Related Experiment Video
Updated: Jul 2, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Free-energy transition in a gas of noninteracting nonlinear wave particles
A Fratalocchi1, C Conti, G Ruocco
1Centro Studi e Ricerche Enrico Fermi, Via Panisperna 89/A, I-00184, Roma, Italy.
Abstract:
We investigate the dynamics of a gas of noninteracting particlelike soliton waves, demonstrating that phase transitions originate from their collective behavior. This is predicted by solving exactly the nonlinear equations and by employing methods of the statistical mechanics of chaos. In particular, we show that a suitable free energy undergoes a metamorphosis as the input excitation is increased, thereby developing a first-order phase transition whose measurable manifestation is the formation of shock waves. This demonstrates that even the simplest phase-space dynamics, involving independent (uncoupled) degrees of freedom, can sustain critical phenomena.
Related Concept Videos
Gibbs Free Energy
Entropy
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...
Free Energy Changes for Nonstandard States
Molecular Kinetic Energy
States of Matter and Phase Changes

