Comment on "Extended Born-Infeld theory and the bouncing magnetic universe"
Abstract
In a recent paper [Phys. Rev. D{\bf 85}, 023528 (2012)] the authors proposed a generalized Born-Infeld electrodynamics coupled to general relativity which produces a nonsingular bouncing universe. For a magnetic universe the resulting cosmic evolution inevitably interpolates between asymptotic de Sitter states. Here we shall show that (i) the above theory does not have the standard weak field Maxwell limit, (ii) a sudden curvature singularity -- not better than the big bang -- arises, (iii) the speed of sound squared is a negative quantity signaling instability against small perturbations of the background energy density, and that (iv) the conclusion about the inevitability of the asymptotic vacuum regime in a magnetic universe is wrong.
Keywords
Cite
@article{arxiv.1310.3021,
title = {Comment on "Extended Born-Infeld theory and the bouncing magnetic universe"},
author = {Ricardo Garcia-Salcedo and Tame Gonzalez and Israel Quiros},
journal= {arXiv preprint arXiv:1310.3021},
year = {2014}
}
Comments
6 pages, 6 eps figures, here we have shown that Born-Infeld magnetic universes either are singular or are unstable against small perturbations of the background energy density or both