Would asymptomatic safe gravity grow weaker like QCD?

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The discussion explores whether gravity, like Quantum Chromodynamics (QCD), could exhibit asymptotic safety by growing weaker at higher energies instead of stronger, as classical General Relativity (GR) predicts. It posits that if gravity is asymptotic safe, it might approach a UV fixed point where interaction strengths become dimensionless and non-interacting at high energies. The conversation also touches on the implications for the Newton and cosmological constants, suggesting that the Newton constant could vanish while the cosmological constant diverges at high energies. Additionally, there is uncertainty about how non-perturbative aspects of gravity, such as black holes and the holographic principle, fit into this asymptotic safety framework. The possibility that the holographic principle might be incorrect is also raised.
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QCD is asymptomatic safe well known to grow weaker at higher energies.

if gravity is also asymptotic safe would it grow weaker at higher energies instead of stronger as predicted by classical GR?

if not, is it possible there is a quantum gravity theory that like QCD grows weaker at higher energies?

i.e at low energies it is described as GR, but at high energies it is QCD-like and grows weaker

QCD-gluons and gravitons are non-abelian self-interacting bosons
 
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As far as I understand the proposal, what one requires is that the system approaches a UV fixed point at high energies. The fixed point could be non-interacting but generically I would expect some order one dimensionless interaction strength. Although I haven't thought carefully about it, I would guess that in the case of gravity one could argue against weak interactions at high energy as incompatible with the holographic principle.

EDIT: More generally, I don't understand much about how non-perturbative aspects of gravity - black holes, holography, etc. - are supposed to work in the asymptotic safety scenario.
 
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kodama said:
..
if not, is it possible there is a quantum gravity theory that like QCD grows weaker at higher energies?
In partial answer, in the most recent review paper I know of on AsymSafe QG, on page 36 it says
==quote http://arxiv.org/pdf/1202.2274.pdf ==
Hence for k → ∞ and d > 2 the dimensionful Newton constant vanishes while the cosmological constant diverges.
==endquote==

The parameter k is like a wave number, an inverse length. So for low k (the IR or coarse scale) the Newton constant G and the cosmo constant Λ are the usual G and Λ.

A commonly discussed form of the theory concerns dimensionless versions gk and λk which approach a fixed point g*, λ*

As for the dimensionful versions, Gk = gk/k2 goes to zero as g*/k2 and Λk = λkk2 diverges as λ*k2
 
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Physics Monkey said:
As far as I understand the proposal, what one requires is that the system approaches a UV fixed point at high energies. The fixed point could be non-interacting but generically I would expect some order one dimensionless interaction strength. Although I haven't thought carefully about it, I would guess that in the case of gravity one could argue against weak interactions at high energy as incompatible with the holographic principle.

EDIT: More generally, I don't understand much about how non-perturbative aspects of gravity - black holes, holography, etc. - are supposed to work in the asymptotic safety scenario.

maybe the holographic principle is wrong?
 
"Supernovae evidence for foundational change to cosmological models" https://arxiv.org/pdf/2412.15143 The paper claims: We compare the standard homogeneous cosmological model, i.e., spatially flat ΛCDM, and the timescape cosmology which invokes backreaction of inhomogeneities. Timescape, while statistically homogeneous and isotropic, departs from average Friedmann-Lemaître-Robertson-Walker evolution, and replaces dark energy by kinetic gravitational energy and its gradients, in explaining...

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