0
$\begingroup$

I've had a couple of general relativity courses thus far but I'm still not quite sure what the answer to this question is. Let's assume we are on a perfectly spherical planet at the centre of a region which has enough matter around it that collapses into a black hole. Due to relativistic effects the space between the collapsing region and the planet increases. My question is, would this process continue infinitely? Could we think of the inside of a black hole like a never ending "zoom out/in"?

$\endgroup$
1
  • 1
    $\begingroup$ Why would the the space between the collapsing region and the planet increase? In the simplest model of a collapse, the Snyder-Oppenheimer metric, the interior region has the same geometry as a contracting universe. All spaces inside the region decrease with time. $\endgroup$ Dec 31, 2019 at 18:56

1 Answer 1

3
$\begingroup$

My question is, would this process continue infinitely? Could we think of the inside of a black hole like a never ending "zoom out/in"?

No, the observer you describe will hit the singularity in some fixed maximum amount of time. For a solar-mass black hole, this is on the order of milliseconds.

The singularity is not a point in space, it's a spacelike surface that lies in the future for all observers. For observers inside the horizon, it represents the end of time.

$\endgroup$
3
  • $\begingroup$ What if the observer is at the centre of the black hole before it forms? $\endgroup$ Dec 31, 2019 at 22:19
  • $\begingroup$ @fielder: What if the observer is at the centre of the black hole before it forms? Why would that matter? Again, remember that the singularity is not a point in space, so it's not a point at the center of the black hole. $\endgroup$
    – user4552
    Jan 1, 2020 at 0:25
  • 1
    $\begingroup$ Remember, existence of singularity is remarkably a sign of theory beying unsuccessful, not element of physical reality. $\endgroup$
    – kakaz
    Jan 1, 2020 at 16:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.