  A cosmological model is formulated in the context of a scalar-tensor theory
of gravity in which the entire cosmic background evolution is due to a complex
scalar field evolving in Minkowski spacetime, such that its (dimensional)
modulus is conformally coupled, and the (dimensionless) phase is only minimally
coupled to gravitation. The former regulates the dynamics of masses;
cosmological redshift reflects the growth of particle masses over cosmological
time scales, not space expansion. An interplay between the energy density of
radiation and that of the kinetic energy associated with the phase (which are
of opposite relative signs) results in a non-singular cosmological model that
encompasses the observed redshifting phase preceded by a turnaround that
follows a blushifting phase. The model is essentially free of any horizon,
flatness or anisotropy problems. Quantum excitations of the phase during the
matter dominated blueshifting era generate a flat spectrum of adiabatic
gaussian scalar perturbations on cosmological scales. No detectable primordial
tensor modes are generated in this scenario, and cold dark matter must be
fermionic. Other consequences are also discussed.
