| Some of the scientists who helped design the world's first controlled nuclear chain reaction stand outside a building on the University of Chicago campus. Italian-born American physicist Enrico Fermi, front row, left, oversaw the experiment and also made the key discovery that graphite could be used to control a chain reaction. The refugee Hungarian physicist Leo Szilard, mid-row, right (in trench coat), was the first to realize that a chain reaction—the continuous release of nuclear energy—was possible and could be used to make a powerful bomb. |