I am not a physicist nor a mathematician. I am not familiar with Einstein's actual equations so I don't know. This is simply a thought in the form of a question. Photons and electromagnetic waves travel at c. At the speed of light time goes to 0 (zero); also, time is negative in the equations so as objects approach c time goes positive approaching 0. Now in a strictly mathematical exercise if we vary time beyond 0, it goes positive. My question is: If we continue varying time more positive beyond zero does velocity then decrease toward 0? Richard Fynman said that a positron is indistinguishable from an electron traveling backward in time. Wouldn't this be positive time as beyond, or the other side of the 0 time of c? The implication is that there could be something beyond c from our relative view. Time would then be positive and velocity would decrease as time approached +1. We think that our universe is made up of matter. Could antimatter be normal matter with positive time on the other side of the zero time limit in the equations that set c to the value that we observe in our universe? I realize that this may be hard to follow and disorganized. I haven't had time to really get my thoughts straight on this yet, so please bear with me.