S ep 2 00 4 Bouncing Cosmologies and Self - Gravitational Corrections
نویسنده
چکیده
The semiclassical corrections to the Cardy-Verlinde entropy of a five-dimensional Schwarzschild anti de-Sitter black hole (SAdS 5) are explicitly evaluated. These corrections are considered within the context of KKW analysis and arise as a result of the self-gravitation effect. In addition, a four-dimensional timelike brane is considered as the boundary of the SAdS 5 bulk background. It is already known that the induced geometry of the brane is exactly given by that of a radiation-dominated FRW universe. Exploiting the CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the first Friedmann-like equation which is the equation of the brane motion. The additional term that arises due to the semiclassical analysis , can be viewed as stiff matter where the self-gravitational corrections act as the source for it. This result is contrary to standard analysis that regards the charge of SAdS 5 bulk black hole as the source for stiff matter. A very interesting feature of the solutions of FRW equation is that they all (for k = 0, ±1) have a non-vanishing minimum value for the scale factor.
منابع مشابه
Bouncing Cosmologies and Self - Gravitational Corrections
A four-dimensional timelike brane is considered as the boundary of the SAdS 5 bulk background. Exploiting the CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the first Friedmann-like equation which is the equation of the brane motion. The additional term that arises due to the semiclassical analysis, can be viewed as stiff matter where the self-gravitational correcti...
متن کاملIsotropic and Anisotropic Bouncing Cosmologies in Palatini Gravity
We study isotropic and anisotropic (Bianchi I) cosmologies in Palatini f(R) and f(R,RμνR μν) theories of gravity and consider the existence of non-singular bouncing solutions in the early universe. We find that all f(R) models with isotropic bouncing solutions develop shear singularities in the anisotropic case. On the contrary, the simple quadratic model R+ aR/RP +RμνR /RP exhibits regular bou...
متن کاملar X iv : h ep - t h / 04 12 01 6 v 1 1 D ec 2 00 4 Gravitational Forces in the Brane World
We consider the problem of gravitational forces between point particles on the branes in a Randall-Sundrum (R-S) two brane model with S 1 /Z 2 symmetry. Matter is assumed to produce a perturbation to the R-S vacuum metric and all the 5D Einstein equations are solved to linearized order (for arbitrary matter on both branes). We show that while the gauge condition h i5 = 0, i = 0, 1, 2, 3 can alw...
متن کاملBounce Loop Quantum Cosmology Corrected Gauss-Bonnet Gravity
We develop an effective Gauss-Bonnet extension of Loop Quantum Cosmology, by introducing holonomy corrections in modified F (G) theories of gravity. Within the context of our formalism, we provide a perturbative expansion in the critical density, a parameter characteristic of Loop Quantum Gravity theories, and we result in having leading order corrections to the classical F (G) theories of grav...
متن کاملPerturbations in bouncing cosmologies: dynamical attractor vs scale invariance
For bouncing cosmologies such as the ekpyrotic/cyclic scenarios we show that it is possible to make predictions for density perturbations which are independent of the details of the bouncing phase. This can be achieved, as in inflationary cosmology, thanks to the existence of a dynamical attractor, which makes local observables equal to the unperturbed solution up to exponentially small terms. ...
متن کامل