Wikipedia:Reference desk/Archives/Science/2019 June 25

= June 25 =

Anaphylaxis and cardiac arrest
What is the actual physical mechanism that leads to cardiac arrest and death in anaphylaxis? I know blood pressure drops and airways can swell, which leads to less oxygen reaching the blood. But how do these 2 things and other symptoms which I may have missed actually lead to a cardiac arrest? 90.194.63.148 (talk) 17:18, 25 June 2019 (UTC)
 * Presumably fluids leakage and airway obstruction lead to low oxygen supply to the heart, which eventually stops beating regularly i.e. fibrillates. Ruslik_ Zero 20:30, 25 June 2019 (UTC)
 * Anaphylaxis has links to what happens Gem fr (talk) 20:46, 25 June 2019 (UTC)

Black holes
If and when the Big Rip happens, what will happen to black holes? Will they “survive” Rich (talk) 18:28, 25 June 2019 (UTC)
 * I don't think that is something our current understanding of physics can answer. But they won't survive forever - Hawking radiation will make them evaporate. --Stephan Schulz (talk) 19:25, 25 June 2019 (UTC)
 * Very hard to say what will happen; we are talking about an event that may happen in roughly 22 billion years. The Big Rip article states that atoms, spacetime etc. will all be torn apart, so roughly speaking, black holes will not 'survive'. You also have to remember that this is hypothetical - the universe might end in a Big crunch, Big Chill, or several other possibilities, including religious ends to the universe. Even the cause of a Big Rip (Dark energy) is barely understood. Willbb234 (talk) 19:53, 25 June 2019 (UTC)


 * In a Big Rip scenario, black holes will lose all their mass due to accretion of phantom energy, see here and here for details. Count Iblis (talk) 15:57, 26 June 2019 (UTC)