VI. The World Wars and the Interwar Period, 1914–1945 > A. Global and Comparative Dimensions > 4. Science
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  The Encyclopedia of World History.  2001.
 
(See 1911)
 
4. Science
 
Science and technology became increasingly international but major developments were concentrated in Europe and the U.S. Throughout the interwar years, physics remained the center of most scientific activity, illuminating a universe that lacked any absolute reality. In 1919 Ernest Rutherford (1871–1937) showed that the atom could be split. By 1944 seven subatomic particles had been identified. Although few nonscientists understood the revolution in physics, the implications of the new theories and discoveries, as presented by newspapers and popular writers, were disturbing to millions of men and women in the 1920s and 1930s.  1
The major benchmarks in scientific inquiry follow.  2
 
a. Mathematics, Physics, Astronomy
1915
 
Einstein announced his general theory of relativity, which explained the advance of Mercury's perihelion and predicted the subsequently observed bending of light rays near the sun.  3
 
1918
 
Harlow Shapley (1885–1972), from an extensive study of the distribution of globular clusters and cepheid variable stars, increased the estimated size of our galaxy about ten times. He envisioned the galaxy as a flattened lens-shaped system of stars in which the solar system occupied a position far from the center.  4
 
1919
 
Rutherford found that the collision of alpha particles with nitrogen atoms resulted in the disintegration of the nitrogen and the production of hydrogen nuclei (protons) and an isotope of oxygen. He was the first person to achieve artificial transmutation of an element.  5
 
1919
 
Arthur S. Eddington (1882–1944) and others, by studying data obtained during a total solar eclipse, verified Einstein's prediction of the bending of light rays by the gravitational field of large masses.  6
 
1919–29
 
Edwin P. Hubble (1889–1953) detected cepheid variable stars in the Andromeda Nebula, a discovery that allowed him to determine the distances between galaxies.  7
 
1924
 
Louis-Victor de Broglie (1892–1987) determined from theoretical considerations that the electron, which had been considered a particle, should behave as a wave under certain circumstances. Experimental confirmation was obtained in 1927 by Clinton Davisson (1881–1958) and Lester H. Germer (1896–1971).  8
 
1925
 
Wolfgang Pauli (1900–1958) announced the exclusion principle (in any atom no two electrons have identical sets of quantum numbers). This principle was an important aid in determining the electron structure of the heavier elements.  9
 
1925–26
 
Werner Karl Heisenberg (1901–76) and Erwin Schrödinger (1887–1961) independently, and in different ways, laid the theoretical foundations of the new quantum mechanics, which, though violating classical notions of causality, successfully predicts the behavior of atomic particles.  10
 
1927
 
George Lemaître (1894–1966), in order to explain the red shift in the spectra from distant galaxies, introduced the concept of the expanding universe. Eddington pursued research in this subject from 1930.  11
 
1928
 
Paul A. Dirac (1902–84), by combining quantum mechanics and relativity theory, devised a relativistic theory of the electron.  12
 
 
 
The Encyclopedia of World History, Sixth edition. Peter N. Stearns, general editor. Copyright © 2001 by Houghton Mifflin Company. Maps by Mary Reilly, copyright 2001 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

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