Ray Kurzweil, the famous inventor, is trim, balding, and not very tall. With his perfect posture and narrow black glasses, he would look at home in an old documentary about Cape Canaveral, but his mission is bolder than any mere voyage into space. He is attempting to travel across a frontier in time, to pass through the border between our era and a future so different as to be unrecognizable. He calls this border the singularity. Kurzweil is 60, but he intends to be no more than 40 when the singularity arrives.