A Black Hole Cooks Up Radiation Like a Pot of Soup express
The 'double copy' method in physics is a culinary trick: a chef takes a cold soup recipe, doubles the ingredients, and gets a recipe for a hot roast. Likewise, particle interactions via electric forces (the basis of the Standard Model) morph into gravity, which describes spacetime curvature.
Until now, this trick was only tested in empty space. Now it's been applied to Stephen Hawking radiation from a black hole. The original 'soup' — particle creation in an electric field — is a process with no temperature or horizon. After double copying, radiation emerges with entropy (a measure of disorder), as if from a hot object. The horizon and temperature weren't put into the recipe: they just appeared on their own.
Original abstract
as written by the authors arXiv:2510.25852
Gravity and gauge theory are concretely linked by the double copy. Although well-studied at the level of perturbative scattering in vacuum, far less is known about non-perturbative aspects or extensions of the double copy beyond trivial backgrounds. We show here how Hawking radiation in a collapse metric, its associated thermal spectrum, and horizon-dependence, emerges from the double copy of particle production in a background gauge field, where there is no global horizon, nor a thermal spectrum. Our approach combines worldline and amplitudes methods, and allows the unification of several classical and quantum double copy prescriptions for black hole spacetimes.
Particle creation in a strong electric field (the Schwinger effect) has never been observed in the lab — the energy needed is staggering. However, its double copy, Hawking radiation, is what astronomers aim to catch at the rims of real black holes.