The Unruh effect and its connection to classical radiation

by Georgios Vacalis (University of Oxford)

Thursday 30 Nov 2023, 10:00 → 11:00 Europe/Zurich

4/2-037 - TH meeting room (CERN)

Spontaneous particle production can occur in a curved spacetime. One famous example of this process was predicted by Hawking in 1974. He found that a black hole loses energy in the form of thermal radiation, which is known today as Hawking radiation, and may evaporate. The Unruh effect is a quantum field theory result that is closely connected to Hawking radiation. It states that accelerated observers associate a thermal bath of particles to the vacuum state of inertial observers. The Unruh effect has been given special attention because contrary to black hole evaporation, it is a prediction made in a flat (Minkowski) spacetime and therefore can be, in principle, tested in the laboratory.

Recently, we have investigated the connection between the Unruh effect and classical radiation for a uniformly accelerated particle. This link seems counter-intuitive since the former is a purely quantum effect while the latter is a classic one. Nonetheless, we find that using a full quantum field treatment of the radiation exchanged by an accelerated charge with the surrounding Unruh thermal bath, the resultant power reduces at tree-level to the usual Larmor formula. The results are also consistent with the observation made by Unruh and Wald which states that the emission of a photon in the inertial frame corresponds to the emission or absorption of a photon in the accelerated frame. The fact that the derivation makes the link between the Unruh effect and the Larmor radiation from a uniformly accelerated charged particle clearer will perhaps help in resolving some of the controversies that have surrounded the Unruh effect since its discovery.

Unruh_presentation_Cern.pdf