2026-11-09 京都大学
氷と⽔との相転移（平衡相転移）と化学反応において安定状態が変わる分岐現象（⾮平衡相転移）の概念図。⾮平衡相転移現象では、常に周囲に熱を放出している（熱散逸）。本研究では、この熱散逸に新たな法則があることが発⾒された。
＜関連情報＞
- https://www.kyoto-u.ac.jp/ja/research-news/2026-11-09-1
- https://journals.aps.org/prl/abstract/10.1103/j2x1-tlq7
化学反応ネットワークにおけるエントロピー⽣成の普遍的臨界性 Universal Criticality of Entropy Production in Chemical Reaction Networks
Kyota Tamano and Keiji Saito
Physical Review Letters Published: 9 November, 2026
DOI:https://doi.org/10.1103/j2x1-tlq7
Abstract
Stochastic thermodynamics gives universal relations for microscopic entropy production, yet its critical behavior at macroscopic nonequilibrium transitions remains unclassified. We study well-mixed reversible chemical reaction networks by first taking the macroscopic limit and next the long-time limit. We then characterize nonequilibrium transitions described by the bifurcations of the mass-action dynamics in terms of entropy production. Using linear-noise formulas, center-manifold normal forms, and Floquet theory, we obtain generic exponents for entropy-production fluctuations and responses at pitchfork, transcritical, saddle-node, and Hopf bifurcations. Beyond this low-order classification, a trajectory-space Cramér-Rao-type bound yields the universal scaling inequality −2≥0. Hence divergent responses require divergent fluctuations, but not conversely, making entropy-production fluctuations a sharper probe of nonequilibrium criticality.
