Order from disorder in closed systems via time reversal violation
  Definitions of entropy usually assume time-reversal (T) invariance of
interactions, yet microscopically T is known to be violated. We present a
detailed computational example of (uncharged) particle species separation
(Maxwell demon) using an interaction that violates both parity (P) and T so
that PT is preserved, consistent with the CPT invariance required in quantum
field theory (C is charge conjugation). This illustrates how T-violating forces
can produce more organized states from disorganized ones, contrary to
expectations based on increase of entropy. We also outline several scenarios in
which T-violating forces could lead to an organized state in the early
Universe, starting from a still earlier disorganized state.
