Ergodic theory of nonlinear waves in discrete and continuous excitable media

Abstract

In this thesis, we analyze discrete and continuous models of excitable media with the intention to reveal similarities between both approaches in terms of wave propagation and interaction. While the discrete perspective is represented by the one-dimensional Greenberg-Hastings cellular automata (GHCA), as a continuous model we consider the $\theta$-equations which are basic partial differential equations (PDE) for pure phase dynamics. On the one hand, qualitatively, collision and annihilation of waves can be observed in both models in striking resemblance. However, on the other hand, it turns out that a quantitative comparison of discrete and continuous wave interactions is limited due to weak wave interactions in the PDE. Specifically, complexity considerations show that a direct comparison of discrete and continuous strong wave interactions is problematic.