It is known by experts in the field that the
constancy of the speed of light is only valid in vacuum. The speed of light
within transparent physical medium is a local variable v = c/n as historically
established, among others, by Lorentz; failed search for the in-variance of
local speeds 9v = c/n (this is "the historical Lorentz problem"),
which he achieved only for n = 1 and c = constant. There is no need for an
experimental verification of the local character of the speed of light since
already in water we all know that the speed of light is reduced by 1/3. The
usual twisting to adapt special relativity to water is that of reducing light
to photons scattering among the water molecules while propagating in vacuum.
However, this twist fails to represent the angle of refraction, the reduction
of speed, the propagation of a light beam in water as a beam, and other
experimental data. To my knowledge, the most important research in the field
has been done by R. M. Santilli who first generalized Lie's theory into a form
applicable to non-linear systems (as necessary for locally varying speeds of
light), as well as for inhomogeneous and anisotropic physical media during his
stay at Harvard University from 1977 to 1981 (see his Foundations of
Theoretical Mechanics, Volumes I and II, http://www.santilli-foundation.org/docs/Santilli-209.pdf; after that, Santilli achieved in 1983 the
solution of the historical Lorentz problem, namely, the universal invariance of
v = c/n, today known as the Lorentz-Santilli isosymmetry, Lettere Nuovo Cimento{\bf 37} 545 (1983), and applied the new symmetry to a
number of problems for interior dynamical conditions, see the 160-page review Invited paper, in press, December 2016
Finally, it should be confirmed what also
indicated by others elsewhere, namely, that Lorentz transformations do not fix
the speed of light c. They merely provide the invariance of a constant
arbitrary speed. The full compatibility of arbitrary speeds with Lorentz
Transformations and special relativity has also been studied by Santilli, see,
e.g., the paper American Journal of Modern Physics 2016; 5(2-1): 143-160
As with the photon's speed 'c' given, it is a
reference measured by the observer in the same system affected by the same
variable (gravity), gravity variations won’t account for a C variation for the
observer since he is part of the system; so to isolate light speed variations
we need an measurement system not influenced by the gravity, since it will
drive us to the perceptual idea of a distorted space-time continuum which IMHO
it’s just an elegant way to explain things w/o going to the root of the
problem. So assuming the true value of C is higher in 'denser' gravity systems,
it’s plausible it was close to infinite at the big bang, in harmony with Magueijo’s “Faster than the Speed of Light”
and Afshordi theory?
