if you play the scene in the "brainwashing" room #23 where the Others had Karl locked up, Clockwork Orange style, it loops over and over "Only fools are slaves to time and space" or something along those lines.
The Island is in another (parallel) dimension and Desmond can see into the 4th dimension!
I'm pretty confident the whole show is going to be moving in the direction of "time travel", alternate dimensions, black holes, and dark matter.
Anyone else have any other theories?