- #36
PeterDonis
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kimbyd said:Those solutions don't describe any mass distribution at all.
But they are idealized solutions. A realistic solution would contain a region of nonzero stress-energy, joined by a boundary to a vacuum region with Schwarzschild or Kerr geometry. An example of such a solution (still idealized, but less so than the pure vacuum solutions) is the Oppenheimer-Snyder model of a spherically symmetric collapsing object. Even in such a solution, an observer falling through the event horizon long after the collapse of the object will not pass through any region of nonzero stress-energy; that was the scenario I was describing in my previous post.
kimbyd said:Very likely GR breaks down some distance outside the singularity.
Yes, this is the current belief of most physicists. But we won't know until we have a better theory and a way to test it experimentally.
kimbyd said:How far outside is at this point unknown.
This is a more contentious area, since there are different conflicting opinions on how strong quantum gravity effects are at or near the horizon. Again, we won't know until we have a better theory and a way to test it experimentally.