Hawking radiation, Unruh radiation and the equivalence principle

TL;DR

This paper compares the responses of Unruh-DeWitt detectors in different space-times, revealing a detailed violation of the equivalence principle by showing that detectors in Schwarzschild space-time measure higher temperatures than accelerating detectors at the same acceleration.

Contribution

It demonstrates a detailed violation of the equivalence principle by analyzing detector responses in Schwarzschild space-time versus accelerated frames.

Findings

Detectors in Schwarzschild space-time measure higher temperatures than equivalent accelerating detectors.

The equivalence principle is restored at the horizon where temperatures converge.

Response functions differ significantly between the two scenarios, indicating local distinguishability.

Abstract

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.