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Related to isotropy: Isotropy group


(ÿ-sot -rŏ-pee) The property by which all directions appear indistinguishable to an observer expanding with the Universe. Isotropy about every point in space implies homogeneity but the reverse is not necessarily true. See cosmological principle.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



identity of the physical properties of a medium in all directions (the opposite of anisotropy).

All gases, liquids, and solids are isotropic in the amorphous state in all physical properties. Most physical properties in crystals are anisotropic. However, the isotropy of the properties of a crystal increases with increasing symmetry. Thus, the elasticity, strength, and electro-optical properties are anisotropic in highly symmetrical crystals (diamond, germanium, and rock salt), but the index of refraction, electrical conductivity, and coefficient of thermal expansion are isotropic (in less symmetrical crystals, these properties are likewise anisotropic).

Homogeneous polycrystals are usually isotropic with respect to all properties, if their properties are studied in a volume that is considerably larger than the grain size.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The quality of a property which does not depend on the direction along which it is measured, or of a medium or entity whose properties do not depend on the direction along which they are measured.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Local linearity now implies that the "other" endpoint of [J.sub.2] corresponds to an orbit with isotropy subgroup (conjugate to) [A.sub.4] and is an interior point of [J.sub.3], the "other" endpoint of [J.sub.3] corresponds to an orbit with isotropy subgroup (conjugate to) [D.sub.6] and is an interior point of [J.sub.2], and the "other" endpoint of [J.sub.5] corresponds to an orbit with isotropy subgroup (conjugate to) [D.sub.10] and is an interior point of [J.sub.2].
(It is akin to the task of specifying what is meant by spatial isotropy without being able to appeal to the notion of 3-tensors).
Isotropy remains relatively constant until [xi]/[l.sub.0] [approximately equal to] 1.2, before suppression or amplification of isotropy at [xi]/[l.sub.0] [approximately equal to] 0.3.
Equations (4b)and (fc), together with the transformation u = [r.sup.2], give the pressure isotropy condition
The underlying requirement of structural isotropy can be expected violated however inside the ITZ, so the method should be applied to bulk cement only.
Linearity primarily varies with field strength and much less with frequency while isotropy depends largely on symmetry.
Unfortunately most modeling software assumes isotropy, which may result in over or underestimation of the heat removal.
Stretching of rubber causes orientation of rubber molecules, but as the orientation is in the direction of stretching, the assumption of isotropy can be said to remain valid.
A fundamental concern worth mentioning is that all the Friedmann models are based on the assumption that the universe has the same density at all places (homogeneity) and the same expansion rate in all directions (isotropy).
We'll prove that if the generic isotropy subgroup [H.sup.1.sub.0] of D is connected semi-simple, then I'([phi]) is absolutely convergent for every [phi][Epsilon] S(XA), and this convergence is invariant under castling transforms, which means that if two irreducible regular prehomogeneous vector spaces (G,X) and [Mathematical Expressions Omitted] are castling transforms of each other and [Mathematical Expressions Omitted] for (G,X) is absolutely convergent for every [phi][Epsilon] S([X.sub.A]), so is [Mathematical Expressions Omitted] for [Mathematical Expressions Omitted].
Yield strength and Lankford coefficient have been shown to have little correlation with specimen orientation; therefore planar isotropy can be assumed for the chosen material.