A new study of the Unruh effect

Abstract

We revisit the Unruh effect using probability-level calculations, deriving the transition rate of a uniformly accelerating Unruh-DeWitt monopole detector coupled to a massive scalar field. We examine this from both inertial (Minkowski) and accelerating (Rindler) observer perspectives, showing that both perspectives yield the same transition rate at finite measurement times. The research confirms that an inertial detector in a thermal bath of Minkowski particles responds differently than an accelerated detector perceiving a thermal bath of Rindler particles—except for massless fields, where agreement occurs at all times. The paper also presents new numerical results highlighting transient effects caused by the field initially being in the Minkowski vacuum state.

Layman’s Abstract

An observer accelerating through empty space will detect particles and heat, even though a stationary observer sees nothing—a surprising effect predicted by Bill Unruh in 1976. This paper revisits this “Unruh effect” using new calculation methods that work directly with probabilities rather than quantum amplitudes. We show that whether you analyse the situation from the perspective of someone standing still or someone accelerating, you get the same answer for what the detector sees. We also explore what happens when the detector is turned on suddenly, revealing interesting transient behaviour that wasn’t fully understood before.

Links

• Classical and Quantum Gravity
• arXiv:2409.12697
• InspireHEP

Recommended citation: Dickinson, R., Forshaw, J., Jenkinson, R., & Millington, P. (2025). "A new study of the Unruh effect." Classical and Quantum Gravity.
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