Nuclear Weapons 1930

1930

Schrцdinger views electrons as continuous clouds and introduces "wave mechanics" as a mathematical model of the atom.

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1931

Albert Einstein urges all scientists to refuse military work.

Harold C. Urey of the United States and associates discover deuterium (heavy hydrogen) which is present (0.014%) in all natural hydrogen compounds including water.

John D. Crockcroft of Great Britain develops high-voltage apparatus for atomic transmutation.

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1932

James Chadwick proves the existence of neutrons, using alpha particles striking a beryllium foil. He determines their mass by measuring the recoil tracks of known atoms of the rarefied

gas in his cloud chamber.

John Cockcroft and E. T. S. Walton of Great Britain split the atom on a linear accelerator built at

Ernest Rutherford's Cavendish Laboratory at Cambridge University. Their experiment proves Albert Einstein's theory of relativity.

Leo Szilard reads H.G. Wells' novel, The World Set Free, in which Wells prophesizes an atomic war in which the major cities of the world are destroyed (See Related Links on top right for on-line version of the book.)

August 2

American experimentalist Carl Anderson discovers a new particle the "positron." It is an electron with a positive instead of negative charge.

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1933

January 30

Adolph Hitler becomes Chancellor of Germany.

March 23

Following the Reichstag fire and subsequent suspension of constitutional liberties, Reichstag voluntarily gives over its powers to Hitler's cabinet.

April 7

Third Reich promulgates its first anti-Jewish ordinance.

September 12

Leo Szilard, a Hungarian physicist who took refuge in London from Nazi Germany, reads about a speech in which Lord Rutherford ridiculed the idea of using the transformation of atoms as a source of power. Szilard realizes that, "if we could find an element which is split by neutrons, and which would emit two neutrons when it absorbs one neutron, such an element could sustain a nuclear chain reaction."

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1934

Frederic and Irene Joliot-Curie of France discover artificial radioactivity, i.e. the radioactivity of atoms produced in transmutation experiments.

Enrico Fermi of Italy irradiates uranium with neutrons. He believes he has produced the first transuranic element, but unknowingly achieves the world's first nuclear fission.

June 28 and July 4

Leo Szilard files for patent amendments for "the liberation of nuclear energy for power production and other purposes through nuclear 'transmutation.' " He proposes a "chain reaction" for the first time.

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1935

April 9

Leo Szilard files patent amendment identifiying uranium and bromine as "examples for elements from which neutrons can liberate multiple neutrons..."

When Szilard learns that the only way for his patents on liberating nuclear energy can be kept secret is to assign them to an agency of the British government he offers them to the British War Office.

October 8

The British War turns down Leo Szilard's offer to give them his patents on nuclear energy stating, "There appears to be no reason to keep the specification secret so far as the War Department is concerned."

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1936

February

Leo Szilard's