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Dirac, Paul Adrien Maurice

(Encyclopedia)Dirac, Paul Adrien Maurice dĭrăkˈ [key], 1902–84, English physicist. He was educated at the Univ. of Bristol and St. John's College, Cambridge, and became professor of mathematics at Cambridge in...

neon

(Encyclopedia)neon nēˈŏn [key] [Gr.,=new], gaseous chemical element; symbol Ne; at. no. 10; at. wt. 20.1797; m.p. −248.67℃; b.p. −246.048℃; density 0.8999 grams per liter at STP; valence 0. Neon is a col...

Shepard, Sam

(Encyclopedia)Shepard, Sam, 1943–2017, one of the major American playwrights and actors of his era, b. Fort Sheridan, Ill., as Samuel Shepard Rogers 3d. A product of the 1960s counterculture and an important figu...

thorium

(Encyclopedia)thorium thôrˈēəm [key] [from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750℃; b.p. about 4,790℃; sp. gr. 11.7 at 20℃; va...

electromagnet

(Encyclopedia)CE5 Electromagnet electromagnet, device in which magnetism is produced by an electric current. Any electric current produces a magnetic field, but the field near an ordinary straight conductor is ...

group

(Encyclopedia)group, in mathematics, system consisting of a set of elements and a binary operation a∘b defined for combining two elements such that the following requirements are satisfied: (1) The set is closed ...

tennessine

(Encyclopedia)tennessine tĕnˈəsēn [key], artificially produced radioactive chemical element; symbol Ts; at. no. 117; mass number of most stable isotope 294; m.p., b.p., sp. gr., and valence unknown. Tennessine ...

baryon

(Encyclopedia)baryon bârˈēŏnˌ [key] [Gr.,=heavy], class of elementary particles that includes the proton, the neutron, and a large number of unstable, heavier particles, known as hyperons. From a technical poi...

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...

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...