Quantum Oscillations Can Prevent the Big Bang Singularity in an Einstein-Dirac Cosmology

TL;DR

This paper demonstrates that quantum oscillations of Dirac particles in an Einstein-Dirac cosmology can prevent the universe's singularities, leading to cyclic or bouncing cosmological models.

Contribution

It introduces a quantum mechanism within Einstein-Dirac cosmology that can halt collapse and avoid singularities, enabling cyclic or periodic universe models.

Findings

Quantum oscillations prevent big bang and big crunch singularities.

Numerical models show collapse can be reversed by quantum effects.

Fine-tuning parameters yields a time-periodic universe.

Abstract

We consider a spatially homogeneous and isotropic system of Dirac particles coupled to classical gravity. The dust and radiation dominated closed Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find a mechanism where quantum oscillations of the Dirac wave functions can prevent the formation of the big bang or big crunch singularity. Thus before the big crunch, the collapse of the universe is stopped by quantum effects and reversed to an expansion, so that the universe opens up entering a new era of classical behavior. Numerical examples of such space-times are given, and the dependence on various parameters is discussed. Generically, one has a collapse after a finite number of cycles. By fine-tuning the parameters we construct an example of a space-time which is time-periodic, thus running through an infinite number of contraction and expansion cycles.