I Black Hole Fermion Count

[.Scott]

TL;DR Summary

Researchers at UK's University of Portsmouth consider the effects of Pauli Exclusion on fermions in a black hole.

A recent paper ( PhyRevD, arxiv, asxiv pdf ) from researchers at UK's University of Portsmouth entitled "Gravitational Bounce from the Quantum Exclusion Principle" considers the effect of any fermions (including quarks and electrons) contained within the event horizon of a black hole.

The discussion is interesting because it can match up with conditions observed in our universe.

But it also makes me wonder how a fermion count can be maintained in the interior of a black hole without also being reflected on its surface.
When a black hole eventually evaporates, would the total number of fermions be preserved?

 

[PeterDonis]

When a black hole eventually evaporates, would the total number of fermions be preserved?

I don't think we know enough about black hole evaporation to give a firm answer to this question.

As best I understand current models, dumping a bunch of fermions (and no antifermions) into a black hole does not mean the same number of fermions will eventually come out. The expectation is that many fewer fermions will come out (quite possibly zero), because the vast majority of the radiation from the evaporation of the hole will be photons.

As far as I know, conservation laws are not violated by black hole evaporation, so, for example, if you dump a bunch of charged fermions into a black hole, the same charge has to come back out somehow. But I don't think there is any general law of "conservation of fermions". The charge might come out as charged bosons.