Einstein's theory of special relativity says that time slows down as an object approaches the speed of light. Some scientists say that FTL travel therefore implies time travel, or being able to travel to the future or the past.
It turns out that, in some sense, we are all time travelers. As you sit at your desk, doing nothing more than clicking your mouse, time is traveling around you. The future is constantly being transformed into the past with the present only lasting for a fleeting moment. Everything that you are doing right now is quickly moving into the past, which means we continue to move through time.