Abstract Light-pulses that are reflected recurrently to one another by two kinematically equivalent dynamically identical inertial systems moving collinearly and irrotationally with uniform relative velocity generate sequences of contiguous time-intervals in both. By means of clocks stationed in the two systems, each time-interval is both measurable locally and calculable non-locally in accord with basic requirements of special relativity theory. Their ratio yields the velocity dependent dilation-of-time relation of Einstein, but an equivalent spatially dependent version of it is obtained as well, because the time-intervals involved are actually determined by the distances that exist between the systems when the reflections occur. As a result, the Einstein relation involves no time-rates of clocks that are actually affected kinematically by the systems containing them.
On some possibilities of generalizing the Lorentz group in the special relativity theory
