On the Nature of the Gravitational Constant G

It is shown that free fall, light deflection, perihelion precession, and gravitational redshift are expressed through the rate of matter expansion \\(\\tau\\), radius \\(R\\), density ratio \\(\\rho_{\\text{body}}/\\rho_{\\text{ref}}\\), and the speed of light \\(c\\) without using \\(G\\). The quantity \\(G\\) arises only in the transition to mass units and depends on the choice of reference density, whereas physical predictions do not depend on this choice. Numerical verifications are given for Solar System bodies, light deflection at the Sun, and the perihelion precession of Mercury. In the final section, a decisive testable prediction is formulated: the dependence of the refractive index of glass on gravitational acceleration, testable on Earth using a centrifuge.