From: spudnik on
yes, it varies with index of refraction of "the medium of space,"
which existeth always but is not "the" aether. and,
it might vary with other parameters.

> the speed of light isn't constant, so you can forget that.

thus quoth:
This was Gamow’s version of the Big Bang, the predecessor of the
modern accepted brand. One of its worst byproducts was the placing
into general circulation of the really unproven assumption that the
composition of matter in the universe as a whole is now known. It
would surprise most people today to learn that at the time of ABC
Humbug, and for some years after, almost all astronomers thought that
the core of the Sun, and of most stars, was iron. Although the truth
of this matter seems unknowable at this time—for we cannot get to the
core of our Earth, not to speak of stars—there is not really sound
proof otherwise. The accepted view of solar composition rests on a
peculiar construct known as the neutrino, conceived in 1930 by the
Robert Fludd-admiring mystic Wolfgang Pauli. In million-gallon vats of
carbon tetrachloride, buried deep underground, a minute number of
phenomena supposed to correspond to this little reaction-particle are
observed. Is it the neutrino, or are we merely being taken to the
cleaners?

The Harkins School
This was Gamow’s version of the Big Bang, the predecessor of the
modern accepted brand. One of its worst byproducts was the placing
into general circulation of the really unproven assumption that the
composition of matter in the universe as a whole is now known. It
would surprise most people today to learn that at the time of ABC
Humbug, and for some years after, almost all astronomers thought that
the core of the Sun, and of most stars, was iron. Although the truth
of this matter seems unknowable at this time—for we cannot get to the
core of our Earth, not to speak of stars—there is not really sound
proof otherwise. The accepted view of solar composition rests on a
peculiar construct known as the neutrino, conceived in 1930 by the
Robert Fludd-admiring mystic Wolfgang Pauli. In million-gallon vats of
carbon tetrachloride, buried deep underground, a minute number of
phenomena supposed to correspond to this little reaction-particle are
observed. Is it the neutrino, or are we merely being taken to the
cleaners?

The Harkins School
http://21stcenturysciencetech.com/articles/fall%202003/Humbuggery.html