A few months before the Second World War started in Europe, the
physics world was shaken by a discovery that would change Ernest
Lawrence's life. German scientists reported that the uranium
nucleus, when hit by a neutron, splits into two smaller
nucleinuclear fission. Unlike the earlier splitting off of small
pieces of atoms, fission released some of the huge store of
energy bound in the nucleus. When the news reached the United
States, staff in Lawrence's Radiation Laboratory bombarded
uranium with neutrons and confirmed that they had missed another
major discovery. Like many physicists, Lawrence sensed the
tremendous possibilities of a nuclear chain reaction. Lawrence
to John Cockcroft; February 9, 1939 Concern about the military
potential of fission would lead physicists to hesitate about
revealing results of their investigations to the world. But
before self-censorship was established, Berkeley physicists
announced an important discovery. Edwin McMillan used the large
neutron flux from Lawrence's 37-inch-