On adiabatic perturbations in the ekpyrotic scenario

A Linde, V Mukhanov, A Vikman
2010 Journal of Cosmology and Astroparticle Physics  
In a recent paper arXiv:0910.2230, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will
more » ... that the methods used in arXiv:0910.2230 are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.
doi:10.1088/1475-7516/2010/02/006 fatcat:dbpsmyumw5ahthgdpgtuurwufq