It is well-known that observers bounded in a space-time manifold that possesses horizons can detect radiation whose characteristics bear a remarkable resemblance to that from a black body; this includes free quantum fields in either the Rindler case (constant accelerating frame) or the Schwarzschild solution (black hole). Recently, a new derivation has been given which makes it transparent why in these cases, even though the state vector is a coherent one, the vacuum expectation value for any observable inside the manifold can assume the form of a canonical ensemble. In this talk, I wish to give a brief review of the situation and also generalize the proof to include arbitrary interactions (but treating gravity only as a given background metric).
URL : http://ptp.ipap.jp/link?PTPS/85/271/
DOI : 10.1143/PTPS.85.271