  A physical system should be in a local equilibrium if it cannot be
distinguished from a global equilibrium by ``infinitesimally localized
measurements''. This seems to be a natural characterization of local
equilibrium, however the problem is to give a precise meaning to the
qualitative phrase ``infinitesimally localized measurements''.
  A solution is suggested in form of a {\em Local Equilibrium Condition} (LEC)
which can be applied to non-interacting quanta.
  The Unruh temperature of massless quanta is derived by applying LEC to an
arbitrary point inside the Rindler Wedge.
  Massless quanta outside a hot sphere are analyzed. A stationary spherically
symmetric local equilibrium does only exist according to LEC if the temperature
is globally constant.
  Using LEC a non-trivial stationary local equilibrium is found for rotating
massless quanta between two concentric cylinders of different temperatures.
This shows that quanta may behave like a fluid with a B\'enard instability.
