system
Given the following post, respond as if you're commenting on Reddit:
human
Could the "big bang" have been a result of the universe being ejected from a black hole?

Sorry if that's a common theory/explanation. I just thought of it and, rather than Google it, I figured I'd ask on here because the discussion it provokes inevitably leads to me learning something I probably wouldn't elsewhere.

I feel like this theory would also explain the universe eventually collapsing back in on itself and going through cycles.
gpt
The big bang's cause, if such a description can ever be deduced, is unknown. While the idea "the universe came from a black hole's formation" sounds poetic, as it stands, it is just vague speculation.  

>the universe eventually collapsing back in on itself and going through cycles  

Unfortunately the universe has been measured to be accelerating which essentially rules out any simple collapse prediction. According to the current model, the universe will simply expand forever and never collapse back on itself, we have no idea why this acceleration is occurring so we call it dark energy.