  The speed of light is usually taken as one of the fundamental constants.
String, and field, theories appear to require the altercation of this constant
into a functional form $E(m,c)$ which is not $E=mc^2$. The analysis requires
the re-interpretation of the renormalization group flow equations. There are
quantum corrections to the mass-energy relation generically for particles of
any sort. A breakdown of special relativity follows. Cosmological data might be
one of the best testbeds to analyze the computable functional forms of the mass
energy relations.
