Intuitive

Since in general relativity the curvature corresponds to the gravitational field, QFT in curved spacetime corresponds to a normal QFT with an external source (=the gravitational field).

For a curvature that depends on the time, we are dealing with a time varying source that can, for example, produce particles. A proper analogy is a driven harmonic oscillator.

It is important to note that QFT in curved spacetime is not quantum gravity. In a theory of quantum gravity we would take the backreaction of quantum effects on the spactime into account. In contrast, in curved spacetime QFT the curved spacetime is merely a background structure, i.e. an external source and not treated quantum mechanically.

Concrete

• The standard reference is Quantum Fields in Curved Space by N.D. Birrell, P.C.W. Davies

Abstract

Why is it interesting?