Wikipedia:Reference desk/Archives/Science/2017 January 18

= January 18 =

Mass, space etc
Space cannot exist without mass. So, before the big bang, there was no space?? If so, where abouts (ie in what existence) did the big bang occur? Also, what happened to all the negative matter/energy that must have been created also? --213.205.192.126 (talk) 00:24, 18 January 2017 (UTC)


 * There's a slightly-fringe theory (called Zero-energy universe) that the negative energy is in gravity and space itself. The standard theory for the origin of space-time doesn't require any previous existence, though it doesn't preclude the possibility.    D b f i r s   00:49, 18 January 2017 (UTC)
 * Space cannot exist without mass. General relativity doesn't require mass-energy to exist: see empty universe. Models of the Big Bang don't necessarily say there was no space prior to it, just that the universe was incredibly dense. We deduced that the Big Bang happened by simply extrapolating backwards the observed expansion of the universe. Eventually we get to a point where the currently-understood theories of physics blow up and stop working. Figuring out how to describe the universe before that point is one of the motivations behind the search for a theory of everything. --47.138.163.230 (talk) 01:57, 18 January 2017 (UTC)


 * The conventional answer to the question "Where did the big bang occur?" is "Everywhere," because at the time of the putative "Big Bang" (which was also the start of Time itself) all space was compressed into a single point, from which it subsequently expanded, initially by Inflation.
 * Negative energy exist as a mathematical concept in a similar way to deceleration being a negative acceleration; it is also applied to other more exotic concepts (as the article explains), but these may not be quite what the OP envisaged.
 * The question of "where did all the antimatter go?" (since current theories say that equal amounts of matter and antimatter should have been created) is perhaps the largest (in both senses) unanswered puzzle in astrophysics today: anyone who succeeded in solving it would be awarded a Nobel Prize, amongst other accolades. {The poster formerly known as 87.81.230.195} 2.122.62.241 (talk) 12:43, 18 January 2017 (UTC)
 * Small quibble: The Universe need not have ever been compressed to a single point. If the size of the universe is infinite, it has always been infinite, and the Big Bang was simply the moment of maximum density. Someguy1221 (talk) 16:09, 18 January 2017 (UTC)
 * That's why I deliberately wrote "conventional", not wanting (or being competent) to delve into subtleties beyond the apparent tone of the query. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 12:09, 19 January 2017 (UTC)

How loud and "shaky" is an H-bomb at various distances?
Shaking from air-transmitted sound like infrasound or a subwoofer, not earth-transmitted earthquake (which would require exploding in or at least near the ground I think) Sagittarian Milky Way (talk) 01:10, 18 January 2017 (UTC)


 * You need to rephrase this question so that it makes sense.--Aspro (talk) 01:20, 18 January 2017 (UTC)


 * Better? Sagittarian Milky Way (talk) 02:01, 18 January 2017 (UTC)


 * To give you an idea of how "shaky" thermonuclear weapon ("H-bomb") detonations are, according to  our article on the first thermonuclear detonation, the first indication outside the US military and United States Atomic Energy Commission was a seismic signal detected thousands of miles away at the University of California at Berkeley. California, USA.  Co-designer of the weapon Edward Teller read the seismograph and immediately informed a colleague at  the USAEC's nuclear weapon design laboratory at Los Alamos, New Mexico, USA four hours before official news of the successful detonation reached the continental United States by an unclassified telegram reading "It's a Boy".


 * Specific answers to your questions can be found in the US National Nuclear Security Administration reference work The Effects of Nuclear Weapons by Samuel Glasstone and Philip J. Dolan. Chapter 1 of that book, "General Principles of Nuclear Explosions" should give you enough comprehension of how thermonuclear devices behave to let you use the rest of the book to answer your question. loupgarous (talk) 01:38, 18 January 2017 (UTC)


 * I will read that. (when it finishes downloading) Sagittarian Milky Way (talk) 02:03, 18 January 2017 (UTC)


 * ? Berkeley isn't "thousands of miles away" from New Mexico; or am I thinking of the wrong bang? Where was the news before it reached the continental United States? —Tamfang (talk) 08:47, 18 January 2017 (UTC)
 * The colleague was in New Mexico. The Ivy Mike test was way out in the Pacific. ←Baseball Bugs What's up, Doc? carrots→ 09:18, 18 January 2017 (UTC)
 * OK. Just for clarity's sake, the Ivy Mike test of the first thermonuclear device was held on Elugelab atoll - a few thousand miles from North America. loupgarous (talk) 14:02, 18 January 2017 (UTC)


