Excuse me if this is a very simple question but I am no physicist I am just very interested in astrophysics.

If I'm not mistaken the whole reason black holes are formed in the first place is because the Schwartzschild radius exists, where if an object is compressed to or smaller than its specific radius, it turns into a black hole. I am wondering if or why this even applys to the singularity. The singularity is an infinitely dense point at the centre of a black hole to my knowledge. And everything that falls radially inward is brought into this dense point. So why is all this mass at the centre of the black hole In such a small radius not turning into another black hole? And if it does would this cycle continue infinitely because of the constant creation of more singularities?

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    $\begingroup$ Re, "if an object is compressed ... it turns into a black hole." Not quite. The object does not "turn into" a black hole, it creates a black hole. The black hole is not the object (or rather, it is not the object's mass, since the object itself ceases to have an identity when even its very atoms are crushed into who-knows-what.) The black hole (as Cort Ammon mentions, below) is the region of spacetime in which all geodesics lead to the singularity. $\endgroup$ – Solomon Slow Jun 16 '17 at 16:51

There's a difference. A black hole is simply a region of space where any light that enters cannot escape because the pull of gravity is too great. A singularity is a point where our mathematical models break down entirely and cease to be able to model the physical universe as we know it.

We literally could not answered your question if we wanted to, because the math breaks down at the singularity, so we could not address the concept of something forming in it.

  • $\begingroup$ the math breaks down at the singularity, so we could not address the concept of something forming in it. Another way of putting it is that the singularity acts like a future boundary on spacetime, basically a literal end of time, so we can't discuss it evolving further into the future. But AFAIK there is no fundamental principle that prevents the separate formation of multiple singularities inside a single event horizon through gravitational collapse. E.g., the Penrose singularity theorem only guarantees at least one singularity. $\endgroup$ – Ben Crowell Jun 16 '17 at 22:06

No, the singularity in the black hole is apart of the black hole and does not obey normal spacetime rules regarding mass. The reasoning behind your question: if the singularity is so dense, why doesn't that collapse into another black hole? Because the singularity is already so small it cannot get any smaller, it's schwartzchild radius is unattainabally small- no matter how dense the singularity is. This goes back to my previous point; how the singularity does not obey normal spacetime rules. That is my interpretation at least.


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