1. The coordinates xi will denote rectangular coordinates in Euclidean space. Repeated indices satisfy the Einstein summation convention. A dot over a symbol indicates total time derivative. A comma (,) indicates partial differentiation. A primed symbol (') denotes differentiation with respect to the indicated argument.
2. For references to the time‐varying G problem refer to the survey article by P. S. Wesson, Physics Today 33, 32 (July, 1980).PHTOAD0031-9228
3. H. Goldstein, Classical Mechanics, 2nd ed. (Addison‐Wesley, Reading, MA, 1980).
4. The symbol (≐) denotes equality on a dynamical path, that is for those xi = xi(t) that are solutions of the dynamical equations (1.2).
5. In the analysis of case 3 we assumed α≠0 to exclude the time‐independent case.