I could get a spaceship, travel at the speed of light for 20 years and come back, and the earth would have aged 100 years, so I would have time-traveled into the future!
I could gather up all the winning lottery numbers and stock market quotes!
Not sure what I’d do with them, though.
I revise and extend my remarks.
Apparently, the best I could hope for would be maybe 90% speed of light.
In which case, after a 20 year flight, the world would have aged maybe 40-some years.
And according to Al Gore, would have since become a flaming globe covered in water.