The Isotropy Group. Solids, Isotropic Materials, Fluids, Fluid Crystals

Abstract

In the older literature a material is said to be “isotropic” if it is “unaffected by rotations.” This means that if we first rotate a specimen of material and then do an experiment upon it, the-outcome is the same as if the specimen had not been rotated. In other words, within the class of effects considered by the theory, rotations cannot be detected by any experiment. The response of the material with respect to the reference configuration κ̰ is the same as that with respect to any other obtained from it by rotation.