#### PeterDonis

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- Summary
- A recently published paper claims that a source term that looks like dark energy naturally appears when spatial inhomogeneity is taken into account in cosmological models. Is this claim valid?

The thread title is the title of a recently published paper:

The paper claims to resolve an ambiguity in "cosmological backreaction" models, which are models that take into account spatial inhomogeneity to derive correction terms to the homogeneous and isotropic FRW spacetime model. The paper says that cosmological backreaction will appear as an effective source term with ##p = - \rho##, i.e., a source that looks just like dark energy. However, I'm not sure I follow all of the steps of the argument, and some of the steps look to me like they might be questionable. I'm wondering if any experts can comment on this paper and on "cosmological backreaction" in general.

The paper claims to resolve an ambiguity in "cosmological backreaction" models, which are models that take into account spatial inhomogeneity to derive correction terms to the homogeneous and isotropic FRW spacetime model. The paper says that cosmological backreaction will appear as an effective source term with ##p = - \rho##, i.e., a source that looks just like dark energy. However, I'm not sure I follow all of the steps of the argument, and some of the steps look to me like they might be questionable. I'm wondering if any experts can comment on this paper and on "cosmological backreaction" in general.