If time travel was possible in the future you would not be aware of it today unless someone travelled back in time instead of forward. Have you ever had an unsettling feeling like everything was changing but just by a little bit? A moment of unsteadyness for a fleeting moment. This may have been caused by someone travelling back in time and doing something that changed your timeline, if even very slightly. They may have come back to change something on the other side of the planet, but it changed your reality persptibly.