# Lorentz contraction

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## Lorentz contraction

(lôr`ĕnts), 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 earlier suggestion by G. F. Fitzgerald; it is sometimes called the Fitzgerald, or Lorentz-Fitzgerald, contraction. The Lorentz contraction hypothesis was put forward in an attempt to explain the negative result of the Michelson-Morley experiment of 1887 designed to demonstrate the earth's absolute motion through space (see ether**ether**

or

**aether,**

in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics all waves are propagated through a medium, e.g.

**.....**Click the link for more information. ; relativity

**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.

**.....**Click the link for more information. ). The hypothesis held that any material body is contracted in the direction of its motion by a factor √1−

*v*

^{2}/

*c*

^{2}, where

*v*is the velocity of the body and

*c*is the velocity of light. Although the Lorentz contraction did not succeed entirely in reconciling the results of the Michelson-Morley experiment with classical theory, it did serve as the basis for the mathematics of Einstein's theory of relativity. The equations used in relativity theory to change from a coordinate system, or frame of reference, in which the observer is at rest to a second system that is moving at constant velocity with respect to the first system are known as the Lorentz transformation. The Lorentz transformation will result in a stationary observer recording an effect equivalent to the Lorentz contraction when observing an object in uniform motion relative to his system of coordinates. Einstein showed, however, that this effect is due not to the actual deformation of the body in question, as Lorentz had originally supposed, but to a change in the way space and time are measured.

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## Lorentz contraction

[′lȯr‚ens kən′trak·shən] (relativity)

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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