system
Given the following post, respond as if you're commenting on Reddit:
human
Is the universe a closed system?

Is the universe a closed system? What happens to matter that enters (leaves?) through a black hole?
gpt
There are a number of theory's about black holes, but all of them (that I've read about) stay within our universe.

As for your actual questions, that is not something that can really be answered right now. Even an educated guess would just be wild speculation. We really know very little about the universe as a whole. And we know jack squat about anything not in our universe.