Manhattan Project

Manhattan Project

II. The Race for the Bomb

The theoretical possibility that an explosion could be brought about by atomic fission became known in 1939, the year that war broke out in Europe. Scientists discovered then that uranium atoms can fission when struck by neutrons to split other atoms in a chain reaction, releasing large amounts of energy.

Two Hungarian physicists who had recently emigrated to the United States, Leo Szilard and Eugene Wigner, alerted the US government to the possibility of an atomic bomb. Along with Albert Einstein, they wrote a letter to President Roosevelt warning that Nazi Germany might also be working towards a uranium bomb; many of the important discoveries in atomic physics had been made at German universities. Roosevelt responded by setting up an advisory committee on uranium in October 1939.

Under the aegis of this committee, American scientists at several centres examined the problem. The uranium that fissions is an isotope, a variation of an element that is chemically indistinguishable but different in its atomic structure. It is uranium-235, which constitutes only 0.7 per cent of uranium. Scientists questioned whether significant quantities could ever be separated.

Much of the initial work was done at Columbia University in New York, and the military direction was from an office in Manhattan. This was located in the Manhattan Engineering District, and the whole programme became the Manhattan Project, under the command of Major General Leslie Groves.

Meanwhile, in Britain, two immigrant physicists, the Austrian Otto Frisch and the German Rudolf Peierls,