Biophysics and Soft Matter Seminar

Making a Two-Dimensional Thermal Ideal Gas by Shaking Your Breakfast

Wednesday, 08 November 2017 12:00PM PST
Biophysics and Soft Matter Seminar
Eric Corwin
Dept of Physics, University of Oregon
Making a Two-Dimensional Thermal Ideal Gas by Shaking Your Breakfast
Nov 08, 2017 at 12PM


Active, driven systems as diverse as flocking starlings, swarming bacteria, and vibrating granular beds are by definition non-equilibrium, lacking a well defined thermal temperature that characterizes their dynamics. Because of this, the creation of a coherent non-equilibrium statistical mechanics has proven elusive, and it remains unclear whether, for any non-equilibrium system, a meaningful effective temperature exists. We have constructed an active, driven system of chaotic faraday waves whose statistical mechanics, we find, are surprisingly simple, mimicking those of a thermal ideal gas. We use real-time tracking of a single floating probe, energy equipartition, and the Stokes-Einstein relation to define and measure a pseudotemperature, diffusion constant, and coefficient of viscous friction for a test particle in this pseudothermal gas. Because of its simplicity this system serves as a starting point for direct experimental investigation of non-equilibrium statistical mechanics, much as the ideal gas is the starting point for equilibrium statistical mechanics.