The Varying Speed of Light in Eddington-inspired Born-Infield Gravity with Rainbow Metric

Abstract

In this paper, we proposed that at each point of spacetime, in addition to the Riemannian metric tensor which describes the geometry of spacetime and the gravitational field, there is an rainbow metric tensor which shows the geometry of spacetime depends on the energy of the test particle. Because Eddington-inspired Born-Infield(EiBI) gravity can be seen as a special bi-metric gravity, we research a varying speed of light theory for a bi-metric gravity corresponding to EiBI gravity. For FRW universe, we find the energy of test particle will increase with rising energy density of universe. We also research the varying speed of light for three different kinds of rainbow functions and find the sign of parameter $\kappa$ would influence the trend of spend of light.