Quantum gravity in the very early universe

TL;DR

This paper reviews quantum gravity in the early universe, highlighting a discrete space-time structure and its potential observable effects on cosmic evolution and fundamental symmetries.

Contribution

It introduces recent results on the quantum nature of space-time, emphasizing a discrete, atomic picture affecting high-energy cosmological phenomena.

Findings

Discrete space-time may influence matter propagation

Quantum effects could alter universe expansion

Potential observable traces in cosmic measurements

Abstract

General relativity describes the gravitational field geometrically and in a self-interacting way because it couples to all forms of energy, including its own. Both features make finding a quantum theory difficult, yet it is important in the high-energy regime of the very early universe. This review article introduces some of the results for the quantum nature of space-time which indicate that there is a discrete, atomic picture not just for matter but also for space and time. At high energy scales, such deviations from the continuum affect the propagation of matter, the expansion of the universe, and perhaps even the form of symmetries such as Lorentz or CP transformations. All these effects may leave traces detectable by sensitive measurements, as pointed out here by examples.