Columbia Encyclopedia
Search results
500 results found
motion
(Encyclopedia)motion, the change of position of one body with respect to another. The rate of change is the speed of the body. If the direction of motion is also given, then the velocity of the body is determined; ...relativity
(Encyclopedia)relativity, physical theory, introduced by Albert Einstein, that discards the concept of absolute motion and instead treats only relative motion between two systems or frames of reference. One consequ...celestial mechanics
(Encyclopedia)celestial mechanics, the study of the motions of astronomical bodies as they move under the influence of their mutual gravitation. Celestial mechanics analyzes the orbital motions of planets, dwarf pl...Sitter, Willem de
(Encyclopedia)Sitter, Willem de vĭlˈəm də sĭtˈər [key], 1872–1934, Dutch astronomer and mathematician. He was professor from 1908 at the Univ. of Leiden and in 1919 became director of its observatory. His ...Lorentz contraction
(Encyclopedia)Lorentz contraction lôrˈĕnts [key], in physics, contraction or foreshortening of a moving body in the direction of its motion, proposed by H. A. Lorentz on theoretical grounds and based on an earli...Newton's laws of motion
(Encyclopedia)Newton's laws of motion: see motion. ...perpetual-motion machine
(Encyclopedia)perpetual-motion machine, device that would be able to operate continuously and supply useful work, in violation of the laws of thermodynamics. A machine that would produce more energy in the form of ...mechanics
(Encyclopedia)mechanics, branch of physics concerned with motion and the forces that tend to cause it; it includes study of the mechanical properties of matter, such as density, elasticity, and viscosity. Mechanics...Eddington, Sir Arthur Stanley
(Encyclopedia)Eddington, Sir Arthur Stanley, 1882–1944, British astronomer and physicist. He was chief assistant (1906–13) at the Royal Observatory, Greenwich, and was from 1913 Plumian professor of astronomy a...perturbation
(Encyclopedia)perturbation pŭrˌtərbāˈshən [key], in astronomy and physics, small force or other influence that modifies the otherwise simple motion of some object. The term is also used for the effect produce...Browse by Subject
- Earth and the Environment +-
- History +-
- Literature and the Arts +-
- Medicine +-
- People +-
- Philosophy and Religion +-
-
Places
+-
- Africa
- Asia
- Australia and Oceania
- Britain, Ireland, France, and the Low Countries
- Commonwealth of Independent States and the Baltic Nations
- Germany, Scandinavia, and Central Europe
- Latin America and the Caribbean
- Oceans, Continents, and Polar Regions
- Spain, Portugal, Italy, Greece, and the Balkans
- United States, Canada, and Greenland
- Plants and Animals +-
- Science and Technology +-
- Social Sciences and the Law +-
- Sports and Everyday Life +-
