Relativistic electrodynamics: Various postulate and ratiocination frameworks

Presently various models consistent with Einstein's Special Relativity theory are explored. Some of these models have been introduced previously, but additional models are possible, as shown here. The topsy-turvy model changes the order of postulates and conclusions of Einstein's original theory. Another model is given in the spectral domain, with the relativistic Doppler Effect formulas replacing the Lorentz transformation. In this model a new principle tantamount to the constancy of the speed of light in vacuum is stated and analyzed, dubbed as the constancy of light slowness in vacuum. Because the slowness is derived in the spectral domain from the Doppler Effect formulas, this result is not trivially semantic. It is shown that potentials and equations of continuity can replace the Maxwell Equations used by Einstein for his "Principle of Relativity" in electrodynamics. It is also shown that defining convection currents and assuming the current-charge densities transformations can replace the Lorentz transformation. The list of feasible models representative rather than exhaustive, since parts of the models presented here can be combined to yield additional models. The two underlying elements of Einstein's original Special Relativity theory are always present: (1) the theory requires a kinematical element (e.g., the constancy of the speed of light in vacuum in Einstein's original model), and (2), a dynamical element (e.g., the form-invariance of the Maxwell Equations in all inertial systems of reference in Einsteins original model).