2004/06/30 by Thorsten Battefeld, Robert Brandenberger · 1 citation
Physics and Astronomy · #hep-th #astro-ph #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.70.121302
published as Phys.Rev. D70 (2004) 121302 · v3. Two reference added; Identical with version accepted for publication at PRD
arxiv created 2004/10/22 · arxiv updated 2009/12/01
In this note we show that vector perturbations exhibit growing mode solutions in a contracting Universe, such as the contracting phase of the Pre Big Bang or the Cyclic/Ekpyrotic models of the Universe. This is not a gauge artifact and will in general lead to the breakdown of perturbation theory -- a severe problem that has to be addressed in any bouncing model. We also comment on the possibility of explaining, by means of primordial vector perturbations, the existence of the observed large scale magnetic fields. This is possible since they can be seeded by vorticity.