  A common assumption in quantum field theory is that the energy-momentum
4-vector of any quantum state must be time-like. However it has been recently
shown [4] that this is not the case for a Dirac-Maxwell field in the coulomb
gauge. Here we will present a proof that is simpler then the proof of Ref. [4]
that there must exist quantum states which are space-like for a Dirac-Maxwell
field in the coulomb gauge.
