system
Given the following post, respond as if you're commenting on Reddit:
human
Why didn't the univers collapse back into a black hole?

Why didn't the universe collapse back into a black hole right after the big bang? After all wasn't it dense enough? Everything in the universe in such a small region?
gpt
There is a common misconception that *everything* was in a small region right after the big bang. While it's true that the *observable* universe was in a small region right after the big bang, the whole universe was still infinite in size (as far as we know). Thus, even though things would have been very dense shortly after the big bang, it would have still been roughly uniform everywhere, and so no black hole would have formed.