The Cosmological Constant as a Zero Action Boundary

Abstract

The cosmological constant $\Lambda$ is usually interpreted as Dark Energy (DE) or modified gravity (MG). Here we propose instead that $\Lambda$ corresponds to a boundary term in the action of classical General Relativity. The action is zero for a perfect fluid solution and this fixes $\Lambda$ to the average density $\rho$ and pressure $p$ inside a primordial causal boundary: $\Lambda =4\pi G<\rho +3p>$. This explains both why the observed value of $\Lambda$ is related to the matter density today and also why other contributions to $\Lambda$, such as DE or MG, do not produce cosmic expansion. Cosmic acceleration results from the repulsive boundary force that occurs when the expansion reaches the causal horizon. This universe is similar to the $\Lambda$CDM universe, except on the largest observable scales, where we expect departures from homogeneity/isotropy, such as CMB anomalies and variations in cosmological parameters indicated by recent observations.

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Cited by in corpus (13)

• Challenges for $\Lambda$CDM: An update
• Is the Observable Universe Consistent with the Cosmological Principle?
• Explaining Cosmological Anisotropy: Evidence for Causal Horizons from CMB data
• Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
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• Cold Collapse and Bounce of an FLRW Cloud
• Micro-cosmos model of a nucleon