Speed of light in the extended gravity theories

TL;DR

This paper explores the concept of varying speed of light within extended gravity theories using Palatini formalism, analyzing different light speeds and inertial frames to understand their implications in gravitational physics.

Contribution

It introduces a framework for VSL in Palatini non-linear Ricci scalar and Ricci squared theories, distinguishing local frames and their inertial properties.

Findings

Two local frames are distinguishable based on light speed.

The inertial nature of these frames is analyzed.

Implications for causal structure and gravitational wave speeds are discussed.

Abstract

We shall investigate the possibility of formulation of varying speed of light (VSL) in the framework of Palatini non-linear Ricci scalar and Ricci squared theories. Different speeds of light including the causal structure constant, electromagnetic, and gravitational wave speeds are discussed. We shall see that two local frames are distinguishable and discuss about the velocity of light in these two frames. We shall investigate which one of these local frames is inertial.