The Old Man of the Stars — John Burke

Who was the man who never grew old? Even in the enlightened society of near-future Earth, he was feared, reviled, castigated for remaining forever young. But when Matthew admits to his amazing longevity, and its source in biological science, he's called a liar. Life on Earth becomes intolerable, until he volunteers to travel on the world first interstellar spaceship--a multi-generation colony ship that will take centuries to complete its voyage. And even when he reaches journey's end--the planet Elysium--he finds personal discontent--a restlessness that will only be settled when he returns to his distant past!

Paired with this novella is "The Recusants," the story of the creation of mental supermen--a race generated by ourselves! But when one of the advanced humans turns on the others, civil war may loom. Two great SF stories by a great storyteller.