I have a simple question on the relativistic view point with regard to light. From wiki, "All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration." Simply I understand if a physical object keep the motion unchanged in time o uniform velocity, then it is considered as the IFR. Also I think that light itself is IFR because it moves in the empty space with constant velocity. In Einstein's relativistic view, I have learned that the velocity can be only defined with regard to other reference. And between two IRFs(A and B), either side can claim to be at rest or moving so that A is at rest but B is moving and vice versa. So assuming that I and a quanta of light are both the IFRs, I would like to ask a question to you. By definition of IRF, light is also IRF. So let me describe my velocity with regard to light. It will be common sense to say that I am at rest and light is moving at c. But problem is that I can take another view point that I am moving at c and light is at rest. If the latter is valid, then it seems that I am mass-less because I am moving at c. It seems to be a problem to say that I am moving at c. I believe that every physical raw must be consistent with no exception. A massive object under a uniform motion and light both must be treated as IRF by definition. If an IRF can be treated as resting or moving upon choice between two massive IRFs, same rule must be applied between a massive IRF and light and even further a massive IRF can have the velocity of light c. So my question is what follows: Is it safe to say that a massive physical object can have a relativistic velocity same to c and zero (relativistic) mass with regard to the light moving in empty space?