate for the following year. Dbfirs 06:40, 30 October 2011 (UTC)

By the way, the word "horse" doesn't come from the supposed resemblance of buds to horses, but to distinguish its fruit from the edible sweet chestnut, the idea being that "horse" = horses might eat them but humans wouldn't. --TammyMoet (talk) 09:24, 30 October 2011 (UTC)

Which is ironic, because we were always warned not to let our horses eat horse chestnut, because it's poisonous to them. It was one of the short list of common and dangerous plants in the UK that our instructor made us learn. Not as bad as yew (an inch could kill a horse, we were told) or ragwort. 86.163.1.168 (talk) 16:05, 30 October 2011 (UTC)

The smell of winter

Everytime winter comes around, sometimes as soon as early October, there's this wintry smell in the air, that stays until spring. Every year it's the same sort of smell. I've experienced it on two different continents and in three different countries. Does anyone else know what I'm talking about? What's causing it? What's the scientific explanation? Thanks in advance! ElMa-sa (talk) 21:42, 29 October 2011 (UTC)

Perhaps decaying leaves? Dbfirs 22:05, 29 October 2011 (UTC)

many plants and soil types give off distinctive odors which vary with changing weather conditions. The smell of damp earth, falling leaves, nuts and fruits. I'm guessing that all three locations had similar plant and soil conditions. giving the same type of odors.190.56.105.233 (talk) 22:24, 29 October 2011 (UTC)

Relevant articles about a similar effect when it rains are petrichor and geosmin. Dbfirs is probably onto something with the decaying leaves which will contain Streptomyces that produce geosmin. Another idea would be that you are noticing a lack of summer smells - this lists many smells associated with summer, so maybe once those have gone, you are left smelling everything else. SmartSE (talk) 13:57, 30 October 2011 (UTC)

Humans have about 1,000 different kinds of olfactory receptors, almost all of which attenuate. Dualus (talk) 15:31, 31 October 2011 (UTC)

If you are talking about the soft musky smell, that's probably what the people above me said. However, I also notice a tingling metallic smell during winter, usually a few days before it starts to snow. Now, I don't have a scientific background so I'm not sure, but I believe that smell is ozone. Something in the change in atmosphere causes it to heap up near the ground, allowing us to smell it.212.123.1.140 (talk) 12:35, 31 October 2011 (UTC)

October 30

botany

i ask question about photo pared that the short day plants cannot give the flower in long day & long day plant cannot give flower in short day. question is that in the gardens whole night the light provide for the garden beauties in whole day also the sun light are available but in spring season the plant in garden give the flower with. There is no effect are accrue with light but in books says that light effect flowerings.(HAROON UR RASEED OF PK.MARDN) — Preceding unsigned comment added by Haroonmuskan (talk • contribs) 04:50, 30 October 2011 (UTC)

If I have understood your question correctly, the answer is that plants are not sensitive to light itself, but to sunlight, which has its own spectrum. If the artificial lights are "full spectrum" lights, then the plants will respond to them. If not, they won't be affected. See Full-spectrum light and Gardening under lights. --TammyMoet (talk) 09:22, 30 October 2011 (UTC)

Note that it's not the full spectrum of lights that is thought to cause the short day/long day effect, but rather specific wavelengths, primarily in the red end of the spectrum [9]. Short day and long day plants have phytochromes which are sensitive to the red end of the spectrum, and they're the one used to regulate photoperiodism. - For the gardeners, the key to enure flowering is to avoid too much red light during the night for short day plants, and to provide sufficiently large amounts of red light during the day for long day plants. Note that the light provided doesn't have to actually look red to work, the red wavelengths in white light work just as well, which is why full-spectrum artificial lights (and sunlight) work. Note also that the reliance on red light is only for photoperiodism - other plant processes, like photosynthesis, need other wavelengths of light as well. -- 174.24.217.108 (talk) 18:11, 30 October 2011 (UTC)

Photon as source of gravity

Do photons have a gravitational field around them ? Suppose a bunch of photons whizz past some uncharged particle like a neutron or anything with mass, will the mass be deflected or attracted to the photon? The photon itself will change course due to the gravitational field of the particle (neglecting electromagnetic, weak and strong interactions). So to conserve the total momentum, I assume, the particle will also move. 117.231.72.65 (talk) 12:41, 30 October 2011 (UTC)

