  David Albert claims that classical electromagnetic theory is not time
reversal invariant. He acknowledges that all physics books say that it is, but
claims they are "simply wrong" because they rely on an incorrect account of how
the time reversal operator acts on magnetic fields. On that account, electric
fields are left intact by the operator, but magnetic fields are inverted.
Albert sees no reason for the asymmetric treatment, and insists that neither
field should be inverted. I argue, to the contrary, that the inversion of
magnetic fields makes good sense and is, in fact, forced by elementary
geometric considerations. I also suggest a way of thinking about the time
reversal invariance of classical electromagnetic theory -- one that makes use
of the invariant four-dimensional formulation of the theory -- that makes no
reference to magnetic fields at all. It is my hope that it will be of interest
in its own right, Albert aside. It has the advantage that it allows for
arbitrary curvature in the background spacetime structure, and is therefore
suitable for the framework of general relativity. The only assumption one needs
is temporal orientability.
