On the role of viscosity in early cosmology

Nakia Carlevaro, Giovanni Montani

Research output: Contribution to journalArticle


We present a discussion of the effects induced by bulk viscosity on the very early Universe stability. The viscosity coefficient is assumed to be related to the energy density ρ via a power-law of the form ζ = ζ0ρs(where ζ0, s = const.) and the behavior of the density contrast in analyzed. In particular, we study both Einstein and hydrodynamic equations up to first and second order in time in the so-called quasi-isotropic collapsing picture near the cosmological singularity. As a result, we get a power-law solution existing only in correspondence to a restricted domain of ζ0. The particular case of pure isotropic FRW dynamics is then analyzed and we show how the asymptotic approach to the initial singularity admits an unstable collapsing picture. © 2008 World Scientific Publishing Company.
Original languageEnglish
Pages (from-to)1248 - 1252
Number of pages5
JournalInternational Journal of Modern Physics A
Issue number8
Publication statusPublished - 30 Mar 2008
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Astronomy and Astrophysics

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