  We suggest that the dark side of the universe builds a dark medium modifying
the Standard Model particle dispersion relations. We introduce the generic form
for the modified dispersion relations and provide explicit models of the dark
medium. We use the derived neutrino dispersion relations to show that the size
of the corrections are smaller than the SN1987a bounds. We argue that before
invoking modifications of Einstein's theory of relativity one should
investigate the dark medium effects.
