Is Eddington-Born-Infeld theory really free of cosmological singularities?

TL;DR

This paper investigates whether the Eddington-inspired-Born-Infeld (EiBI) theory can avoid cosmological singularities, finding that while it can delay the Big Rip singularity caused by phantom energy, it cannot prevent it entirely.

Contribution

The study provides a detailed analysis of singularity behavior in EiBI theory with phantom energy, showing limitations in its ability to avoid the Big Rip singularity.

Findings

EiBI theory delays the Big Rip singularity

Big Rip remains unavoidable in EiBI with phantom energy

The theory differs from general relativity in singularity behavior

Abstract

The Eddington-inspired-Born-Infeld (EiBI) theory has been recently resurrected. Such a theory is characterized by being equivalent to Einstein theory in vacuum but differing from it in the presence of matter. One of the virtues of the theory is to avoid the Big Bang singularity for a radiation filled universe. In this paper, we analyze singularity avoidance in this kind of model. More precisely, we analyze the behavior of a homogeneous and isotropic universe filled with phantom energy in addition to the dark and baryonic matter. Unlike the Big Bang singularity that can be avoided in this kind of model through a bounce or a loitering effect on the physical metric, we find that the Big Rip singularity is unavoidable in the EiBI phantom model even though it can be postponed towards a slightly further future cosmic time as compared with the same singularity in other models based on the standard general relativity and with the same matter content described above.