Following the discovery of nuclear fission in 1938, scientists in Germany, France, Great Britain, the Soviet Union, Japan, and the United States began to investigate the possibility of exploiting this energy source for military purposes. The United States alone was able to draw its governmental, industrial, and scientific capabilities into an efficient bombbuilding collaboration. It had not only the manpower, materials, and industrial support needed for the expensive project – eventually to cost $2.2 billion – but also a sizable and competent physics community well versed in technology, strengthened by talented emigrés, with ties to government and industry, and close international contacts. Some American scientists, like Ernest Lawrence, were experienced in managing large research efforts. This community also included older scientific statesmen, like Vannevar Bush, with political experience and proven abilities in coordinating government-sponsored applied research projects. On 9 October 1941 Bush persuaded President Franklin Roosevelt to authorize American research on the feasibility of a fission bomb.

The Discovery of Nuclear Fission

The events leading to Los Alamos began in 1933, when Frédéric Joliot and Irène Curie produced artificial radioactivity by bombarding aluminum with alpha particles. The next year Enrico Fermi and his co-workers in Rome bombarded a variety of elements with neutrons, the neutral fundamental particles that James Chadwick had discovered in 1932. Upon bombarding uranium, Fermi's group found an unexplained radioactive substance and speculated that they had created a new transuranic element.