Progress and plans are reported for a program of gravitational physics experiments using cryogenic torsion pendula undergoing large amplitude torsional oscillation. The program includes a UC Irvine project to measure the gravitational constant G and joint UC Irvine– U. Washington projects to test the gravitational inverse square law at a range of about 10 cm and to test the weak equivalence pri...

Multidimensional cosmological models with factorizable geometry and their dimensional reduction to effective four-dimensional theories are analyzed on sensitivity to different scalings. It is shown that a noncorrect gauging of the effective four-dimensional gravitational constant within the dimensional reduction results in a non-correct rescaling of the cosmological constant and the gravexciton...

In Brans–Dicke theory the Universe becomes divided after inflation into many exponentially large domains with different values of the effective gravitational constant. Such a process can be described by diffusion equations for the probability of finding a certain value of the inflaton and dilaton fields in a physical volume of the Universe. For a typical chaotic inflation potential, the solutio...

We investigate the possibility that dark energy does not couple to gravitation in the same way as ordinary matter, yielding a violation of the weak and strong equivalence principles on cosmological scales. We build a transient mechanism in which gravitation is pushed away from general relativity by a Born-Infeld gauge interaction acting as an abnormally weighting (dark) energy. This mechanism a...

Multidimensional cosmological models with factorizable geometry and their dimensional reduction to effective four-dimensional theories are analyzed on sensitivity to different scalings. It is shown that a noncorrect gauging of the effective four-dimensional gravitational constant within the dimensional reduction results in a non-correct rescaling of the cosmological constant and the gravexciton...

We estimate the possible variations of the gravitational constant G in the framework of a generalized (BergmannWagoner-Nordtvedt) scalar-tensor theory of gravity on the basis of the field equations, without using their special solutions. Specific estimates are essentially related to the values of other cosmological parameters (the Hubble and acceleration parameters, the dark matter density etc....

The Machian cosmological solution satisfying φ = O(ρ/ω) for the perfect-fluid with negative pressure is discussed. When the coefficient of the equation of state γ → −1/3, the gravitational constant approaches to constant. If we assume the present mass density ρ0 ∼ ρc (critical density), the parameter ǫ (γ = (ǫ− 1)/3) has a value of order 10−3 to support the present gravitational constant. The c...

We generalize the standard model of particle physics such it displays global scale invariance. The gravitational action is also suitably modified such that it respects this symmetry. This model is interesting since the cosmological constant term is absent in the action. We find that the scale symmetry is broken by the recently introduced cosmological symmetry breaking mechanism. This simultaneo...

A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength ω and the mass of the skew symmetric field μ = 1/λ. A fit to the available anomalous acceleration data ...

In this paper we are going to examine the effect, if any exists, that a modification of the Schwarzchild metric by a lamda term could have on the so called Sakharov’s upper temperature limit. It’s known that Zakharov’s limit is the maximum possible black body temperature that can occur in our universe. Introduction: In 1966 Sakharov first came up with an upper temperature bound for the black bo...