Universality of the isospecial relativity for the invariant description   of arbitrary speeds of light
  We review the recent experimental evidence on arbitrary values of the speed of light within physical media (interior dynamical problems); we recall that classical (operator) theories with speeds of light different than that in vacuum are noncanonically (nonunitarily) related to the special relativity, thus losing the original invariant character with consequential rather serious problems of physical consistency; we show that the isominkowskian geometry, the isopoincar\'e symmetry and the isospecial relativity provide a formulation of arbitrary speeds of light within physical media as invariant as that of the special relativity for the propagation of light in vacuum; we prove that the isospecial relativity is directly universal, in the sense of holding for all possible spacetime models with a symmetric metric directly in the frame of the observer; we outline the broader genotopic and hyperstructural formulations which are directly universal for single- and multiple-valued irreversible systems, respectively, with a generally nonsymmetric metric; we review the anti-isomorphic isodual formulations for the classical and operator representation of antimatter and the prediction of the new "isodual photon"; we finally point out a few representative connections between the invariant isotopic formulations and a rather large variety of generalized theories existing in the literature. 
Ruggero Maria Santilli