News of the death of John Wheeler came yesterday, and many people have already written detailed, touching and informative pieces about the man, his life and scientific achievements. See for example here, here, and here. With Wheeler gone, physics loses one of its very few living contacts with the early days of quantum mechanics, since his career reached back to the early thirties when he went to study with Bohr.
My most extensive contact with Wheeler was surely through learning GR from the marvelous textbook he co-authored on the subject. By the time I got to Princeton as a student, he had recently left for the University of Texas, in order to evade Princeton’s mandatory retirement age policy. He still was a presence in the department though, returning to give talks (I remember one that was an advertisement for the importance of the notion of a complex: “the boundary of a boundary is zero!” was the slogan). My only conversation with him was at a meeting organized between graduate students and a visiting committee of people evaluating the department. I recall a very friendly older man who came up to talk to me, and listened attentively to my going on for quite a while about how things could be improved. Only after we had finished speaking and he had left did I realize who I had been talking to. My overwhelming feeling immediately was that if I had realized this earlier I’d have much more enjoyed keeping quiet and getting the chance to ask him a few questions.
Update: See here for another article about Wheeler, from the University of Texas. It includes the claim that “Wheeler was the first person to emphasize the importance of string theory”, which, as far as I know, has nothing to do with reality.