Gauging away Physics
  We consider the recent argument by Higuchi, Marolf and Morrison [1] that a
nonlocal gauge transformation can be used to eliminate the infrared divergence
of the graviton propagator, when evaluated in Bunch-Davies vacuum on the open
coordinate submanifold of de Sitter space in transverse-traceless-synchronous
gauge. Because the transformation is not local, the equal time commutator of
undifferentiated fields no longer vanishes. From explicit examination of the
Wightman function we demonstrate that the transformation adds anti-sources in
the far future which cancel the bad infrared behavior but also change the
propagator equation. The same problem exists in the localized version of the
recent argument. Adding such anti-sources does not seem to be legitimate and
could be used to eliminate the infrared divergence of the massless, minimally
coupled scalar. The addition of such anti-sources in flat space QED could be
effected by an almost identical gauge transformation, and would seem to
eliminate the well known infrared divergences which occur in loop corrections
to exclusive amplitudes.
