A Testable Solution of the Cosmological Constant and Coincidence Problems

TL;DR

This paper proposes a new, testable solution to the cosmological constant and coincidence problems by promoting Lambda to a field, linking its value to observable universe properties, and making predictions without relying on anthropic reasoning or new fields.

Contribution

The model links the cosmological constant to observable universe parameters through a causally restricted variation principle, providing testable predictions and avoiding anthropic assumptions.

Findings

Predicts the dimensionless spatial curvature Omega_k0 = -0.0056.

Successfully predicts the observed value of Lambda (~10^(-120)).

Shows the coincidence of universe age and Lambda scale is typical in the model.

Abstract

We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, $\Lambda$, is linked to other observable properties of the universe. This is achieved by promoting the CC from a parameter which must to specified, to a field which can take many possible values. The observed value of Lambda ~ 1/(9.3 Gyrs)^2$ (approximately 10^(-120) in Planck units) is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible universe, the model makes a testable prediction for the dimensionless spatial curvature of Omega_k0 = -0.0056 s_b/0.5; where s_b ~ 1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given Lambda. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the observed coincidence between t_Lambda = Lambda^(-1/2) and the age of the universe, t_U, is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different $\Lambda$-values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.