[OT] Re: Negative Energy

Brian Bell asked:
> I have heard photons described as "free electrons". Has physics
predicted
an
> anti-photon? If so, since light is energy (or at least energy
expressed),
> what is the result of a photon/anti-photon collision? Nothing
(annihilation
> without side-effect), Non-EM radiation? Matter? Other?

(You may recall that I have previously said "I'm not an expert in
anything,
but I cheerfully make comments anyway."  This is such a case).

If you think of a photon as a wave, then an anti-photon would be what
cancels out the original photon, eg an identical wave out of phase so
its
troughs are at the same point as the original wave's peaks.  Right? 
This is
not a rhetorical question--my degrees are in communications, not
physics.

If, on the other hand, this is your day to consider photons as
particles,
then I have no idea what the anti-particle would be.  If there is such a
critter, I'd assume you could generate interference patterns from
anti-photons of different phases, just as you could with regular
photons. If
so, what do you get when you create an interference pattern (using
anti-photons) in the same place as an interference pattern (using normal
photons)?