Possible astrophysical probes of quantum gravity

TL;DR

This paper explores how quantum gravity could alter space-time at tiny scales, affecting photon and neutrino propagation, and discusses astrophysical observations as potential tests for these quantum effects.

Contribution

It proposes using astrophysical observations, like gamma-ray bursts, to detect possible quantum gravity effects on space-time structure and particle propagation.

Findings

Quantum gravity may cause a 'foamy' space-time affecting particle speeds.

Potential Lorentz invariance violation detectable via astrophysical observations.

Astrophysical sources can serve as probes for quantum space-time phenomena.

Abstract

A satisfactory theory of quantum gravity will very likely require modification of our classical perception of space-time, perhaps by giving it a 'foamy' structure at scales of order the Planck length. This is expected to modify the propagation of photons and other relativistic particles such as neutrinos, such that they will experience a non-trivial refractive index even in vacuo. The implied spontaneous violation of Lorentz invariance may also result in alterations of kinematical thresholds for key astrophysical processes involving high energy cosmic radiation. We discuss experimental probes of these possible manifestations of the fundamental quantum nature of space-time using observations of distant astrophysical sources such as gamma-ray bursts and active galactic nuclei.