Time is NOT an absolute. Einstein proved it and it's been proven again. As someone mentioned traveling very fast can distort time and we stoners I guess can agree that time seems slower when really high! have anyone of you read about DMT? users tell that they experienced what to they felt like really more than just the minutes that supposedly passed. I think that traveling back in time is really weird and has a lot of paradoxes (killing your father, etc), of course who am I to say it's impossible but I subscribe to the idea that time travel only makes sense if to the future, it's known that when astronauts go to space their clocks desynchronize with the clocks here on earth! sorry I don't have links but I read books about and don't take it from me, look it up it's really interesting.