Perturbation analysis provides the framework for an understanding of the effects of a small mass moving through a “background” spacetime. The analysis begins with a background spacetime metric gab which is usually a vacuum solution of the Einstein equations Gab(g) = 0. An object of small mass μ then disturbs the geometry by an amount hab = O(μ) which is governed by the perturbed Einstein equati...

We use conformal, but ghostful, Weyl gravity to study its ghost-free, second derivative, partially massless (PM) spin 2 component in presence of Einstein gravity with positive cosmological constant. Specifically, we consider both gravitationaland selfinteractions of PM via the fully non-linear factorization of conformal gravity’s Bach tensor into Einstein times Schouten operators. We find that ...

Evolution of primordial fluctuations in a Brans-Dicke type scalar-tensor gravity theory is comprehensively investigated. The harmonic attractor model, in which the scalar field has its harmonic effective potential in the Einstein conformal frame and the theory relaxes toward Einstein gravity with time, is considered. The evolution of adiabatic initial perturbations in flat SCDM models is examin...

Einstein algebras have been suggested (Earman 1989) and rejected (Rynasiewicz 1992) as a way to avoid the hole argument against spacetime substantivalism. In this article, I debate their merits and faults. In particular, I suggest that a gauge-invariant interpretation of Einstein algebras that avoids the hole argument can be associated with one approach to quantizing gravity, and, for this reas...

A theory of gravitation is proposed, modeled after the notion of a Ricci flow. In addition to the metric an independent volume enters as a fundamental geometric structure. Einstein gravity is included as a limiting case. Despite being a scalar-tensor theory the coupling to matter is different from Jordan-Brans-Dicke gravity. In particular there is no adjustable coupling constant. For the solar ...

Nonlocal cosmological models with quadratic potentials are considered. We study the action with an arbitrary analytic function F( g), which has both double and simple roots. The formulae for non-local energy-momentum tensor, which correspond to double roots have been obtained. The way to find particular solutions of non-local Einstein equations in the case when F( g) has both simple and double ...

The response of a gravitational wave detector to scalar waves is analysed in the framework of the debate on the choice of conformal frames for scalar-tensor theories. A correction to the geodesic equation arising in the Einstein conformal frame modifies the geodesic deviation equation. This modification is due to the non-metricity of the theory in the Einstein frame, yielding a longitudinal mod...

We propose to compute the action and global charges of the asymptotically antide Sitter solutions in Einstein-Gauss-Bonnet theory by adding boundary counterterms to the gravitational action. The general expression of the counterterms and the boundary stress tensor is presented for spacetimes of dimension d ≤ 9. We apply this tehnique for several different types of black objects. Apart from stat...

Distributed sources are included in the Einstein equations. Such modification of the general relativity provides a simple description of the accelerated expansion of the Universe with a dynamical scaling. Distributed sources can also be applied to more local cosmological phenomena, which defy conventional explanation. A possibility of superluminary effects is indicated. The Einstein equations f...

We construct exact solutions of the Einstein-Dirac equation, which couples the gravitational field with an eigenspinor of the Dirac operator via the energymomentum tensor. For this purpose we introduce a new field equation generalizing the notion of Killing spinors. The solutions of this spinor field equation are called weak Killing spinors (WK-spinors). They are special solutions of the Einste...