> [...] there's no firm consensus on whether it's literally infinite. If it is finite, there is no "wall" or "center", since it's not a big sphere -- a finite Universe just means that if you go straight long enough, you end up in the same spot.
My understanding is that for your interpretation here of "finite" to be true, there must be some curvature. If you only consider the geometry of the universe, then what we see with our instruments does allow us to put a bound on the size of the curvature.
If you want to say something along the lines of "outside of the observable universe is probably cheese whiz" then that's your perogative, and no-one can refute that. But (from the article) the geometry of the universe that we have measured is consistent with an infinite universe, and gives a minimum bound on its size which is many multiples of the observable universe.
It's mathematically simple for a space to loop without being curved locally, although I am under the impression that there are physics reasons to infer we don't exist in such a space.
The pac-man universe acts euclidean until you have universe-sized effects. For example, a circle will satisfy circumference = diameter * pi until its diameter is greater than the span of the universe. Basically the universe could 'hide' the fact that it is a torus from pac-man by simply being really large.
My understanding is that for your interpretation here of "finite" to be true, there must be some curvature. If you only consider the geometry of the universe, then what we see with our instruments does allow us to put a bound on the size of the curvature.
If you want to say something along the lines of "outside of the observable universe is probably cheese whiz" then that's your perogative, and no-one can refute that. But (from the article) the geometry of the universe that we have measured is consistent with an infinite universe, and gives a minimum bound on its size which is many multiples of the observable universe.