Roy Kerr: Do Black Holes Have Singularities?

Re:Roy Kerr: Do Black Holes Have Singularities? by ben_w on Thursday December 14, 2023 @08:40AM (#38641193)

Black holes have a finite volume on the outside, but I'd have to do an integral above my skill level to work out the volume inside; if I understand right, the radial direction and the time direction switch roles at the event horizon.

Also, I'm not sure you need stuff to always approach without ever getting there: it's not clear what happens to quantum fields at a singularity, but if you no longer have time displacement symmetry you don't get energy conservation so stuff might just cease to exist.

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Re:Roy Kerr: Do Black Holes Have Singularities? by nyssos on Thursday December 14, 2023 @09:08AM (#38641463)

> but I'd have to do an integral above my skill level to work out the volume inside; if I understand right, the radial direction and the time direction switch roles at the event horizon.

If you try to naively apply the same procedure you would use to define volumes outside the event horizon, it's proportional to the lifetime of the black hole (infinite in the classical case) for the reason you note.

Of course the better way to interpret this is probably just that the interior volume of a black hole is ill-defined.

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