  We review the quantization of scalar and gauge fields using Rindler
coordinates with an emphasis on the physics of the Rindler horizon. In the
thermal state at the Unruh temperature, correlators match their Minkowski
vacuum values and the renormalized stress tensor vanishes, while at any other
temperature the renormalized stress-energy diverges on the horizon. After
giving a new derivation of some of these results using canonical quantization
in the thermofield double state, we comment on the relevance of fluxes and
boundary conditions at the horizon, which have arisen in calculations of
entanglement entropy.
