The Birth of Modern Physics

The road to Los Alamos began in the late 19th century with the discovery of X-rays by Wilhelm Roentgen. His discovery opened the door to further inquiry about the nature of matter and the study of nuclear physics. On the heels of Roentgen's work came the discovery of radiation by Antoine Becquerel in 1886, as well as the discoveries of radium and polonium by Marie and Pierre Curie in 1898. In 1905, Albert Einstein published the first of his seminal papers on relativity. In 1911, Ernest Rutherford conducted experiments at the University of Manchester describing atoms as "miniature universes." Niels Bohr expanded Rutherford's findings and published, in 1913, the first of three articles on the structure of the atom. Bohr's work created quantum mechanics, which is the foundation of modern physics.

The birth of modern physics created a rich environment for the study of physical processes in nature. Werner Heisenberg discovered the uncertainty principle in 1927. Wolfgang Pauli formulated the exclusion principle in 1924 and deduced the presence of the neutrino in 1930. Harold Urey discovered deuterium in 1931. J. Robert Oppenheimer, the man who would lead Los Alamos during World War II, postulated the existence of black holes in the cosmos. Most importantly, James Chadwick discovered the neutron in 1932. The discovery of the neutron made possible the exhaustive investigation of the nucleus. Having a neutral electrical charge, the neutron could easily penetrate the negatively charged electron shell and the positively charged nucleus of an atom and provide a wealth of data about the nuclear properties of elements.

Fission is Discovered

In 1938, working at the Kaiser Wilhelm Institute in Berlin, Otto Hahn and Fritz Strassmann bombarded uranium with neutrons in an experiment studying radioactive substances. Unknowingly, they split uranium atoms. Perplexed by their findings, Hahn wrote to a former colleague, Lise Meitner, describing the experimental results. Meitner in turn discussed those results with her nephew, Otto Frisch. Together, Meitner and Frisch deduced what had really happened - atoms of uranium had been split into two nearly equal halves and, in the process, some matter had been converted to energy. Fission had been discovered.

The Einstein Letter

It became immediately obvious to physicists that if enough uranium atoms could be split, the cumulative energy released in the process would produce an explosion of unprecedented magnitude. Fearing that Germany might develop an atomic bomb, Leo Szilard, Edward Teller, and Eugene Wigner convinced Albert Einstein to alert President Roosevelt of this possibility. In a letter to Roosevelt dated August 2, 1939, drafted mostly by Szilard, Einstein made clear the dangers of a Germany armed with nuclear weapons. It stated, "...it is conceivable - though much less certain - that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory."

The Manhattan Project

In response to Einstein's letter, the United States government began a modest program of nuclear research. After the Japanese attacked Pearl Harbor, President Franklin Roosevelt directed the War Department to build an atomic bomb. The Army Corps of Engineers created the Manhattan Engineering District (MED) in August 1942 for this purpose. The name Manhattan came from the first headquarters of the new Corps of Engineers District, which was located in New York City. Under the command of General Leslie R. Groves, the MED began to work procuring uranium ore, land for sites such as Oak Ridge, Hanford, and Los Alamos, and the scientific and technical labor needed to build an atomic bomb.