Fractional-order derivatives in cosmological models of accelerated expansion

TL;DR

This review explores the application of fractional derivatives in cosmological models, highlighting their potential to explain the universe's accelerated expansion through modified General Relativity theories.

Contribution

It provides a comprehensive overview of fractional calculus in cosmology, including exact solutions and their relevance to late-time cosmic acceleration.

Findings

Fractional derivatives can modify Einstein's equations for cosmology.

Several exact solutions suggest fractional calculus models can explain accelerated expansion.

The approach aligns with recent observational tests of cosmological models.

Abstract

In this brief review, we present the results of the fractional differential approach in cosmology in the context of the exact models of cosmological accelerated expansion obtained by several authors to date. Most of these studies are devoted to the problem of introducing fractional derivatives or fractional integrals into the classical General Relativity (GR). There are several observational and theoretical motivations to investigate the modified or alternative theories of GR. Among other things, we cover General Relativity modified by a phenomenological approach dealing with fractional calculus. At the same time, a sufficiently large number of exact solutions of the cosmological equations modified by this approach were obtained. Some of these models may be especially relevant in the light of solving the problem of late accelerated expansion of the universe. These studies are largely motivated by rapid progress in the field of observational cosmology that now allows, for the first time, precision tests of fundamental physics on the scale of the observable Universe. The purpose of this review is to provide a reference tool for researchers and students in cosmology and gravitational physics, as well as a self-contained, comprehensive, and up-to-date introduction to the subject as a whole.