Oral comunication
J. P. Mimoso
Abstract
In Newton's law of gravitation, the gravitational constant, G, is assumed to be positive. This sign is a matter of choice, and it was Laplace that used the constant for the first time in his "Traité de Mécanique Céleste". Extended gravity theories with couplings between the space-time geometry and the matter sector prescribe the variation of this fundamental quantity, which hence ceases to be a constant. Scalar-tensor are the archetypal class of theories with such a feature. It thus becomes, in principle, possible for G to change sign, trading attracting into repulsive gravity. In the present work, we have investigated a cosmological mechanism that stabilizes the positiveness of the sign of G, even though it might exhibit transient periods in the negative region. We show that this cosmological feature relies on the role of a cosmological potential, which reproduces a positive cosmological constant in the so-called Einstein frame. From this latter viewpoint it can be understood as another role of paramount importance of this remarkable constant.
Spanish-Portuguese Relativity Meeting
Lisboa, Portugal
2016 September
