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.

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

References in corpus (7)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Causality and the speed of sound
• A covariant and gauge invariant formulation of the cosmological "backreaction"
• Gauge invariant averages for the cosmological backreaction
• On Primordial Density Perturbation and Decaying Speed of Sound
• Dynamics of generalized tachyon field
• Bouncing Cosmologies

Cited by in corpus (7)

• Acceleration of Universe by Nonlinear Electromagnetic Fields
• Inflation of universe due to nonlinear electrodynamics
• Rational nonlinear electrodynamics causes the inflation of the universe
• Universe Inflation Based on Nonlinear Electrodynamics
• Universe inflation and nonlinear electrodynamics
• Exploring the Evolution of Nonlinear Electrodynamics in the Universe: A Dynamical Systems Approach
• Inflation of Universe by Nonlinear Electrodynamics