Local and global Stability of the Universe (original) (raw)

The stability of a bouncing universe

We investigate the stability of a spatially homogeneous and isotropic non-singular cosmological model. We show that the complete set of independent perturbations (the electric part of the perturbed Weyl tensor and the perturbed shear) are regular and well behaved functions which have no divergences, contrary to previous claims in the literature.

On the stability of the Einstein Static Universe in Massive Gravity

2012

We consider static cosmological solutions along with their stability properties in the framework of a recently proposed theory of massive gravity. We show that the modifcation introduced in the cosmological equations leads to several new solutions, only sourced by a perfect fluid, generalizing the Einstein Static Universe found in General Relativity. Using dynamical system techniques and numerical analysis, we show that the found solutions can be either neutrally stable or unstable against spatially homogeneous and isotropic perturbations.