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conservation laws

(Encyclopedia)conservation laws, in physics, basic laws that together determine which processes can or cannot occur in nature; each law maintains that the total value of the quantity governed by that law, e.g., mas...

pregnancy

(Encyclopedia)pregnancy, period of time between fertilization of the ovum (conception) and birth, during which mammals carry their developing young in the uterus (see embryo). The average duration of pregnancy in h...

symbol

(Encyclopedia)symbol, sign representing something that has an independent existence. The most important use of symbols is in language. To say so, however, does not solve the perennial philosophical questions as to ...

weather

(Encyclopedia)weather, state of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation. The term weather is restricted to co...

aerodynamics

(Encyclopedia)aerodynamics, study of gases in motion. As the principal application of aerodynamics is the design of aircraft, air is the gas with which the science is most concerned. Although aerodynamics is primar...

Jupiter, in astronomy

(Encyclopedia)Jupiter jo͞oˈpətər [key], in astronomy, 5th planet from the sun and largest planet of the solar system. Astronomers have discovered 79 satellites orbiting Jupiter, but five of those, small sate...

Solomon Islands

(Encyclopedia)Solomon Islands, independent Commonwealth nation (2015 est. pop. 587,000), c.15,500 sq mi (40,150 sq km), SW Pacific, E of New Guinea. The islands that constitute the nation of the Solomon Islands—G...

Tennessee Valley Authority

(Encyclopedia)Tennessee Valley Authority (TVA), independent U.S. government corporate agency, created in 1933 by act of Congress; it is responsible for the integrated development of the Tennessee River basin. The h...

glacier

(Encyclopedia)glacier, moving mass of ice that survives year to year, formed by the compacting of snow into névé and then into granular ice and set in motion outward and downward by the force of gravity and the s...

prison

(Encyclopedia)prison, place of confinement for the punishment and rehabilitation of criminals. By the end of the 18th cent. imprisonment was the chief mode of punishment for all but capital crimes. At that time, la...