Entropy considerations in Many-Body Gravity and General Relativity, and the impact on cosmic inflation

TL;DR

This paper introduces a 5-D framework for Many Body Gravity (MBG) that can reproduce cosmic inflation and other gravitational phenomena without dark matter, analyzing fundamental relations between interaction, time, and gravity.

Contribution

It demonstrates how MBG can model cosmic inflation using a 5-D approach and explores the fundamental relations between interaction, time, and gravity in this context.

Findings

MBG can reproduce cosmic inflation within a 5-D framework.

Entropic terms in MBG accelerate inflation consistent with QFT.

The slow-roll condition naturally emerges from MBG equations during inflation.

Abstract

Many body gravity (MBG) is a novel modified theory of gravity formulated in a 5-D space-time-temperature framework, in which the variation in temperature is recast as a variation in the 5-D metric. Previous work on MBG has shown that it can reproduce galaxy rotation curves, radial acceleration relation and the weak gravitational lensing of the bullet cluster, without the inclusion of dark matter. In this work we show that MBG can reproduce cosmic inflation, and in the process, analyze fundamental relations between interaction, time and gravity. To analyze cosmic inflation using interacting massless scalar fields, we first analyze theoretically a hypothetical universe with a single massive particle, or a collection of non-interacting massive particles. A quantitative relation between time and interaction is developed using Quantum Field Theory (QFT), which suggests that the notion of time becomes ill-defined for such a universe. The mass terms in MBG and General Relativity cause a discrepancy with the QFT results. An interacting massless scalar field then becomes a necessity to resolve the issue at the onset of inflation. However, the entropic terms in the MBG field equations are seen to be consistent with the QFT results and further accelerate inflation. The slow-roll condition is shown to be a natural consequence of the Euler-Lagrange equations of motion governing the massless scalar field in 5-D space-time-temperature, during the early phase of inflation. Finally, the MBG field equations are solved in the context of a Friedmann metric, leading to inflation. The matter era is also investigated.