Special Relativity breaks down in matter??? The same idea was proposed by several authors( Ravndal arXiv:0810.1872v1, Crenshaw arXiv:0812.3348v2 , Wang arXiv:0909.1856v2, et al ) to study Abraham-Minkowski controversy (http://en.wikipedia.org/wiki/Abraham–Minkowski_controversy). They pointed out light speed c of special relativity should be replaced by c/n (n is refractive index) within a medium. :surprised That is, the theory of relativity is not universal and extended theory will reduce to the old one in case of n=1(vacuum). See Wiki, an experimental report "Crucial experiment to resolve Abraham-Minkowski controversy" published by Optik just now supports their argument. Are they reasonable? If wrong, how to explain "Abraham-Minkowski Controversy"?