Microphysics Needs an Invariant Electrodynamics
A first-order Galilean-invariant covering theory of Maxwell?s equations of vacuum electromagnetism, first proposed by Heinrich Hertz, is reappraised in modern context. Physically, when properly formulated and interpreted for electromagnetic description, Hertz? theory is found to be both necessary, and ? insofar as the empirical facts are presently known ? sufficient. Mathematically, its use of the total time derivative instead of the Maxwellian partial time derivative is shown to be logically necessary under broadly applicable conditions. The physical superiority of the Hertzian formulation in the weak-field limit is emphasized.