There is another Kurzweil, though—the one who makes seemingly unbelievable, implausible predictions about a human transformation just around the corner. This is the Kurzweil who tells me, as we’re sitting in the unostentatious offices of Kurzweil Technologies in Wellesley Hills, Mass., that he thinks his chances are pretty good of living long enough to enjoy immortality. This is the Kurzweil who, with a bit of DNA and personal papers and photos, has made clear he intends to bring back in some fashion his dead father.

Mr. Kurzweil’s frank efforts to outwit death have earned him an exaggerated reputation for solemnity, even caused some to portray him as a humorless obsessive. This is wrong. Like the best comedians, especially the best Jewish comedians, he doesn’t tell you when to laugh. Of the pushback he receives from certain theologians who insist death is necessary and ennobling, he snarks, “Oh, death, that tragic thing? That’s really a good thing.”

“People say, ‘Oh, only the rich are going to have these technologies you speak of.’ And I say, ‘Yeah, like cellphones.’ “