Non-Local Modification of Gravity and the Cosmological Constant Problem

TL;DR

This paper introduces a non-local, covariant modification to gravity at large scales to address the cosmological constant problem, suggesting that vacuum energy has negligible effect on curvature and proposing a natural inflation termination mechanism.

Contribution

It presents a novel non-local gravity modification that reduces the impact of vacuum energy on spacetime curvature, offering a new approach to the cosmological constant problem.

Findings

Effective Newton constant diminishes at large scales.

Vacuum energy produces negligible curvature effects.

Inflation may naturally end due to wavelength stretching.

Abstract

We propose a phenomenological approach to the cosmological constant problem based on generally covariant non-local and acausal modifications of four-dimensional gravity at enormous distances. The effective Newton constant becomes very small at large length scales, so that sources with immense wavelengths and periods -- such as the vacuum energy-- produce minuscule curvature. Conventional astrophysics, cosmology and standard inflationary scenaria are unaffected, as they involve shorter length scales. A new possibility emerges that inflation may ``self-terminate'' naturally by its own action of stretching wavelengths to enormous sizes. In a simple limit our proposal leads to a modification of Einstein's equation by a single additional term proportional to the average space-time curvature of the Universe. It may also have a qualitative connection with the dS/CFT conjecture.