# Time Reversal

Lessons from the Light, 5.2

Note that among C, P, T, only T is an “antilinear operator” which means that

 T | \lambda \psi \rangle = \lambda* T | \psi \rangle

including the asterisk which means complex conjugation (that’s the reason of the prefix, anti-). Various combinations of C, P, T are linear or antilinear depending on whether T is included.

Note that the complex conjugation is needed for the time reversal already in ordinary non-relativistic quantum mechanics because the complex conjugation is the only sensible way to change ( \exp(+ipx/\hbar) ) to ( \exp(-ipx/\hbar) ), i.e. to change the sign of the momentum p – and the velocity v = dx/dt – which is needed for particles to evolve backwards.

— BaBar directly measures time reversal violation

— Lubos Motl

2014.06.11 Wednesday ACHK