Is the cosmological "constant" a nonlocal quantum residue of discreteness of the causal set type?

TL;DR

This paper reviews the idea that the cosmological constant may be a nonlocal quantum residue arising from causal set discreteness, discussing phenomenological models and implications for spacetime dimensionality.

Contribution

It introduces a concrete phenomenological model based on causal set theory predicting a fluctuating cosmological term and explores its potential consequences.

Findings

Evidence supports a fluctuating cosmological constant from causal set theory.

A phenomenological model incorporating these ideas has been devised and tested.

Possible implications for the dimensionality of spacetime are discussed.

Abstract

The evidence for an accelerating Hubble expansion appears to have confirmed the heuristic prediction, from causal set theory, of a fluctuating and ``ever-present'' cosmological term in the Einstein equations. A more concrete phenomenological model incorporating this prediction has been devised and tested, but it remains incomplete. I will review these developments and also mention a possible consequence for the dimensionality of spacetime.