Potential Sensitivity of Gamma-Ray Burster Observations to Wave Dispersion in Vacuo

TL;DR

Gamma-ray burst observations could potentially detect tiny variations in light speed caused by quantum gravity effects, offering a way to test fundamental physics at near-Planck energy scales.

Contribution

This paper demonstrates the sensitivity of gamma-ray burst data to wave dispersion in vacuum, proposing a method to test quantum gravity theories near the Planck energy.

Findings

GRB time structure is sensitive to vacuum dispersion effects

Potential to probe quantum gravity energy scales near 10^{19} GeV

Outlines observational strategies for testing fundamental physics

Abstract

The recent confirmation that at least some gamma-ray bursters (GRBs) are indeed at cosmological distances raises the possibility that observations of these could provide interesting constraints on the fundamental laws of physics. Here we demonstrate that the fine-scale time structure and hard spectra of GRB emissions are very sensitive to the possible dispersion of electromagnetic waves in vacuo with velocity differences $\delta v \sim E/E_{\QG}$, as suggested in some approaches to quantum gravity. A simple estimate shows that GRB measurements might be sensitive to a dispersion scale $E_{QG}$ comparable to the Planck energy scale $E_{P} \sim 10^{19}$ GeV, sufficient to test some of these theories, and we outline aspects of an observational programme that could address this goal.