Yes, the photon will have its own gravitational field. The photon has energy, which is equivalent to it having mass (E=mc²), so it has the same kind of gravitational field as anything else with mass. I don't think you could have a one-way gravitational interaction - if something can respond to a gravitational field then it also creates a gravitational field. --Tango (talk) 13:42, 30 October 2011 (UTC)

yes, anything that has any of the following: energy, momentum, pressure, or stress, will produce gravity. Dauto (talk) 14:02, 30 October 2011 (UTC)

Yes; however, the gravitational field of its probability density function point cloud is so wide as to make it useless for predicting the outcome of gravitationally influenced events except in the most extreme boundary conditions. Dualus (talk) 23:13, 30 October 2011 (UTC)

Buying electronic components

If you buy some resistors, transistors or any other small electronic components, will some online shop send them through the normal post? Or do you have to pay relatively huge delivery costs for a component which only cost some cents (probably)? 88.9.210.218 (talk) 13:48, 30 October 2011 (UTC)

A lot of places charge relatively high postage and packing for small orders, while offering free delivery on much larger orders. I've recently bought some stuff from Bitsbox (in the UK) which sent them through the Royal Mail first class for only £1.50, but didn't give much information on the specs so it isn't really an option if you need the datasheet or anything particularly unusual. Places with more detailed information and wider choice tended to add more p&p. So, it depends on whether you're doing something basic that just needs a few cheap resistors and LEDs with vague properties, or whether you're doing more delicate work where you need to keep accurate track of voltage and current. (I got my batteries from Amazon, which was far cheaper than anywhere else) 86.163.1.168 (talk) 15:59, 30 October 2011 (UTC)

On ebay there are many component sellers, many with free postage via normal post. You will find that the minimum purchase is perhaps 10 items for around a dollar, or 1000 items for $10. Some places such as Hong Kong or Singapore have cheap postage. You will not be able to pay less than the cost of posting a small packet.

Solar System

Is it possible that there are more than 8 planets on our solar system? or it has two suns? Do we know all the Big heavenly bodies thats rotating around the Sun? Is there any Papers written regarding this issues? — Preceding unsigned comment added by 203.112.82.128 (talk) 21:56, 30 October 2011 (UTC)

Wikipedia is a good place to start.--Aspro (talk) 22:01, 30 October 2011 (UTC)

Extra planets are possible but not likely. An extra sun would have already been found if it existed. Dauto (talk) 22:14, 30 October 2011 (UTC)

The possibility of extra planets in the solar system depends on your definition of "planet". 67.169.177.176 (talk) 22:55, 30 October 2011 (UTC)

If there were any other large bodies near the other planets, then we would able to detect the effects of its gravity on those planets. It is possible there are some large bodies out in the Kuiper belt or Oort cloud, though. See Nemesis (hypothetical star) and Tyche (hypothetical planet) for a couple of theories (although they aren't considered very likely to be true). --Tango (talk) 22:23, 30 October 2011 (UTC)

I asked because cracked.com says its one of the things science has no asnwers yet. — Preceding unsigned comment added by 203.112.82.128 (talk) 22:26, 30 October 2011 (UTC)

You appear very familiar with Wikipedia. Why are you asking these things here, instead of using this encyclopedia yourself? Do you want to be spoon fed?--Aspro (talk) 22:30, 30 October 2011 (UTC)

I agree with the OP that this is really not a polite or useful response. Please keep in mind the "be polite" guideline for people answering questions. The entire point of the Ref Desk is to help people with questions, not just say "look on Wikipedia" without providing any guidance as to where to look. --Mr.98 (talk) 23:44, 30 October 2011 (UTC)

Thanks!

Maybe because its possible that im not able to get the answers on my own, so im asking some wikipedians who i believe is more knowledgeable than me to provide some answers or atleast refer me to articles that can give me answers, im sorry if i wasted your time reading and answering my questions. — Preceding unsigned comment added by 203.112.82.128 (talk) 22:54, 30 October 2011 (UTC)

The definition of what constitutes a planet has recently been called in to question, so the number of planets has become controversial and indeterminate in the exact. Dualus (talk) 23:15, 30 October 2011 (UTC)

Take a look at the links that Tango gave; they are probably the sort of thing they were referring to. When you talk about things orbiting WAAAY out from the Sun (e.g. tens of thousands of astronomical units, where an astronomical unit is the distance from the Earth to the Sun), there is a lot of uncertainty as to what is out there. There isn't a lot of evidence to suspect there being a large planet or small sun out there, but apparently it's not totally impossible that one could be hiding in all the noise. --Mr.98 (talk) 23:43, 30 October 2011 (UTC)

