Every now and then, you run across a piece of entertainment that isn't intended to be horrific, but which nonetheless leaves you with goose bumps.  For me, the movie The Thirteenth Floor was such an event.  Coming in the wake of The Matrix, this action film with an intellectual / philosophical twist was far from a big success at the box office, but the questions it raised were a lot harder to shake off than the nature of Neo's quest.

The film wasn't the first to bring up the issues, or the last, and years of examination by science have failed to make these issues fade.  In fact, some top scientists are starting to consider seriously the idea that life is just a dream.