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universal time

(Encyclopedia)universal time (UT), the international time standard common to every place in the world, it nominally reflects the mean solar time along the earth's prime meridian (renumbered to equate to civil time)...

uncertainty principle

(Encyclopedia)uncertainty principle, physical principle, enunciated by Werner Heisenberg in 1927, that places an absolute, theoretical limit on the combined accuracy of certain pairs of simultaneous, related measur...

Baryshnikov, Mikhail

(Encyclopedia)Baryshnikov, Mikhail mĭˈkhail bərĭˌshnĭkävˈ [key], 1948–, Russian-American dancer and choreographer, b. Riga, Latvia (then in the USSR). He studied in Riga and performed with the Kirov Balle...

shaft sinking

(Encyclopedia)shaft sinking, excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnels, which are horizontal. Little difficulty is experien...

Ruscha, Ed

(Encyclopedia)Ruscha, Ed (Edward Joseph Ruscha 4th) ro͞oshāˈ [key], 1937–, American artist, b. Omaha, Neb. He is closely associated with Los Angeles, where he moved to attend (1956–60) the Chouinard Art Inst...

Saint Paul's Cathedral

(Encyclopedia)Saint Paul's Cathedral, London, masterpiece of Sir Christopher Wren and one of the finest church designs of the English baroque. It stands at the head of Ludgate Hill, where, according to tradition, a...

Cepheid variables

(Encyclopedia)Cepheid variables sēˈfēĭd [key], class of variable stars that brighten and dim in an extremely regular fashion. The periods of the fluctuations (the time to complete one cycle from bright to dim a...

Rijksmuseum

(Encyclopedia)Rijksmuseum rīksˈmyo͞ozēˌəm [key], Dutch national museum in Amsterdam, founded in 1808 by Louis Bonaparte, king of Holland (see under Bonaparte), as the Great Royal Museum in the Royal Palace. I...

black hole

(Encyclopedia)black hole, in astronomy, celestial object of such extremely intense gravity that it attracts everything near it and in some instances prevents everything, including light, from escaping. The term was...

Angkor

(Encyclopedia)Angkor ăngˈkôr [key], site of several capitals of the Khmer Empire, north of Tônlé Sap, NW Cambodia, for about five and a half centuries (9th to 15th), the heart of the empire. Extending over an ...