Is the speed of light frequency-dependent?

On Dec 26, 8:21*pm, Tom Roberts wrote in
sci.physics.relativity:
Schaefer puts an incredibly small limit on the variation of the speed of
light with frequency, using gamma-ray bursters. This light must have
traveled through significant gravitational fields. His limit is so
small....

Other Masters of yours, Honest Roberts, believe that the variation of
the speed of light with frequency, even if small, refutes at least the
original version of special relativity:

Joao Magueijo, PLUS VITE QUE LA LUMIERE, Dunod, 2003, pp. 298-299:
"La racine du mal etait clairement la relativite restreinte. Tous ces
paradoxes resultaient d'effets bien connus comme la contraction des
longueurs, la dilatation du temps, ou E=mc^2, tous des predictions
directes de la relativite restreinte. (...) La consequence en etait
inevitable: pour edifier une theorie coherente de la gravite
quantique, quelle qu'elle soit, nous [Joao Magueijo et Lee Smolin]
devions commencer par abandonner la relativite restreinte. (...) Mais,
comme nous l'avons vu, celle-ci repose sur deux principes
independants. Le premier est la relativite du mouvement, le second la
constance de la vitesse de la lumiere. Une des solutions possibles a
notre probleme pouvait etre d'abandonner la relativite du mouvement.
(...) C'est une possibilite bien sur, mais nous avons choisi
l'alternative evidente: preserver la relativite du mouvement, mais
admettre qu'a de tres hautes energies, la vitesse de la lumiere ne
soit plus constante."

http://www.fqxi.org/data/articles/Se...lden_Spike.pdf
"Loop quantum gravity also makes the heretical prediction that the
speed of light depends on its frequency. That prediction violates
special relativity, Einstein's rule that light in a vacuum travels at
a constant speed for all observers..."

http://www.edge.org/3rd_culture/smol...n03_print.html
Lee Smolin: "Now, here is the really interesting part: Some of the
effects predicted by the theory appear to be in conflict with one of
the principles of Einstein's special theory of relativity, the theory
that says that the speed of light is a universal constant. It's the
same for all photons, and it is independent of the motion of the
sender or observer. How is this possible, if that theory is itself
based on the principles of relativity? The principle of the constancy
of the speed of light is part of special relativity, but we quantized
Einstein's general theory of relativity.....But there is another
possibility. This is that the principle of relativity is preserved,
but Einstein's special theory of relativity requires modification so
as to allow photons to have a speed that depends on energy. The most
shocking thing I have learned in the last year is that this is a real
possibility. A photon can have an energy-dependent speed without
violating the principle of relativity! This was understood a few years
ago by Amelino Camelia. I got involved in this issue through work I
did with Joao Magueijo, a very talented young cosmologist at Imperial
College, London. During the two years I spent working there, Joao kept
coming to me and bugging me with this problem.....These ideas all
seemed crazy to me, and for a long time I didn't get it. I was sure it
was wrong! But Joao kept bugging me and slowly I realized that they
had a point. We have since written several papers together showing how
Einstein's postulates may be modified to give a new version of special
relativity in which the speed of light can depend on energy."

Are Joao Magueijo and Lee Smolin two very clever Masters of yours,
Honest Roberts? Two very silly Masters of yours?

Pentcho Valev