2008/05/30 by E. G. D. Cohen · 1 citation
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Phase Equilibria and Thermodynamics #Quantum Electrodynamics and Casimir Effect #cond-mat.stat-mech
paper · pdf · doi:10.1088/1742-5468/2008/07/p07014
published as J. Stat. Mech.: Theory and Experiment, P07014 (2008). · 31 pages, 4 figures. Three changes made to this version; 1) On the line below equation 18 subscript w has been removed from italic L 2) In section 9. Comments and Open Questions, the last sentence of the last paragraph of comment 6 has been replaced by: "Although...average". 3) In the Acknowledgements, an additional acknowledgement has been made to J. Alonzo
arxiv created 2008/05/30 · openalex publication_date 2008/07/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
A number of properties of systems in a nonequilibrium steady state (NESS) are investigated by a generalization of the Onsager–Machlup (OM) path integral approach for systems in an equilibrium state (ES). A thermodynamics formally identical to that in an ES can be formulated, but with definitions of work and heat as needed to maintain the NESS. In this approach, the heat plays a crucial role and is directly related to the different behavior of a system's forward and backward paths in time in an appropriate function space. However, an ambiguity in the choice of the time-backward path corresponding to a given time-forward path prevents a unique general formal theory for systems in a NESS. Unique unambiguous physically acceptable physical results for a system in a NESS appear to be obtainable only after specifying the physical nonequilibrium parameters, which define a system in a NESS as part of a larger system. NESS systems are therefore fundamentally different from those in an ES. Furthermore, an example is given for a particular system that the fluctuations of a system in a NESS behave in many respects very differently from those in a system in an ES.