Wikipedia:Reference desk/Archives/Science/2019 November 23

= November 23 =

nuclear fission bombs inside white dwarfs
As heavier elements sink to the core of a white dwarf, does enough uranium, radium, etc, become concentrated to start a chain reaction and explode? In a bomb on Earth made by humans, the material needs to be concentrated very rapidly to prevent the chain reaction from pushing itself apart too soon. But the might not be needed inside the pressure and gravity of a white dwarf, and any sinking of heavy elements might happen very fast, fast enough to make a bomb. If such a bomb went off, the debris might be stifled by pressure and gravity, causing sudden extreme compression and maybe a nova?Rich (talk) 15:53, 23 November 2019 (UTC)
 * AFAIK, white dwarf, being lighter than Chandrasekhar Limit, does not fuse anything heavier than iron. אילן שמעוני (talk) 18:29, 23 November 2019 (UTC)
 * Nuclear reactions in ordinary stars, including white dwarfs, never create anything heavier than iron. But the heavy metals could have been present in the material that the star formed from in the first place: the same reason that they exist in our solar system.  See nucleosynthesis.  The question is whether they could be present in sufficient quantity to react in this way, and what would happen if so.  I have no information about that. --76.69.116.4 (talk) 20:11, 23 November 2019 (UTC)
 * This is wrong. In ordinary stars s-process creates elements heavy than than iron, though not radioactive staff like uranium. Ruslik_ Zero 20:46, 23 November 2019 (UTC)
 * The heavy elements will eventually concentrate in the center of the white dwarf. However their mass is very low - about a few thousandth parts of percent, So, any fissile explosion will have negligible influence on the white dwarf (or more likely the black dwarf). Ruslik_ Zero 20:54, 23 November 2019 (UTC)
 * No, to make a fission bomb you need weapons grade uranium or plutonium, which is made by removing unwanted isotopes which spoil the prompt critical reaction. A star will have these isotopes present. (Stars are where they're all made in the first place.) For an implosion-type bomb, you also need the core to be compressed extremely rapidly, or you just get a "fizzle". I don't think this would happen outside of a stellar core collapse, which already makes a really big boom. --47.146.63.87 (talk) 01:56, 24 November 2019 (UTC)
 * All fissile materials would have probably decayed long before there had concentrated in the center as their life-times are rather short. Ruslik_ Zero 13:53, 24 November 2019 (UTC)

How vinegar can be salt substitute?
According to this article: "vinegar is kick ass salt substitute you should be using". Now, logically when I think about it, it's difficult for me to understand the mechanism of it, since the feeling of saltiness is caused by tongue sensors of salts (or maybe NaCl only). Now, vinegar is acidic, and it should cause a sourness rather than saltiness. Isn't it? ThePupil (talk) 20:23, 23 November 2019 (UTC)
 * The article is talking about using salt (or vinegar) in sufficiently small quantities that it doesn't make the food taste actually salty (or saltier). Used at such low concentrations it instead has the effect of enhancing the other tastes present in the food, a usage called seasoning.
 * As the Wikipedia article Seasoning suggests, vinegar used for seasoning does not give a result identical to that of salt, but it does enhance other food tastes in a broadly similar way. Quite how either of them do this is beyond my ken, though I suspect that it has something to do with modifying sensory threshold processes (see also the links in that article's 'See also' section). {The poster formerly known as 87.81.230.195} 2.217.209.178 (talk) 22:22, 23 November 2019 (UTC)
 * I doubt it would be widely effective. One of the reasons why salt enhances other flavors is that many of the receptors involved in flavor make use of sodium co-transport. Vinegar won't make up for the lack of sodium ions for co-transport. Sodium acetate would. --OuroborosCobra (talk) 23:33, 23 November 2019 (UTC)
 * ...Or more commonly, sodium diacetate. 2606:A000:1126:28D:144E:A9EA:EDD2:AB72 (talk) 04:09, 24 November 2019 (UTC)
 * Thank you all for the answers. 05:49, 25 November 2019 (UTC)