SWARM INTELLIGENCE

Active Matter

I first caught wind of Active Matter through the work of one of my favorite researchers, Tamas Vicsek, whose intellectual bling includes a fractal bearing his name.

My understanding of this sprawling sub-domain of physics is that we can study the activity of individuals agents and systems as though studying something like hydrodynamics, kinematics, and non-equilbrium statistical phsyics. Crowds become streams. Flocks become rivers. Networks of agents become oceans.

It is this vision of Active Matter that I’ll be discussing in this post, and on my site in general, but make not mistake of it, this field is awesome and sprawling, and worthy of a more extensive tour than I will ever be able to give.

Collective Motion

What governs the shape of a moving crowd leaving a moving theater? We know there’s not a central choreographer, and I don’t think we’d go so far as to say we have a genetic predisposition to filing out of a theater, so why is it we can identify patterns in crowd dynamics?

The interesting behavior outlined in Vicsek et al’s paper Novel Type of Phase Transition in a System of Self-Driven Particles is a phase transition as agents fall into sync. Just as there is a specific moment, a phase transition, from gas to liquid, there is a point of inflection in system. There are a lot of assumptions in the model though, including particles that maintain a constant absolute velocity, with an update to the average direction of neighbors in each time step. How are neighbors calculated (the range of perception)? Does doubt play a role? Such questions are not addressed in this article, nor are they immediately relevant, but I ask them to hightlight the distance between the assumptions of this model and real, biological system Such questions are not addressed in this article, nor are they immediately relevant, but I ask them to hightlight the distance between the assumptions of this model and real, biological system Such questions are not addressed in this article, nor are they immediately relevant, but I ask them to hightlight the distance between the assumptions of this model and real, biological systems.