Supergravity, Dark Energy and the Fate of the Universe

TL;DR

This paper explores supergravity models with de Sitter solutions to explain dark energy, predicting the universe's fate as either eternal expansion or eventual collapse, with observable implications for cosmology.

Contribution

It introduces supergravity-based models with quantized scalar masses and analyzes their implications for the universe's long-term evolution and potential observational signatures.

Findings

Models with dS minima lead to eternal expansion.

Models with dS maxima or saddle points predict eventual collapse.

Collapse time is comparable to the current age of the universe.

Abstract

We propose a description of dark energy and acceleration of the universe in extended supergravities with de Sitter (dS) solutions. Some of them are related to M-theory with non-compact internal spaces. Masses of ultra-light scalars in these models are quantized in units of the Hubble constant: m^2 = n H^2. If dS solution corresponds to a minimum of the effective potential, the universe eventually becomes dS space. If dS solution corresponds to a maximum or a saddle point, which is the case in all known models based on N=8 supergravity, the flat universe eventually stops accelerating and collapses to a singularity. We show that in these models, as well as in the simplest models of dark energy based on N=1 supergravity, the typical time remaining before the global collapse is comparable to the present age of the universe, t = O(10^{10}) years. We discuss the possibility of distinguishing between various models and finding our destiny using cosmological observations.