I'm not sure what forum I am suppose to post GR questions so I am sorry if this is in the wrong spot. Ok my question is this. In classic phys. newton required mass to have gravity. I read that in GR einstein required stress energy. If light has not mass or should I say a photon but EM waves produce radiation pressure as a force then integrated over time would give you work and energy. So what I am asking does light or an EM wavelength cause a force, have energy, and most of all cause fluctuations in gravity. IE a large super star produces the force of gravity to a small planet beside it but also its light that is shined does too??? Is this possible or true.