Weyl's geometry and massive vector fields

Dirac's revitalization of Weyl's gauge invariant geometry is examined. Weyl's geometry is characterized by the breaking of the symmetries of charge conjugation (C) and time reversal (T), but not CT. When an attempt is made to introduce a very simple form of symmetry breaking material into the theory, it is found that the geometric role formerly played by the electromagnetic field is suddenly taken over by a very short range massive vector field. (author)