Parity

Parity, in physics, symmetry between an event and its reflection in a mirror. Physicists say that parity is conserved when an event and its mirror image both satisfy identical laws of nature. In 1956, 2 Chinese physicists, Tsung Dao Lee and Chen Ning Yang conducted experiments which showed that parity is not conserved in a type of nuclear event called a weak interaction. Their work and other experiments demonstrated that conservation of parity is not a universal law of nature.

See also: Physics.