Photons don't have a mass. If they did, they wouldn't be able to travel at the speed of light (it takes infinite energy to make any mass travel at the the speed

Photons don't have a mass. If they did, they wouldn't be able to travel at the speed of light (it takes infinite energy to make any mass travel at the the speed of light). http://en.wikipedia.org/wiki/Photon#Experimental_checks_on_photon_mass http://en.wikipedia.org/wiki/Photon#Experimental_checks_on_p... E = mc^2 applies to matter, not photons.