# Did the big bang start at ONE infinitely curved point (or a 4D curved ball shrunk to a point) with an infinite density of energy?

I'm confused. In this question it is said:

The simple answer is that no, the Big Bang did not happen at a point. Instead, it happened everywhere in the universe at the same time.

How could it have happened everywhere in the Universe if the Universe hadn't come into existing yet? Or do I have a wrong image of the Universe at the moment of the big bang? Or did inflation began when the Universe already had a size (after $$10^{-34}$$ seconds, give or take)? Which begs the question, how did the Universe evolve from an infinitely dense and curved point until inflation took of?

• As a simplified illustration, imagine a 2D universe as a surface of a sphere and project it back in time by making the sphere smaller and smaller. No matter how close you get to time zero, the universe still is a sphere, not a point. If the shortest possible time is the Planck time, then the first moment of time in the universe was 1 Plank, at which the universe was already a Planck size sphere. Thus the Big Bang happened everywhere in space on this sphere at once, but not only at one point on the sphere. – safesphere Oct 10 at 4:06