Eli5 If the universe expanded from a single point why do scientists say its flat and not spherical?

Question

Why would it only expand in one plane not every direction like you’d expect?

Also how is a flat universe even possible? Surely since we live in 3 dimensions the universe needs to be a 3 dimensional shape.

Im probably misunderstanding what physicists are trying to say but that’s why im here.

In: 229

Answer 1

What you think of spherical is how the observable universe is. “Flat” just means the universe lies on a relatively constant plane, rather than the universe having fundamental curvature, which would influence how far we see something from something else. You could think of a “donut” or taurus where seeing one “end” of the universe could be seen from the other “end. We don’t see things like that, or reasons to believe it works like that.