More on the fact that Rastall = GR

Abstract

Rastall gravity is the same as General Relativity, with a simple algebraic redefinition of what is called the energy-momentum tensor. Despite it having been very clearly explained by M. Visser several years go, there are still many papers claiming big differences between the two formulations of gravitational equations and trying to use them for problems of physics. When going this way, the totally ignored task is to explain why the conserved energy-momentum quantities and the quantities used for other purposes are different from each other. Moreover, when researchers are using the non-conserved energy density and pressure for determining the sound speed, it is just inconsistent with the Rastall gravity. I carefully explain all this, and also show how one could construct a variational principle for producing equations in the Rastall form.

6 pages; minor additions

References in corpus (3)

• Einstein and Rastall Theories of Gravitation in Comparison
• Non-trivial class of anisotropic compact stellar model in Rastall gravity
• Disforming to Conformal Symmetry

Cited by in corpus (4)

• Role of Non-conserved Gravity Theory and Electric Charge in Constructing Complexity-free Stellar Models: A Novel Approach under Non-minimal Coupling
• Implications of Rastall Theory on Stellar Solutions admitting Vanishing Complexity: A New Perspective
• Gravitational Collapse of an Inhomogeneous Fluid in Rastall Theory
• Singularity Avoidance in Gravitational Collapse of an Inhomogeneous Fluid in Rastall Gravity