To my mathematical brain, the numbers alone make thinking about aliens perfectly rational.
Stephen HawkingThere are plenty of dead scientists I admire, but I can't think of any living ones. This is probably because it is only in retrospect that one can see who made the important contributions.
Stephen HawkingGravity is so strong that space is bent round onto itself, making it rather like the surface of the earth. If one keeps traveling in a certain direction on the surface of the earth, one never comes up against an impassable barrier or falls over the edge, but eventually comes back to where one started.
Stephen Hawking