# Cosmological perturbation theory and quantum gravity

May 09, 2016

It is shown how cosmological perturbation theory arises from a fully
quantized perturbative theory of quantum gravity. Central for the derivation is
a non-perturbative concept of gauge-invariant local observables by means of
which perturbative invariant expressions of arbitrary order are generated. In
particular, in the linearised theory, first order gauge-invariant observables
familiar from cosmological perturbation theory are recovered. Explicit
expressions of second order quantities are presented as well.

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