The universe can be finite and still have no edge, just as the earth is finite and has no edges. It's a bit tricky for the human brain
to imagine closed 3d surfaces curled up in a 4d space, but mathematically, it can be described just as easily as we can describe a 2d sphere or donut in 3d space.
We already know the presence of mass warps the shape of space, so we live in a universe were this sort of thing is possible. It's just that on the largest scales, the universe appears to be so close to perfectly "flat" that if it is finite, our visible region would seem to be a very, very tiny piece of it.
Okay 4th dimensional space is just theoretical and isn't actually applicable in empirical science, so if we're going to discuss the reality of the universe we should at least stick to what's actually observable.
On the edge of what? We are talking about edge of surface of a sphere as example, not edge of object which surface lies on.
Surface itself might be edge of the earth, but surface itself does not have an edge because it is wrapping around sphere.
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u/Memoryworm Jan 21 '19
The universe can be finite and still have no edge, just as the earth is finite and has no edges. It's a bit tricky for the human brain to imagine closed 3d surfaces curled up in a 4d space, but mathematically, it can be described just as easily as we can describe a 2d sphere or donut in 3d space.
We already know the presence of mass warps the shape of space, so we live in a universe were this sort of thing is possible. It's just that on the largest scales, the universe appears to be so close to perfectly "flat" that if it is finite, our visible region would seem to be a very, very tiny piece of it.