Regarding black holes, I'm not sure how much has been discovered lately, but... I can see some of you are thinking with using Newtons equations. What Einstein did was to prove that Newtons equations do not hold since time is relative. But we still use them since they are almost perfectly accurate in our world with very slow speeds (compared to light).
First they said that gravity is an acceleration, not a force. Regardless of the size of the object, it will accelerate at the same speed. (eg. 9.8 m2/sec on earth). This is when the mass of the falling object is not significantly big compared to the big mass (planet) creating the gravitational field. When the falling object actually is big enough, the acceleration changes as well (i believe it gets smaller).
So when something is falling into a blackhole, it gets very close to the lightspeed and its mass increases tremendously, creating a big gravitational force in itself. This causes the atoms to collapse. The protons and electrons bind and form neutrons. Now the object is only made of neutrons, so its pure matter with no spaces, since no electric force exists within itself. The center of the blackhole is made of same type of object. When this falling object gets so heavy and since the time is also expanding, the acceleration actually drops, and i believe thats why it probably doesnt reach lightspeed. (since acceleration is relative with time).
I'm not 100% sure of all that, but nobody actually knows what exactly happens withing the black holes. And nobody will ever be able to observe it either, its always gonna stay as a mystery within theories and equations.
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