[inspector-g]

This reminds me of a question I’ve had for a while, and have not been able to formulate it well enough to do any searching for an answer on my own (total layman here).

Do we have any hypotheses of what the matter inside a black hole might be like? I mean “hypotheses” in a strict sense; I do not mean “a good/definitive answer”

To oversimplify a bit: white dwarves are supported by electron degeneracy pressure, and if such pressure is exceeded by gravity then e.g. a neutron star can form. Neutron stars are supported by neutron degeneracy pressure, and if such pressure is exceeded by gravity then a black hole can form.

For each of those “steps” we have an idea of what the matter within must be like to support/exceed such pressures. Are there any hypotheses for what the matter might be like after such known pressures are exceeded and a black hole is formed?

[wcoenen]

Degeneracy pressure comes from the Pauli exclusion principle.

There is no limit to how high this pressure can go, as there are always higher energy states to occupy. (Except that for electrons at a high enough energy state, they will disappear by fusing with protons.)

For neutrons, there is no such disappearing effect, so the degeneracy pressure can keep on increasing. So how can this pressure ever be "overcome by gravity"?

Apparently at some point the degeneracy pressure itself starts to contribute significantly to spacetime curvature. This increases gravitational pressure, which compresses the neutrons, which increases the degeneracy pressure, which increases curvature, etc. No balance is possible anymore and collapse happens.

Presumably this process of ever increasing neutron degeneracy pressure continues within the black hole until unknown physics come into play.