"That would be the result if the hole had no spin, but a physically realistic hole will have spin."

Hi:

As long as we are interested in mathematical elegance, we need to remember that all singularity is related, and has a mathematical nowhere everywhere characteristic. By that I mean, of course, that for conceptual reasons the universe must be permeated by amorphous non-spin singularity.

Depending on our reference frame we may see the "big bang" and "big crunch" at the universal antipodes in opposite directions, and observe time to flow "differently" but amorphous and attenuated (from our frame!) singularity accounts for gravitation and most of the mass of the universe- so it is important.

Our particulate 4D reality originates in this spin phenomena, so it is also very important. Spin is probably created by the momentum of GR in areas of energy density variation.

It is easy to forget that the big bang did not happen at a geometric point. It "happened" everywhere. There is nothing outside a GR universe, and everything which is a part of it is intimately related- even if part of that "everything" is on the other side of the known universe!

If that last paragraph makes the universe sound awfully cozy- it is. Getting lost in a GR cosmos is just plain impossible, because the ultimate way it is observed, and brought into existence is at each invariant frame of reference...how can we get lost if we never, in any real cosmic sense, go anywhere?

Change in the momentum of GR is real, all too real, but it is expressed in observed energy density differences in the cosmos. Since we are a part of the universe, we see ourselves, and our environment, change with the momentum of GR too- and perceive the passage of time.

Best Wishes, Sam Cox