Appearently, two beams of light in a vacuum are attracted to each other. Photons have no newtonian mass, but their relativistic mass (e=mc^2 or mass-energy equivalence) causes this (as is my understanding). So will a 10^4 Hz beam bend more towards a 10^20 Hz beam than the 10^20 Hz bends towards the 10^4 Hz beam? After all, e=mc^2 indicates the 10^20 Hz beam has more relativistic mass doesn't it? However, if they equally bend, why?