Wikipedia:Reference desk/Archives/Science/2014 November 9

= November 9 =

Falling into a black hole
Suppose an astronaut in a modern spacesuit gets teleported to 10 Schwarzchild radii from an active galactic nucleus, inside the accretion disc. How long does she survive? Will the hot gas in the accretion disc cook her to death? Would the X-rays and gamma rays kill her within a few hours? Or will she survive long enough to be ripped apart by tidal forces?

I know that a quasar's accretion disc is extremely hot, but by earthly standards, I think it's still a near-vacuum. Hence my confusion about the survivability of the environment. --50.46.159.94 (talk) 05:42, 9 November 2014 (UTC)


 * The pressure caused by the heat alone is a breaking force a significant fraction of the inward desire. In Jupiter, where the forces are exactly balanced, it's hotter than the surface of the Sun and pressurized enough to turn hydrogen metallic and the ionizing radiation would kill a human in short order. A Cessna (a small airplane) will vaporize on the surface of the Sun within 1 second, according to xkcd what if, and the surface of the Sun is only 0.001 times the density of air and only partially surrounded by opaque plasma. The gravity, heat and X-rays is far above this at the event horizon of a black hole, so I would guess it's not survivable. Also, if the black hole is huge enough, tidal forces would not be able to kill. However, fuzzball theory mentioned in a previous thread on black holes a few weeks/months ago states that in that case the body substance would be disintegrated to quarks, gluons etc. and join a ball of string extremely instantly (within a few Planck lengths at 670 million miles an hour). In that case tidal disruption is impossible. Sagittarian Milky Way (talk) 09:09, 9 November 2014 (UTC)

I'd like a further explanation of the pressure at the center of accretion disks. I was just looking at this in the very different context of a Herbig-Haro object where a protoplanetary disk spits out a stellar jet in one or two directions along its axis. But the situation seems sort of the same: gravity pulls all this material in, it "piles up" somehow, and then it gets shot out in jets along the direction the material isn't accreting from. But how much does it "pile up"? And why doesn't it find a way to pile up in a more typical spherical shape rather than reaching escape velocity? And above all, how much actual pressure are we talking about? Is this (in your case) a black hole with an atmosphere??? Wnt (talk) 14:58, 9 November 2014 (UTC)

Bugs?
This split cashew has been roasted and salted for a while, but are these larva? — Preceding unsigned comment added by DRosenbach (talk • contribs) 16:22, 9 November 2014


 * Stomped on this one. Have you thought of asking your local Food and Drug Administration office. If they don't have an insect expert at hand, ask them to forward you image to an entomologist. If and when you get an answer, your image could be useful on what ever WP article we have for cashews.--Aspro (talk) 20:04, 9 November 2014 (UTC)


 * They sure look like larva to me, yes. StuRat (talk) 20:44, 9 November 2014 (UTC)


 * Yes, maggots. Are they live?  Was the nut like this when you opened it, or did you leave it sit out?  If they were canned, take them back for a refund.  If they were from a local producer let him know. μηδείς (talk) 22:03, 9 November 2014 (UTC)


 * Think you mean retailer rather than producer (the US imports cashew). Next: “This split cashew has been roasted and salted for a while” so why should they be alive (if they are in fact larva)? Finally: “If they were from a local producer let him know.” So what exactly do you think he is going to do about it!!!? If you have ever worked in the retail business, you will know that customers are forever coming into complain. If a retailer followed up each ever complaint...  Do you think the business proprietor or manager would have any time left over to get around to serving any customers? That is why I suggested that the OP goes to his local  FDA. That is what they are their for and they can call on expert that can provide learned analyses.  Cashew are boiled or steamed so are safe in this respect, but they would realize that a US citizen deserves a proper answer as to what he is consuming when he has doubts.  It also gives the FDA a rare opportunity to assure  John Doe's   that they (the FDA) is doing a good job (cough, cough).--P.g.champion (talk) 21:34, 10 November 2014 (UTC)


 * I don't think the FDA cares about every worm in an apple. The right person to complain to is obviously the manufacturer of the product (or at least who is listed on the container), who probably has the option to choose which farm, inspect the nuts at the time of sale, etc., and is powerfully motivated not to have this happen too often. Wnt (talk) 15:58, 11 November 2014 (UTC)


