Ulam was scheduled to give a talk at the University of Chicago titled “The future of mathematics.” Stanislaw Ulam was a rather famous mathematician and a major player in building the H-bomb, so a large audience gathered.
Ulam had trousers with two suspenders ending at a single front button. At some point in the talk, when Ulam became excited, this single button collapsed, the suspenders got untied and the trousers came down slowly, revealing colorful boxer underwear. Ulam did not notice it for a couple of minutes and then when he did, he raised the trousers and just supported them with his hand, which was fine, except that when he got over-excited and waved both hands, the trousers went down again.
Besides the colorful boxer under-pants, Ulam’s lecture was a completely mundane mathematical talk: problems, lemmas, theorems, conjectures, little proofs, nothing unusual, and not a word about the future of mathematics.
When it was time to ask questions, a person from the audience asked Ulam about the future of mathematics. Ulam looked at him rather surprised, and replied very slowly.
“Young man” Ulam said, “you must understand: we are now in the present, and the future only comes later, so it is not possible to know what the future of mathematics will be, simply because it has not happened yet.”
Then other people asked similar questions and reminded Ulam that the title of the talk was “The Future of Mathematics”, but Ulam insisted that these questions were misguided since the future would only come at a later time.
(I heard this story from Peter Jones.)
WordPress automatically referred to an interesting post from entartaining research reading: “In the April 2008 issue of the Notices of AMS, Philip J Davis and David Mumford write (pdf) about Poincare’s The future of mathematics (pdf) talk delivered a century ago;”
Update (sept 19) Fabrice Baudoin kindly contributed the following: