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Would a black hole with a rotating quadrupole moment in its mass distribution generate gravitational waves?

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    If I had water that wasn’t wet could I wash myself with it? – TimRias Jan 19 '23 at 18:48
  • As I said here, the matter and energy inside the event horizon cannot affect the outside universe in any way. – PM 2Ring Jan 19 '23 at 19:00
  • @PM2Ring What about frame dragging? http://ion.uwinnipeg.ca/~vincent/4500.6-001/Cosmology/Rotating_Black_Hole.htm In the ergosphere the rotating Black Hole drags space around with it (called frame dragging) in such a way that all objects inside the ergosphere must rotate with the Black Hole. – foolishmuse Jan 19 '23 at 21:34
  • @foolishmuse All of the properties of the BH are determined by what the matter & energy were doing before they crossed the EH. That applies to the angular momentum and the electric charge, as well as the gravity. That's why we call it a fossil field. Also see https://physics.stackexchange.com/a/3204/123208 – PM 2Ring Jan 19 '23 at 21:54
  • @PM2Ring you are basically saying that all the warping of spacetime, i.e. the gravity of a black hole was determined at the moment the star collapsed past the event horizon. And if the matter inside the black hole some how disappeared, then the black hole would continue to exist. This is rather a new concept to me. – foolishmuse Jan 19 '23 at 22:18
  • @foolishmuse I'm just saying that events in your future light cone cannot affect your present. Events inside the EH are in the future light cone of any observer outside the EH. Furthermore, the singularity of a BH is not in the past light cone of any observer, even those inside the EH. – PM 2Ring Jan 20 '23 at 10:29

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