Cosmological Constant: A Lesson from Bose-Einstein Condensates

TL;DR

This paper explores the cosmological constant problem using an analogue gravity model based on Bose-Einstein condensates, suggesting emergent gravity scenarios can naturally produce a small effective cosmological constant.

Contribution

It demonstrates how emergent gravity models can account for a small cosmological constant through analogue gravity, linking quantum microphysics to macroscopic cosmological observations.

Findings

Emergent gravity models can produce a small effective cosmological constant.

The vacuum source term in Bose-Einstein condensates resembles a cosmological constant.

Understanding Einstein equations emergence is crucial for the cosmological constant problem.

Abstract

The cosmological constant is one of the most pressing problems in modern physics. We address this issue from an emergent gravity standpoint, by using an analogue gravity model. Indeed, the dynamics of the emergent metric in a Bose-Einstein condensate can be described by a Poisson-like equation with a vacuum source term reminiscent of a cosmological constant. The direct computation of this term shows that in emergent gravity scenarios this constant may be naturally much smaller than the naive ground-state energy of the emergent effective field theory. This suggests that a proper computation of the cosmological constant would require a detailed understanding about how Einstein equations emerge from the full microscopic quantum theory. In this light, the cosmological constant appears as a decisive test bench for any quantum or emergent gravity scenario.