# Stability of the Einstein static universe in Eddington-inspired Born-Infeld theory

## TL;DR

This paper investigates the stability of the Einstein static universe within Eddington-inspired Born-Infeld (EiBI) theory, finding that stability depends on spatial curvature and perturbation type, impacting the viability of the emergent universe scenario.

## Contribution

It provides a stability analysis of the Einstein static universe in EiBI theory considering both homogeneous and inhomogeneous scalar perturbations across different spatial curvatures.

## Key findings

- No stability in flat and closed cases for emergent universe scenario.
- Stability possible in open case under certain conditions.
- Emergent universe viability depends on spatial curvature and perturbation stability.

## Abstract

By considering the realization of the emergent universe scenario in Eddington-inspired Born-Infeld (EiBI) theory, we study the stability of the Einstein static universe filled with perfect fluid in EiBI theory against both the homogeneous and inhomogeneous scalar perturbations in this work. We find that in both the spatially flat and closed cases, the emergent universe scenario is no longer viable, since the Einstein static universe cannot be stable against both the homogeneous and inhomogeneous scalar perturbations simultaneously. However, the emergent universe scenario survives in the spatially open case, while the Einstein static universe can be stable under some conditions.