relativity

rel·a·tiv·i·ty  (rl-tv-t)

n.

1. The quality or state of being relative.

2. A state of dependence in which the existence or significance of one entity is solely dependent on that of another.

3. Physics

a. Special relativity.

b. General relativity.

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relativity

Noun

1. either of two theories developed by Albert Einstein, the [special theory of relativity], which requires that the laws of physics shall be the same as seen by any two different observers in uniform relative motion, and the [general theory of relativity], which considers observers with relative acceleration and leads to a theory of gravitation

2. the state of being relative

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relativity  (rl-tv-t)

Either of two theories in physics developed by Albert Einstein, General Relativity or Special Relativity. See Notes at Einstein Albertgravityspace-time

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relativistic adjective

A Closer Look Albert Einstein's two theories of relativity were the first successful revisions of Newtonian mechanicsa mechanics so simple and intuitive that it was held to be a permanent fixture of physics. Uniting the theories is the idea that two observers traveling relative to each other may have different perceptions of time and space, yet the laws of nature are still uniform, and certain properties always remain invariant. Einstein developed the first theory, the theory of Special Relativity (1905), to explain and extend certain consequences of Maxwell's equations describing electromagnetism, in particular, addressing a puzzle surrounding the speed of light in a vacuum, which was predicted always to be the same, whether the light source is stationary or moving. Special Relativity considers the laws of nature from the point of view of frames of reference upon which no forces are acting, and describes the way time, distance, mass, and energy must be perceived by observers who are in uniform motion relative to each other if the speed of light must always turn out the same for all observers. Two implications of Special Relativity are space and time dilation. As speed increases, space is compressed in the direction of the motion, and time slows down. A famous example is the space traveler who returns to Earth younger than his Earth-dwelling twin, his biological processes proceeding more slowly due to his relative speed. These effects are very small at the speeds we normally experience but become significant at speeds approaching the speed of light (known as relativistic speeds). Perhaps the best-known implication of Special Relativity is the equation E=mc², which expresses a close relation between energy and mass. The speed of light is a large number (about 300,000 km per second, or 186,000 mi per second), so the equation suggests that even small amounts of mass can be converted into enormous amounts of energy, a fact exploited by atomic power and weaponry. Einstein's General Theory of relativity extended his Special Theory to include non-inertial reference frames, frames acted on by forces and undergoing acceleration, as in cases involving gravity. The General Theory revolutionized the way gravity, too, was understood. Since Einstein, gravity is seen as a curvature in space-time itself.

Thesaurus

Noun	1.	relativity - (physics) the theory that space and time are relative concepts rather than absolute concepts Einstein's theory of relativity, relativity theory, theory of relativity scientific theory - a theory that explains scientific observations; "scientific theories must be falsifiable" natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" Einstein's general theory of relativity, general relativity, general relativity theory, general theory of relativity - a generalization of special relativity to include gravity (based on the principle of equivalence) Einstein's special theory of relativity, special relativity, special relativity theory, special theory of relativity - a physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems event - a phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory
	2.	relativity - the quality of being relative and having significance only in relation to something else quality - an essential and distinguishing attribute of something or someone; "the quality of mercy is not strained"--Shakespeare