The fourth roundtable was an opportunity for all students to discuss the topic “Collective Behavior” on Zoom with a panel of guests: Clemens Bechinger from the University of Konstanz, Ivo Buttinoni from Heinrich Heine University in Dusseldorf and Caroline Beck Adiels from Gothenburg University. The event was organized by Daniela Pérez, Danne van Roon, Davide Breoni, Jérémie Bertrand, Laura Natali and Liam Ruske on March 24th.
Although the guests had different background they seemed to agree on the fact that complex behavior can emerge from an ensemble of entities that obey a small number of simple rules. Indeed, minimalistic models such as the Vicsek model account for phase transition from a disordered motion to large scale motion and more; phenomena that appear to be universal.
A question on the role of intelligence and communication in collective behavior started the discussion. Although some animals or colony of bacteria may seem intelligent (e.g. escaping from a predator in a clever way or making long-lasting symbiotic microfilms), we must bear in mind that collective behavior is… collective, and rarely arises from decisions made individually. It may be said that in the animal kingdom, the need for survival requires a need to adapt and therefore to be intelligent, but this need for intelligence can be outsourced and solved at the level of the group rather than hardwired in the physical brain of each animal (or human).
It is also conceivable that one of the entities acts as a leader and ignites a collective behavior. Giovanni Volpe made an interesting remark, stating that a leader is the one who defines the objective function to be optimized by the group. The idea of leadership in collective behavior of microscopic systems remain largely unexplored by physicists.
After one hour of fruitful discussion and back and forth between the students and the guests, the session was finished and we resumed our activities with a better understanding of collective behavior. We thank the panelists for their inputs and attendance!
The topic of the round table was phoretic propulsion mechanisms and we
had four panelists – Juliane Simmchen, Frank Cichos, Ivo Buttinoni and Felix
Ginot – and a guest speaker, Antoni Homs Corbera. After a brief introduction of
the panelists, we had a chance to ask all the questions we collected from the
The discussion started with the definition of the term “phoresis” and continued with the simulation frameworks for phoretic colloids. It included a brief discussion of the complexity involved in these processes and the typical length scales at which interfacial effects are relevant.
The conclusion was “a common joke at conferences is that the phoresis starts when coffee is about to be served”. The real conclusion was that phoretic interaction needs very large gradients on the macroscopic scale and is hidden by diffusion on a very small scale.
All participants had the possibility to jump in and add upcoming questions. We ended the round table by discussing the possible applications of phoretic colloids, highlighting the environmental aspects like microplastics’ filtration in water.
We thank all the guests and participants for making it a successful discussion moment.
On the 10th of September, at the online kick-off meeting of the ActiveMAtter ITN, the ESRs presented themselves to the other members of the network. A short video in which Danne van Roon introduces himself can be found below.
The ActiveMatter PI+ESRs meeting took place on 10 September 2020. Because of the current travel restrictions and regulations imposed to hinder the spread of the CoViD-19 epidemics, the meeting was held online.
The aim of the meeting was to give an update to all the members on the progress of the ActiveMatter network.
Currently 12 of the 15 Early Stage Researchers (ESRs) have already been recruited and could started their project. During the meeting the ESRs had the opportunity to introduce themselves to the rest of the network and to present their research project.