I Black Hole Radiation: Questions Clarified

[Ibix]

I use that line all the time, but in this case, not sure why many/we even define a black hole as containing a singularity.

We don't, strictly speaking. We say that GR models a black hole as containing a singularity, but we have reason to believe that this means that GR goes wrong somewhere along the way.

 

[jbriggs444]

I use that line all the time, but in this case, not sure why many/we even define a black hole as containing a singularity.

Our mathematical description of a black hole has a feature which we term a "singularity". To say that this means that a black hole "contains" a singularity is, perhaps, an abuse of terminology, but it is a common abuse.

 

[PeterDonis]

How strong does the latter weaken the consistency argument

It is true that having a single self-consistent theory that accounts for all known experimental data carries weight; having one theory that has GR and our current quantum field theory as special cases--approximations valid under particular conditions--would be better, by some criteria, than just having the two separate theories, even if there were no experimental data that could not be accounted for by one of the two separate theories. But I don't know how you would quantify this.

are there cases known in the past that a physical problem seemed to be solved from a mathematical point of view which however has turned out later to be wrong?

Sure. Newtonian mechanics. It accounted for all the known experimental data when it was formulated, and for at least a century afterwards, and it unified at least two domains--falling bodies on Earth and motions of the Sun, planets, and Moon--that were previously covered by separate theories (roughly speaking, the mechanics implied by Galileo's experiments with inclined planes, and Kepler's model of the solar system), without any new experimental data that could not be accounted for by one of those two theories. But Newton's model was a clear unification of all that was known at that time about mechanics--yet, as we now know, it is not correct, it's just an approximation valid in a particular regime.

 

[timmdeeg]

It is true that having a single self-consistent theory that accounts for all known experimental data carries weight; having one theory that has GR and our current quantum field theory as special cases--approximations valid under particular conditions--would be better, by some criteria, than just having the two separate theories, even if there were no experimental data that could not be accounted for by one of the two separate theories. But I don't know how you would quantify this.

Perhaps it depends on how the singularity problem can be solved. Perhaps it might be even more convincing if it could be shown that gravity is an emergent phenomenon which reproduces General Relativity. Or do you think that it is quite compelling that QFT should be a special case?

Sure. Newtonian mechanics.

Ah yes. Whereby fortunately in this case the range of validity could investigated experimentally.

Thank you for your comments!

EDIT I'm realizing "perhaps" is just speculation, so please ignore it.

 

[Teslascience]

Where? Please give a reference.

Sorry, can't remember or find it again. It was years before.