What happens to the matter inside a black hole?

[KurtLudwig]

What happens to matter after it falls into a black hole? Are electrons pushed closer to the nucleus? Do electrons combine with protons to form neutrons? Are there nuclear reactions occurring in the process? Since no light can escape from a black hole and cool it, then how can a black hole contain all that accumulating thermal energy?
Only gravity "escapes" from a black hole.

 

[Nugatory]

What happens to matter after it falls into a black hole?

Short answer: No one knows.
Longer answer: General relativity says that the infalling matter is compressed without limit as it approaches the singularity at the "center" (not the event horizon - as far as the infalling matter is concerned there's nothing special about it). Carried to its logical extreme, we would end up with a point of zero volume and infinite density. However, long before then we're dealing with pressures and densities that far exceed anything covered by any of our existing theories of how matter behaves - so there's no reason to trust that logical extreme, and no way to give a better answer than the short one above.

 

[pervect]

Some very small changes to General relativity, such a Einstein-Cartan theory can dramatically change what we expect to happen inside a black hole. Nikoderm Poplawski has a number of papers on the topic of Einstein-Cartan theory. So by far the safest answer to "what happens to matter after it falls into a black hole" is "we don't know".

In general, we expect quantum gravity to be important inside a black hole, and there isn't any consensus on what the best theory of quantum gravity is. Einstein-Cartan theory is just one particular and specific example of the vast array of possibilities. Many of the possibilties are utterly beyond are ability to experimentially distinguish at the current time, and for the forseeable future.

Even discounting possible modifications to GR, exactly what happens inside a realistic black hole is still not totally understood. There are some interesting papers on the topic, such as Poisson and Israel's 1990 paper, 'Internal structure of black holes', but the problem is a complex one. The Schwarzschild solution is mathematically fairly simple, but unstable against small pertubations. So theoretical models of a perfectly symmetrical dust collapse discussed in introductory textbooks won't tell us what happens if a less-than-perfect dust cloud, with small fluctuations in density, collapses.

 

[PeterDonis]

: General relativity says that the infalling matter is compressed without limit as it approaches the singularity at the "center"

Actually, it's not quite that simple. GR says that the infalling matter will be squeezed along some dimensions and stretched along others. (The details depend on which solution you adopt for the interior of the black hole). But this doesn't change the key point that the pressures (and tensions) and densities far exceed what can be withstood by any known material well before the singularity.

 

[kent davidge]

far exceed what can be withstood by any known material

material at what level? molecular level?

 

[PeterDonis]

material at what level? molecular level?

GR is a classical theory; it models matter as a continuum, with material properties like tensile strength. All known materials have a tensile strength many orders of magnitude too small to withstand the stresses from tidal gravity well before the singularity of a black hole is reached.

Properties of materials like tensile strength do ultimately arise from the underlying quantum mechanics of atoms and molecules, and we can also deal quantum mechanically with states of matter far denser and with very different properties, like neutron star matter. But relativity still imposes a finite limit on the ability of any material to maintain its structure in the presence of increasing tidal gravity, because of the finite speed of light. So even exotic materials like neutron star matter would eventually be destroyed by large enough tidal gravity. At least, that's our best current belief. There are speculations that at high enough densities, other quantum effects might come into play that would cause a "bounce" instead of continuing collapse, but those are just that, speculations.

 

[KurtLudwig]

Do particle collisions in the Large Hadron Collider create, for a very short moment, the state of matter in a black hole?

 

[Vanadium 50]

Do particle collisions in the Large Hadron Collider create, for a very short moment, the state of matter in a black hole?

No.

 

[Outhouse]

like neutron star matter

With size of a sun being the factor that determines a neutron star or black hole, why couldn't there be a limit for the amount of neutrons as the only factor determining if a black hole is formed? In other words why is a black hole not just a large enough amount of neutrons? I am sure there is math that refutes such an obvious question. Do we suspect a when a large enough sun has collapsed that has the mass to form a black hole, that the electrons are thus broken down into there elemental properties? if we were to take it a step further? or is unknown still the best explanation?

 

[Ibix]

In other words why is a black hole not just a large enough amount of neutrons?

Look up the Chandrasekhar Limit. It turns out that neutron degeneracy pressure isn't enough to support the weight of a star above a certain mass (about 1.4 solar masses) once fusion has stopped. If it can't support its own weight, a star must collapse. And we don't know of anything that would ever stop it if neutron degeneracy pressure isn't enough - so you get a black hole.

Future theories or observational evidence might modify this, of course, but that's our current understanding.