How big is the entire universe?
Max Tegmark had an interesting article in Scientific American a while back discussing the implications of an infinite universe:<p><a href="http://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf" rel="nofollow">http://space.mit.edu/home/tegmark/PDF/multiverse_sciam.pdf</a><p>Perhaps the most disturbing of which would be the fact that, by definition, at some distance, there would have to be a duplicate of yourself.