I'm sure others have asked this before, but I just wonder what others think of this. If the cosmological principle holds and the universe is expanding, then everybody everywhere sees an equal expansion. People often use the analogy of the surface of a balloon to illustrate the situation. So my question is, the number of points on a balloon is finite, because the surface curves back on itself. You can travel in a straight line and get back to where you started. So in our universe, either the universe is infinite, or it curves back on itself, and so if we had a powerful enough telescope we might be able to see the earth. So of course, if the universe started with a big bang, then there can't be an infinite number of stars, so the possibility that remains is that it curves back on itself. Is this a fair conclusion?