Related Experiment Video
Updated: Aug 19, 2026

Thermocapillary Convection Space Experiment on the SJ-10 Recoverable Satellite
Published on: March 11, 2020
Independence of the transient fluctuation theorem to thermostatting details
Stephen R Williams1, Debra J Searles, Denis J Evans
1Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
Abstract:
The fluctuation theorems show how macroscopic irreversibility arises from time reversible microscopic dynamics. They have been confirmed in computer simulations and in laboratory experiments. The standard proofs of the transient fluctuation theorems involve the use of time reversible deterministic thermostats to control the temperature of the system of interest. These mathematical thermostats do not occur in Nature. However, since in a gedanken experiment the thermostatting regions can be removed arbitrarily far from the system of interest, it has been argued that the precise details of the thermostat cannot be important and that the resulting fluctuation theorems apply to natural systems. In this paper we give a detailed analysis showing how the fluctuation theorem is independent of the precise mathematical details of the thermostatting mechanism for an infinite class of fictitious time reversible deterministic thermostats. Our analysis reinforces the implications of the gedanken experiment and implies that thermostats used in the derivations of fluctuation theorems are a convenient but ultimately irrelevant device.
Related Concept Videos
Control System Problem
When forming a closed-loop system, issues can arise if the poles cross into the unstable region, leading to potential...
Reynolds Transport Theorem
Joule-Thomson Effect
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
Transient and Steady-state Response
These test signals are integral in designing control systems to exhibit two key performance aspects: transient response and steady-state response.
Zeroth Law of Thermodynamics
Entropy
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
