Does the Grandfather Paradox make time travel a logical impossibility?

Question

The Grandfather Paradox is a contradiciton in the theory of time travel. It proposes the hypothetical situation of a man who goes back in time and kills his grandfather before his grandfather would have met his grandmother. This means the man travelling back in time never would have existed, meaning he could never have lived to go back in time in the first place. Doesn't this suggest that time travel is impossible becasue any alteration of the past would lead to different circumstances in the future?

Answer 1

Only if there is only one universe. There is a "many worlds interpretation" to quantum mechanics that states that all possibilities happen simultaniously everywhere all the time in an infinite number of different universes. If you killed grandpa, you'd just never be born in that particular time line.

Answer 2

Pretty much along with the Time Machine Paradox:

Man builds his time machine, man uses his time machine to return to the distant past before his time machine existed.

If the time machine did not occupy any time/space in the past, how can it exist?

The solution is that time is circular, that you can go so far into the future that you arrive at the past. But there is no way of knowing this unless we somehow travel far into the future.

Currently time travel with our physics is impossible.

Answer 3

Yes, like many other obvious reasons. A very easy one to grasp is that nobody could ever die, if time travel was possible we would all have to be on hand forever to greet any visitor from the past or the future.

Answer 4

Not necessarily. Maybe it's already been done many times. The trouble is that the people who travel back in time and kill their grandfather, vanish before they can tell anyone about their success. :-)