George Weil, US physicist and member of the team, that built the world's first atomic pile (or nuclear reactor) under the direction of Enrico Fermi. The pile was built in a squash court at the University of Chicago. It consisted of blocks of graphite, with slugs of uranium at regular intervals. Weil's task, under Fermi's direction, was to operate the control rod that initiated the first self-sustaining chain reaction at 3.36 pm on 2 December 1942. It was the beginning of the atomic age.