Journal Article10.1103/PHYSREVD.62.043527
A New approach to the evolution of cosmological perturbations on large scales
TL;DR: In this article, the evolution of linear perturbations about a Friedmann-Robertson-Walker background metric, using only the local conservation of energy momentum, has been discussed, and it has been shown that on sufficiently large scales the curvature perturbation on spatial hypersurfaces of uniform density is conserved when the non-adiabatic pressure is negligible.
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Abstract: 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 perturbations as being composed of separate Robertson-Walker universes gives a simple understanding of the possible evolution of the curvature perturbation, in particular clarifying the conditions under which super-horizon curvature perturbations may vary.
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References
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Theory of Cosmological Perturbations
Viatcheslav Mukhanov,Viatcheslav Mukhanov,Hume A. Feldman,Robert H. Brandenberger +3 more
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TL;DR: In this paper, the authors present in a manifestly gauge-invariant form the theory of classical linear gravitational perturbations in part I, and a quantum theory of cosmological perturbation in part II.
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