PHOTONS HAVE MASS.
well, of course they do. it's really crazy to think they don't.
http://phys.org/news/2013-09-scientists-never-before-seen.html
http://en.wikipedia.org/wiki/Photon#Experimental_checks_on_photon_mass
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html