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From science class, I'm led to belive that all matter breaks down once it's sucked into a black hole. I get that part, but doesn't all that matter still exist in the center of the black hole? yes it's no longer what i used to be, but it's still there in a different form right? If so, what's it look like? does it look like a pea? or maybe it would be bigger in some cases and it would look like a basketball? a planet sized sphere even? If light were "allowed to escape" would it have color and look like some mushed up piece of multicolored clay-dough? How would it look like if we could somehow bypass gravity and observe it? does anyone know?

Qmechanic
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Awpung Elric
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  • Possible Duplicate: https://physics.stackexchange.com/questions/26704/what-happens-to-light-and-mass-in-the-center-of-a-black-hole –  Apr 17 '19 at 10:38
  • The "center" of the simplest non-rotating uncharged black hole is not a place in space, but a moment in time. So it cannot "have" anything. – safesphere Apr 18 '19 at 07:59
  • This is an interesting question. For very large BHs, the tidal forces at the EH are quite modest. So you could survive a (one-way) trip across the EH. Then, what would the singularity look like? N.B. all in the reference frame of the voyager. – Oscar Bravo Apr 18 '19 at 09:30

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We don't know for certain what lies inside the event horizon of a black hole, since we can never observe what happens inside the event horizon. General relativity predicts a gravitational singularity at the centre of a black hole, but this may not be physically meaningful - how can the curvature of spacetime actually become infinite in reality ? We need a theory of quantum gravity to make a better prediction. It is possible that some form of extremely dense degenerate matter may exist at near the centre of a black hole - but we do not know for sure as our current state of knowledge only allows us to speculate.

gandalf61
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    This answer is incorrect. "It is possible that some form of extremely dense degenerate matter may exist at the centre of a black hole" - A black hole does not have a center. A Schwarzschild singularity is asymptotically an infinitely long straight line. It is also spacelike meaning that it is not a place in space, but a moment in time, the last one, the end of time inside of the black hole. "To exist" means "to move in time". A singularity does not move in time, it is a moment in time, so the singularity does not "exist" in the "center" of a black hole. – safesphere Apr 18 '19 at 07:55
  • @safesphere you seem to assume that general relativity is applicable to the region of space inside a black hole. That is far from certain. In fact, string theory predicts that the space inside a black hole is perfectly flat because all mass is concentrated at the event horizon. – John Dvorak Apr 18 '19 at 09:03
  • @safesphere Doesn't the existence of a singularity in GR models simply show that the GR models cease to describe physical reality at or near the centre of a black hole ? Can a point with infinite spacetime curvature actually be real/physically meaningful ? – gandalf61 Apr 18 '19 at 09:04
  • @safesphere Incorrect is a bit harsh... Gandalf61 is just speculating in the same tone as the OP - they're chatting over a beer. He clearly states that no-one knows what happens as the curvature of space-time approaches infinity. – Oscar Bravo Apr 18 '19 at 09:26
  • @OscarBravo I have explained why the answer is incorrect. I don't do "harsh" on a difference in opinions, but when a wrong answer gets accepted, it must be pointed out. This site is not for chatting over a beer. Wrong answers, especially if accepted, do a disservice to users worldwide. – safesphere Apr 18 '19 at 14:29
  • @JohnDvorak The answer refers to the GR solution inside the horizon, but misinterprets the spacelike nature of the singularity (the fact that it is not a place in space where anything could be located). Aside from this question and answer, personally I believe that GR is applicable inside a black hole, but the Schwarzschild solution is invalid inside the horizon, because its metric is not static there. Also, "all mass concentrated at the horizon" is not trivial and what it makes of spacetime inside is unclear: https://physics.stackexchange.com/questions/414695/whats-inside-a-frozen-star – safesphere Apr 18 '19 at 14:51
  • @gandalf61 "Can a point with infinite spacetime curvature actually be real/physically meaningful ?" - Once again, a singularity is not a point in space, but a moment in time. The duration of this moment is zero. What happens there is clear - time ends and matter (energy) disappears, because time and energy are two sides of the same reality (mathematically, Fourier conjugates). How exactly they disappear is an open question for quantum gravity, but it doesn't change what happens. Similarly, we don't know how exactly the Big Bang happened, but we know without quantum gravity that it happened. – safesphere Apr 18 '19 at 15:07