We know that the mass of the Oort cloud is probably much larger than people thought it was thirty years ago. Dualus (talk) 04:05, 31 October 2011 (UTC)

See Nemesis (hypothetical star) for your second sun (which as indicated is just speculation). See Eris (dwarf planet) for what by right might be another planet; more generally planets beyond Neptune. Wnt (talk) 03:33, 31 October 2011 (UTC)

Non-stiff motorcycle/bike helmets

Do helmets have to be stiff? It's clear that they have to protect against penetration of pointed objects and against abrasion, but couldn't they be just made of thick Kevlar covered by small pieces of hard plastic (but without forming a stiff ball)? — Preceding unsigned comment added by 88.9.210.218 (talk) 23:42, 30 October 2011 (UTC)

I think the MAIN thing they protect against is impact, not abrasion or penetration. For impact, stiff is definitely better. Vespine (talk) 00:15, 31 October 2011 (UTC)

I am not sure you are right about stiff being better. Stiff is often better because most soft materials won't distribute the impact force, But, wouldn't Kevlar protect against impact too? It seems to me this material is fantastic at distributing the force of the impact. 88.9.210.218 (talk) 00:20, 31 October 2011 (UTC)

Kevlar IS stiff AND already used in Kevlar#Armor including kevlar helmets; There is kevlar weave which is maybe what you are thinking of, such as used in Sailcloth#Kevlar and also now popular now in motorcycle clothing, but that is almost purely for abrasion protection, not impact resistance, so won't make a good helmet. Vespine (talk) 01:44, 31 October 2011 (UTC)

This is true.. while you could probably make a pretty good helmet out of kevlar weave- and it could work for multiple impacts- it would have to be pretty damn heavy. Stiff materials tend to be pretty kick ass for cheap, compact, one-use applications like motorcycle helmets and hardhats. Nevard (talk) 06:59, 31 October 2011 (UTC)

This brings to mind the classic 'hairnet' bicycle helmets from 30+ years ago. The article claims "This offered acceptable protection from scrapes and cuts, but only minimal impact protection". Remember that part of the point of a helmet is not just to distribute a force or withstand an impact, but to collapse on impact thus reducing the acceleration forces on the brain; something like polystyrene can do this well, while being very lightweight for its volume, necessary properties in a helmet. --jjron (talk) 14:50, 31 October 2011 (UTC)

October 31

Colliding black holes

So I was wondering what it would be like if two black holes collided and so I decided to search YouTube which is where I go for most of my astrophysics animations. I found [10], [11], [12], [13], [14], and [15]. Which do you think most accurately depicts colliding black holes? Dualus (talk) 00:25, 31 October 2011 (UTC)

The second one is definitely the best of them all. The first one isn't very good (low resolution). The third one is a galaxy collision (nice graphics). The fourth one like the first has low resolution. The fifth one has only a very brief scene of a simulation (most of the time is taken showing interviews). The last one also has very good graphics, it shows the collision of neutron stars (with the eventual formation of a black hole as a result). In short, the second video is clearly the best choice. Dauto (talk) 02:22, 31 October 2011 (UTC)

I think the last one may be the best, but I haven't decided yet. Dualus (talk) 04:34, 31 October 2011 (UTC)

The last one is showing the collision of neutron stars. That's not the same thing as the collision of black holes which is what you were asking about. I agree that it shows an interesting simulation but it is slightly off topic. Dauto (talk) 14:34, 31 October 2011 (UTC)

Well, a black hole is produced, so in a way it's like when we say "a tree collision" we mean the tree even if it isn't there anymore after the collision. Dualus (talk) 20:22, 31 October 2011 (UTC)

Scientific integrity

Recently I was reading http://scienceprogress.org/2011/10/overdue-and-underdone/ on the White House Office of Science and Technology Policy scientific integrity initiative. I have questions:

