(Encyclopedia) electric and magnetic units, units used to express the magnitudes of various quantities in electricity and magnetism. Three systems of such units, all based on the metric system, are…
(Encyclopedia) Yucca Mountain, mountain in the SW Nevada desert about 100 mi (161 km) northwest of Las Vegas. It is the proposed site of a Dept. of Energy (DOE) repository for up to 77,000 metric…
Physical ScienceScience Projects for BeginnersPhysical ScienceWhy Do Some Objects Fall Faster Than Others?Do Objects Float Better in Salt Water Than in Fresh Water? Does It Matter How Much Air Is…
(Encyclopedia) micrometermicrometermīkrŏmˈətər, mīˈkrōmēˌtər [key]. 1 Instrument used for measuring extremely small distances. Typical examples are devices used in astronomical telescopes to measure…
(Encyclopedia) Morley, Edward Williams, 1838–1923, American scientist, b. Newark, N.J., grad. Williams College, 1860. From 1869 to 1906 he was professor of chemistry at Western Reserve College (now…
(Encyclopedia) Mitchell, Wesley Clair, 1874–1948, American economist, b. Rushville, Ill. He received his Ph.D. (1899) from the Univ. of Chicago, where he studied under Thorstein Veblen and John Dewey…
(Encyclopedia) mass-luminosity relation, in astronomy, law stating that the luminosity of a star is proportional to some power of the mass of the star. More massive stars are in general more luminous…
(Encyclopedia) Hertzsprung, EjnarHertzsprung, Ejnarīˈnär hĕrtsˈspr&oomacr;ng [key], 1873–1967, Danish astronomer. Although trained as a chemical engineer, Hertzsprung made his career in astronomy…
(Encyclopedia) Haroche, Serge, 1944–, French physicist, Ph.D. Paris VI Univ., 1971. He was a professor at Pierre and Marie Curie Univ. from 1975 to 2001 and at Paris VI Univ. from 1982 to 2001, when…
(Encyclopedia) clepsydraclepsydraklĕpˈsĭdrə [key] or water clock, ancient device for measuring time by means of the flow of water from a container. A simple form of clepsydra was an earthenware…
