You've been watching the The Butterfly Effect It's a great film, showing you going back to the past can change every thing.
Einstein said if you travel at light's speed, within 2 hours you will cross 20 years in time. it is non-reversible. Few years ago They said it is impossible to have more that 360K memory on a single chip.
He was restating the "time flies when you are having fun" theorem. He was so unoriginal....except for the hairstyle.
We arent physically capable of flying but again we managed to overcome that defect by flying in big metal birds....I don't see why in the future there wouldn't be extensive project about time travel.