; Cell biology: If the properties of the cell wall are more or less the same everywhere, it is said to be isotropic.
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Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented.
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; Quantum mechanics or Particle physics: When a spinless particle (or even an unpolarized particle with spin) decays, the resulting decay distribution must be isotropic in the rest frame of the decaying particle regardless of the detailed physics of the decay.
In 1968 Henri Bacry and Jean-Marc Lévy-Leblond showed that the de Sitter group was the most general group compatible with isotropy, homogeneity and boost invariance.
Yet another phenomenon that Sachs' theory can accommodate that standard cosmology might not is the Huge-LQG large quasar group, since general relativity does not presuppose homogeneity or isotropy, i.e., the cosmological principle.