The holographic bound in Brans-Dicke k = 1 matter dominated Cosmology is discussed. In this talk, both the apparent horizon and the particle horizon are taken for the holographic bound. The covariant entropy conjecture proposed by Bousso is also discussed.

It is shown that a minimally coupled scalar field in Brans–Dicke theory yields a non–decelerated expansion for the present universe for open, flat and closed Friedmann-Robertson-Walker models.

We present calculations of Post-Newtonian parameters for Brans-Dicke tensor-scalar gravity in an arbitrary number of compact extra dimensions in both the Jordan and Einstein conformal frames. We find that the parameter γ, which measures the amount of spacetime curvature per unit mass, becomes a function of ω, the coefficient of the scalar kinetic term in the Brans-Dicke Lagrangian. Experiment h...

We study the cosmology of the Brans-Dicke theory with perfect fluid type matter. In our previous work [7], we found exact solutions for any BransDicke parameter ω and for general parameter γ of equation of state. In this paper we further study the cosmology of these solutions by analyzing them according to their asymptotic behaviors. The cosmology is classified into 19 phases according to the v...

The role of the auxiliary scalar field φ in Brans-Dicke theory is discussed. If a constant vacuum energy is assumed to be the origin of dark energy, then the corresponding density parameter would be a quantity varying with φ; and almost all of the fundamental components of our universe can be unified into the dynamical equation for φ. As a generalization of Brans-Dicke theory, we propose a new ...

A quantum correction to the Brans-Dicke theory due to interactions among matter fields is calculated, resulting in violation of WEP, hence giving a constraint on the parameter ω far more stringent than accepted so far. The tentative estimate gives the lower bounds > ∼106 and > ∼108 for the assumed force-range > ∼1m and > ∼1AU, respectively. E-mail: [email protected] Many aspects o...

Any quantum theory of gravity which treats the gravitational constant as a dynamical variable has to address the issue of superpositions of states corresponding to different eigenvalues. We show how the unobservability of such superpositions can be explained through the interaction with other gravitational degrees of freedom (decoherence). The formal framework is canonically quantized Jordan-Br...

We study the structure and stability of the recently discussed spherically symmetric Brans-Dicke black-hole type solutions with an innnite horizon area and zero Hawking temperature , existing for negative values of the coupling constant !. These solutions split into two classes: B1, whose horizon is reached by an infalling particle in a nite proper time, and B2, for which this proper time is in...