1. Will scientific integrity in the Environmental Protection Agency mean fuel synthesis? I.e., http://windfuels.com + http://www.greentechmedia.com/articles/read/guest-post-kicking-oil-addiction-permanently-with-windfuels/ + http://www.pnas.org/content/early/2009/06/19/0904101106 + http://dodreports.com/pdf/ada530365.pdf + Wind power#Economics + http://www.dtic.mil/cgi-bin/GetTRDoc?Location%20=U2&doc=GetTRDoc.pdf&AD=ADA299090 + http://www.youtube.com/watch?v=fiK5-oAaeUs#t=10m00s + http://www.youtube.com/watch?v=ocBBrYYYYqg + http://www.youtube.com/watch?v=TlRavcMZpX4 + http://www.youtube.com/watch?v=Cjf3gRq32eo ?
2. Will scientific integrity in the National Institutes of Health mean single-payer health care?
3. Will scientific integrity in the Office of Management and Budget mean more progressive taxation and an end to tax havens?

Dualus (talk) 04:34, 31 October 2011 (UTC)

I am unable to understand your question. Perhaps you could explain your question better please? Dmcq (talk) 07:17, 31 October 2011 (UTC)

Answer to 1.,2.,3.: NO. From the article you linked to: "the focus appears mostly on ensuring the proper conduct of agency scientists." It does not imply to follow a specific policy. 88.9.210.218 (talk) 09:30, 31 October 2011 (UTC)

I suggest you read the definition of integrity (the first one on that page is the one being used here). You seem to have be misunderstanding the word. --Tango (talk) 20:16, 31 October 2011 (UTC)

Firecracker pollution

What chemical residues do firecrackers leave in the air and on the ground? What effects do those residues have on the natural environment? How do city street cleaners dispose of these chemicals?
—Wavelength (talk) 04:50, 31 October 2011 (UTC)

On the ground they mainly leave paper. In the air you will find sulfur dioxide, carbon dioxide, potash and smoke. Graeme Bartlett (talk) 05:01, 31 October 2011 (UTC)

...Which are all found naturally in the environment, (excluding the paper) and since they are suspended in the air, they are readily dispersed and diluted. Plasmic Physics (talk) 10:58, 31 October 2011 (UTC)

Fireworks#Pollution discusses pollution from fireworks. In the context of my three questions, are there important differences between firecrackers and fireworks?
—Wavelength (talk) 16:50, 31 October 2011 (UTC)

Qualitatively, not much at all. The difference is purely quantitative; its a rather large quantitative difference, maybe on the order of 2-3 orders of magnitude given that a firecracker weighs a few grams at most, and some fireworks can exceed a kilogram. --Jayron32 17:56, 31 October 2011 (UTC)

Dubois and Fernholz

I noticed some red links at Nutrition#From_1900_to_the_present:

"Eugene Floyd Dubois showed that work and school performance are related to caloric intake. In 1938, Erhard Fernholz" discovered Vitamin E. Dualus (talk) 06:22, 31 October 2011 (UTC)

Does anyone know anything about Dubois and Fernholz? Does anyone know who discovered magnesium is vital? Dualus (talk) 06:22, 31 October 2011 (UTC)

There's lots online about Dubois, e.g. [16][17]. Fernholz is a little less well-known, but there's still information if you Google. He seems to have mysteriously disappeared in 1941.[18][19] --Colapeninsula (talk) 14:05, 31 October 2011 (UTC)

Australia's beaches

Australia seems to have a much higher proportion of its coastline adorned with sandy beaches than any other landmass. (I haven't been able to find figures, but there seem to be many thousands of miles of sand. It even has the world's largest sand island.) Is this true and is there something about its geography that predisposes it to endless beaches? I couldn't find anything in the relevant articles.--Shantavira|^{feed me} 09:10, 31 October 2011 (UTC)

As an Aussie I've wondered the same thing myself. (And yes, we do laugh at those rocky places called beaches in Europe.) My suggestion is that it would be somehow related to the fact that Australia is one of the oldest land masses on Earth, and/or has been largely unaffected by glaciation. HiLo48 (talk) 09:27, 31 October 2011 (UTC)

You may laugh at our beaches, but at least we don't have quite such an unnecessarily malevolent fauna. Equisetum (talk | contributions) 10:32, 31 October 2011 (UTC)

I have been told by several Australians that there aren't ANY sandy beaches in Britain. This seems to stem from Aussies who stay in London and hop on the train to Brighton, which has (unusually) a pebble beach. My two childhood favourite British sandy beaches are Whitsand Bay in Cornwall and Oxwich Bay in South Wales. There are many, many others besides[20]. Alansplodge (talk) 13:49, 31 October 2011 (UTC)

