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Lanzhou

(Encyclopedia)Lanzhou or Lanchow both: länˈjōˈ [key], city (1994 est. pop. 1,295,600), capital of Gansu prov., W China, on the Huang He (Yellow River) at its confluence with the Wei. It is a rail, highway, and ...

Soddy, Frederick

(Encyclopedia)Soddy, Frederick sŏdˈē [key], 1877–1956, English chemist. He worked under Lord Rutherford at McGill Univ. and with Sir William Ramsay at the Univ. of London. After serving (1910–14) as lecturer...

work

(Encyclopedia)work, in physics and mechanics, transfer of energy by a force acting to displace a body. Work is equal to the product of the force and the distance through which it produces movement. Although both fo...

gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

radiation

(Encyclopedia)radiation rāˌdēāˈshən [key], term applied to the emission and transmission of energy through space or through a material medium and also to the radiated energy itself. In its widest sense the te...

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...

quantum theory

(Encyclopedia)quantum theory, modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity togethe...

gamma radiation

(Encyclopedia)gamma radiation, high-energy photons emitted as one of the three types of radiation resulting from natural radioactivity. It is the most energetic form of electromagnetic radiation, with a very short ...

foreign aid

(Encyclopedia)foreign aid, economic, military, technical, and financial assistance given on an international, and usually intergovernmental level. U.S. foreign aid programs have included at least three different ob...

ozone

(Encyclopedia)ozone ōˈzōn [key], an allotropic form of the chemical element oxygen (see allotropy). Pure ozone is an unstable, faintly bluish gas with a characteristic fresh, penetrating odor. The gas has a dens...