 * Verily. Cashew may be advertized as Raw but it is very unlikely that they have not been heat treated due to presence of urushiol in completely raw nuts -thus the heat treatment killing any meanies at the same time. So health-wise, one can consider store purchased cashews are  safe to feed to  pigeons and chipmunks. Otherwise why did  Tom Lehrer (and girl fiend)  offer  peanuts and not cashew to their feathery friends?. .--Aspro (talk) 22:22, 10 November 2014 (UTC)


 * Maybe because peanuts are far cheaper, at least in the US ? This is why we have the phrase "Working for peanuts", meaning very little money. StuRat (talk) 16:39, 13 November 2014 (UTC)


 * Or just eat the nuts, maggots and all. Once they are cooked they are harmless.
 * Jack, eating rotten cheese, did say,
 * Like Samson I my thousands slay;
 * I vow, quoth Roger, so you do,
 * And with the self-same weapon too.


 * Greglocock (talk) 23:43, 9 November 2014 (UTC)

symbol of Diploma Supplement what does it say?
I saw on this site (Medical university) that they show the symbol of "EU" (on the side of the side in the slide: accreditation) ,and I don't understand what it says. If I get a diploma of this university, can I work with it in Europe without to pass any exam? and what it says about the university? (every university in Ukrane can do the same procedure?) Thank you 5.28.158.164 (talk) 17:17, 9 November 2014 (UTC)
 * No. If you click on the logo it tells you that it is "A document describing the knowledge and skills acquired by holders of higher education degrees. It provides additional information to that included in the official degrees / diplomas and/or transcript, making it more easily understood, especially by employers or institutions outside the issuing country" and it is not "an automatic system that guarantees recognition"  Richerman    (talk) 21:37, 9 November 2014 (UTC)
 * The logo in question is that of TEMPUS, an EU organization that "supports the modernisation of higher education in the EU's surrounding area." This is the relevant page from their website. Tevildo (talk) 21:44, 9 November 2014 (UTC)
 * Er, no it doesn't seem to be. There is a Tempus logo there also, but the one in question is the Europass logo from the European Centre for the Development of Vocational Training.  Richerman    (talk) 22:00, 9 November 2014 (UTC)
 * What does it say? (I mean about Tampus) 5.28.158.164 (talk) 01:57, 10 November 2014 (UTC)
 * TEMPUS is an organisation dedicated to improving the standard of educational qualifications across Europe. Richerman    (talk) 10:22, 10 November 2014 (UTC)

How complex is the brain of a common shrimp?
In other words, I know it's more of a fused ganglion thing going on, but is there some measure of average complexity for them, eg. the total number of neurons or an encephalization quotient figure or something? I'm unable to find much of anything on the subject and the only crustacean listed on the wiki page listing animals by number of neurons is the lobster. — Preceding unsigned comment added by 142.105.176.81 (talk) 20:24, 9 November 2014 (UTC)


 * Shrimp is not an official biological category, so you have to be more specific. See harlequin shrimp which live in mated pairs, and mantis shrimp for one mean critter.  The latter are believed to have perhaps the most elaborate visual system of any animal, being able to se up to 16 primary colors, compared to our three. μηδείς (talk) 03:04, 10 November 2014 (UTC)
 * "Shrimp" can mean different things in common language and science, but mantis shrimp aren't even Decapoda, so they're not shrimp in any scientific categorization. As explained in our article, shrimp usually refers to the grouping of Caridea and Dendrobranchiata suborders of Decapoda when used in scientific contexts. Anyway, here's a recent article titled "Brain evolution in decapod crustacea" . It doesn't give an ecephalization quotient, but it has other measures of the size and complexity of the brains of shrimp-ish organisms. It would be a good starting place for anyone interested in shrimp brains. SemanticMantis (talk) 17:51, 10 November 2014 (UTC)
 * Nevertheless, my Mantis shrimp are better than your shrimp, Mantis. μηδείς (talk) 18:19, 10 November 2014 (UTC)
 * Thank you for the response. It's where I basically ended up too so I guess I'll start reading!

