im not a student, teacher, researcher in fact I've never even taken a physics class. But I Love to argue!, i spent a day proving (in my mind anyway) that, 1. a photon does have mass. 2. its impossible to say a photon's mass is x, because its variable, and can not be at rest.
so how is the speed of light is possible in nature since photons can only travel at the speed of light in a vacuum, a vacuum has no gravity, gravity it a result of particles. in space there is particles, gasses, dust, antimatter, gravity, and on and on. in nature there is no perfect vacuum. is my thinking flawed? someone said the space between atoms, but what about quantum foam. and a vacuum is the absence of matter, if you have matter in a jar thats not full, is the epmty space a vacuum? so eithet space IS a PERFECT vacuum, or its NOT a PERFECT vacuum. thoughts?
response to a comment.............
In the center of momentum frame, the colliding antiparticles have no net momentum, whereas a single photon always has momentum (since it is determined, as we have seen, only by the photon's frequency or wavelength—which cannot be zero)
A so-called massless particle (such as a photon, or a theoretical graviton) moves at the speed of light in every frame of reference. In this case there is no transformation that will bring the particle to rest. The total energy of such particles becomes smaller and smaller in frames which move faster and faster in the same direction. As such, they have no rest mass, because they can never be measured in a frame where they are at rest. This property of having no rest mass is what causes these particles to be termed "massless." However, even massless particles have a relativistic mass, which varies with their observed energy in various frames of reference,