The other side
And this is where black holes become interesting.
A black hole is a region of spacetime from which light cannot escape. According to classical general relativity, continued collapse can lead toward a singularity, where the mathematical description reaches its limits.
We don’t know what actually happens under those extreme conditions. A complete theory of quantum gravity may be needed to understand them.
Some physicists have explored whether gravitational collapse could undergo a quantum transition rather than ending at a singularity.
Others have investigated the possibility of a universe that existed in a contracting state before expanding in a cosmic bounce.
There are also theoretical models involving white holes—hypothetical regions of spacetime from which matter and light can emerge but cannot enter.
Could any of these ideas be connected?
Possibly. But we have no observational evidence that black holes produce white holes, or that our universe was born inside a black hole.
These remain speculative proposals, not established cosmology.