another universe. and inside black holes in our universe are different universes. goes both directions, who knows how deep. black holes all the way down and up.
Our part of the universe*... The presumption is that neutron stars are the results of gravity overcoming nuclear forces, and black holes are the results of some other force being overcome, and therefore our visible universe is the inside of a greater collapse... Or the explosive eventual death of a black holes...
It's a novel idea, but it's just turtles all the way down
No, that's not really what I'm saying. A black hole is a just a region that light can't escape from. It is entirely possible for the inside of the black hole to be composed of normal, everyday matter, non-singularity matter. The Schwartzchild radius scales linearly with mass, an unusual relationship that means that for any density the O(r^3) volume will eventually be overtaken by the O(r) Schwartzchild radius.
