You guys are forgetting, the edge of the universe, does not need to be the edge of space, it could just be an edge to interesting space. Perhaps, there is only a finite region of space were matter can form... Maybe the initial "egg" of matter that formed the universe was of finite size. It could be that the mass distribution in the universe is not constant, but indeed there is an edge. Beyond that, there is no matter. Of course, because matter would continue to expand out at the speed of light, we could never physically reach that edge. However, eventually we would be able to see it.
Of course, I am not saying this is the case. But given our current level of understanding, we could neither prove or disprove this conjecture at this point in time.