  The interplay of electron-electron interactions and spin-orbit coupling leads
to a new contribution to the homogeneous optical conductivity of the electron
liquid. The latter is known to be insensitive to many-body effects for a
conventional electron system with parabolic dispersion. The parabolic spectrum
has its origin in the Galilean invariance which is broken by spin-orbit
coupling. This opens up a possibility for the optical conductivity to probe
electron-electron interactions. We analyze the interplay of interactions and
spin-orbit coupling and obtain optical conductivity beyond RPA.
