Quantum field theory in curved spacetime

Summary

Quantum field theory in curved spacetime studies quantum fields that propagate on a fixed curved Lorentzian manifold, treated as a classical background. The geometry acts on the fields, but the fields do not change the geometry. Without the symmetries of Minkowski space there is in general no preferred vacuum state and no unique notion of particle. This framework predicts particle creation by expanding universes, the Unruh effect and Hawking radiation from black holes.