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lepton

(Encyclopedia)lepton lĕpˈtŏnˌ [key] [Gr.,=light (i.e., lightweight)], class of elementary particles that includes the electron and its antiparticle, the muon and its antiparticle, the tau and its antiparticle, ...

diffraction

(Encyclopedia)diffraction, bending of waves around the edge of an obstacle. When light strikes an opaque body, for instance, a shadow forms on the side of the body that is shielded from the light source. Ordinarily...

promethium

(Encyclopedia)promethium prōmēˈthēəm [key], artificially produced radioactive chemical element; symbol Pm; at. no. 61; mass no. of most stable isotope 145; m.p. 1,042℃; b.p. 3,000℃ (estimated); sp. gr. unk...

hydrogen bomb

(Encyclopedia)hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that togethe...

stellar populations

(Encyclopedia)stellar populations, two broadly contrasting distributions of star types that are characteristic of different parts of a galaxy. Population I stars are young, recently formed stars, whereas population...

Mattis, James

(Encyclopedia)Mattis, James, 1950–, American general and secretary of defense (2017–18), b. Pullman, Wash., grad. Central Washington Univ. (1971). Commissioned as a second lieutenant (1972) in the Marines after...

Robinson, Bill

(Encyclopedia)Robinson, Bill, 1878–1949, African-American tap dancer popularly known as “Bojangles,” b. Richmond, Va., as Luther Robinson. An influential virtuoso tap dancer, he was a tap innovator and repute...

Rodino, Peter Wallace, Jr.

(Encyclopedia)Rodino, Peter Wallace, Jr. rōdēˈnō [key], 1909–2005, U.S. congressman, b. Newark, N.J., as Pellegrino Rodino, Jr.; grad. New Jersey Law School, 1937. Awarded the Bronze Star while serving (1941�...

Conte, Giuseppe

(Encyclopedia)Conte, Giuseppe, 1964–, Italian political leader, grad. Sapienza Univ. of Rome law school, 1988. A law professor at the Univ. ...

Crawford, Joan

(Encyclopedia)Crawford, Joan, 1908–77, American movie star, b. San Antonio, Tex., as Lucille Le Sueur. After working as a Broadway chorus dancer, Crawford began making films in 1926, eventually moving from musica...