Wikipedia:Reference desk/Archives/Science/2016 May 15

= May 15 =

H2CL2
Why does this here is 2HCL but not H2CL2 ? --Ip80.123 (talk) 01:02, 15 May 2016 (UTC)
 * It is dichloromethane, there is a "C" (carbon), that is not labeled, in the center of this skeletal diagram. And it's completely not true that the two H are "across" from each other or at right angles to the two Cl and vice versa. Our article has some nice 3D diagrams of the shape of this chemical, a detail that is easy to mis-understand in the image you found. DMacks (talk) 02:14, 15 May 2016 (UTC)
 * The Implicit carbon and hydrogen atoms section of the above article is the most important. LongHairedFop (talk) 16:54, 15 May 2016 (UTC)

Where are Salmonella bacteria are founded in the eggs?
Sometimes I hear about the risk to consume eggs in some places in the world since they contains a high level of salmonella. Where are Salmonella bacteria are founded or located in the eggs, are they founded on the shell from outside or into the eggs or maybe both places? (it matters for example, for case that we can wash well the eggs with soap)93.126.95.68 (talk) 06:18, 15 May 2016 (UTC)


 * See Salmonellosis, which says that an infected hen can transmit the bacteria to eggs she produces, or bacteria can enter the egg through the shell. Egg shells contain small pores to allow in air for the embryo to "breathe". --71.110.8.102 (talk) 06:59, 15 May 2016 (UTC)
 * The U.S., Japan and a few other countries do wash them for that reason but then you need to keep them refrigerated. Rmhermen (talk) 12:52, 15 May 2016 (UTC)
 * If you wash an egg with soap then the soap can get inside... The Quixotic Potato (talk) 13:13, 15 May 2016 (UTC)
 * In Israel it's forbidden to wash eggs in water according to the health minister (this is for public places) and for the citizens it's not recommended, because the bacteria can get inside through the shell. I would like to know about other countries. 93.126.95.68 (talk) 03:23, 16 May 2016 (UTC)
 * Same here, in the Netherlands, it is not recommended (but I don't know if its forbidden in public places). Washing eggs is a bad idea. My brother has pet chickens. If you google "wash eggs" you will find many sites that all say something similar to this: "Eggs are laid with a natural coating on the shell that is applied as the last step in the laying process called the "bloom" or sometimes the "cuticle". This coating is the first line of defense in keeping air and bacteria out of the egg. Since eggshells are porous, if you wash your eggs as soon as you collect them, you are removing that natural barrier." The Quixotic Potato (talk) 12:01, 16 May 2016 (UTC)
 * This PDF says: Current European Union legislation prohibits the washing of Class A eggs. The Quixotic Potato (talk) 12:09, 16 May 2016 (UTC)
 * Here are the recommendations from the Food Standard Agency in Ireland regarding egg washing. DrChrissy (talk) 16:03, 16 May 2016 (UTC)
 * This is a rather informative, non-technical account of the pros and cons of egg washing. DrChrissy (talk) 16:07, 16 May 2016 (UTC)

Looking for the Full List
Over ten years ago, I read a tract in which the Author spoke of seven, what I believed he called, principles of engineering, or principles of mechanics, and named them as the cog, hinge, lever, pulley, screw, spring and wedge. I think what we was saying was that these were the seven foundations of mechanical movement, and I wonder, whether there were more, and also, if anyone else has heard of such a list, and what it was called. I could think also of the wheel, the ball, a ball and socket joint, although that could kind of be thought of as some specialised kind of hinge, bearings, couplings, nails, chains, among other things. But perhaps the list was about such things at their most basic level, where these become the basic parts to more complicated machines. I suspect also that the rubber band is seen as a kind of spring, at least in a more basic sense. If anyone has any other information on this, that would be good. Thank You. Chris the Russian Christopher Lilly  06:34, 15 May 2016 (UTC)


 * Simple machines. Sagittarian Milky Way (talk) 06:39, 15 May 2016 (UTC)

Thank You for that.Chris the Russian Christopher Lilly  00:39, 16 May 2016 (UTC)

Nostrils--- one or two?
Both my nostrils have been clear for the last couple of months. ie I can breathe thro both of them at the same time. Is this normal? I seem to remember reain on a WP page that nostreils alternate in being clear for operation. Is that statement false? — Preceding unsigned comment added by 178.106.99.31 (talk) 17:44, 15 May 2016 (UTC)
 * Yes sorry I forgot to sign.,--178.106.99.31 (talk) 17:46, 15 May 2016 (UTC)


 * See Nasal cycle. However, although there is a regular alternation, most people are not acutely aware of one nostril being blocked and the other open. If you feel that one nostril is blocked for a longish period, you have a problem. 81.132.106.10 (talk) 17:55, 15 May 2016 (UTC)
 * Both my nostrils have been clear for a few months. Is that usual?--178.106.99.31 (talk) 17:57, 15 May 2016 (UTC)
 * It's unclear whether asking why no one has punched you lately or telling you to read our guideline against medical advice would be more helpful. μηδείς (talk) 19:03, 15 May 2016 (UTC)
 * I dont think my inferior turbinates are undergoing alternating complete turgescence as far as I can tell at the moment. Am I fooling myself,or is it that I am in the 20% of the population that does not exhibit alternating turgesence? Or is it possible that I only experience partial turgesence in either nostril?--178.106.99.31 (talk) 22:56, 16 May 2016 (UTC)

Gas analysis
Can it be told what is wrong with a persons body by analising the anal gas emanations?--178.106.99.31 (talk) 17:57, 15 May 2016 (UTC)


