American physicist and son of
a Scotch-Irish stonecutter, he helped build the first nuclear reactor in a
Chicago squash court in 1942 and then went to Los Alamos to help build the
atomic bomb. On May 6, 1945, he autographed the first atomic bomb and few
in the Hiroshima mission as an observer. Although he was only 24 years
old, he was the only person to witness the entire procedure, from the pile
in Chicago, to the building of the bomb, to the bombing of Hiroshima.