Potier's Principle: A Trap for Unwary Etherists and Others
Thomas E. Phipps
Keywords: Poiter's principle, light-speed constancy, Fermat's principle, convecture velocity, ether, first-order effect
A national way to express an hypothesized first-order departure from light-speed constancy is by addition to c of a scalar product of some convective velocity and the normalized light propagation vector. This is the form proposed in a recent paper by Hill [4] in this journal. It is shown here that a principle discovered by Potier [2] during the last century, based on Fermat's principle, denies the theoretical possibility of any simple optical testing (proof and disproof) of such a presumed first-order effect. It was Potier's principle, joined to physical interpretation of the convective velocity as ether velocity, that established motional "relativity" as a first-order empirical fact before the advent of either Michelson-Morley (second-order empiricism) or Poincare-Einstein (higher-order theory).
