  A scalar-tensor theory of gravity is formulated in which $G$ and particle
masses are allowed to vary. The theory yields a globally static cosmological
model with no evolutionary timescales, no cosmological coincidences, and no
flatness and horizon `problems'. It can be shown that the energy densities of
dark energy ($\rho_{DE}$) and non-relativistic baryons and dark matter
($\rho_{M}$) are related by $\rho_{DE}=2\rho_{M}$, in agreement with current
observations, if DE is associated with the canonical kinetic and potential
energy densities of the scalar fields. Under general assumptions, the model
favors light fermionic dark matter candidates (e.g., sterile neutrinos). The
main observed features of the CMB are naturally explained in this model,
including the spectral flatness of its perturbations on the largest angular
scales, and the observed adiabatic and gaussian nature of density
perturbations. More generally, we show that many of the cosmological
observables, normally attributed to the dynamics of expanding space, could be
of kinematic origin. In gravitationally bound systems, the values of G and
particle masses spontaneously freeze out by a symmetry breaking of the
underlying conformal symmetry, and the theory reduces to standard general
relativity (with, e.g., all solar system tests satisfied).
