I Am Cultivating Immortality Next Door to the Earth

The universe is vast. Are there other civilizations besides the earth? If so, is there a civilization that cultivates immortality? Ren Su: Yes, the nearest one is only 4 light years away from the earth. Don't ask me how I know. When I traveled back in time, at first I thought I was in another world, but in the end I didn't even leave the Milky Way!