A New approach to the evolution of cosmological perturbations on large scales

  title={A New approach to the evolution of cosmological perturbations on large scales},
  author={David Wands and Karim A. Malik and David H. Lyth and Andrew R. Liddle},
  journal={Physical Review D},
We discuss the evolution of linear perturbations about a Friedmann-Robertson-Walker background metric, using only the local conservation of energy-momentum. We show that on sufficiently large scales the curvature perturbation on spatial hypersurfaces of uniform-density is conserved when the non-adiabatic pressure perturbation is negligible. This is the first time that this result has been demonstrated independently of the gravitational field equations. A physical picture of long-wavelength… 

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