Cosmological Singularities and Quantum Particles

TL;DR

This paper investigates the behavior of quantum particles near cosmological singularities, finding that fermions can cross these singularities while scalars cannot, highlighting differences in their resilience.

Contribution

It demonstrates that Dirac spinor solutions remain non-singular at various cosmological singularities, allowing fermions to cross them, unlike scalar particles.

Findings

Fermionic solutions are non-singular at big bang, big crunch, big rip, and big brake singularities.

Fermions can be described across singularities, enabling their crossing.

Scalar particles remain singular and cannot cross these singularities.

Abstract

We study if there is an opportunity to describe quantum particles in the vicinity of three types of cosmological singularities, big bang-big crunch, big rip and big brake. Writing down the Dirac equation for spinors, and choosing a convenient parametrization for basis functions of the spinor field, we show that the corresponding second-order differential equation has two independent solutions which are non-singular in the case of all three types of singularities. That permits us to construct the Fock space for the spinor particles and to interprete this fact as their opportunity to cross these cosmological singularities. We show also that this is impossible to do for scalar particles and changing the parametrization does not help. Thus, fermions look more resilient to the passage of the cosmological singularities than bosons.