Question

If space has no medium, than what is the black hole "punching" a hole in?

If you answer spacetime, than what is spacetime?

Answer 1

Obviously the answer is spacetime.

There are long discussions about "what is space-time" and of course no one really knows but quantum mechanics and quantum field theory in particular, I believe, posits space time is discrete rather than continuous as in classical relativity. That suggests it to possibly be something but there is no agreement here either: continuous or discrete?. You can also look up causal dynamic triangulation as to how spacetime might form, and spin foam is another variety. Space time forms from entropy and while unproven offers I think fascinating possibilities. And of course one can utilize incomplete theories about the universe being formed of information, a relative of entropy.... And a case can be made that the holographic principle offers yet another insight into spacetime, and everything else that we perceive as being three dimensionally space enclosed...maybe everything we know is really area rather than volume based...information content and flow sure seems to be that way. Another hint at an answer, might be contained in the big bang versus black hole singularities. Apparently Weyl curvature in the former approach zero, or is at least finite, while Weyl Curvature in the latter diverges...so the low entropy of the big bang might be markedly different than the exceedingly high entropy.