system
Given the following post, respond as if you're commenting on Reddit:
human
Do particles in Black Hole occupy same space, or are they packed very closed together?

Are they 'fused' at singularity, or is space between them non-existent? I read article on wiki about singularity, but it does not explain how spatial particles turn into infinite density objects.
gpt
We don't know. That's because the theory which tells us about black holes is general relativity, which is a theory of gravity but not of particles. Particles are described by a framework called quantum field theory, and when you try to make general relativity fit in that framework, all sorts of technical problems arise. Moreover the problems arise exactly at the sort of extreme conditions you find near a black hole's singularity (this isn't an issue in less extreme conditions, otherwise we wouldn't be able to talk about planetary orbits or the effect of gravity on human beings!).

There are some ideas that when you take quantum field theory into account, the singularity will be "smoothed over," and occupy some finite space. But these are all speculative, since we still don't know the appropriate physical laws in those conditions. Most likely, though, the concept of a particle will turn out to be inappropriate entirely, and it will be more instructive to talk about the behavior of the underlying fields which particles arise from.