Millennium Nucleus Physics of Active Matter

In the XIX and XX centuries, the emergence of thermodynamics and statistical mechanics was vital in the technological advances of the Industrial Revolution and generated many devices like integrated circuits, solar panels, or LCD screens. This development was possible because these theories allowed scientists to describe and predict the processes and properties of matter in thermal equilibrium. It was also possible to describe the processes slightly out of equilibrium, like the electrical and thermal conductivity and spread.

However, in nature, we can find the existence of matter out of equilibrium, for which thermodynamics tools and statistical mechanics have no use.
Although during the last 20 years there has been major progress in the study of the out of equilibrium systems, there is still no theory able to understand or predict all its processes, so they have become the new focus of interest of physics.
The great paradigm of these out of equilibrium systems is the active matter.

We have seen how flocks of birds, shoals of fishes, and other collectives of animals seem to move in a synchronous and organized way, to such a point that a swarm looks like having its own life. The same thing happens at a smaller level: bacterial suspensions, cellular tissues, and artificial swimmers show surprising and unpredictable group movements.
Physicists call “active matter” to these systems, a term coined to describe structures composed of many elements, either biological or artificial, where each individual can extract energy from the environment and generate movement or self-propulsion.
Why is it important to study active matter? As active matter presents many aspects of non-equilibrium physics, it is the perfect prototype to build and test a new theoretical framework for all these systems.
Besides, the cutting-edge technologies that use biological material, either at micro or nanoscale, incorporate active matter. So, describe and predict its properties and behavior, promise to impact the new technologies.
Finally, the study of active matter requires a multidisciplinary focus that includes the collaboration of physicists and biologists.

To deliver those answers is the aim of the Millennial Nucleus Physics of Active Matter, an academic center dedicated to research this field through the study of the self-organization and collective motion of the living beings, the necessary conditions for life, the energy flows, the information that exists inside a cell and the ability to generate self-assembled devices.
In the first triennial period, besides the theoretical and experimental research realized between 2017 and 2020, the Nucleus accomplished four graduated students and 16 publications. In the new triennial period (2021 to 2023), our Nucleus increased to six principal researchers, adding to the original team conformed by three researchers, two young ex-researchers, and one associate researcher.

Rodrigo Soto, Felipe Barra, María Luisa Cordero and Néstor Sepúlveda, from the Department of Physics of the University of Chile (DFI-FCFM); Francisca Guzmán Lastra from the Department of Physics of the University of Chile (DFC-UChile) and Juan Keymer from the Department of Natural Sciences and Technology of Universidad de Aysén. To this team, joints Miguel Concha from the Faculty of Medicine of the University of Chile, who continues as an associate researcher.
The whole team has experience in biophysics, fluids, and statistical mechanics, which allows them to study the physics of active matter theoretical, numerical, and experimentally. Besides, there is another multidisciplinary team of national and international researchers, who have been collaborating from South America, North America, Europe, and Asia.

Our main objective is to extend the thermodynamics and the statistical mechanics to the non-equilibrium conditions of the active matter.

With this objective in mind, during the next three years, we are going to research the following lines:

• Microfluidic manipulation of bacterial suspensions
• Statistical mechanics of the active matter
• Ecology-on-a-chip
• Stochastic thermodynamics theory
• Active colloids and confined swimmers
• Biomechanics and cellular migration