Maybe it is related to its many coral reefs? Plasmic Physics (talk) 10:22, 31 October 2011 (UTC)

My brief visit to Australia a while ago, left me with the impression that the whole landmass is almost entirely composed of sand. Most of the exposed rocks I saw appeared to be sandstone and the soil seemed to have plenty of sand content too. This is a completely arbitary observation and I wait to be shot down in flames by someone better acquainted with Australian geology. Alansplodge (talk) 11:50, 31 October 2011 (UTC)

I can think of several contributing factors. Reflecting some other comments, Australia has had relatively little impact by geological processes (mountain formation, volcanism, etc) for hundreds of millions of years making it's exposed rocks and soils very ancient, fragile, and easily eroded. Being the world's driest continent (excluding Antarctica) also contributes to the sandy soils. Additionally it is very flat (again significantly related to the lack of geological activity) making it more susceptible to beaches, compared to say more mountainous coastlines that plunge steeply down into the sea, although we do see that in some parts of Australia (consider the Great Australian Bight for example). It's also been quite exposed to oceanic erosion for a long time, having separated from what was left of Gondwana as much as 80MYA, and having existed as an island ever since. The coastline is also reasonably open and exposed, i.e., long open coastlines tend to be more sandy compared to say coasts with lots of little bays and inlets. I kind of like the coral reef suggestion too, but I'm not sure Australia has relatively greater reefs than elsewhere to make that a reality. --jjron (talk) 14:39, 31 October 2011 (UTC)

Quote from the article Geology of Australia: "A thin veneer of mainly Phanerozoic sedimentary basins cover much of the Australian landmass (these are up to 7 km thick). These in turn are currently undergoing erosion by a combination of aeolian and fluvial processes, forming extensive sand dune systems". Dauto (talk) 14:46, 31 October 2011 (UTC)

Accurate test for mercury poisoning

When I was in school (about 12 years ago) I played with some open mercury a few times not realizing the danger - I might have breathed in quite a bit. I'd like to undergo a test to see if my body still has excess levels of mercury but doing a search on the internet there seems to be a lot of scams out there, with most types of test being disputed (including hair test and chelation challenge). Is there a kind of test that I can request at my GP or a hospital that is generally considered accurate in the medical world? 41.164.7.242 (talk) 10:34, 31 October 2011 (UTC) James

Have you read mercury poisoning? I think that mercury is automatically removed from the body, since it is naturally present in very small amounts in certain food anyways. I don't think that you would find any mercury above background levels. Just a note, don't decide whether or not to have any medical tests done based on coments made on Wikipedia. If you are genuinely considering this, then you should ask a professional. Plasmic Physics (talk) 10:47, 31 October 2011 (UTC)

I always thought mercury was not automatically removed from the body, quite in contrary. I was sure it bio-accumulates with time. Quest09 (talk) 13:58, 31 October 2011 (UTC)

Mercury poisoning#Diagnosis discusses diagnosis. The reference desk does not offer medical advice, so if you are worried about mercury poisoning, you should consult a doctor. --Colapeninsula (talk) 14:13, 31 October 2011 (UTC)

If someone plays with elemental mercury, as in a thermometer, there's not much danger. As our article says: "Quicksilver (liquid metallic mercury) is poorly absorbed by ingestion and skin contact. It is hazardous due to its potential to release mercury vapor." What it doesn't say is that the amount of mercury that becomes vapor at room temperature is negligible. This would only be a concern if someone worked with mercury at elevated temperatures, or over many years, or were reacting it with other chemicals. StuRat (talk) 17:22, 31 October 2011 (UTC)

Hence, for example, Mad hatter disease. {The poster formerly known as 87.81.230.195} 90.193.78.35 (talk) 18:39, 31 October 2011 (UTC)

The whole point of doctors is that they know how to treat you. You don't need to find out what test you need and then ask for it. You just go to the doctor and let them decide what tests you do (or don't) need. --Tango (talk) 20:13, 31 October 2011 (UTC)

Scientist who controlled a bull's brain

Who was the scientist who implanted an electric device in a bull's brain, rigged up a remote control, let the bull charge at him, and made the bull stop just before hitting him?198.228.194.215 (talk) 11:49, 31 October 2011 (UTC)

First result for a Google search of "science who controlled a bull's brain" for me is [21] which says José M.R. Delgado. Come on, you could have done that. --Mr.98 (talk) 12:25, 31 October 2011 (UTC)

