system
Given the following post, respond as if you're commenting on Reddit:
human
moments after the big bang, if all matter was inside the swarzchild radius, why didn't gigantic black hole form?
gpt
The reason that a black hole normally forms is because there is a lot of matter in a small space that's all being pulled gravitationally toward the center of mass. This means that you need a mass differential: you need a very strong gravitational force pulling each particle in a single direction (i.e. toward the center of mass) compared to a much weaker gravitational force in all other directions (i.e. toward empty space).

With the universe just after the Big Bang, that latter condition didn't exist. Yes there was a lot of mass...but it was incredibly uniform in its distribution, such that each individual particle was being pulled by gravity in all directions equally. As such, the gravitational forces all canceled out and no black hole could form.