Polarising

Polarising, the process of causing polarisation, has both physical and social meanings. In physics, polarisation describes the orientation of oscillations in a wave, such as light. A polarising element transmits waves with a preferred orientation while attenuating others, effectively shaping the wave's polarization state.

Optical polarising devices include polarising filters, often made from anisotropic crystals or polymer films. Linear polarisation selects a single plane of vibration, while circular polarisation, produced with a quarter-wave plate and a linear polariser, yields rotation of the electric field with constant magnitude. Polarisation can be created by reflection at special angles (Brewster's law), scattering, or transmission through birefringent or dichroic materials. The polarisation state can be described by parameters such as the Stokes vector and degree of polarisation, which quantify how much of the light is polarised.

Practically, polarisation is used in photography to suppress glare, in liquid crystal displays to control light transmission, and in scientific instrumentation for optical communication and measurement. In social contexts, polarisation refers to the division of opinions into opposing camps. Causes include media fragmentation, selective exposure to information, social identity processes, and psychological factors. Polarisation can influence public discourse by reducing cross-cutting interactions and increasing perceived differences, though it may also reflect genuine differentiation on issues.