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arXiv · 2511.12366

The Unruh Effect in Relativistic Fluids

Eren Erberk Erkul
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Abstract

We identify the relativistic-fluid counterpart of the Unruh effect, in which a comoving probe measures a Thermodynamic Unruh temperature. Frame changes in first-order hydrodynamics are recast as a local, time-dependent hyperbolic rotation in a Rindler-style state space where the instantaneous map between frames is the Thermodynamic Boost and its proper-time variation defines the Thermodynamic Acceleration, which results in an Unruh-like thermal spectrum. To leading order, the Thermodynamic Unruh temperature is frame-independent and universal across out-of-equilibrium relativistic fluid descriptions, from Israel-Stewart to modern theories.

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Eren Erberk Erkul. 2025-11-15. The Unruh Effect in Relativistic Fluids. https://arxiv.org/abs/2511.12366

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