The Unruh effect and its applications

TLDR

The Unruh effect, discovered about 30 years ago, demonstrates that particle content in a field theory depends on the observer and provides insight into particle emission from black holes and cosmological horizons. This review focuses on the Unruh effect’s applications and seeks to clarify common misconceptions. The authors discuss recent developments and controversies related to the Unruh effect.

Abstract

It has been $30\phantom{\rule{0.3em}{0ex}}\text{years}$ since the discovery of the Unruh effect. It has played a crucial role in our understanding that the particle content of a field theory is observer dependent. This effect is important in its own right and as a way to understand the phenomenon of particle emission from black holes and cosmological horizons. The Unruh effect is reviewed here with particular emphasis on its applications. A number of recent developments are also commented on and some controversies are discussed. Effort is also made to clarify what seem to be common misconceptions.