Fundamental symmetry aspects of chirality.

Physical systems which exhibit distinguishable enantiomers under space inversion are not necessarily chiral. A new definition of chirality is proposed that enables true and false chirality to be distinguished. Although spatial enantiomorphism is sufficient to guarantee chirality in a stationary object, enantiomorphous systems are not necessarily chiral when motion is involved. Only a truly chiral influence can induce absolute asymmetric synthesis in a reaction mixture at thermodynamic equilibrium, but false chirality might suffice if equilibrium is not attained. Parity violation lifts only the degeneracy of enantiomers of truly chiral systems, the true enantiomers (i.e. strictly degenerate) being interconverted by space inversion together with charge conjugation. The time-independence of optical activity arising from parity violation is contrasted with the time-dependence of that arising from spontaneous parity breaking.