You two are talking about different meanings of "time". Traveling 5,000 LY at 0.5 c will cause you the spaceship pilot to age 20,000 years. It's non-relativist

You two are talking about different meanings of "time". Traveling 5,000 LY at 0.5 c will cause you the spaceship pilot to age 20,000 years. It's non-relativistic, inside that inertial frame. Clock second hands still sweep slow but noticeable circles. Meanwhile, everyone outside of the spaceship is happening FAST, by your observations. You'll see stars turn red and go supernova.