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Perrin, Jean Baptiste

(Encyclopedia)Perrin, Jean Baptiste zhäN bätēstˈ pĕrăNˈ [key], 1870–1942, French physicist. From 1910 to 1940 he was professor at the Univ. of Paris, and in 1941 he came to the United States. Perrin specia...

Einstein, Albert

(Encyclopedia)Einstein, Albert īnˈstīn [key], 1879–1955, American theoretical physicist, known for the formulation of the relativity theory, b. Ulm, Germany. He is recognized as one of the greatest physicists ...

Schwinger, Julian Seymour

(Encyclopedia)Schwinger, Julian Seymour, 1918–94, American physicist, b. New York City, Ph.D. Columbia, 1939. He was a professor at the Univ. of California, Berkeley (1939–47) and worked under J. Robert Oppenhe...

Diogenes of Apollonia

(Encyclopedia)Diogenes of Apollonia ăpəlōˈnēə [key], 5th cent. b.c., Greek philosopher. An eclectic, he reverted to the Milesian tradition of a century earlier in seeking to explain the constitution of all ma...

bow and arrow

(Encyclopedia)bow and arrow, weapon consisting of two parts; the bow is made of a strip of flexible material, such as wood, with a cord linking the two ends of the strip to form a tension from which is propelled th...

North Dakota, University of

(Encyclopedia)North Dakota, University of, at Grand Forks; state supported; coeducational; chartered 1883, opened 1884. It has several professional schools, including those for aerospace sciences, engineering and m...

correspondence principle

(Encyclopedia)correspondence principle, physical principle, enunciated by Niels Bohr in 1923, according to which the predictions of the quantum theory must correspond to the predictions of the classical theories of...

radiation

(Encyclopedia)radiation rāˌdēāˈshən [key], term applied to the emission and transmission of energy through space or through a material medium and also to the radiated energy itself. In its widest sense the te...

electron

(Encyclopedia)electron, elementary particle carrying a unit charge of negative electricity. Ordinary electric current is the flow of electrons through a wire conductor (see electricity). The electron is one of the ...

earth, in geology and astronomy

(Encyclopedia)CE5 A. Cross section of the earth, showing its shells B. Detailed cross section of the crust and upper mantle: The lithosphere consists of the hard rock in the crust and upper mantle, lying above t...