What do you know about General Relativity?
Because the high level version is basically: if you add enough mass/energy in a small enough volume, you get enough gravity going on that even light can’t escape that are of space.
Basically, everything in that area of space has to move towards the center in pretty much the same way that everyone has to move forward in time in a normal region of space.
You can still move in other directions. Yup can move slower or faster towards the center, but moving away from it is going to be impossible.
That’s a black hole.
Einstein Field Equation predicts that.
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