Surface singularities in Eddington-inspired Born-Infeld gravity

TL;DR

This paper critically examines Eddington-inspired Born-Infeld gravity, revealing that it shares fundamental issues with Palatini f(R) gravity, including surface singularities and problematic Newtonian limits, questioning its viability as an alternative to general relativity.

Contribution

The study identifies and analyzes the similarities between Eddington-inspired Born-Infeld gravity and Palatini f(R) gravity, highlighting shared pathologies that challenge the theory's viability.

Findings

Presence of curvature singularities at star surfaces

Unacceptable Newtonian limit in the theory

Shared pathologies with Palatini f(R) gravity

Abstract

Eddington-inspired Born-Infeld gravity was recently proposed as an alternative to general relativity that offers a resolution of spacetime singularities. The theory differs from Einstein's gravity only inside matter due to nondynamical degrees of freedom, and it is compatible with all current observations. We show that the theory is reminiscent of Palatini f(R) gravity and that it shares the same pathologies, such as curvature singularities at the surface of polytropic stars and unacceptable Newtonian limit. This casts serious doubts on its viability.