This paper which just appeared on arxiv http://arxiv.org/abs/0709.2365 Loop quantum gravity corrections to gravitational wave dispersion Martin Bojowald, Golam Mortuza Hossain 27 pages (Submitted on 14 Sep 2007) "Cosmological tensor perturbations equations are derived for Hamiltonian cosmology based on Ashtekar's formulation of general relativity, including typical quantum gravity effects in the Hamiltonian constraint as they are expected from loop quantum gravity. This translates to corrections of the dispersion relation for gravitational waves. The main application here is the preservation of causality which is shown to be realized due to the absence of anomalies in the effective constraint algebra used." It cites an earlier one which is not on arxiv but was published in July this year in Physical Review D and of which I obtained a paper copy. The other references are online. http://link.aps.org/abstract/PRD/v75/e123521 Radiation equation of state and loop quantum gravity corrections Martin Bojowald, Rupam Das Phys. Rev. D 75, 123521 (2007) (11 pages) (Received 16 January 2007; published 28 June 2007) "The equation of state for radiation is derived in a canonical formulation of the electromagnetic field. This allows one to include correction terms expected from canonical quantum gravity and to infer implications to the universe evolution in radiation dominated epochs. Corrections implied by quantum geometry can be interpreted in physically appealing ways, relating to the conformal invariance of the classical equations."