Black Hole Fragmentation

[javisot]

TL;DR

Entanglement between black holes produced by fragmentation.

I would like to ask about the recent article https://arxiv.org/abs/2606.24642 "when black holes can wear pants". This article discusses the "fragmentation" of black holes. We know that two black holes can merge into one, accompanied by the emission of gravitational waves; the article addresses the opposite question: can a black hole split into several others?

The answer: classical black holes, no; quantum gravity black holes, yes. My question concerns the context of "yes, in quantum gravity".

The article does not discuss whether or not the fragments are entangled, but it is reasonable to assume that if I can split a quantum-gravity black hole into two, the resulting black holes are entangled, right?

 

[PeterDonis]

My question concerns the context of "yes, in quantum gravity".

Since nobody has a good theory of quantum gravity, anything along these lines is going to be speculation.

it is reasonable to assume that if I can split a quantum-gravity black hole into two, the resulting black holes are entangled, right?

I think that would depend on whether the same quantities that are conserved in standard GR remain conserved in these speculative quantum gravity models. If, for example, a spinless black hole splits into two, and angular momentum is conserved, the spins of the two product holes would have to be entangled. But if angular momentum is not conserved (for example, if gravitational wave emission during the splitting process can carry off an arbitrary amount of angular momentum), then I don't see why the two product holes would need to be entangled.

Note that in the reverse process, black hole mergers, in standard GR, there are no conservation laws that apply to the holes considered in isolation; only when you include the effects of gravitational wave emission during the merger can you obtain conservation of things like energy and angular momentum.