Feynman, Nobel laureate, bongo player, safecracker, and the most brilliant showman in physics, has decided this is the most interesting problem in America.

Feynman grins—that famous, impish, world-is-a-toy-store grin. He points at the Music & Speech Building, then at the physics lab across the quad.

Finally, around 11 p.m., Feynman emerges into the crisp Ohio night. A few students remain, sitting on the grass. One raises a hand.