The Best Traveling At 20 Speed Of Light References. The parker solar probe, seen here. Special relativity shows that time slows down for anything moving, including people, and that distances shrink in the direction of motion.
Web einstein's special theory of relativity was born from this very question, and the answer is as weird as you'd expect. Percent of its usual value. At that speed, even individual atoms can damage the vehicle, and a collision with a bit.
