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Event Summary 

1931: Anderson discovers the positron (anti-electron)
Pauli suggests the existance of the neutrino
1932 Chadwick discovers the neutron
Cockcroft & Walton produce the first nuclear reaction with a high-voltage accelerator
1933
1934
1935 Yukawa proposes the existance of mesons
1936 Jesse Owens breaks the Olympic record in the 200-meter race
1937 Shannon Invents Switching Algebra
1938 Hahn & Strassmann discover nuclear fission
Bethe proposes thermonuclear fusion as the energy source of stars
1939 Einstein informs Roosevelt of the possibility of the Atomic Bomb
The world's first jet-propelled airplane makes its maiden flight
Garmany Invades Poland, starting WWII
Zworkin Invents the Photomultiplier
1940 Leon Trotsky fatally wounded
Watson-Watts Invents RADAR (RAdio Detection And Ranging)
McMillan, Seaborg, et al. produces the first synthetic transuranic elements
(transuranic = heavier than uranium)