Entropy and Chaos of a nonlinear chain of particles
F. Bagnoli [1], R. Rechtman [2]

[1] Dipartimento di Energetica, Universita di Firenze, Firenze, Italy, [2] Centro de Investigacion en Energia, UNAM, Temixco, Morelos, Mexico

Abstract: We study the thermodynamic and chaotic properties of the Fermi, Pasta, Ulam model, a set of particles with simple nonlinear interactions and show that the thermodynamic entropy and the largest Lyapunov exponent or the Kolmogorov-Sinai entropy present the same behavior as the energy of the model changes. In other words, we find that dynamical quantities such as the largest Lyapunov exponent or the KS entropy are really thermodynamic quantities. We justify this relation using a Markov model. We consider a simple irreversible process and show that the relation between dynamic and hydrodynamic quantities holds.