Hossenfelder is refering to the ongoing discussion in the physicist community on this topic. Some of the giants of the field (Wald, Ellis) semi-regularly exchan

Hossenfelder is refering to the ongoing discussion in the physicist community on this topic. Some of the giants of the field (Wald, Ellis) semi-regularly exchange papers on this. It's not a hunch. Green and Wald tried to proof that the inhomogeneities don't matter, others disagree that they proofed anything of the sort. It's a fairly robust debate, and I am not qualified to summarize the state of play. Here are some slides: https://cosmoback.sciencesconf.org/data/program/Ostrowski.pdf https://cosmoback.sciencesconf.org/data/program/Ostrowski.pd... Edit: The rebuttal paper to Green-Wald from three years ago already has 100 citations... https://arxiv.org/abs/1505.07800 https://arxiv.org/abs/1505.07800 It's possible that the question will be settled in the next years through numerical simulations: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.251302 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.11... Edit 2: All of this is for dark energy, for dark matter I don't know if there is a similar discussion on the role of the post-newtonian approximation that is used there.