Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

TL;DR

This paper explores how a decaying cosmological constant can lead to chaotic cyclic universe models, especially with positive spatial curvature, using phase plane analysis and scalar field dynamics.

Contribution

It demonstrates that a decaying dark energy component can produce cyclic cosmologies, extending previous models to include evolving cosmological constants and scalar fields.

Findings

Chaotic cyclic universes are possible if dark energy decays and spatial curvature is positive.

Current observations do not exclude the possibility of a decaying cosmological constant or closed universe.

Phase plane analysis supports the existence of eternal bouncing models under these conditions.

Abstract

We use the phase plane analysis technique of Madsen and Ellis to consider a universe with a true cosmological constant as well as a cosmological "constant" that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof of principle, with no definite claim on the physical mechanism required for the present dark energy to decay.