3 ms·

While I’m totally in agreement with the second part of your comment, the first part may not be true. No, this is not correct. Once an event horizon forms, ever

While I’m totally in agreement with the second part of your comment, the first part may not be true. No, this is not correct. Once an event horizon forms, everything inside the horizon will hit the singularity, because the singularity is not a place in space, it's a moment of time, which is in the future (and the not too distant future for holes of reasonable size--the time from horizon to singularity for a black hole of 10 solar masses is about 100 microseconds) for everything inside the horizon. We don’t actually know if there’s a singularity within the event horizon. GTR predicts it, but that’s in the context of the breakdown of the predictive power of the theory. Until/Unless we have a viable theory of quantum gravity what is inside an EH is speculative. Quark stars or any form of conventional matter are right out obviously, but Fuzzballs or some other novel “structure” can’t be ruled out yet. Having said that, I’m not a string theory adherent, I’m just pointing out that within the event horizon we need a complementary theory to augment GTR and QM.

pdonis 9y ago
> We don’t actually know if there’s a singularity within the event horizon. Not if we take quantum effects into account, no. I was describing what classical GR predicts. I agree that GR also predicts that it should break down in the regime close to the singularity. It's also worth noting that there is a school of thought among physicists that says that quantum effects are non-negligible even at the horizon of a black hole of stellar mass or larger. This is the "firewall" debate that is currently ongoing. I personally don't find the arguments in favor of a "firewall" convincing, but it is an area of ongoing debate.
- IntronExon 9y ago
  Agreed on all points, and the firewall is interesting, but I can’t see how it doesn’t somehow create a privileged frame of reference. It’s still very cool/terrifying, even in the already notoriously cool/terrifying realm of black holes.
  - qubex 9y ago
    The whole controversy about the firewall hypothesis is that I’d does create a privileged frame of reference, directly contradicting general relativity (that indirectly forms the basis for predicting the firewall’s existence).

pdonis 9y ago

> We don’t actually know if there’s a singularity within the event horizon. Not if we take quantum effects into account, no. I was describing what classical GR predicts. I agree that GR also predicts that it should break down in the regime close to the singularity. It's also worth noting that there is a school of thought among physicists that says that quantum effects are non-negligible even at the horizon of a black hole of stellar mass or larger. This is the "firewall" debate that is currently ongoing. I personally don't find the arguments in favor of a "firewall" convincing, but it is an area of ongoing debate.

IntronExon 9y ago
Agreed on all points, and the firewall is interesting, but I can’t see how it doesn’t somehow create a privileged frame of reference. It’s still very cool/terrifying, even in the already notoriously cool/terrifying realm of black holes.
- qubex 9y ago
  The whole controversy about the firewall hypothesis is that I’d does create a privileged frame of reference, directly contradicting general relativity (that indirectly forms the basis for predicting the firewall’s existence).