Interesting, I wonder if the operating principle of Delgado's stimoceiver is the same as that employed in the God helmet, only with wires in the case of the stimoceiver and less-invasive fields in the case of the helmet. 20.137.18.53 (talk) 12:47, 31 October 2011 (UTC)

On You Tube here, or so it seems.--Shantavira|^{feed me} 15:44, 31 October 2011 (UTC)

This stuff was seriously overhyped. What Delgado actually did was to implant electrodes into a part of the brain where electrical stimulation causes an animal to turn sideways (the basal ganglia). When the bull would charge at him, he would activate the stimulator, and the bull would veer off to the side. It was not really very sophisticated, but it got huge press at the time as an example of "mind control". Looie496 (talk) 17:09, 31 October 2011 (UTC)

Sounds like it influenced the minds of journalists at least a little. :) I wonder if it (the publicity stunt) ended up loosening any funding dollars his way. 20.137.18.53 (talk) 18:14, 31 October 2011 (UTC)

Identify large structures

See advert on http://content.yudu.com/Library/A1u4hi/HLPFISeptOct2011/resources/49.htm (Heavy Lift and Project Forwarding International, Sept/Oct 2011, p.47 (enter p.49-49 - Goldhofer advert) - there are two structures - the scale of which leaves me blank as to what they are? Anyone know (thanks in advance)Imgaril (talk) 16:43, 31 October 2011 (UTC)

They look like sections of an offshore production platform (for oil and/or natural gas). In the photo they're shown on their sides - the same photo also appears on Goldhofer's offshore applications webpage. It's modern practice to build complex offshore systems in modules, with all the equipment, wiring, pipework etc. prefabricated. -- Finlay McWalterჷTalk 20:08, 31 October 2011 (UTC)

Yes, so it never occurred to me they were on their sides for some reason - I'm not familiar at all with the oil industy - but I guess they must be some sort of Spar (platform) - http://www.globalsecurity.org/military/systems/ship/platform-spar.htm has a diagram deep link image for same site.

Still the ones I linked look really big to me - larger than Brent Spar (and until today I never realised "Brent Spar" was a "spar" - I just thought spar was some obscure geological term they'd decided to use in naming the thing.)

Thanks.Imgaril (talk) 21:32, 31 October 2011 (UTC)

Florida building code

why is it that in Florida the building code is so lax when it comes to insulation I read that in new construction is only required to have r-5 insulation that is just mind-boggling to me. Why is this? In most other states next to them like Georgia and South Carolina they have much stricter building code and require the homes to be well insulated and have vinyl double pained windows also other hot states like Nevada and Arizona also require good insulation — Preceding unsigned comment added by 92.48.194.151 (talk) 16:24, 31 October 2011 (UTC)

You're looking at how hot the states get, when you should be looking at how cold they get. Being surrounded by water, it rarely goes below freezing in Florida (except for the panhandle). So, I'd compare with Hawaii building codes. And, while insulation also helps with air conditioning in summer, it rarely gets more than about 20° F warmer than you'd want, in most of Florida, so insulation isn't much needed for that. StuRat (talk) 17:13, 31 October 2011 (UTC)

20° is actually a big difference it regularly gets up to 100° in South Florida and In North Florida they can actually get fairly cold in the winter. Florida's climate is only slightly different than the climate for a place like Nevada or South Carolina and they have much stricter building codes for example in Nevada the state actually recommends r-20 in walls and r-40 in attics that is a huge difference to r-five. I have some friends in South Florida and they tell me they pay 3 to 400 a month air conditioning and 200 a month for heating in the winter obviously those bills would be much lower with proper insulation and its ridiculous in this day and age that the state would not ask for higher insulation values — Preceding unsigned comment added by 92.48.194.181 (talk) 17:27, 31 October 2011 (UTC)

20° F is a tiny difference, compared with many places where temps get down to 100° F colder than you'd want. As for Nevada, I find temperature ranges of -50° F to +125° F, versus -2° F to +109° F in Florida, or a 175° F range versus a 111° F range, at this site: [22]. And, of course, this includes the panhandle. If you only look at the peninsula, then temperature ranges are even less. For example, according to our Climate of Miami article, the temperature range in Miami is +24° F through +100° F. So, state-wide codes don't make much sense, they need different codes for the panhandle and peninsula. StuRat (talk) 17:39, 31 October 2011 (UTC)

you have ignored the huge heating and cooling bills these people have clearly they could benefit from better insulation — Preceding unsigned comment added by 92.48.194.188 (talk) 17:52, 31 October 2011 (UTC)

