Stacy McGaugh suggests in his latest blog post that the Hubble tension is probably due to the estimate of Hubble's constant from the cosmic microwave background (CMB) which has gotten lower as greater precision measurements of it have been made, rather than from errors in recent time Hubble constant measurements as it is more common to suppose.
He argues that observed early galaxy formation, which is contrary to the LambdaCDM model and thus not accounted for by it when calculating the early time Hubble constant from the CMB, is likely to be a big part of the discrepancy.
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a more comprehensive gravity theory should derive MOND ao from cc
you might also want to study arXiv:2109.11217
We propose a covariant formulation of refracted gravity (RG), a classical theory of gravity based on the introduction of the gravitational permittivity -- a monotonic function of the local mass density -- in the standard Poisson equation. The gravitational permittivity mimics the dark matter phenomenology. Our covariant formulation of RG (CRG) belongs to the class of scalar-tensor theories, where the scalar field φ has a self-interaction potential V(φ)=−Ξφ, with Ξ a normalization constant. We show that the scalar field is twice the gravitational permittivity in the weak-field limit.
RG (CRG) belongs to the class of scalar-tensor theories, where the scalar field φ has a self-interaction potential V(φ)=−Ξφ,
self interactions with a scalar-
like Deur but with scalar-and rigorous derived
this might be better than Deur
What Deur has going for him is minimalism, novel predictions supported by observations, the lack of the need for a new scalar field or dark energy (hence preserving conservation of mass-energy), and a broad range of applicability that has been explored.
the lack of the need for a new scalar field or dark energy
but here is used to explain both dark matter and energy
scalar-tensor theories of gravity have been research over decades
Deur is 1 guy and over at PF there is intense skepticism of the idea
A tensor theory has lots of virtues over a scalar-tensor theory (incidentally, GR with a cosmological constant is a scalar-tensor theory).
"Deur is 1 guy and over at PF there is intense skepticism of the idea"
Physics isn't a democracy. And as I (and others) have said there, even if his approach isn't, as claimed, actually identical to GR for some subtle reason, so what?
It is similar enough to do everything that GR has been proven to be correct about (unlike MOND that has to be relativistically generalized in some way), and solves the problems of all dark matter phenomena (including replicating all of the successes of MOND from first principles instead of with a phenomenological fit as well as cases that MOND gets wrong), and all dark energy phenomena, and can resolve the Hubble tension. It does so without violating mass-energy conservation (as GR with a cosmological constant does at a global level), it has a broader range of applicability than any other theory on offer, it can actually be applied here and now in its classical form, and it can do it without introducing any particles not present in GR + the Standard Model. In principle it should have one less experimentally determined physical constant than GR (the cosmological constant).
Einstein came up with an amazing improvement of Newtonian gravity and physics, but he wasn't a god.
If it turns out that someone can tweak his work (at least in the manner conventionally applied) working from basic axioms, and get a result with fewer moving parts that explain galactic rotation curves, galaxy clusters, the Bullet cluster, the CMB, early galaxy formation, and the different amounts of apparent dark matter in different shaped galaxies, then let's go with that theory.
Another highly attractive element, generically, to having a tensor theory, rather than a scalar-tensor or scalar-vector-tensor theory is that it is much easier in principle to convert from a classical theory to a quantum theory.
In the tensor theory only case, you need a massless spin-2 graviton that couples in proportion to mass-energy. In any other classical theory, you need more carrier bosons. And, in dark energy, you need a scalar boson that doesn't observe mass-energy conservation.
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