  Gamma ray bursts can potentially be used as distance indicators, providing
the possibility of extending the Hubble diagram to redshifts ~7. Here we follow
the analysis of Schaefer (2007), with the aim of distinguishing the timescape
cosmological model from the \LambdaCDM model by means of the additional
leverage provided by GRBs in the range 2 < z < 7. We find that the timescape
model fits the GRB sample slightly better than the \LambdaCDM model, but that
the systematic uncertainties are still too little understood to distinguish the
models.

Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology