Towards a thermodynamics of active matter

Area of Science:

• Physics
• Thermodynamics
• Soft Matter Physics

Background:

• Living systems exhibit self-organization and unique phase behavior due to self-propulsion.
• Active matter systems operate far from thermal equilibrium, challenging classical thermodynamic laws.

Purpose of the Study:

• To explore the applicability of classical thermodynamic concepts to nonequilibrium active matter.
• To develop a predictive theory for phase separation in active matter systems.

Main Methods:

• Development of a simple theory based on the swim pressure perspective.
• Utilizing purely mechanical arguments to construct a phase diagram.
• Defining a nonequilibrium chemical potential to interpret phase boundaries.

Main Results:

• Generation of a phase diagram for active matter, including a spinodal and critical point.
• Successful generalization of thermodynamic concepts (free energy, temperature) for active systems.
• Quantitative and qualitative agreement between the theory and existing simulation data.

Conclusions:

• The swim pressure theory provides a robust framework for understanding active matter.
• This approach offers a method for predicting phase separation in nonequilibrium systems.
• The study bridges classical thermodynamics and the behavior of active matter.