John W. Moffat

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A covariant scalar-tensor-vector gravity theory is developed which allows the gravitational constant G, a vector field coupling ω and the vector field mass μ to vary with space and time. The equations of motion for a test particle lead to a modified gravitational acceleration law that can fit galaxy rotation curves and cluster data without non-baryonic dark(More)
A relativistic modified gravity (MOG) called Scalar-Tensor-Vector Gravity (STVG) desribes a self-consistent, stable gravity theory that contains Einstein’s general relativity in a well-defined limit. The theory has an extra degree of freedom, a vector field called a “phion” field whose curl is a skew symmetric field that couples to matter (“fifth force”).(More)
A new version of nonsymmetric gravitational theory is presented. The field equations are expanded about the Minkowski metric, giving in lowest order the linear Einstein field equations and massive Proca field equations for the antisymmetric field g[μν]. An expansion about an arbitrary Einstein background metric yields massive Proca field equations with(More)
A dynamical model for varying light velocity in cosmology is developed, based on the idea that there are two metrics in spacetime. One metric gμν describes the standard gravitational vacuum, and the other ĝμν = gμν + βψμψν describes the geometry through which matter fields propagate. Matter propagating causally with respect to ĝμν can provide acausal(More)
The possible role of gravity in a noncommutative geometry is investigated. Due to the Moyal *-product of fields in noncommutative geometry, it is necessary to complexify the metric tensor of gravity. We first consider the possibility of a complex Hermitian, nonsymmetric gμν and discuss the problems associated with such a theory. We then introduce a complex(More)
The field equations in the nonsymmetric gravitational theory are derived from a Lagrangian density using a first-order formalism. Using the general covariance of the Lagrangian density, conservation laws and tensor identities are derived. Among these are the generalized Bianchi identities and the law of energy-momentum conservation. The Lagrangian density(More)
The gravitational wave solutions obtained from a perturbation about conformally flat backgrounds in Einstein gravity are investigated. A perturbation theory analysis of the Lesame, Ellis and Dunsby results, based on a covariant approach, shows that for gravitational waves interacting with irrotational dust, the equations are linearization unstable. The(More)
The local Lorentz and diffeomorphism symmetries of Einstein’s gravitational theory are spontaneously broken by a Higgs mechanism by invoking a phase transition in the early Universe, at a critical temperature Tc below which the symmetry is restored. The spontaneous breakdown of the vacuum state generates an external time and the wave function of the(More)
The basic features of a quantum field theory which is Poincaré invariant, gauge invariant, finite and unitary to all orders of perturbation theory is reviewed. Quantum gravity is perturbatively finite and unitary to all orders of perturbation theory. The Bekenstein-Hawking entropy formula for a black hole is investigated in a conical Rindler space(More)