  We ask the question 'what happens to Bloch waves in gratings synthetically
moving at near the speed of light?'. First we define a constant refractive
index (CRI) model in which Bloch waves remain well defined as they break the
light barrier, then show their dispersion rotating through 360 degrees from
negative to positive and back again. Next we introduce the effective medium
approximation (EMA) then refine it into a 4-wave model which proves to be
highly accurate. Finally using the Bloch waves to expand a pulse of light we
demonstrate sudden inflation of pulse amplitude combined with reversal of
propagation direction as a luminal grating is turned on.
