system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What was the universe like prior to the big bang?

I have googled and I have wikied this multiple times but despite being a relatively intelligent person my brain refuses to wrap itself around the concept, and I have a hard time believing what I do understand.
gpt
The big bang is what we get when we take all the evidence we have for the expansion of the universe and rewind the clock back as far as we can. The farthest we can rewind shows us that the entire universe was condensed in a very small fine space. But that's where our current physics and mathematics fail us. We exhausted all our evidence and our science rewinding it to the point of the big bang. We need new physics and new mathematics to rewind farther. So we don't know. There are many hypothesis with
 a lot of good math behind them, but until there is any evidence for them, they will only stay hypotheses.