Evolution of nonlinear cosmological perturbations.

  title={Evolution of nonlinear cosmological perturbations.},
  author={David Langlois and Filippo Vernizzi},
  journal={Physical review letters},
  volume={95 9},
We define fully nonperturbative generalizations of the uniform density and comoving curvature perturbations, which are known, in the linear theory, to be conserved on sufficiently large scales for adiabatic perturbations. Our nonlinear generalizations are defined geometrically, independently of any coordinate system. We give the equations governing their evolution on all scales. Also, in order to make contact with previous works on first- and second-order perturbations, we introduce a… 

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