Can the effective gravitational constant become negative

A discussion is given of the recently advanced hypothesis that in the presence of a Higgs scalar field the effective gravitational constant may have changed sign in the early universe. A new effect is found and investigated: any anisotropy and inhomogeneity in the gravitational field will grow without bound as the amplitude of the conformal scalar field (in particular, the Higgs field) approaches a definite value. The cosmological model will accordingly evolve such that the effective gravitational constant always remains positive (until the singularity is reached). The possibility of spontaneous symmetry breaking through interaction of the scalar field with the anisotropic part of the gravitational field is considered. If radiation corrections are neglected, such an effect will not occur in a homogeneous cosmological model.