Comment by cmarschner
4 years ago
Question in this regard: current theory seems to predict a singularity with “infinite” space-time curvature (IIUC) in the center of a black hole. This seems utterly improbable to me. Is it common sense to treat this as a given or is it considered a weird quirk of general relativity that is sought to be overcome?
In this universe of ours, there isn't anything profoundly improbable about a point particle with a mass of a million suns. We commonly treat electron's as point particles with tiny mass - and there isn't yet any hint in theory or experiment that this model is incorrect (when the particles dynamics are calculated through QM).
That being said, physicists dislike discontinuities. A theoretical point particle with high mass means that there must be a mechanism to merge large quantities of mass into black hole matter. If it is a point particle with extremely large gravitational fields, these final interactions would also require some version of quantum gravity to predict. In fact, it's entirely plausible that what we observe as black holes are actually not GR singularities at all https://en.wikipedia.org/wiki/Black_hole#Alternatives
There is hope for improving observational data on black hole interiors by measuring the gravitational waves of merging black holes. Different types of black hole singularities will have different event horizon shapes, and the merger of these black holes should produce different gravitational waves, amongst other observable effects. https://en.wikipedia.org/wiki/Kerr_metric
Thank you this is what I love HN for
It’s generally regarded as major flaw with general relativity - and that general relativity is only an approximation for a better theory.
You don’t need anything as exotic as a black hole, general relativity can’t say anything about how gravity works at small scales at all.