Abstract:
How can physics help us understand the remarkable organization and collective behaviour of living systems,
which operate far from thermodynamic equilibrium? Active matter provides a minimal physical framework for
addressing this question: individual constituents consume energy to generate stress or persistent motion,
while their interactions give rise to emergent collective behaviour.
In this talk, I will trace a path from the stochastic dynamics of a single active particle to collective motion
and, ultimately, to organization in living systems. I will begin with the stochastic thermodynamics of active
particles, focusing on how microscopic irreversibility can be quantified through entropy production. I will then
introduce an exact analytical framework that we developed for active-particle dynamics, and show how confinement,
inertia, chirality, and fluctuating propulsion give rise to non-trivial re-entrant transitions. Together, these
results highlight how exact approaches can help us build a deeper physical understanding of non-equilibrium dynamics.
I will then move from individual particles to the collective behaviour that emerges through interactions, including
ordering, phase separation, pattern formation, and collective motion. Finally, I will broaden the perspective to
biological systems, showing how ideas from statistical physics can help us understand chromosome organization and
segregation in bacteria, FtsZ-mediated Z-ring formation during cell division, and robust intracellular transport
by molecular motors.
Across these examples, theory is closely connected to experiment, with several of our predictions already supported
by observations. Together, they show how a small set of physical ingredients –stochastic dynamics, interactions,
confinement, and energy consumption — can generate rich organization across scales, highlighting the predictive
power of statistical physics in understanding living matter.
