[davidm]

Originally Posted by The Lone Ranger

Yeah, that's the sort of thing that can make you a little crazy, if you think about it too much.

It's something that computer scientists like to point out. The basic idea, as I understand it, goes like this:

1. A sufficiently sophisticated computer could run a simulation of the Universe.
   
2. There are potentially lots of computers out there running simulated Universes.
   
3. There is only one real Universe.
   
4. Therefore it is more probable that we are living in a computer-simulated Universe than that we're living in the real one.
   
5. Sleepless nights ensue.

Right, it is Nick Bostrom's simulation argument.