  I expose nonrelativistic quantum electrodynamics in the Weyl-Wigner
representation. Hence I prove that an approximation to first order in Planck
constant has formal analogy with stochastic electrodynamics (SED), that is
classical electrodynamics of charged particles immersed in a random radiation
filling space. The analogy elucidates why SED agrees with quantum theory for
particle Hamiltonians quadratic in coordinates and momenta, but fails
otherwise.
