Entropy of state transitions in macroscopic active matter

TL;DR

This paper introduces a framework to measure entropy in macroscopic active matter systems, demonstrating phase transitions characterized by entropy changes, bridging thermodynamics and active matter physics.

Contribution

It presents a novel method to quantify entropy in active matter and shows that such systems can undergo phase transitions similar to classical thermodynamic systems.

Findings

Active matter exhibits entropy-driven phase transitions.

Discrete entropy jumps correspond to changes in degrees of freedom.

Active systems can be analyzed using thermodynamic principles.

Abstract

The extension of thermodynamic principles to active matter remains a challenge due to the non-equilibrium nature inherent to active systems. In this study, we introduce a framework to assess entropy in our minimal macroscopic experiment based on the utilized degrees of freedom. Using motorized spheres as active particles, we demonstrate that the system transitions between distinct active states. Analogous to the phase transition in classic solids, liquids, and gases, each phase is characterized by a quantifiable change in entropy. We show that the corresponding phase transitions are accompanied by discrete jumps in entropy, resulting from newly utilized degrees of freedom. Our findings reveal that active matter can exhibit phase transitions analogous to classical thermodynamic systems, quantifiable in terms of their entropy and temperature. By bridging equilibrium thermodynamics and active matter, this work shows how underlying principles extend to complex, living systems.