acute alan, on 18 February 2012 - 10:11 PM, said:
I can tell you right now that time travel is impossible.
Otherwise, we would currently be swamped with visitors from every point in the future.
Ok then. I demend you proof that time travel is impossible.
Saying it is impossible just because we are not aware of any time travelers is just not an argument at all.
Nothing is impossible until we can prove it without any doubt which is not always an easy thing to do because there is always the possibility of discovering something else that would change the conclusion. Maby we just simply haven't figured out the right way of doing it.
Maby Hawking's invitation was seen by future people but they decided not to interfere with us for various and/or obvious reasons. Or maby they did come back but by doing so they created a parallele universe in which we are but that we cannot perceive. We could theorise about many possibilities here.