People on every continent have claimed to see the footprints of Bigfoot. And ancient myths and legends speak of an ape-like giant stalking the earth. What if, as Ancient Astronaut theorists believe, there is evidence to connect Bigfoot with an alien species that once visited Earth in the distant past?

Is it possible that sightings of alien beings or UFOs may actually be evidence of time travelers from the future? And might ancient astronauts actually be time travelers from our future? Scientists explore the theoretical possibility of time travel. How can it be achieved? And what might people from 10,000 years in the future look like?