I loved the ending - you could see, he would have been happy to
   continue back past the sun to the history of the universe -- but
   he stopped, and let you wonder. Genius. If you ever get a chance
   to look at some of his full lectures (they're on various places
   online) where he describes quantum electrodynamics, omg, i GOT
   it, and his way of explaining things just makes sense. He's one
   of the few people I've known that were 100% comfortable with the
   idea that the arrow of time can just as easily flow backwards as
   it does forwards -- from the point of view of electrons they
   just don't care which way time is flowing. phenomenol. "