 * Nuclear explosions produce considerable infrasound, which is one of the ways that they can be detected, at least in theory. There is a global infrasound monitoring network, but I can't find any public data about what a nuclear explosion looks like to them (they are looking for illegal atmospheric nuclear tests, although they can pick up underground tests). However, 17 of the stations heard the infrasound from the Chelyabinsk meteor explosion, which is probably similar to a small nuclear explosion - the furthest station to hear it was in Antarctica. It produced a 17 minute long soundwave at around 1-2 Hz. You can hear a sped up version here. Smurrayinchester 14:20, 18 January 2017 (UTC)

Binomial badgers
Why is badger called Meles meles? DuncanHill (talk) 02:38, 18 January 2017 (UTC)


 * I think this is common, for the most common or first-named animal to have the same species name as the genus name. That way they don't need to find some unique characteristic to name that species after.  Another way to go is to make the species name something like "vulgaris", meaning common, but if they become less common in the future this name will no longer be accurate.  StuRat (talk) 02:47, 18 January 2017 (UTC)
 * Yes, but why Meles? That is to say, I am perfectly well aware that binomials are often duplicate (I am, after all, over 12 years of age), but what is the significance of Meles? DuncanHill (talk) 02:53, 18 January 2017 (UTC)
 * The European Badger was originally named Ursus meles by Linnaeus (see Mammalia in the 10th edition of Systema Naturae), who had mistaken the badger for a type of bear. This was changed to Meles meles by Brisson four years later. "Meles" means "badger" in New Latin. So basically, Linnaeus published the first taxonomic description of this species, saying it is a "bear badger", only for Brisson to point out that it is, in fact, a "badger badger". It is common practice that when a species is relocated to a new genus, the species name is left unchanged. Now, we could ask why Brisson didn't use a different name for the genus (Linnaeus heavily avoided double naming like this), and if there's an answer, it's probably in one of the two works he published in 1762, which are in latin. My guess though, is that he simply states the new name without saying why he likes double-names. Someguy1221 (talk) 02:57, 18 January 2017 (UTC)
 * Thanks, that's more what I was looking for. Now, how did meles come to be badger in New Latin? Our article on Meles meles suggests that meles means "marten or badger" in Latin, and I find it hard to believe that the Romans did not distinguish between the two. DuncanHill (talk) 03:22, 18 January 2017 (UTC)


 * Pliny the Elder in Natural History first records the badger as Ursus meles, i.e. "honey-eating bear", according to this site Though I can't find the exact use of ursus meles in the Badger section of Natural History, its commentary uses meles: "There has been some difference of opinion respecting the identity of the animal, which Pliny calls "meles;" by some it has been supposed to be the polecat, or else the weasel."(Bostock, 1855) "Meles" was certainly called that before Linnaeus's description, as the word is analysed in Isidore of Seville's Etymologies, which, as well as the honey-eating meaning, proposes a link to malum "round fruit".  --Hillbillyholiday talk 03:06, 18 January 2017 (UTC)
 * Of note, mel and its various forms has meant "sweet" or "honey" in ancient Latin. Someguy1221 (talk) 03:47, 18 January 2017 (UTC)
 * *And ironically, neither meles meles or even meles meles meles is particularly known for eating honey, though they'll eat it if it's available. And the actual honey badger is not even in meles! Instead it is Mellivora capensis, or "capetown honey-eater". It's interesting how names change meaning over time. Someguy1221 (talk) 03:54, 18 January 2017 (UTC)
 * Not that honey badger gives a shit. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 05:54, 18 January 2017 (UTC)


 * (Of tangential interest: Tautonymic binomial names are allowed for animals, but are explicitly forbidden for plants. So we have Gorilla gorilla but no e.g. Pinus pinus.) SemanticMantis (talk) 15:08, 18 January 2017 (UTC)
 * We even have a Gorilla gorilla gorilla. Iapetus (talk) 17:32, 18 January 2017 (UTC)


 * Major Major Major Major? -- Jayron 32 17:52, 18 January 2017 (UTC)
 * Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo? -- Jayron 32 17:53, 18 January 2017 (UTC)
 * Hatnote Warning: any reference to that damn Monty Python sketch would be completely inappropriate; this thread has already become exceedingly silly. 2606:A000:4C0C:E200:185C:A689:C3A8:9F8 (talk) 19:55, 18 January 2017 (UTC)
 * I fart in your general direction (to be said in a very stereotypical French accent) DrChrissy (talk) 15:31, 19 January 2017 (UTC)
 * In Germany der Fahrt is in any direction. 92.2.72.206 (talk) 17:32, 19 January 2017 (UTC)

