Wikipedia:Reference desk/Archives/Science/2020 May 12

= May 12 =

Is body odor Nature's way to enforce social distancing?
Body odor is influenced by sweat, so the body has some control over what bacteria will grow on the skin. Also, the brain can flag smells in any way that it sees fit. So, if we find body odor in general unpleasant, is this then caused by the advantage of keeping some distance to each other? Count Iblis (talk) 05:53, 12 May 2020 (UTC)
 * We do have an article on Body odor, but it doesn't seem to address social distancing. Well worth a read though. HiLo48 (talk) 07:57, 12 May 2020 (UTC)
 * Yes. The body also emits odors that can't be smelled, such as pheromones. 67.175.224.138 (talk) 10:41, 12 May 2020 (UTC).
 * Pheromones tend to lead to the opposite of social distancing. HiLo48 (talk) 11:13, 12 May 2020 (UTC)
 * Oooo HiLo48, you brute. Martinevans123 (talk) 11:17, 12 May 2020 (UTC)
 * People were not particularly bothered by body odor until marketing told them to be. Disgust can be socially conditioned (i.e. a learned behavior rather than a programmed one), and there's nothing natural about being repulsed by body odor (in the sense of "it is the proper order of things").  For thousands of years people were unbothered by body odor until marketing in the early 20th century convinced people they should be.  .  There's little evidence that the natural scent of otherwise clean humans is inherently repulsive.  -- Jayron 32 12:31, 12 May 2020 (UTC)
 * On a similar line, this research on the use of deodorant by those with naturally low body odour (a non functional ABCC11 variants) may be of interest [//www.sciencedirect.com/science/article/pii/S0022202X15363259]/[//www.ncbi.nlm.nih.gov/pmc/articles/PMC3674910/] [//www.smithsonianmag.com/science-nature/a-lucky-two-percent-of-people-have-a-gene-for-stink-free-armpits-2508106/] [//www.livescience.com/26351-no-smell-gene-wear-deodorant.html] [//www.theguardian.com/science/sifting-the-evidence/2013/feb/14/wasting-money-deodorant-ears]. Also before anyone says it, note that while it's true that this non functional ABCC11 variant seems to result in changes which result in lower body odour, this doesn't mean that this mutation was favoured for that reason and especially not for the preference of other humans, as it appears to have a number of effects. We really have no idea what, if any, evolutionary advantage resulted from the variant. And I say "if any" especially since the variant is hypothesised to have arisen in cold environments and also results in fewer sweat glands. It could easily have been simply genetic drift due to a lack of an evolutionary disadvantage. (There is some general research into the variant e.g. [//www.ncbi.nlm.nih.gov/pubmed/20937735] [//www.discovermagazine.com/planet-earth/body-odor-asians-and-earwax] which I haven't really looked at.) Of course such findings are also then seen as a potential money maker in another direction, namely making recommendations on such matters in a personalised pharmacogenetics type approach [//www.sciencedirect.com/science/article/pii/S0022202X15363326]/[//www.ncbi.nlm.nih.gov/pubmed/23760047]. Nil Einne (talk) 08:19, 13 May 2020 (UTC)
 * Manly sweat makes other men more cooperative. --Lambiam 19:39, 12 May 2020 (UTC)

False color images in astronomy
When most people think of the sun, the image that often comes to mind is to the point where sci-fi movies often depict it that way and a lot of users have insisted that the aforementioned image stay at the top of the infobox in the article Sun. Of course, that image is actually false-color while the sun is actually white yellow and is a much more accurate depiction of how it appears in real life to human eyes. Are all the colorful images of nebulae and other galaxies, many of them quite iconic, such as the ones in here also false-color? If not, are there obvious indications in ones that actually are false-color? StellarHalo (talk) 19:55, 12 May 2020 (UTC)
 * Majority of colorful images are in false color. Real color images of galaxies and nebular are rather bland. Ruslik_ Zero 20:32, 12 May 2020 (UTC)
 * That said, some astronomical photographs use filters to isolate particular narrow portions of an object's full spectrum corresponding to the output of particular elements. These can be informative about the processes going on in the objects: for example, Hydrogen-alpha filters are useful for observing the Sun, which is bright enough to give a good optical or photographic image using only the light of this spectral line. They might also or instead make a faint object or feature stand out more clearly: many amateur telescope users employ a Nebular filter to increase the contrast and hence visibility of faint Nebulae, and various colour filters to enhance markings on/in planetary surfaces or atmospheres.
 * While most astronomical false-colour images do not represent what the human eye, if closer to the object, might theoretically see, they are genuinely derived from the object's actual light and thus give useful information. They are not just arbitrary choices to make it "look prettier", although that might be a fortunate by-product. {The poster formerly known as 87.81.230.195} 90.197.24.23 (talk) 00:51, 13 May 2020 (UTC)
 * The well-known Pillars of Creation image often seen on posters or T-shirts is a good example. Its colours were constructed by combining many images taken with three different narrow-band filters and combining the three monochromatic signals by interpreting them "falsely" as an RGB signal. More detail is given in an article on the National Geographic website: Photographing the Pillars of Creation. A dead give-away of the image colour being false is the brightly pink colour of the stars. In true colour, the image would not nearly be as captivating. Someone's perspective of the universe can, allegedly, be ruined by that realization, --Lambiam 07:55, 13 May 2020 (UTC)