articleJournal of Cosmology and Astroparticle PhysicsJul 30, 2012GREEN OA

Cosmological non-linearities as an effective fluid

DBDaniel BaumannANAlberto NicolisLSLeonardo SenatoreMZMatias Zaldarriaga

University of Cambridge · Institute for Advanced Study · +1 more institution

Indexed inarxivcrossref

Abstract

The universe is smooth on large scales but very inhomogeneous on small scales. Why is the spacetime on large scales modeled to a good approximation by the Friedmann equations? Are we sure that small-scale non-linearities do not induce a large backreaction? Related to this, what is the effective theory that describes the universe on large scales? In this paper we make progress in addressing these questions. We show that the effective theory for the long-wavelength universe behaves as a viscous fluid coupled to gravity: integrating out short-wavelength perturbations renormalizes the homogeneous background and introduces dissipative dynamics into the evolution of long-wavelength perturbations. The effective fluid…

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638
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Authors

4
  • DB
    Daniel BaumannCorresponding

    University of Cambridge, Institute for Advanced Study

  • AN
    Alberto Nicolis

    Columbia University

  • LS
    Leonardo Senatore

    Institute for Advanced Study

  • MZ
    Matias Zaldarriaga

    Institute for Advanced Study

Topics & keywords

Topics
Keywords
  • Cosmological perturbation theory
  • Dissipative system
  • Universe
  • Perturbation theory (quantum mechanics)
  • Volume viscosity
  • Perturbation (astronomy)
  • Spacetime
  • Horizon
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