Columbia Encyclopedia

Search results

500 results found

nucleus, in physics

(Encyclopedia)nucleus, in physics, the extremely dense central core of an atom. Following the discovery of radioactivity by A. H. Becquerel in 1896, Ernest Rutherford identified two types of radiation given off b...

Mitchell, William

(Encyclopedia)Mitchell, William (Billy Mitchell), 1879–1936, American army officer and pilot, b. Nice, France. He enlisted (1898) in the U.S. army in the Spanish-American War and received a commission in the regu...

Deerfield, river, United States

(Encyclopedia)Deerfield, river, 70 mi (113 km) long, rising in S Vt. and flowing S into NW Mass., then SE to the Connecticut River at Greenfield, Mass. The river has extensive hydroelectric facilities but is also a...

aviation

(Encyclopedia)aviation, operation of heavier-than-air aircraft and related activities. Aviation can be conveniently divided into military aviation, air transport, and general aviation. Military aviation includes al...

aviation medicine

(Encyclopedia)aviation medicine, scientific study of the biological effects of aviation, especially on human beings. Although aviation medicine is concerned with such problems as the spread of diseases by persons t...

equal-time rule

(Encyclopedia)equal-time rule, a Federal Communications Commission rule that requires equal air time for all major candidates competing for political office. It was preceded by the fairness doctrine, abolished in 1...

Bossier City

(Encyclopedia)Bossier City bōˈzhər [key], city (2020 pop. 62,701), Bossier parish, NW La., on the Red River, ...

thunder

(Encyclopedia)thunder, sound produced along a path of a lightning flash, caused by the rapid heating and expansion of the adjacent air; lightning can heat air to temperatures as much as five times hotter than those...

Doolittle, James Harold

(Encyclopedia)Doolittle, James Harold, 1896–1993, American aviator, b. Alameda, Calif. After serving in World War I as a flier he returned to school and earned a Sc.D. from MIT. He then became noted for his speed...

Guericke, Otto von

(Encyclopedia)Guericke, Otto von ôˈtō fən gāˈrĭkə [key], 1602–86, German physicist, noted for his study of pneumatics. He carried out his most important researches while burgomaster (1646–81) of Magdebu...