Viscous gravitational aether and the cosmological constant problem

TL;DR

This paper proposes a modification to the gravitational aether model by introducing bulk viscosity, aiming to better decouple gravity from vacuum energy and align theoretical predictions with observations.

Contribution

It introduces bulk viscosity into the gravitational aether framework, loosening previous bounds on Newton's constants ratio and enhancing model flexibility.

Findings

Loosens the upper bound on Newton's constants ratio from 0.75

Provides a more adaptable model for matching observational data

Suggests improved decoupling of gravity from vacuum energy

Abstract

Recently a notion of gravitational aether is advocated to solve the cosmological constant problem.Through the modification of the source of gravity one finds that the effective Newton's constant is source dependent so as to provide a simple but consistent way to decouple gravity from the vacuum energy.However,in the original paper the ratio of the effective Newton's constants for pressureless dust and radiation has an upper bound which is 0.75.In this paper we propose a scheme to loose this bound by introducing a bulk viscosity for the gravitational aether,and expect this improvement will provide more space for matching predictions from this theoretical programm with observational constraints.