Energy nonconservation as a link between $f(R,T)$ gravity and noncommutative quantum theory

TL;DR

This paper links $f(R,T)$ gravity's energy nonconservation to quantum noncommutativity, proposing a 5D model where energy flows between dimensions restore conservation, constraining the form of $f(R,T)$ functions.

Contribution

It introduces a 5D noncommutative spacetime model connecting energy nonconservation in $f(R,T)$ gravity with quantum effects, deriving a differential equation for the theory's functional form.

Findings

Energy flows between dimensions restore conservation.

Derived a differential equation constraining $f(R,T)$.

Analyzed solutions in a spherically symmetric setting.

Abstract

$f(R,T)$ gravity was proposed as an extension of the $f(R)$ theories, containing not just geometrical correction terms to the General Relativity equations, but also material correction terms, dependent on the trace of the energy-momentum tensor $T$. These material extra terms prevent the energy-momentum tensor of the theory to be conserved, even in a flat background. Energy nonconservation is a prediction of quantum theory with time-space noncommutativity. If time is considered as an operator and there are compact spatial coordinates which do not commute with time, then the time evolution gets quantized and energy conservation can be violated. In the present work we construct a model in a 5-dimensional flat spacetime consisting of 3 commutative spatial dimensions and 1 compact spatial dimension whose coordinate does not commute with time. We show that energy flows from the 3-dimensional commutative slice into the compact extra dimension (and vice-versa), so that conservation of energy is restored. In this model the energy flux is proportional to the energy density of the matter content, leading to a differential equation for $f(R,T)$, thus providing a physical criterion to restrict the functional form of $f(R,T)$. We solve this equation and analyze the behavior of its solution in a spherically symmetric context.