How Near-Light-Speed Travel Makes Time Travel to the Future Possible

Do you think time travel will ever be possible?

Not into the past. So into the future, yes.

There's a calculation in one of my books with Jeff where you ... we, we work out ... So if you travel at ninety-nine point nine nine nine nine nine nine nine nine, that's eight nines, percent the speed of light to Andromeda, which is two and a half million light years away,

and then turn around and come back again, then for you on the rocket, one hundred years will have passed on the round trip journey, but five million years will have passed on Earth. So by traveling fast relative to people who are stationary, your clock runs slow relative to theirs.

That takes you into the future. So you can travel into the future, arbitrarily far into someone else's future.