Grandfather paradox The “grandfather paradox” is an argument used to prove the impossibility of time travel. The idea is that an individual (usually called "Tim" because the name looks a lot like "time") who could travel backwards in time, could kill his grandfather, prior to the conception of his father. But this would imply that Tim’s father would never have been born, and that in turn would imply that Tim would never be born. And if Tim was not born, Tim could not go back in time. This situation leads to a contradiction. Tim both could and could not kill his grandfather. He could (because he would by hypothesis be in the right time and place with a weapon) yet he could not (because he would have to have been born!) And since our “Tim” could be anyone this means that nobody could - that time travel is impossible. Syllogistically, the macro argument is this: Premise 1. If time travel is possible, then contradictions are possible. Premise 2...