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phonon

(Encyclopedia)phonon fōˈnŏn [key], quantum of vibrational energy. The atoms of any crystal are in a state of vibration, their average kinetic energy being measured by the absolute temperature of the crystal. In ...

Bothe, Walther Wilhelm Georg

(Encyclopedia)Bothe, Walther Wilhelm Georg, 1891–1957, German physicist, Ph.D. Univ. of Berlin, 1923. Bothe was a researcher at the Reich Physical and Technical Institute (1913–30) and a professor at Heidelberg...

Rumford, Benjamin Thompson, Count

(Encyclopedia)Rumford, Benjamin Thompson, Count, 1753–1814, American-British scientist and administrator, b. Woburn, Mass. In 1776 he went to England, where he served (1780–81) as undersecretary of the colonies...

Broglie, Louis Victor, duc de

(Encyclopedia)Broglie, Louis Victor, duc de, 1892–1987, French physicist. In 1928 he became professor in the faculty of sciences, Univ. of Paris. It was known from the earlier quantum theory that light waves some...

sea lily

(Encyclopedia)sea lily, stalked echinoderm of the class Crinoidea. Sea lilies are ancient, having reached their peak in the Middle Mississippian period; about 5,000 fossil species are known. About 80 modern species...

force

(Encyclopedia)force, commonly, a “push” or “pull,” more properly defined in physics as a quantity that changes the motion, size, or shape of a body. Force is a vector quantity, having both magnitude and dir...

Alcuin

(Encyclopedia)Alcuin ălbīˈnəs [key], 735?–804, English churchman and educator. He was educated at the cathedral school of York by a disciple of Bede; he became principal in 766. Charlemagne invited him (781?)...

coeducation

(Encyclopedia)coeducation, instruction of both sexes in the same institution. The economic benefits gained from joint classes and the need to secure equality for women in industrial, professional, and political act...

multiplication

(Encyclopedia)multiplication, fundamental operation in arithmetic and algebra. Multiplication by a whole number can be interpreted as successive addition. For example, a number N multiplied by 3 is N + N + N. In ge...

Mendeleev, Dmitri Ivanovich

(Encyclopedia)Mendeleev, Dmitri Ivanovich mĕndəlāˈəf, Rus. dəmēˈtrē ēväˈnəvĭch myĭndyĭlyāˈəf [key], 1834–1907, Russian chemist. He is famous for his formulation (1869) of the periodic law and t...