Well, everyone could benefit from more insulation, it's just a question of whether the large upfront cost of insulation will be returned in a reasonable period. The figures you quote are meaningless without knowing the size of the home, form of heating, what temperature they keep the home, etc. Another factor in Florida may be that many homes there are "summer homes", so not heated much in winter, when insulation would be most beneficial. There may also be a political reason, with many Floridian voters being Republican, and Republicans wanting less government regulation. StuRat (talk) 19:49, 31 October 2011 (UTC)

Windows of buildings: Europe vs. US

Why are they different? In Europe they are often tilt turn windows, which offer the option of being opened either tilted in vertically or pivoted horizontally, all from a single handle; and in the US they slide like a guillotine. Quest09 (talk) 16:30, 31 October 2011 (UTC)

I'm not sure it's such an even division. In houses in the USA, a sash window (your guillotine) is common, but in many other contexts, the casement window (your hinged window) is not at all unheard of. Our window article implies that sash windows are common in UK countries and former UK colonies, and says casements are more popular specifically on the continent, but even then I can't wonder if there's a lot of variation being concealed there. In any case, it seems like this is just differences in architectural styles and not much else. You can certainly get both types of window in your average American Home Depot. --Mr.98 (talk) 16:48, 31 October 2011 (UTC)

I've never seen (or at least, never noticed) a new sash window in the UK, though I've seen a lot of old ones (from Victorian era to maybe 1960s). My answer is "fashion". I guess the UK adopted continental windows at about the same time as discovering the merits of the continental quilt.  Card Zero  (talk) 20:32, 31 October 2011 (UTC)

As for why there is a choice, it has to do with purpose. Assume you require a screen on the outside of your window to keep things like mosquitoes out. If your window tilts or twists outward, it will hit the screen and cause a problem. Now, assume you don't need a screen, but you get a lot of rain. You want to be able to open your window in the rain without having it continuously sprinkle inside. A window that swings out, directing the water outward, is preferable to one that just slides up. So, when building a house, a good designer will consider the use of the window when picking the design of the window. Unfortunately, I suspect they just get whatever is on sale. -- kainaw™ 16:56, 31 October 2011 (UTC)

You simply put the screen inside the window to fix this problem. Of course, this means you can't push the window open and pull it closed manually, so some type of crank is used for that. This does make the window more complicated, and thus more prone to failure, however. Also note that large panes really aren't suitable for tilting, as the forces on the hinges are too high and windows which tilt up or down would also tend to sag out of the frame (the weight also makes raising vertical windows difficult, but this can be countered with springs and even electric motors). StuRat (talk) 17:08, 31 October 2011 (UTC)

These days it comes down to tradition and people's expectations of what's right for their house. Going back 100 years or so, in North America screens were fitted outside the sashes in summer and storm windows in winter, in wood frames. There was no crank hardware on outward-opening casements, for the most part, just a simple retainer bar, and inside screens were highly unusual and cumbersome. Most sashes were double-hung, so the upper sash could be opened to let hot air near the ceiling out, on the same principle as the operable transoms often found over doors in the 19th and early 20th centuries. Nowadays nobody has transoms or uses the upper sash, and screens are permanent and storm windows used only on older houses, but everybody has developed an expectation that windows should look the same. The only remaining reason for single or double-hung sash windows is that they take up no extra room when open. Europe doesn't seem to use screens or storm windows as much, using shutters to a much greater degree. Tilt/turn windows open inwards, by the way, so you have to leave room for the swing of the window. Tilt/turn windows solve almost all the problems and perform all the functions of double-hung sashes, but unfortunately haven't caught on in North America. Acroterion (talk) 20:50, 31 October 2011 (UTC)

Adhesive connecting painted wood and Styrofoam

I put Styrofoam sheets in windows of storage rooms, for insulation during winter, and tape up the edges. I find that the tape adheres poorly, however, particularly halfway up, where the Styrofoam wants to bow inward. The changing temperatures and condensation seem able to defeat any tape I apply. So, is there any tape or adhesive which might hold up, or do I need to screw the Styrofoam down to the window frame, making lots of ugly holes and reducing the resale value of the house ? StuRat (talk) 17:30, 31 October 2011 (UTC)

