Anisotropy is the property of being directionally dependent. An example of anisotropy is the light coming through a polarizer. Another is wood, which is easier to split along its grain than against it. In physics cosmic anisotropy has been seen in the alignment of galaxies’ rotation axes and polarisation angles of quasars. Physicists use the term anisotropy to describe direction-dependent properties of materials. For example: Wood is a naturally anisotropic material. Its properties vary widely when measured with or against the growth grain. For example, wood’s strength and hardness is different for the same sample measured in different orientations.