Most of us accept that our lives are limited. Not Ray Kurzweil. A renowned computer scientist and inventor, Kurzweil, 65, decided decades ago that mortality wasn’t for him. He didn’t have to die, and he wasn’t going to, if he could help it. Fortunately, he believes he can help it, and he’s been working feverishly at the task of staying alive ever since.

“How long do you think you will live?” I asked Kurzweil in a recent interview. “I think I have a good chance, I would put it at 80 percent, of getting to the point where it becomes indefinite, because you’ll be adding more time than is going by to your remaining life expectancy.” […]