Viscous cosmologies

Sergio Bravo Medina, Marek Nowakowski, Davide Batic

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We probe into universes filled with quark gluon plasma with non-zero viscosities. In particular, we study the evolution of a universe with non-zero shear viscosity motivated by the theoretical result of a non-vanishing shear viscosity in the quark gluon plasma due to quantum-mechanical effects. We first review the consequences of a non-zero bulk viscosity and show explicitly the non-singular nature of the bulk-viscosity-universe by calculating the cosmological scale factor which goes to zero only asymptotically. The cosmological model with bulk viscosity is extended to include a cosmological constant. The previous results are contrasted with the cosmology with non-zero shear viscosity. We first clarify under which conditions shear viscosity terms are compatible with the Friedmann-Lamaître-Robertson-Walker metric. To this end we use a version of the energy-momentum tensor from the Müller-Israel-Stewart theory which leads to causal Navier-Stoke equations. We then derive the corresponding Friedmann equations and show under which conditions the universe emerges to be non-singular.

Original languageBritish English
Article number215002
JournalClassical and Quantum Gravity
Issue number21
StatePublished - 10 Oct 2019


  • cosmology with shear viscosity
  • initial singularity
  • shear energy-momentum tensor


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