 * Possibly not what you are asking, but my sister-in-law who is a nurse has told me that they can tell what the difference is between a Clostridium infection, C.diff and gastro-enteritis simply by the smell of the stools. The human nose is, as always, a far superior organ to any artificial nose. --TammyMoet (talk) 18:45, 15 May 2016 (UTC)
 * I'm impressed that she can tell Clostridium from Clostridium difficile! —Tamfang (talk) 08:37, 17 May 2016 (UTC)
 * As for now, you mean. Robotic noses are surveillance technology, and nothing is being funded and developed so much as surveillance technology. Wnt (talk) 16:18, 17 May 2016 (UTC)


 * You can detect some diseases by analysing exhaled gases, which is close to the OP's question. . LongHairedFop (talk) 21:03, 15 May 2016 (UTC)
 * Analyzing gases from breath and skin is well known and can be refined. Tuberculosis makes skin smells like bread, some myocardial infarctions make skin smell burned or like smoke. Some blood suggar problems make breath smell like aceton or paint thinner. -- Hans Haase (有问题吗) 09:19, 16 May 2016 (UTC)


 * Animals have amazingly developed senses of smell.  See  and Canine cancer detection. 5.150.93.133 (talk) 09:49, 16 May 2016 (UTC)


 * There was a larger studie on flatulence gas mixture analysis a read a few years ago (I thought about how the collection was done) and there a peolple with hydrogen as a main compound while others have methane as a main compound, most of it is carbon dioxide any way. But the studie did not mention the trace gases which could indicate the mixture of microorganisms in the digestive tract.--Stone (talk) 10:06, 16 May 2016 (UTC)


 * Flatus can be collected in a "flatal bag" and then analyzed, but this doesn't seem to happen much, presumably because there are more accurate ways to evaluate digestive system problems, such as a stool analysis, where the collection method is simpler. However, a sudden change in flatulence, without any obvious cause like a change in diet, might be reason to see a doctor.  StuRat (talk) 16:08, 16 May 2016 (UTC)
 * The methane test is quite entertaining! ;)--178.106.99.31 (talk) 20:43, 17 May 2016 (UTC)
 * "Flatus bag" being the more standard name (as usual, WP articles tell us things). DMacks (talk) 03:52, 18 May 2016 (UTC)
 * Well, strike a light.--178.106.99.31 (talk) 23:27, 18 May 2016 (UTC)

its all about light
from where does the light gets its speed111111111us (talk) 18:19, 15 May 2016 (UTC)


 * The speed of light in a vacuum appears to be a universal physical constant of the universe. No practical answer to "why is it that way?" exists for such constants except for "because that's the way it is". &mdash; Lomn 18:46, 15 May 2016 (UTC)


 * Exactly. The speed at which light propagates can be decomposed into vacuum permittivity and vacuum permeability, which are fundamental constants that represent electric- and magnetic- components.  Some physics books consider these properties to be even more fundamental constants than c (which can be derived from these other constants, based on our understanding of the way electric- and magnetic- fields interact).  At the end of the day, they're still just constants that never seem to change, no matter how we measure them - and although we can study them from lots of perspectives, we don't actually have any specific explanation for why they take any particular value.
 * Nimur (talk) 20:42, 15 May 2016 (UTC)


 * The article Electromagnetic radiation also sheds some light on the subject. ←Baseball Bugs What's up, Doc? carrots→ 18:53, 15 May 2016 (UTC)


 * Surprisingly, the answer to scientific questions is sometimes "philosophy or religion". The science don't know. (besides "whatever it is, the current speed of light will not be one of the values that makes your species impossible"). Sagittarian Milky Way (talk) 20:51, 15 May 2016 (UTC)


 * I agree it's philosophy but i'm not sure why anyone would call it "religion", it has very little in common with religion. In fact, one of the major philosophical shifts of the scientific revolution was to stop trying to explain the world with answers to "WHY?" questions, using agency and motivation to explain natural phenomena, and instead explain it with answers to "HOW?" questions using mathematics and models. In this case, it's not that "science doesn't know 'why' light travels that fast", it's because that question does not have a useful answer. Of course we can scientifically answer a "why" question like "why does a ball drop when you let it go", but you can't "why?" all the way down, the buck HAS to stop somewhere, and with science, the buck stops at the natural explanan it, because Gravity IS that way, or light IS that way. Religion would always take it one step further and say because god MADE it that way, but that extra step doesn't actually ADD any explanatory power so science dropped it. Vespine (talk) 01:18, 16 May 2016 (UTC)


 * See also Non-overlapping magisteria for one viewpoint on this. -- Jayron 32 02:04, 16 May 2016 (UTC)


 * It's only religion for some people. Sagittarian Milky Way (talk) 03:09, 16 May 2016 (UTC)


 * It depends on what "God" means. If you equate "God" to "Nature", then "God made it that way" is totally valid. But as you say, it doesn't really add any new information. ←Baseball Bugs What's up, Doc? carrots→ 09:40, 16 May 2016 (UTC)


 * It's rather nonintuitive, but light doesn't seem to accelerate or decelerate, it just always goes the same speed (in a given medium), similar to how electrons jump from one energy level to another, without seemingly ever having been in-between. The proverbial "quantum leap". StuRat (talk) 21:56, 15 May 2016 (UTC)


 * There is mention of nanoseconds there, isn't this rather slow in consideration with light ? So you say that the electrons jump ( in a few nanoseconds ), generating light in the process - which does not accelerate but is a full c speed right from the beginning. Is it that the famous quantum leap ? --Askedonty (talk) 11:17, 16 May 2016 (UTC)


 * Yep. StuRat (talk) 04:11, 18 May 2016 (UTC)


 * Watch this video: --71.110.8.102 (talk) 08:32, 16 May 2016 (UTC)