If one were to leave the Earth in a spaceship traveling at an appreciable fraction of the speed of light, turn around, and return, only a few years might have passed on board, but many years might have passed on the Earth. This is known as the ‘twin paradox’ because a traveller who goes on such a journey would return to find himself much younger than his twin.
There is only one problem for anyone who wants to look into the future: to return. It would mean traveling faster than light, and that is not possible.
But there may be a way out in general relativity, Einstein’s theory of gravity that links space and time as “space-time”, which curves in the presence of mass. It allows for the possibility of wormholes, a kind of tunnel through space-time that connects very distant parts of the universe.
If the “mouths” of the wormhole move relative to each other, then crossing the bridge between different points in space would also take a traveler to a different point in time from the one he started.