Quantum Field Theory in Curved Spacetime

TL;DR

This paper reviews key aspects of quantum field theory in curved spacetime, including particle creation, black hole effects, divergences, and the semiclassical gravity framework, highlighting both theoretical foundations and limitations.

Contribution

It provides a comprehensive overview of quantum phenomena in curved spacetime, emphasizing recent insights into particle creation, divergences, and the breakdown of semiclassical gravity.

Findings

Particle creation occurs in expanding universes and near black holes.

Ultraviolet and infrared divergences require renormalization techniques.

Semiclassical gravity has limitations due to metric and lightcone fluctuations.

Abstract

These lectures deal with selected aspects of quantum field theory in curved spacetime including the following topics: (1) Quantization of fields on a curved background, particle creation by gravitational fields, particle creation in an expanding universe; moving mirror radiation. (2) The Hawking effect - particle creation by black holes. (3) Ultraviolet and infrared divergences, renormalization of the expectation value of the stress tensor; global symmetry breaking in curved spacetime. (4) Negative energy in quantum field theory, its gravitational effects, and inequalities which limit negative energy densities and fluxes. (5) The semiclassical theory of gravity and its limitations, breakdown of this theory due to metric fluctuations, lightcone fluctuations.