Why do you need to insulate your Windows? I thought 20° wasnt much of a difference? — Preceding unsigned comment added by 92.48.194.153 (talk) 18:00, 31 October 2011 (UTC)

I don't live in Miami, I live in Detroit, where temps range from -21° F to 105° F. StuRat (talk) 19:38, 31 October 2011 (UTC)

I'm sure there is some way to avoid having to use screws or nails, but if you are talking about painted wood, I don't see how a screw hole will affect the resale value since you would probably have it repainted before selling it, wouldn't you? Dauto (talk) 19:23, 31 October 2011 (UTC)

You'd need to fill the holes with something before repainting, and, even then, it would be difficult to hide the holes entirely. StuRat (talk) 19:43, 31 October 2011 (UTC)

Because it will be expanding/shrinking, you want a glue that remains flexible for a long time. You can use a caulking sealant which has good flexibility but barely acceptable stickiness. On the other extreme, rubber cement retains barely acceptable flexibility with good stickiness. No matter what you choose, there is a very high risk of pulling the paint off the wood. -- kainaw™ 19:28, 31 October 2011 (UTC)

I think you'll find that rubber cement contains solvents that will turn styrofoam into mush - test any adhesive you use on a scrap piece first. AndyTheGrump (talk)

Use wood glue (old fashioned type), latex glue, or PVA glue - according to some forums you can apply one of these glues (possibly diluted with water) - to coat the surface like a paint primer -then tape may work better too. Generally there is an issue getting stuff to stick to it. http://www.istonline.org.uk/Handbook/36-37.pdf -there is specialise glue for it eg http://www.wonderlandmodels.com/products/uhu-por-expanded-polystyrene-glue/ - note standard UHU isn't suitable.

Also you can use decorator's tape (Masking tape) to stick to the painted wood -it comes off easily.94.72.193.44 (talk) 19:38, 31 October 2011 (UTC)

Rubber cement will dissolve the Styrofoam. A possible solution might be to wash down the paint-work with the European version of Sugar soap to clean the surface. Then fix the foam sheeting with wide Masking tape. Also, a 40 mph gust of wide exerts a pressure of approximate 1 psi. The leak-through of that will exert a force over the whole sheet. Cut a hole in it and tape a poly bag over it, so as to form a Ballonet. Yes, you'll loose a little heat but it will be a small percentage. Final, draft-proof the room so as to ensure that the room space provides a little back pressure to the wind forces. As air is compressible, this might not add much resistance but it might help. When the sheet bows inwards or outwards the width/hight dimensions will change a little, so allow for this too. Failing this, move to England. We have a lot of weather here too, but over the centuries we have tamed it to behave like a pussy cat. --Aspro (talk) 20:08, 31 October 2011 (UTC)

I think you may be on the money with the wind issue - the low mass means (assuming the windows are drafty) the foam acts as a pretty good sail - there's no mass to absorb the momentum - it might actually help to glue some heavy chipboard or mdf to the backs of the foam boards - increasing the overall mass.

That said StuRat wasn't completely clear on which bit was coming unstuck ie the connection to the window, or to the foam, or both?Imgaril (talk) 21:36, 31 October 2011 (UTC)

IFF: The German roll

Identification Friend or Foe, the system used to tell friendly aircraft from enemies, started off in WW2, with the Germans doing a roll to create a distinctive blip on a radar (source, the "Beginning of Electronic Identification" section).

1. Would anyone happen to know where I might find a picture or illustration of this "distinctive blip" as opposed to a normal one?
2. Would this information belong in the Identification Friend or Foe article?

Thanks in advance. (captcha: closeexact. huh.) 90.193.232.195 (talk) 20:15, 31 October 2011 (UTC)

The article explanation looks like an over-simplification. See Polarization. Rather than a blip proper, it was more likely a change in signal strength from hight-to-low-back-to-high of the returning echo. If a reliable source can be found for this manoeuvre, then yes it does belong in the article.--Aspro (talk) 20:47, 31 October 2011 (UTC)

In other words the "blip" is a temporal one - ie a pulse (not a shape) - the "dot" will get pulse brighter (or weaker) as the signal reflection is modulated by the varying reflective area as the plane rolls ??Imgaril (talk) 21:38, 31 October 2011 (UTC)