  Three possibilities for the origin of CP violation are discussed: (1) the
Standard Model in which all CP violation is due to one parameter in the CKM
matrix, (2) the superweak model in which all CP violation is due to new physics
and (3) the Standard Model plus new physics. A major goal of B physics is to
distinguish these possibilities. CP violation implies time reversal violation
(TRV) but direct evidence for TRV is difficult to obtain.
