Are black holes gate ways to parallel universes?

Science is not a matter of opinion or belief. It's a matter of facts and evidence. Yes, black holes exist.

By your logic, no one could be sure the Sun exists, since no one has ever been inside it. Or the Earth for that matter. We know black holes exist because we can detect their gravitational effects on other objects and because we can see material falling into them, being super-heated in the process, and emitting x-rays.

Black holes are not actually holes in space. They don't go anywhere. They are dead, dense stars.

Falling 'into' one is like falling to the surface of the Earth from a very high point, only much faster, and with the same result - splat. Anything falling 'into' one gets crushed down on the surface of the dead star and becomes part of the black hole. No, nothing lives inside them.

It's ridiculously degenerate in nature. Even atoms can't survive that.

Black holes have been shown to exist. What lies within them is unknowable to existent science though. However, they do exert a gravity field that would pull everything that comes too close within it.

Now as to whether or not they open into another universe is pure speculation.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.