Question: Is it possible that black holes are actually a "portal" to another dimension? Like, the objects it destroys re-create themselves in the same world only every girl here is a boy there and vice-versa (for example)?
In actual fact if you move towards a black hole, physics says you’ll never really ‘go in’ to it. At some point time will get so dilated that it will actually stop (this will be at the event horizon) and any matter that was there would just… stop.
It’s so hard to imagine the inside of a black hole, our brains aren’t really wired for it. This means that we really don’t understand them very well at all. We have theories about what’s going on at the edge, like Hawking Radiation, but inside is a real mystery. They could end up being anything!
Adam’s talked about black hole’s so I might say something about parallel universes…
There are a bunch of ideas for how alternate, or parallel universes could work. One way, and the case you’ve decribed, is that for every decision made, then two universes split off, and we live in one, and there is another one for the other case. But there are a couple of problems, in that not every decision is a 2 way split so you can have multiple universes from a single point, and also – where do you draw the line for what a decision is. Lots of physical things that happen have knock-on effects (often called the butterfly effect, after the idea that a butterfly flapping its wings could cause a hurricane), so you’d have to have a new universe for every tiny physical change, eventually going down to the movements of single atoms. Then you get infinity possible alternate universes, and our brains are melting from the effort of thinking about it!