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Neutron stars form dense clusters of neutrons which I have heard being called an element 0 and theoretically could form strange matter and the like from what I have read. Given that a black hole is essentially a more extreme version of a neutron star would black holes be made of a new form or state of matter. Essentially what is a black hole made of what state of matter are the particles inside of it in? I have seen a few other questions on here that are similar but I haven't really found a satisfactory answer as to what form of matter makes up a black hole and if it might have any new properties.

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  • $\begingroup$ Related: physics.stackexchange.com/q/354889/123208 As the answers to that question state, we cannot say exactly what happens to matter at the heart of a black hole until we have a theory of quantum gravity. $\endgroup$
    – PM 2Ring
    Oct 19, 2020 at 21:37

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Essentially what is a black hole made of what state of matter are the particles inside of it in?

Currently our only theory that describes black holes and has empirical support is Einstein's theory of general relativity (GR). The standard black hole solutions to the equations of general relativity are vacuum solutions. In a vacuum solution, there are no particles of matter present.

You can of course dump matter into a black hole. If matter falls into a black hole, then according to an observer free-falling along with the matter, that matter exists for only a very short time, typically on the order of milliseconds. After that time, it hits the singularity and stops existing, as does the observer.

You could ask what happens instead according to a distant observer. The distant observer can't observe what has happened to any infalling matter, and if the distant observer asks about the state of the matter that they have seen fall in, GR says that the answer to this question is undefined, because GR doesn't define simultaneity between the inside and outside of a black hole, so it can't say what's going on in there "now."

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  • $\begingroup$ "GR doesn't define simultaneity between the inside and outside of a black hole, so it can't say what's going on in there 'now.'" - While this is not wrong, this viewpoint disregards the cosmological time. This universe is 14 billion yers old and no part of it is older. Noting has happened yet in this universe that would take more than 14 billion years in any coordinate system. So while in general remote simultaneity is undefined, the upper limit of "now" in any coordinates is (at least approximately) the Hubble time. $\endgroup$
    – safesphere
    Oct 21, 2020 at 6:32
  • $\begingroup$ "After that time, it hits the singularity and stops existing" +1 $\endgroup$
    – safesphere
    Oct 21, 2020 at 6:33

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