Bisulphate of baryta
What is Bisulphate of baryta? The substance is named in Conan Doyle's "A Case of Identity", and it appears in an 1858 chemistry book, but I can't understand what composes it. The latter source gives a reaction that includes it:"RO [note that there's a line over the 'R'; I'm not sure what this conveys], BaO + S2O6, 2HO = RO [again, line over 'R'), HO + S2O6, BaO, HO."Is it a mixture of barium oxide and S2O6? I want to create it as a redirect if we have an article on the subject.  Nyttend (talk) 20:36, 9 November 2014 (UTC)


 * By looking at the name, it is the same as barium bisulfate . Plasmic Physics (talk) 20:55, 9 November 2014 (UTC)


 * According to it is  – barium bisulphate. Ruslik_ Zero  20:57, 9 November 2014 (UTC)
 * That reference claims it exists. Another reference is at 100 Chemical Myths saying it does not. Graeme Bartlett (talk) 00:26, 10 November 2014 (UTC)
 * Looks like it's CAS# 25105-31-1; SciFinder has a several reports for its synthesis, including X-ray crystallography and vibrational spectroscopy in 1970s–1990s. DMacks (talk) 09:44, 10 November 2014 (UTC)
 * Looks like has the CAS number, but here's a public web link to a structure:  which is simply Ba 2(H2O4S).  Simply, that is, until you go to place the positive charge on the barium...  The story is at A Case of Identity; though I didn't read it I only see a brief mention of it as being a compound Holmes identified, so there are no 'claims' to confirm about it.  The OP's chemistry book source  has an unfamiliar way of dealing with chemical formulas, but it should be clear that no named atoms but barium, sulfur, oxygen, and hydrogen are present, consistent with "barium bisulfite".  It further says that when the substance is heated on platinum, "fumes of sulphuric acid are evolved in great abundance", leaving neutral sulphate behind.  Barium sulphate is BaSO4; subtracting that from the above formula yields H2SO4 in equal proportion.  So we have one Ba+, one neutral H2SO4, one bisulfate HSO4- ... and a neutral hydrogen left over??  Hmmm.  It would be tempting to suppose that you could have true barium bisulphate, i.e. 2Ba+ 2HSO4-, and you can heat that to liberate 1 H2SO4 and leave behind 2 BaSO4.  However, it is hard to believe that someone would mistake the amount of sulfuric acid liberated per barium ... especially to think there is more produced than the compound possesses.  Either there's a silly clerical error or ... something odd.  Anyway, I think we see what kept Sherlock busy for a day. Wnt (talk) 16:50, 10 November 2014 (UTC)

Why does weather anomalies happen?
Hi,

Last year there was a great storm in NY, and the temperature dropped severely.

My question is why those anomalies happen? Exx8 (talk) 20:50, 9 November 2014 (UTC)


 * You ask an extremely broad question, so we can't provide specific answers. Have you read our Weather article?  It may answer your general questions.  If you want answers on a specific storm, we may be able to provide more details.  Nyttend (talk) 20:56, 9 November 2014 (UTC)


 * The sort of extreme events you are referring to are called Global weirding by some scientists, see: and . Much of it seems to be caused by climate change affecting the Jet stream. Richerman    (talk) 22:36, 9 November 2014 (UTC)


 * The most common reason for a rapid temperature drop is when a cold front arrives. Rain can also lower the temperature quickly, since it forms where the air is usually much colder.   And temperature naturally drops as the Sun sets, so a cold front, with rain, arriving at sunset tends to magnify the effect.  There are also more rare reasons for the temperature to drop suddenly, such as downbursts/microbursts. StuRat (talk) 01:30, 10 November 2014 (UTC)


 * An anomaly, in this context, is something that's rare and hard to predict. Rare weather events come about because of a coincidence of several not-so-unusal things happening at the same time. So slightly elevated temperatures in one place with high humidity someplace else and maybe particular wind patterns at some other place...none of them very unusual individually...come together to make something that is very unusual.  These events are often unpredictable for much the same reasons.  Also, weather patterns are inherently chaotic - in the mathematical sense of that word. SteveBaker (talk) 02:06, 10 November 2014 (UTC)