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ExactCollege3 OP t1_irhlv9c wrote

Reply to comment by 010011100000 in Can an object that’s not a black hole be so dense or massive that it has an event horizon? by ExactCollege3

So how do we know if something is a singularity? So it’s kind of an assumption that this happens every time by general relativity? And what part of it leads to that?

If I’m hearing right, yes some neutron stars could gain enough mass to become black holes, and we’re not sure yet if all black holes are singularities because not everything adds up right and a new rule could be discovered?

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mfb- t1_irhnkkz wrote

> So how do we know if something is a singularity?

We do not. It's a strong prediction of general relativity because inside a black hole, all possible trajectories lead towards the center (or a ring for rotating black holes): Trying to stay at a finite distance is as impossible as trying to stay in Sunday.

> If I’m hearing right, yes some neutron stars could gain enough mass to become black holes

Yes, because they collapse above a certain mass. They are not neutron stars any more if that happens.

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DoodDoes t1_irixcna wrote

The Schwarzschild radius would be a good thing to look up to learn about when and why a black hole forms. And the event horizon is basically the point where we have to rely on math rather than observation to be able to tell what’s going on. But the same used to be true for black holes themselves, and the math held up for that

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