WATCH: How time travel is possible and may already be happening
Technology that allows us to travel time doesn't exist, but it might be possible according to theory. Famous scientist Albert Einstein theorised that time is relative depending on how fast you travel.
In space, the faster you move the slower time goes than on planet Earth, and future generations who end up becoming space-faring would have a slightly warped sense of time.
Someone on Mars for example would experience time a little faster than Earthlings, due to the difference in gravity.
But will we ever actually time travel? According to BBC, some scientists posit that we could do this by creating wormholes that connect two points in time together. However, they tend to collapse, and this issue would have to be resolved if we were ever to travel through them.
Who knows, perhaps time travellers are already walking among us...