New Theories of Nuclear Reactions

Bohr, inspired by Fermi’s discovery of slow neutrons, conceived his theory of the compound nucleus by the end of 1935. He went on to speculate that if the energy of a neutron incident on a nucleus were increased to the fantastically high energy of 1000 million electron volts, the compound nucleus would explode. Using small wooden models Otto Robert Frisch had constructed, Bohr lectured widely on his theory on a trip around the world in the first half of 1937. By then, Russian-born theoretical physicist Gregory Breit and Hungarian-born theoretical physicist Eugene Wigner in Princeton had conceived their fundamentally equivalent theory of neutron+nucleus resonances. Together, their theory and Bohr’s transformed the theory of nuclear reactions. Orso Mario Corbino, Fermi’s mentor, friend, and protector, died on January 23, 1937, at age sixty. Ernest Rutherford, the greatest experimental physicist since Michael Faraday, died on October 19, 1937, at age sixty-six.