Modified entropic gravity revisited

TL;DR

This paper revisits modified entropic gravity theories, deriving generalized equations, analyzing their cosmological implications, and highlighting significant constraints and discrepancies that challenge their viability.

Contribution

It provides a unified formalism for modified entropic gravity, derives generalized gravitational equations, and examines their cosmological consistency and constraints.

Findings

Energy-momentum conservation severely constrains modifications.

Discrepancies found between different methods in cosmological models.

Challenges posed to the viability of modified entropic gravity theories.

Abstract

Inspired by Verlinde's idea, some modified versions of entropic gravity have appeared in the literature. Extending them in a unified formalism, we derive the generalized gravitational equations accordingly. From gravitational equations, the energy-momentum conservation law and cosmological equations are investigated. The covariant conservation law of energy-momentum tensor severely constrains viable modifications of entropic gravity. A discrepancy arises when two independent methods are applied to the homogeneous isotropic universe, posing a serious challenge to modified models of entropic gravity.