We review the concept of dynamical ensembles in nonequilibrium statistical mechanics as specified from an action functional or Lagrangian on spacetime. There, under local detailed balance, the breaking of time-reversal invariance is quantified via the entropy flux, and we revisit some of the consequences for fluctuation and response theory. Frenesy is the time-symmetric part of the path-space action with respect to a reference process. It collects the variable quiescence and dynamical activity as function of the system's trajectory, and as has been introduced under different forms in studies of nonequilibria. We discuss its various realizations for physically inspired Markov jump and diffusion processes and why it matters a good deal for nonequilibrium physics. This review then serves also as an introduction to the exploration of frenetic contributions in nonequilibrium phenomena.

中文翻译：

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Frenesy：非平衡中的时间对称动力活动

我们回顾了非平衡统计力学中动力学系综的概念，如时空上的作用泛函或拉格朗日函数所指定的。在那里，在局部详细平衡下，时间反转不变性的破坏是通过熵通量量化的，我们重新审视了波动和响应理论的一些后果。Frenesy 是路径空间动作相对于参考过程的时间对称部分。它收集变量静止和动态活动作为系统轨迹的函数，并在非平衡研究中以不同形式引入。我们讨论了它对受物理启发的马尔可夫跳跃和扩散过程的各种实现，以及为什么它对非平衡物理学很重要。