It is unclear to me why gravitational mass should differ from gravitational mass-energy for this purpose. Massless particles gravitate if they have energy.
Some time ago, it has been suggested that gravitons can acquire mass in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields [Chamseddine and Mukhanov, JHEP, 2010]. Taking this possibility into account, in the present paper, first we show how the graviton mass intricately reshapes the gravitational potential akin to a Yukawa-like potential at large distances. Notably, this long-range force modifies the Newton's law in large distances and might explain the phenomena of dark matter. The most important finding in the present paper is the derivation of a modified Newtons law of gravity by modifying the Verlindes entropic force relation due to the graviton contribution. The graviton contribution to the entropy basically measures the correlation of graviton and matter fields which then reproduces the Bekenstein-Hawking entropy at the horizon. This result shows the dual description of gravity: in the language of quantum information and entropy the gravity can be viewed as an entropic force, however in terms of particles and fields, it can be viewed as a longe range force. Further we have recovered the corrected Einstein field equations as well as the ΛCDM where dark matter emerges as an apparent effect.
Kimet Jusufi, et al., "Modified gravity/entropic gravity correspondence due to graviton mass" arXiv:2405.05269 (April 25, 2024).
There is also a preprint on the beta function of gravity in a quantum gravity scenario that is particularly relevant globally to the running of Standard Model constants at extremely high energies and the cosmology of the immediate post-Big Bang period and in strong gravitational regimes.
We study the beta functions for the dimensionless couplings in quadratic curvature gravity, and find that there is a simple argument to restrict the possible form of the beta functions as derived from the counterterms at an arbitrary loop. The relation to the recent different results on beta functions is also commented on.
Hikaru Kawai, Nobuyoshi Ohta, "An Observation on the Beta Functions in Quadratic Gravity" arXiv:2405.05706 (May 9, 2024).
7 comments:
re Deur
Vanadium 50
I have a really, really hard time believing rotation curves are caused by some hitherto unknown GR effect. Dark Matter gravity is 5x luminous matter gravity. Newtonian gravity is (approximately) the T00 term in the stress-energt tensor.
The largest other terms are down by one factor of β, which is around 1/1000. So any effect is ~5000x too small. "Non-linearity" simply means I can throw higher powers of β in, which doesn't help unless I have a leading coefficient of not 1/2, not 8π, but thousands.
As I said in another post, "numbers matter".
https://www.physicsforums.com/threads/seifert-solutions-of-einsteins-equations-give-flat-galactic-rotation-curves.1062551/#post-7086330
50 years of numerical GR also failed to getting GR Deur
GEM also have that issue of too weak
neo
You do not get Deur by just doing numerical GR on the standard nonlinear equations of GR.There is more to what Deur is doing. He is trying to put in the self-interaction that is not in standard GR.
jd
still off by ~5000x too smal
@neo
Deur isn't capturing the GEM effect which is too small. He's capturing non-perturbative effects.
Also, again, there is debate over whether he exactly replicates GR or not. But if it works, even if it does so by subtly modifying GR, so what?
my point of GEM is both as Vanadium 50 says "numbers matter"
GR non-perturbative effects are 5000x too weak
Ludwig and Deur are both wrong
Reference for the factor of 5000x? If onr is looking at just throwing in higber order terms in some expansion, that is missing the point. Maybe the sea of particles that is dark matter is a sea of gravitons? Is that Deur? What is the lifetime of a graviton?
"What is the lifetime of a graviton?"
Massless particles don't decay. The exist until they interact with something that absorbs them.
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