Effective theories for dissipative and active matter

Lunch will be provided at 12:00pm, so please come early to eat mingle and eat lunch before the talk begins.

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Abstract:

The Wilsonian paradigm of organizing phases of matter by the symmetries they obey (and break!) is a central tool for understanding equilibrium statistical physics. Can such a program exist for nonequilibrium systems as well? In this talk, I will introduce an effective theory framework for dissipative classical systems both in and out of equilibrium, which describes stochastic dynamics in the presence of a thermal bath as well as nonthermal active matter. Rather than simply guessing stochastic equations, we derive them carefully based on symmetry principles.  The most important symmetry is a generalized time-reversal symmetry, which is sensible even for active matter. Our formalism streamlines derivations of dissipative thermal dynamics such as Landau-Lifshitz-Gilbert spin dynamics or frictional rigid body rotation. More importantly, it generates effective theories for active matter: non-reciprocal matter with predator-prey dynamics, active fluids and solids, and active phase separation.  I will highlight some illustrative examples of the generality and practicality of our new way of thinking about non-equilibrium classical phases.