Isotropisch

Isotropisch, in English isotropic, describes a property that is the same in all directions. The term is used in physics, engineering, mathematics and cosmology to indicate directional uniformity. In formal terms, a medium or space is isotropic if its physical properties are invariant under all rotations; equivalently, measurements do not depend on the orientation of the observation.

In materials science and mechanics, isotropy means that properties such as stiffness, thermal conductivity, or electrical conductivity have the same value in every direction. Liquids are typically isotropic, while many crystalline solids are anisotropic, showing different properties along different crystallographic directions. Even materials that are not perfectly isotropic can behave as isotropic at macroscopic scales if their microstructure averages out directional variation.

In optics, isotropic media have a refractive index that is independent of light’s direction and polarization. Anisotropic materials, such as calcite, exhibit birefringence, where light splits into rays with different speeds depending on direction and polarization.

In diffusion and transport, isotropy implies uniform spreading in all directions; anisotropic diffusion occurs in media with preferred pathways, such as fibrous tissues.

In cosmology, the Cosmological Principle states that the universe is isotropic on large scales, an assumption supported by observations of the cosmic microwave background, though local structures introduce small anisotropies.

Mathematically, isotropy is expressed as invariance under rotations; isotropic tensors or random fields retain their essential character regardless of orientation. Perfect isotropy is an idealization; real systems often approximate it within a given scale or precision.