ABSTRACT
In 1961 a small group of young Boston physicians met in the living room of Dr Bernard Lown, at that time already a highly respected cardiologist. We came together because of our concern about the threat posed by new bombs of unprecedented power that had been developed and tested by the United States and the Soviet Union during the 1950s. The nuclear bombs that had been dropped on Hiroshima and Nagasaki in 1945, each with an explosive power of approximately fifteen thousand tons of TNT, had been based on nuclear fission: the disintegration of a large atom (uranium-235 or plutonium-239), after absorption of a neutron, into smaller atoms, with the release of enormous energy and the release of a neutron to produce a chain reaction. The bombs tested in the 1950s were based on nuclear fusion: the energy liberated in forming a small nucleus (helium) from the fusion of two even smaller nuclei (isotopes of hydrogen).
