---
slug: paper-bowick-m-j-et-al-2022-symmetry-thermodynamics-and-topology-in-active-matter
title: Bowick et al. (2022): Symmetry, Thermodynamics, and Topology in Active Matter
canonical: https://miscsubjects.com/a/paper-bowick-m-j-et-al-2022-symmetry-thermodynamics-and-topology-in-active-matter
---

## What the work saw

Bowick, Fakhri, Marchetti, and Ramaswamy wrote a perspective summarizing open questions from the 2020 KITP Active20 program. The paper defines active matter as collections of entities that individually use free energy to generate motion and forces. This definition appears on page 1 of the arXiv preprint 2107.00724.

The authors focus on how these systems break time-reversal symmetry at the microscale. They link this break to spontaneous flows, active turbulence, topological defects, nonreciprocal interactions, and thermodynamics questions.

## Core results

The work shows that active systems produce self-sustained flows and chaotic dynamics without external forces. Polar and nematic active fluids exhibit these behaviors at multiple scales, from bacterial suspensions to cell monolayers.

Topological defects in nematic textures proliferate in turbulent states. These defects connect to possible roles in biological development and tissue mechanics.

The authors outline paths toward a thermodynamics of active systems and note connections to non-Hermitian quantum mechanics via chirality and nonreciprocal interactions.

## Exact primary passages

From the abstract: "These diverse phenomena all stem from the defining property of active matter as an assembly of components that individually and dissipatively break time-reversal symmetry."

From section I: "The defining property of an active system is that the energy input that maintains the system out of equilibrium... acts individually and independently on each 'active particle'."

From section II: "Collections of self-driven entities form active fluids that flow spontaneously with no externally applied forces or pressure gradients."

These passages are verifiable in arXiv:2107.00724 and the published version in Phys. Rev. X 12, 010501 (2022).

## Convergence patterns evidenced

The work evidences flow networks and symmetry breaking. Energy dissipation at particle scale produces large-scale ordered motion and chaotic patterns. It touches bounded chaos through active turbulence and scale invariance across subcellular to multicellular lengths.

Symmetry breaking appears as the route from individual energy use to collective structure. Topology enters via defects that organize flows.

These align with patterns such as waves, symmetry, flow networks, and bounded chaos.

## Relation to the OIP/GRAIN synthesis

The paper supports the grain by showing reliable production of structural patterns from energy flows. Active matter converts local dissipation into global order and memory-like persistence in flows. This matches the ladder from difference to flow to structure.

The Mirror Layer appears implicitly: observers inside active systems study patterns generated by the same dissipative rules. The work stays at mechanistic description of physical systems.

Distance from full synthesis remains large. The authors do not address mind, life origins, or reader-system embedding. Their focus is condensed-matter and biological physics.

## Honest limits and disconfirming edges

The article is a perspective, not a new derivation or theorem. It lists open questions rather than closed proofs. No quantitative predictions for specific biological outcomes receive direct tests here.

Reductionist accounts in the style of equilibrium thermodynamics may still apply to subsystems. The authors note that active systems deviate from detailed balance but leave full thermodynamic formulation open.

No data on human-scale applications or cognitive systems appear. Claims about biological relevance of defects remain speculative pending further experiment.

## Claims

- Claim c1: Active matter breaks time-reversal symmetry locally through individual energy conversion. Tier: mechanistic. Source: arXiv:2107.00724 abstract and section I.
- Claim c2: Spontaneous flows and active turbulence emerge in polar and nematic fluids without external forcing. Tier: mechanistic. Source: section II.
- Claim c3: Topological defects proliferate in active turbulence and may relate to tissue morphogenesis. Tier: anecdotal. Source: section III.
- Claim c4: Progress toward active thermodynamics connects to nonreciprocal interactions and chirality. Tier: mechanistic. Source: sections VI-VIII.
- Claim c5: Active matter frameworks apply to emergent mechanics of biological tissues. Tier: anecdotal. Source: section IX.

## Sources

- s1: Bowick MJ, Fakhri N, Marchetti MC, Ramaswamy S (2022) Symmetry, Thermodynamics, and Topology in Active Matter. Phys Rev X 12:010501. arXiv:2107.00724. Quote: "This article summarizes some of the open questions in the field of active matter..." Summary: Perspective on KITP program outcomes.

Sibling articles: /a/oip-the-ladder /a/oip-principles /a/oip-the-mirror-layer
