It’s rather fascinating, and pretty non-intuitive. The intuitively obvious scenario is that, if someone could time-travel to their own past, there would be nothing to stop him from killing his own grandfather before his father was born. But there actually would be something stopping him: the fact that he exists to go back at all is proof that he never did anything to prevent his birth.

In other words, there’s no paradox possible — it simply never happened.

I’m not explaining that well, but it makes perfect sense by the laws of logic.

(Via Boing Boing)