Battery as a blasting cap?
I just saw an amazing news item - apparently the "e-cigarettes" some folks like to smoke can explode with remarkable power, knocking out seven of a guy's teeth, even putting a hole in the sink he was near. The injury reminds me of blasting-cap accidents, and the shape seems a little like a blasting cap (well, it's kind of big, more like a regular battery, or a finger, at 65 x 18 mm). So I gotta wonder... can you use a battery like this as a blasting cap? Now yes, it seems ridiculous at first, since the primary explosive inside a blasting cap has a very powerful shockwave, whereas you think of an exploding battery as being a confined gas bursting a container. But ... with a discharge this powerful, maybe it's more like an exploding-bridgewire detonator, which is a blasting cap. Though I'm not clear on whether that necessarily still uses primary explosive.

Where this gets fun is that the primary explosive is hazardous and troublesome for the hobbyist (or, ahem, knight-errant) to create, whereas these things have apparently saturated the countryside. ;) Wnt (talk) 17:49, 18 January 2017 (UTC)
 * This may lead you some interesting places. -- Jayron 32 17:52, 18 January 2017 (UTC)
 * " just pulled off charger " is simple abuse of the battery. I have never seen or heard of any credible instance of a Li-po "incident" caused by use alone, only ever by either mechanical damage or in relation to charging. Heating the battery during charging, then pulling the high current of a vaping coil from it, will certainly be a high risk action.
 * That said, these batteries will easily deflagrate but will not detonate and the battery ought not to explode, as a result of external protection circuits and a vented design for the case - but corners do get cut, especially around vaping.
 * I omitted a source I'd meant to mention, where I found the size:   It explains the frequency of counterfeit "vaping" batteries was quite high at one point due to shortages, and remains pretty high in domestic Chinese markets for example.  It will be interesting to see if this is such a case. Wnt (talk) 23:40, 18 January 2017 (UTC)
 * Veolia's is still one of the biggest fires involving them, and there's video too.
 * http://news.bbc.co.uk/1/hi/england/lancashire/8404129.stm
 * http://www.safety-managementuk.com/veolia.php
 * Andy Dingley (talk) 18:33, 18 January 2017 (UTC)
 * What you are asking is can you use an extreme "failure model" of a specific kind of battery as a blasting cap, the answer is no. Because that battery will NOT reliably fail that way, every time. Several years ago when I started playing with lipo powered remote control vehicles, helicopters and drones, after a while I had a pile of useless cheap batteries which I intentionally made fail, and let me tell you some did fail quite spectacularly and some just fizzled without as much as a little pop. So you "could" use one, but it wouldn't work I suspect more often than not. So could you "on purpose" design something like a lipo but make it so it DID fail spectacularly "on command"? Probably, but then just buy the blasting cap which is designed for that purpose from scratch. Vespine (talk) 22:16, 18 January 2017 (UTC)
 * Well, not every ... patriot has an easy time buying a blasting cap... Wnt (talk) 23:40, 18 January 2017 (UTC)
 * I should take note LiPo = Lithium polymer battery. Wnt (talk) 23:47, 18 January 2017 (UTC)
 * What, it's not lithium-polonium? —Tamfang (talk) 01:39, 22 January 2017 (UTC)
 * RC models generally use 'flat' batteries, wrapped to the necessary size from sheet and broadly rectangular in shape. These have different failure modes from canned cylindricals, such as the 18650. They're more susceptible to external damage, but if they start thermal runaway they burn with continuous gas production, rather than building up pressure and then bursting explosively. Andy Dingley (talk) 00:11, 19 January 2017 (UTC)

Endocrine and exocrine hormones
Is it true to say that endocrine hormones are in the blood and exocrine hormones are outside of the blood? 93.126.88.30 (talk) 23:59, 18 January 2017 (UTC)
 * Yes. See Exocrine gland (sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, and mucous) and Endocrine gland (pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus and adrenal glands). Blooteuth (talk) 14:28, 19 January 2017 (UTC)


 * Well, not really -- there is no such thing as an "exocrine hormone". The substances secreted by exocrine glands are not referred to as hormones. Looie496 (talk) 14:05, 20 January 2017 (UTC)
 * Good catch - I knew something was wrong there. Perhaps exocrine sweat glands are a good example.  They produce sweat, but to the best of my knowledge, sweat is not considered to be a hormone. DrChrissy (talk) 18:55, 20 January 2017 (UTC)
 * One could consider a pheromone as an exocrine hormone, if you extend the definition of a hormone to include an actions on other members of the same species. Perhaps also chemotaxis in sperm guidance in the female reproductive tract (an epithelial-lined space in continuity with the outside world). Klbrain (talk) 23:42, 20 January 2017 (UTC)