  The Lorentz symmetry and the space and time translational symmetry are
fundamental symmetries of nature. Crystals are the manifestation of the
continuous space translational symmetry being spontaneously broken into a
discrete one. We argue that, following the space translational symmetry, the
continuous Lorentz symmetry should also be broken into a discrete one, which
further implies that the continuous time translational symmetry is broken into
a discrete one. We deduce all the possible discrete Lorentz and discrete time
translational symmetries in 1+1-dimensional spacetime, and show how to build a
field theory or a lattice field theory that has these symmetries.
