Comment Re:Flat does not imply infinite. (Score 1) 235
We can't actually take a trip around the universe. I'm talking about a thought experiment in which you mathematically translate some position around the universe. In a Mobius strip, you flip around when you go around the universe. Since you never cross a boundary while going around the Mobius universe, the laws of physics must stay the same as you go around, so the laws of physics have to be independent of parity.
Of course we don't know that the universe doesn't have boundaries. It's just a reasonable guess. And, yes, we don't know the universe is homogeneous. Some of the conjectures for the shape of space, like the Picard horn, aren't homogenous at all.