Unimodular cosmology and the weight of energy

TL;DR

This paper explores models of unimodular cosmology where the gravitational coupling of potential energy can be adjusted relative to kinetic energy, within a framework of coordinate transformations with unit Jacobian.

Contribution

It introduces a class of unimodular models with adjustable gravitational coupling for potential energy, expanding the theoretical landscape of cosmological models.

Findings

Potential energy coupling can be independently varied in these models.

The models maintain gauge symmetry under coordinate transformations with unit Jacobian.

Implications for cosmological dynamics and energy conservation are discussed.

Abstract

Some models are presented in which the strength of the gravitational coupling of the potential energy relative to the same coupling for the kinetic energy is, in a precise sense, adjustable. The gauge symmetry of these models consists of those coordinate changes with unit jacobian.