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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...

pion

(Encyclopedia)pion pīˈŏn [key] or pi meson, lightest of the meson family of elementary particles. The existence of the pion was predicted in 1935 by Hideki Yukawa, who theorized that it was responsible for the f...

Las Vegas

(Encyclopedia)Las Vegas läs vāˈgəs [key], city (1990 pop. 258,295), seat of Clark co., S Nev.; inc. 1911. It is the largest city in Nevada and the center of one of the fastest-growing urban areas in the United ...

X ray

(Encyclopedia)CE5 Typical X-ray composite spectrum (intensity as a function of frequency) X ray, invisible, highly penetrating electromagnetic radiation of much shorter wavelength (higher frequency) than visibl...

Bologna

(Encyclopedia)Bologna bōlôˈnyä [key], city, capital of Emilia-Romagna and of Bologna prov., N central I...

matter

(Encyclopedia)matter, anything that has mass and occupies space. Matter is sometimes called koinomatter (Gr. koinos=common) to distinguish it from antimatter, or matter composed of antiparticles. The atomic th...

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...

Lahore

(Encyclopedia)Lahore ləhôrˈ [key], city (1998 pop. 5,063,499), capital of Punjab prov., E central Pakistan, on the Ravi River. It is the second largest city of Pakistan. A railway and air transport center near t...

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...

physics

(Encyclopedia)physics, branch of science traditionally defined as the study of matter, energy, and the relation between them; it was called natural philosophy until the late 19th cent. and is still known by this na...