Hawking radiation, Unruh radiation and the equivalence principle

Understand

We compare the response function of an Unruh-DeWitt detector for different space-times and different vacua and show that there is a {\it detailed} violation of the equivalence principle.

• In particular comparing the response of an accelerating detector to a detector at rest in a Schwarzschild space-time we find that both detectors register thermal radiation, but for a given, equivalent acceleration the fixed detector in the Schwarzschild space-time measures a higher temperature.
• This allows one to locally distinguish the two cases.
• As one approaches the horizon the two temperatures have the same limit so that the equivalence principle is restored at the horizon.