So first of all, we know the universe has no edge because the universe is everything. Ever. Go out more, still universe. Go out even more, still universe. Astronomers think (we can't prove it absolutely because of the reason about to be stated) that if we look far enough, we'll see back to where we started. The reason we can't prove it absolutely is because we think in three-dimensional volume. According to Euclidean 3 dimensional geometry, that can't happen. The universe is not three dimensional.

Okay, so I read some more and found out that if the universe is finite and has no edge (we know the latter is true, but the former is iffy), the universe could actually be smaller than the observable universe because the light is actually circumnavigating the universe and making duplicate images. Unfortunately I can't find exactly how light circumnavigates it. Yet.