Einstein and Rastall Theories of Gravitation in Comparison

TL;DR

This paper compares Einstein and Rastall theories of gravitation, arguing that they are not equivalent and that Rastall gravity is an open theory suitable for cosmology and quantum gravity challenges.

Contribution

The paper challenges previous claims of equivalence between Einstein and Rastall gravity, establishing that Rastall theory is fundamentally different and more adaptable for modern physics challenges.

Findings

Rastall gravity is not equivalent to Einstein gravity.

Rastall theory is an open theory, unlike Einstein's.

Rastall gravity can better address cosmological and quantum issues.

Abstract

We profit by a recent paper of Visser claiming that Rastall gravity is equivalent to Einstein gravity to compare the two gravitational theories in a general way. Our conclusions are different from Visser's ones. We indeed argue that these two theories are not equivalent. In fact, Rastall theory of gravity is an "open" theory when compared to Einstein general theory of relativity. Thus, it is ready to accept the challenges of observational cosmology and quantum gravity.