Stephen Hawking denied the possibility of travel in time because ¨ if it is possible, we would have been visited by tourists from the future¨.
Years later, he retracted and said that scientifically, in not too distant future, could certainly be the actual time travel.
The question is, if travel is scientifically possible in time, but we have not had visits of tourists from the future ...
Will be ... that who have no future are Human Beings?
Take care of our Planet!