The Universe in a Soap Film

TL;DR

This paper explores the analogy between the cosmological constant and surface tension in fluid membranes, using simulations to demonstrate that quantum fluctuations of the cosmological constant are a general feature of quantum gravity models.

Contribution

It introduces a novel analogy between cosmological constant fluctuations and membrane surface tension, supported by computer simulations, to suggest these fluctuations are a fundamental aspect of quantum gravity.

Findings

Surface tension in fluid membranes exhibits statistical fluctuations.

The analogy supports the idea that a fluctuating cosmological constant is a generic feature of quantum gravity.

Simulations provide insights into the nature of quantum fluctuations of the cosmological constant.

Abstract

The value of the cosmological constant is one of the major puzzles of modern cosmology: it is tiny but nonzero. Sorkin predicted, from the Causet approach to quantum gravity, that the cosmological constant has quantum fluctuations. The predicted order of magnitude of the fluctuations agrees with the subsequently observed value of the cosmological constant. We had earlier developed an analogy between the cosmological constant of the Universe and the surface tension of fluid membranes. Here we demonstrate by computer simulations that the surface tension of a fluid membrane has statistical fluctuations stemming from its discrete molecular structure. Our analogy enables us to view these numerical experiments as probing a small and fluctuating cosmological constant. Deriving insights from our analogy, we show that a fluctuating cosmological constant is a GENERIC feature of quantum gravity models and is far more general than the specific context in which it was originally proposed. We pursue and refine the idea of a fluctuating cosmological constant and work towards making further testable predictions.