MG15 - Talk detail

Back to previous page

 Participant

Institution

Session

Accepted

Order

Time

Talk

Title

Abstract

The behavior of black hole horizons and wormholes under Weyl conformal transformations is presented. First, a shorter, but more general, derivation of the Weyl transformation of the simple prescription for detecting horizons and wormholes given recently in the literature for spherically symmetric spacetimes is provided. Then, the conformal behavior of black hole horizons and wormholes in more general spacetimes, based on more "sophisticated" definitions, is provided. The study shows that black holes and wormholes might always arise in the new frame even if they were absent in the original frame. Moreover, it is shown that the various definitions found in the literature might be transformed into one another under such transformations. Finally, the conformal behavior of the required energy conditions for wormholes are discussed.

Pdf file

Session

Accepted

Order

Time

Talk

Title

Abstract

Density perturbations in the cosmic microwave background within general f(R,ϕ) models of gravity are presented. The general dynamical equations for the tensor and scalar modes in any f(R,ϕ) gravity model are provided. An application of the equations to the (varying power)-law modified gravity toy-model is then given. Formulas and numerical values for the tensor-to-scalar ratio, the scalar tilt and the tensor tilt are all obtained within this specific model. While the model cannot provide a theoretical reason for the value of the energy scale at which inflation should occur, it is found, based on the latest observations of the density perturbations in the sky, that the model requires inflation to occur at an energy scale less than the GUT-scale (10^14GeV). The different energy intervals examined here show that the density perturbations obtained from observations are recovered naturally, with very high precision, and without fine tuning the model's parameters.

Pdf file

Back to previous page