Ralph Chamberlin, Arizona State University

Two types of thermal fluctuations are found in solids: Johnson-Nyquist (white) noise at intermediate frequencies, with excess (1/f-like) noise at lower frequencies. Two other types of response dominate supercooled liquids: secondary (beta) response at intermediate frequencies and primary (alpha) response at lower frequencies. Although white noise is fully understood from normal thermal fluctuations, there is no widely accepted general explanation for the other three types of behavior. We find that a finite-size Ising model with microscopic constraints can mimic all four types of fluctuations. The key constraint is orthogonal dynamics, where conservation of energy and conservation of momentum never occur during the same Monte-Carlo step. I will give several examples showing simulations that match measured response. Then I will discuss how small-system thermodynamics provides a fundamental foundation for the model. Finally, if time permits, I will show how this “nanothermodynamics” also gives a novel solution to Gibbs’ paradox.