Einstein field equations with a cosmological constant are linearized assuming a flat background metric. The final result is a set of EinsteinMaxwell-Proca equations for gravity in the weak field approximation. This linearization procedure implements the breaking of gauge symmetry in general relativity. A brief discussion of the physical consequences is proposed in the framework of the gauge the...

The Gravity and Ocean Circulation Experiment GOCE satellite mission measure the Earth gravity field with unprecedented accuracy leading to substantial improvements in the modelling of the ocean circulation and transport. In this study of the performance of GOCE, a newer gravity model have been combined with the DTU10MSS mean sea surface model to construct a global mean dynamic topography model ...

Monitoring changes in the Earth’s gravity field for terrestrial water storage change (soil moisture, ground water, snow etc.) is a relatively new and novel concept that has been inspired by the Gravity Recovery And Climate Experiment (GRACE) satellite mission. GRACE will soon be providing time varying maps of the Earth’s gravity. However, there has been no field based study to demonstrate that ...

– We investigate the exact renormalization group (RG) in Einstein gravity coupled to N-component spinor field, working in the effective average action formalism and background field method. The truncated evolution equation is obtained for the Newtonian and cosmological constants. We have shown that screening or antiscreening behaviour of the gravitational coupling depends crucially on the numbe...

We calculate the Newtonian gravitational potential and field of a cubic, homogeneous asteroid and we apply it to the orbit of possible satellites. Large astronomical objects such as stars or planets, naturally tend to form spherical shapes due to the dominance of the gravitational forces, but as a thought experiment, we consider the properties of a planet in the form of a perfect cube. We inves...

We introduce a discrete 4-dimensional module over the integers that appears to have maximal symmetry. By adjoining the usual Minkowski distance, we obtain a discrete 4-dimensional Minkowski space. Forming universe histories in this space and employing the standard causal order, the histories become causal sets. These causal sets increase in size rapidly and describe an inflationary period for t...

We describe and study a certain class of modified gravity theories. Our starting point is Plebanski formulation of gravity in terms of a tripple B of 2-forms, a connection A and a “Lagrange multiplier” field Ψ. The generalization we consider stems from presence in the action of an extra term proportional to a scalar function of Ψ. As in the usual Plebanski general relativity (GR) case, a certai...

We study the nature of boundary dynamics in the teleparallel 3D gravity. The asymptotic field equations with anti-de Sitter boundary conditions yield only two non-trivial boundary modes, related to a conformal field theory with classical central charge. After showing that the teleparallel gravity can be formulated as a Chern-Simons theory, we identify dynamical structure at the boundary as the ...

The new EGM2008 global gravity field model is evaluated by comparisons of geoid heights computed from the model with those available at GPS levelling stations in various regions and by computing sea surface topography solutions from the difference between the mean sea surface and the geoid from this model. In order to identify how good the model performs the same tests also are performed for ot...