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  Timeline of the Nuclear Age 1930s  1939


Hans A. Bethe, a German-born physicist, recognizes that the fusion of hydrogen nuclei to form deuterium releases energy. He suggests that much of the energy output of the Sun and other stars results from energy-releasing fusion reactions in which four hydrogen nuclei unite and form one helium nucleus.

Frederic Joliot demonstrates the possibility of splitting the atom of uranium isotope 235.

Lise Meitner and Otto Frisch of Austria announce the theory of nuclear fission.

Otto Frisch detects fission fragments in an ionization chamber. He adopts the term "fission."

The first experimental fission in the U.S. takes place at Columbia University.

Niels Bohr announces discovery of fission at a conference in theoretical physics at George Washington University in U.S.

Upon hearing about the discovery of fission, Robert Oppenheimer immediately grasps the possibility of atomic bombs.

Leo Szilard writes to Enrico Fermi describing the concept (uranium lattice in carbon) for creating a chain reaction.

Albert Einsteinís first letter to President Franklin Roosevelt leads to the formation of the Committee on Uranium. The letter, originally drafted by Leo Szilard, states, "that the element uranium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration." After the bombing of Hiroshima, Einstein states, "I could burn my fingers that I wrote that first letter to Roosevelt."

Germany invades Poland. World War II begins.