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tegeek | 5 years ago
A "finished" black hole (The end state of the gravitational collapse) doesn't have a volume or any density.
This is the mathematical solution first obtained by Schwarzschild in 1916. So standard mathematical solutions of the black holes are vacuum solutions.
There is "nothingness" inside the event horizon.
The outside observer would see a collapsing sphere of dust, but over time, as the radius of the sphere approaches the (yet to form) event horizon, gravitational time dilation makes everything appear increasingly in slow motion. The actual moment of horizon formation is never seen, it remains forever in the future for the outside observer.
For the in falling observer, the situation is different. The moment once the horizon is crossed, there is no escape. The observer will find himself inside an ever shrinking “universe” of dust everywhere. The singularity is an unavoidable future moment in time, when the density of this “universe” becomes divergent and time itself comes to an end.
So there you've a vacuum. A "universe" of vacuum everywhere where there is no time exists.
simiones|5 years ago
So, take any such description with a grain of salt. It's much more correct to say that our current models can't accurately predict what is happening past the event horizon of a black hole.
tegeek|5 years ago
TeMPOraL|5 years ago
Makes me wonder. We used to believe that it's possible for our universe to eventually collapse, reversing the Big Bang in a Big Crunch. From what I recall, current evidence points against it, but if we were to live in such a universe doomed to a collapse - wouldn't that mean we'd be living in a universe-sized black hole?
(A black metahole if you like.)