You need to understand something before we begin. The theoretical framework we have to gauge and answer this sort of thing is called General Relativity, which was proposed by Einstein in It describes things such as gravity, black holes, or just about any phenomena where large densities of mass or energy are involved. There's another chapter in Physics called Quantum Mechanics. This describes, usually, what happens at very small scales - things that are super-tiny. Both GR and QM are fine in their own way.
Black holes are 'portals to other universes,' according to new quantum results
Into a Black Hole - Stephen Hawking
This new theory is based on a concept known as 'loop quantum gravity' or LQG. It was first formulated as a way of merging standard quantum mechanics and standard general relativity, in order to remedy incompatibilities between the two fields. Basically, LQG proposes that spacetime is granular, or atomic, in nature; It is made up of miniscule, indivisible chunks about the same size as the Planck length — which roughly amounts to meters in size. What they found was far different from what happens according to general relativity alone: Instead, just as the black hole began to squeeze tight, it suddenly loosened its grip again, as if a door was being opened. It might help to conceptualize exactly what this means if you imagine yourself traveling into a black hole.
Can you hear me. So he gets into a space probe, and dives into the black hole. Michell suggested that there might be a large number of stars like this. How then could gravity slow down light, and make it fall back. This was impossible, according to the then accepted ideas of space and time.