Energy dependent speed of gammaray photons may have been observed, by the MAGIC collaboration at its Canary Islands observatory. Lee Smolin has been making the point for several years now that if an energy dependent speed of gammarays is ever observed it will be an enormous stimulus to LQG. AFAIK it has never been proven that any full 3+1D LQG-related theory NEEDS the slight bending of special relativity involved here-----"deformed special relativity" (DSR). But DSR is very "Loop-friendly" and if some deformation of special relativity---with, for instance, a slight energydependent speed of light---were confirmed that would facilitate several research lines in the Loop community. By itself, this doesnt PROVE anything. It strikes me as something analogous to the relation of the string community to SUPERSYMMETRY. Observing SUSY at LHC would be a big shot in the arm for stringfolks. But they aren't predicting it. Or maybe a better analogy would be detectable extra dimensions. They'd like it but they aren't betting serious money or professional honor on it. ======================== But I just want to remind whoever's around that Laurent Freidel et al DID PROVE THAT deformed relativity WAS NECESSARY IN SPINFOAM in the 2+1D case. This is an important result and it was reported in a Physical Review Letters piece by Freidel and Livine last year. IF A SIMILAR RESULT happens to be proved for the next higher dimension case then that Spinfoam model will be falsifiable and if the MAGIC result is confirmed it will have passed a test. It is always possible that such a result for the 3+1D case will be proved. They may even be working on it. So we should check out the Freidel Livine paper. http://arxiv.org/abs/hep-th/0512113 3D Quantum Gravity and Effective Non-Commutative Quantum Field Theory Laurent Freidel, Etera R. Livine Phys.Rev.Lett. 96 (2006) 221301 4 pages (Submitted on 9 Dec 2005 (v1), last revised 17 May 2006 (this version, v2)) "We show that the effective dynamics of matter fields coupled to 3d quantum gravity is described after integration over the gravitational degrees of freedom by a braided non-commutative quantum field theory symmetric under a kappa-deformation of the Poincare group." =========== the idea is if you take a spinfoam picture of gravity, and couple matter to it so that you now have a combined quantum spacetime-and-matter picture, and then if you TURN OFF GRAVITY then you get back a certain quantum field theory, of the matter, on a spacetime that is now FLAT because you turned off gravity. And the symmetry of that quantum field theory turns out to be a deformed special relativity. There are some people around who are more familiar with this work and can interpret it better. I hope they correct me if I've made any major blunders here. What I'm saying is that IF by good fortune Freidel and or some others should happen to extend this result to the full 4D, then it would be an example of a spinfoam QG theory that MUST have deformed relativity in the flat case. And that is very nearly tantamount to saying that it should have energydependent speed of gamma, in the flat case of little or no gravity. And that flatness is what prevails most of the way between the sources of those gammaray flares and where we are observing them. Then there would be a really falsifiable QG that would be shot down if the MAGIC observation is not confirmed. and would survive if it was confirmed.