If black holes crush things into infinite density, shouldn't they all be the same size?
Black hole size is expressed in terms of its event horizon, which is proportionate to its mass.
(Note that when I say "inside a black hole," I mean "inside the event horizon.")
To elaborate, nobody really knows what on ... in the Universe happens inside a black hole, our current theories say they should collapse into 0 size, but some (a lot, from what I gather) think this just means our theories no longer apply perfectly in these situations.
So trying to describe stuff in terms of what's going on inside a Black Hole is going to be pretty much pointless, so we have to describe stuff in terms of what can be measured from outside the black hole.
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