Gravity Driven Inflation

TL;DR

This paper explores a novel form of inflation driven by the kinetic energy of a varying Planck mass, avoiding potential-based mechanisms and addressing exit challenges in early universe cosmology.

Contribution

It introduces a gravity-driven kinetic inflation model with variable Planck mass, providing solutions to exit problems in string and Kaluza-Klein theories.

Findings

Kinetic inflation can be driven without potential or cosmological constant.

General Planck field couplings can facilitate graceful exit from inflation.

The model suggests a heating mechanism for the big bang.

Abstract

The union of high-energy particle theories and gravitation often gives rise to an evolving strength of gravity. The standard picture of the earliest universe would certainly deserve revision if the Planck mass, which defines the strength of gravity, varied. A notable consequence is a gravity-driven, kinetic inflation. Unlike standard inflation, there is no potential or cosmological constant. The unique elasticity in the kinetic energy of the Planck mass provides a negative pressure able to drive inflation. As the kinetic energy grows, the spacetime expands more quickly. The phenomenon of kinetic inflation has been uncovered in both string theory and Kaluza-Klein theories. The difficulty in exiting inflation in these cases is reviewed. General forms of the Planck field coupling are shown to avoid the severity of the graceful exit problem found in string and Kaluza-Klein theories. The completion of the model is foreshadowed with a suggestion for a heating mechanism to generate the hot soup of the big bang.