Related Experiment Video
Updated: Jul 14, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Entropy production and time asymmetry in nonequilibrium fluctuations
D Andrieux1, P Gaspard, S Ciliberto
1Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, Code Postal 231, Campus Plaine, B-1050 Brussels, Belgium.
Physical Review Letters
|May 16, 2007
Summary
This study experimentally verifies time-reversal symmetry in nonequilibrium fluctuations for Brownian motion and electric circuits. The findings link dynamical randomness to thermodynamic entropy production, offering insights into fundamental physics.
Area of Science:
- Non-equilibrium statistical mechanics
- Experimental physics
- Dynamical systems theory
Background:
- Understanding the behavior of systems far from thermodynamic equilibrium is crucial.
- Fluctuations in these systems exhibit unique properties not seen in equilibrium.
Purpose of the Study:
- To experimentally investigate the time-reversal symmetry of nonequilibrium fluctuations.
- To characterize the dynamical randomness of these fluctuations using theoretical frameworks.
- To establish a quantitative relationship between fluctuation properties and thermodynamic entropy production.
Main Methods:
- Experimental setup involving a Brownian particle in a moving trap.
- Experimental setup with an electric circuit under a mean current.
- Characterization of fluctuations using standard and time-reversed entropies per unit time.
Main Results:
- Experimental data collected for both the Brownian particle and electric circuit systems.
- Fluctuations were analyzed using dynamical systems theory metrics.
- A direct correlation was found between the difference in entropies and thermodynamic entropy production.
Conclusions:
- The experimental results confirm the theoretical predictions regarding time-reversal symmetry.
- The difference between standard and time-reversed entropies quantifies thermodynamic entropy production.
- This work provides an experimental validation of fundamental principles in non-equilibrium thermodynamics.
Related Concept Videos
01:14The Second Law of Thermodynamics
In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Scientists refer to the measure of randomness or disorder within a system as entropy. High entropy means high disorder and low energy. To better understand entropy, think of a student’s bedroom. If no energy or work were put into it, the room would quickly become messy. It would exist in a very disordered state, one of high entropy. Energy must be put...
02:49Second Law of Thermodynamics
In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Processes that involve an increase in entropy of the system (ΔS > 0) are very often spontaneous; however, examples to the contrary are plentiful. By expanding consideration of entropy changes to include the surroundings, a significant conclusion regarding the relation between this property and spontaneity may be reached. In thermodynamic models, the...
00:53Second Law of Thermodynamics
The Second Law of Thermodynamics states that entropy, or the amount of disorder in a system, increases each time energy is transferred or transformed. Each energy transfer results in a certain amount of energy that is lost—usually in the form of heat—that increases the disorder of the surroundings. This can also be demonstrated in a classic food web. Herbivores harvest chemical energy from plants and release heat and carbon dioxide into the environment. Carnivores harvest the chemical energy...
01:26Entropy and the Second Law of Thermodynamics
Consider an isolated system in which a hot object is placed in contact with a cold one. This is an irreversible process that eventually leads both objects to reach the same equilibrium temperature. It is crucial to note that the constituents of any substance exhibit increased disorder at higher temperatures. As a cold substance absorbs heat, its constituents become more disordered. The energy transfer from a hotter object to a cooler one increases the system's disorder or randomness. This...
01:20Entropy and the Second Law of Thermodynamics
The second law of thermodynamics can be stated quantitatively using the concept of entropy. Entropy is the measure of disorder of the system.
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...
02:39Entropy
Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...