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Chladni, Ernst Florens Friedrich

(Encyclopedia)Chladni, Ernst Florens Friedrich ĕrnst flōˈrĕns frēˈdrĭkh klädˈnē [key], 1756–1827, German physicist. An authority on acoustics, he made studies of the transmission of sound in various gas...

Nash, John Forbes, Jr.

(Encyclopedia)Nash, John Forbes, Jr., 1928–2015, American mathematician, b. Bluefield, W.Va., grad. Carnegie Institute of Technology (now Carnegie-Mellon Univ., B.A. and M.A. 1948), Ph.D. Princeton 1950. During a...

decompression sickness

(Encyclopedia)decompression sickness, physiological disorder caused by a rapid decrease in atmospheric pressure, resulting in the release of nitrogen bubbles into the body tissues. It is also known as caisson disea...

liquid air

(Encyclopedia)liquid air, ordinary air that has been liquefied by compression and cooling to extremely low temperatures (see liquefaction). Its commercial preparation involves purification by washing to remove solu...

pollution allowance

(Encyclopedia)pollution allowance or emission rights, government-issued permit to emit a certain amount of a pollutant. The holder of the permit may use it to pollute legally, may trade permits, or may sell the per...

relativity

(Encyclopedia)relativity, physical theory, introduced by Albert Einstein, that discards the concept of absolute motion and instead treats only relative motion between two systems or frames of reference. One consequ...

Sommerfeld, Arnold Johannes Wilhelm

(Encyclopedia)Sommerfeld, Arnold Johannes Wilhelm ärˈnōlt yōhänˈəs vĭlˈhĕlm zômˈərfĕlt [key], 1868–1951, German physicist and teacher. He received a Ph.D. at Königsburg Univ. in 1891 and was a prof...

Laurent, Auguste

(Encyclopedia)Laurent, Auguste ōgüstˈ lōräNˈ [key], 1808–53, French organic chemist. He devised a systematic nomenclature for organic chemistry. His studies on naphthalene and its chlorination products led ...

rotary engine

(Encyclopedia)rotary engine, internal-combustion engine whose cycle is similar to that of a piston engine, but which produces rotary motion directly without any conversion from reciprocating motion. A major problem...

Young, Thomas

(Encyclopedia)Young, Thomas, 1773–1829, English physicist, physician, and Egyptologist. He established (1799) a medical practice in London and was elected (1811) to the staff of St. George's Hospital there. His l...