  Advanced electromagnetic potentials are indigenous to the classical Maxwell
theory. Generally however they are deemed undesirable and are forcibly
excluded, destroying the theory's inherent time-symmetry. We investigate the
reason for this, pointing out that it is not necessary and in some cases is
counter-productive. We then focus on the direct-action theory in which the
advanced and retarded contributions are present symmetrically, with no
opportunity to supplement the particular integral solution of the wave equation
with an arbitrary complementary function. One then requires a plausible
explanation for the observed broken symmetry that, commonly, is understood
cannot be met by the Wheeler-Feynman mechanism because the necessary boundary
condition cannot be satisfied in acceptable cosmologies. We take this
opportunity to argue that the boundary condition is already met by all
expanding cosmologies simply as a result of cosmological red-shift. A
consequence is that the cosmological and thermodynamic arrows of time can be
equated, the direct action version of EM is preferred, and that advanced
potentials are ubiquitous.
