  It is shown that the Lorentz group plays prominent roles in at least two
areas in condensed matter physics, namely in the Bogoliubov transformation and
optical filters. It is pointed out that the underlying symmetry of the
Bogoliubov transformation is that of two coupled oscillators, and that the
underlying symmetry of two coupled oscillators in that of the group $O(3,3)$.
The Lorentz group is also shown to be the underlying symmetry group for the
Jones matrix formalism which is standard language for optical filters.
