Careful analysis proves that the gravitational potential energy of a
massive object resides not in the gravitational field, but in the object
itself, manifesting as a change in the rest mass of the object. This effect,
gravitational rest mass reduction, is not only the cause of the gravitational
red shift, but also responsible for an effect heretofore unrecognized:
gravitational size dilation. This latter effect implies that the true geometry
of three-space surrounding a star or a black hole differs dramatically from the
currently accepted form. In particular, light rays do follow the spatial geodesics
of the true geometry, indicating that gravity does not couple to the free
electromagnetic field, contrary to current opinion, which is based on the
incorrect proper geometry. This fact is of inestimable importance in regard to
quantum gravity: the spin zero graviton has been rejected on the ground that it
cannot couple to light, since it can only couple to the trace of the target
field, and the electromagnetic field has a zero trace. But in the correct
geometry, there is no coupling, so the spin zero graviton must be accepted.
This gives a promise to a simple linear theory of quantum gravity. The variable
rest mass concept also has transformative cosmological implications. The cosmic
red shift is currently understood to result from the expansion of space itself—the
wavelength of radiation is thought to be continually stretched in flight,
resulting in a continual reduction of the momentum of the radiation. But in a
spatially homogeneous universe, momentum, including that of the cosmic photons,
must be conserved. It is easily proved that conservation of momentum in a Robinson-Walker
universe demands that rest mass must be increasing in proportion to the
function, A(t), which is currently identified (incorrectly) as that describing
the temporal expansion of space. Surprisingly, a simple argument shows that
momentum conservation implies that A(t), now understood as describing the
manner in which rest mass evolves, has to be a simple exponential function of
world time, or a linear function of proper time.