New theory identifies how physics principle of 'rattling' relates to self-organization

Rattling news!

"... This goal is the motivation behind a recently introduced principle of physics called rattling, which posits that systems with sufficiently "messy" dynamics organize into what researchers refer to as low rattling states. ...

how rattling is related to the amount of time that a system spends in a state. Their theory further identifies the classes of systems for which rattling explains self-organization. ..."

From the significance and abstract:

"Significance

Fundamentals of statistical physics explain that systems in thermal equilibrium exhibit spontaneous order because orderly configurations have low energy. This fact is remarkable, and powerful, because energy is a “local” property of configurations. Nonequilibrium systems, including engineered and living systems, can also exhibit order, but there is no property analogous to energy that generally explains why orderly configurations of these systems often emerge. However, recent experiments suggest that a local property called “rattling” predicts which configurations are favored, at least for a broad class of nonequilibrium systems. We develop a theory of rattling that explains for which systems it works and why, and we demonstrate its application across scientific domains.

Abstract

The global steady state of a system in thermal equilibrium exponentially favors configurations with lesser energy. This principle is a powerful explanation of self-organization because energy is a local property of configurations. For nonequilibrium systems, there is no such property for which an analogous principle holds, hence no common explanation of the diverse forms of self-organization they exhibit. However, a flurry of recent empirical results has shown that a local property of configurations called “rattling” predicts the steady states of some nonequilibrium systems, leading to claims of a far-reaching principle of nonequilibrium self-organization. But for which nonequilibrium systems is rattling accurate, and why? We develop a theory of rattling in terms of Markov processes that gives simple and precise answers to these key questions. Our results show that rattling predicts a broader class of nonequilibrium steady states than has been claimed and for different reasons than have been suggested. Its predictions hold to an extent determined by the relative variance of, and correlation between, the local and global “parts” of a steady state. We show how these quantities characterize the local-global relationships of various random walks on random graphs, spin-glass dynamics, and models of animal collective behavior. Surprisingly, we find that the core idea of rattling is so general as to apply to equilibrium and nonequilibrium systems alike."

New theory identifies how physics principle of 'rattling' relates to self-organization

Rattling Physics with New Math (original news release)

A local–global principle for nonequilibrium steady states (no public access)

Professor Dana Randall

Self-organization: What robotics can learn from amoebae

Amazing stuff!

"... Background: The term “active matter” refers to biological or technical systems from which larger structures are formed by means of self-organization. Such processes are based upon exclusively local interactions between identical, self-propelled units, such as amoebae or indeed robots.

Inspired by biological systems, ... authors propose a new model in which self-propelled agents communicate with each other. These agents recognize chemical, biological, or physical signals at a local level and make individual decisions using their internal machinery that result in collective self-organization. This orientation gives rise to larger structures, which can span multiple length scales.

The new paradigm of communicating active matter forms the basis of the study. Local decisions in response to a signal and the transmission of information, lead to collectively controlled self-organization.

... a possible application of the new model in soft robots – which is to say, robots that are made of soft materials. Such robots are suitable, for example, for performing tasks in human bodies. They can communicate with other soft robots via electromagnetic waves for purposes such as administering drugs at specific sites in the body. The new model can help nanotechnologists design such robot systems by describing the collective properties of robot swarms. ..."

From the abstract:

"The emergence of collective motion among interacting, self-propelled agents is a central paradigm in non-equilibrium physics. Examples of such active matter range from swimming bacteria and cytoskeletal motility assays to synthetic self-propelled colloids and swarming microrobots. Remarkably, the aggregation capabilities of many of these systems rely on a theme as fundamental as it is ubiquitous in nature: communication. ... Here we report on the multi-scale self-organization of interacting self-propelled agents that locally process information transmitted by chemical signals. We show that this communication capacity dramatically expands their ability to form complex structures, allowing them to self-organize through a series of collective dynamical states at multiple hierarchical levels. Our findings provide insights into the role of self-sustained signal processing for self-organization in biological systems and open routes to applications using chemically driven colloids or microrobots."

Self-organization: What robotics can learn from amoebae LMU researchers have developed a new model to describe how biological or technical systems form complex structures without external guidance.

Multi-scale organization in communicating active matter (open access)

Credits: Self-organization: What robotics can learn from amoebae -- ScienceDaily

Fig. 1: Schematics of the agent-based model for communicating active matter and summary of collective dynamic states.