A FOOTNOTE TO EINSTEIN 1907

Abstract

An add-on to Einstein’s equivalence principle of 1907, specifically to its third point, is offered. The three points read: (1) gravitational redshift, (2) gravitational light-ray bending, and (3) local reduction of the speed of light c. The third point can be replaced by a more general effect that explains it: (3’) gravitational light-ray tilting. The consequence is “global constancy of the speed of light c.†This retrieved implication of the equivalence principle is bound to carry over to general relativity. A new “analogical†subfield of digital numerical simulations is called for.