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gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

acceleration

(Encyclopedia)acceleration, change in the velocity of a body with respect to time. Since velocity is a vector quantity, involving both magnitude and direction, acceleration is also a vector. In order to produce an ...

conducting

(Encyclopedia)conducting, in music, the art of unifying the efforts of a number of musicians simultaneously engaged in musical performance. In the Middle Ages and Renaissance the conductor was primarily a time beat...

uncertainty principle

(Encyclopedia)uncertainty principle, physical principle, enunciated by Werner Heisenberg in 1927, that places an absolute, theoretical limit on the combined accuracy of certain pairs of simultaneous, related measur...

Steichen, Edward

(Encyclopedia)Steichen, Edward stīˈkən [key], 1879–1973, American photographer, b. Luxembourg, reared in Hancock, Mich. Steichen is credited with the transformation of photography into an art form. At 16, whil...

Lincoln Memorial

(Encyclopedia)Lincoln Memorial, monument, 107 acres (45 hectares), in Potomac Park, Washington, D.C.; built 1914–17. The building, designed by Henry Bacon and styled after a Greek temple, has 36 Doric columns rep...

Liberalia

(Encyclopedia)Liberalia lĭbərāˈlēə [key], in Roman religion, festival of Liber and Libera. The rustic festival of great rejoicing and merrymaking was held on Mar. 17. Roman youths generally first assumed the ...

Luton

(Encyclopedia)Luton lo͞oˈtən [key], borough and unitary authority (1991 pop. 163,209), S central England on the Lea River. Hats, automobiles, ball bearings, and aircraft parts are among the products manufactured...

John I, king of Aragón and count of Barcelona

(Encyclopedia)John I, 1350–95, king of Aragón and count of Barcelona (1387–95), son and successor of Peter IV. During his reign Aragón lost (1388) the duchy of Athens. An enthusiastic patron of learning and a...

Hérold, Louis Joseph Ferdinand

(Encyclopedia)Hérold, Louis Joseph Ferdinand lwē zhôzĕfˈ fĕrdēnäNˈ ārôldˈ [key], 1791–1833, French composer. He composed a number of operas, two of which—Zampa (1831) and Le Pré aux clercs (1832)�...