Using the covariant approach and conformal transformations, we present a gauge-invariant formalism for cosmological perturbations in generalized Einstein theories (GETs), including the Brans-Dicke theory, theories with a non-minimally coupled scalar field and certain curvature-squared theories. We find an enhancement in the growth rate of density perturbations in the Brans-Dicke theory, and dis...

It is shown that in the weak field approximation solutions of Brans-Dicke equations are simply related to the solutions General Relativity equations for the same matter distribution. A simple method is developed which permits to obtain Brans-Dicke solutions from Einstein solutions when both theories are considered in their linearized forms. To illustrate the method some examples found in the li...

We study the effect of the solitonic degree of freedom in string cosmology following the line Rama. The gas of solitonic p-brane is treated as a perfect fluid in a Brans-Dicke type theory. In this paper, we find analytic solutions for a few solvable cases of equation of states with general Brans-Dicke parameter ω and study the cosmology of the solutions. In some cases the solutions are free fro...

There does not exist a notion of time which could be transferred straightforwardly from classical to quantum gravity. For this reason, a method of time quantification which would be appropriate for gravity quantization is being sought. One of the existing proposals is using the evolving matter as an intrinsic 'clock' while investigating the dynamics of gravitational systems. The objective of ou...

The evolution of a universe with Brans-Dicke gravity and nonzero curvature is investigated here. We present the equations of motion and their solutions during the radiation dominated era. In a Friedman-Robertson-Walker cosmology we show explicitly that the three possible values of curvature κ = +1, 0,−1 divide the evolution of the Brans-Dicke universe into dynamically distinct classes just as f...

In the covariant cosmological perturbation theory, a 1+3 decomposition ensures that all variables in the frame-independent equations are covariant, gauge-invariant and have clear physical interpretations. We develop this formalism in the case of BransDicke gravity, and apply this method to the calculation of cosmic microwave background (CMB) anisotropy and large scale structures (LSS). We modif...

Exact solutions for Shapovalov wave spacetimes of type I in Brans–Dicke’s scalar-tensor theory gravity are constructed. describe gravitational models that allow the separation variables privileged coordinate systems. In contrast to general relativity, vacuum field equations Brans–Dicke lead exact spaces, allowing construction observational tests detect such disturbances. Furthermore, trajectori...

The backreaction of inhomogeneities on the cosmic dynamics is studied in the context of scalar-tensor gravity. Due to terms of indefinite sign in the non-canonical effective energy tensor of the Brans–Dicke-like scalar field, extra contributions to the cosmic acceleration can arise. Brans–Dicke and metric f(R) gravity are presented as specific examples. Certain representation problems of the fo...

Use of agriculture by-products (brans and meal) as food for Artemia franciscana (Kellogg, 1906) effects on performance biochemical compositions

The possibility that a charged particle propagating in a gravitational field described by Brans-Dicke theory of gravity could emit Cerenkov radiation is explored. This process is kinematically allowed depending on parameters occurring in the theory. The Cerenkov effect disappears as the BD parameter ω → ∞, i.e. in the limit in which the Einstein theory is recovered, giving a signature to probe ...