Reuter makes quantum gravity renormalizable by letting the action run to a fixed point as the proximity k --> infty.(adsbygoogle = window.adsbygoogle || []).push({});

so he gets a whole series of metrics g_{k}

these metrics probe spacetime at a finer and finer scale. k is like the reciprocal of the characteristic length of an interaction---a kind of 1/r where r is an interaction distance or wavelength typical of the process studied.

or if that is too simple, k is monotonically related to such a characteristic 1/r

The reason Reuter gets classical relativity out of this is that he has a trajectory where for a long long range of k the action stays the classical action and the metric g_{k}stays the same. Only when k gets very large does g_{k}leave off being classical and start heading for the fixed point.

So suppose you have two galaxies A and B and one is sending photons to the other.

THE DISTANCE between A and B depends on what metric g_{k}you use to measure. they are approximately classical but slightly different. What metric is appropriate to use depends on the WAVELENGTH of the photon that is doing the traveling.

this is the scale at which it interacts with the (possibly quantum-bumpy) geometry of the space between the galaxies.

It is possible that in Reuter's picture the more energetic photon sees a bumpier road from A to B and actually a LONGER DISTANCE that it must travel.

So even if they both nominally travel at speed c, the more energetic one might get there a little bit later.

Any thoughts? Would anyone like some links to Martin Reuter papers?

I am following through on the MAGIC report of a 4 minute delay of some TeV photons after a half-billion year trip.

We can dismiss the MAGIC report as indicating nothing more than some unknown effect at the source, and perhaps observational error, or we can consider possible explanations assuming that their finding might turn out to be significant.

http://arxiv.org/abs/0708.2889

Probing Quantum Gravity using Photons from a Mkn 501 Flare Observed by MAGIC

J. Albert, et al., for the MAGIC Collaboration, John Ellis, N.E. Mavromatos, D.V. Nanopoulos, A.S. Sakharov, E.K.G. Sarkisyan

5 pages, 3 figures, submitted to Phys. Rev. Lett

(Submitted on 21 Aug 2007)

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# Reuter explain MAGIC?

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