Thermal radiation of various gravitational backgrounds

We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasi--classical tunneling of particles through a gravitational barrier. We show that our procedure can reproduce the results of Hawking and Unruh radiation. We also show that under certain kinds of coordinate transformations the temperature of the thermal radiation will change in the case of the Schwarzschild black holes. In addition we apply our procedure to a rotating/orbiting system and show that in this case there is no radiation, which has experimental implications for the polarization of particles in circular accelerators.