## CANCELLED: The unreasonable effectiveness of cluster scaling

**Note:**https://bostonu.zoom.us/j/95421155441?pwd=c2p2WWZBRHdjdUVxQy9TWGVTZi9idz09

**Speaker:**Sakib Matin, Boston University, Physics Department

**When:**November 17, 2020 (Tue), 11:30AM to 12:30PM (add to my calendar)

*This event is part of the Preliminary Oral Exam. *

Equilibrium statistical mechanics requires assumptions such as a Hamiltonian description and ergodicity. Nevertheless, the tools of statistical mechanics have been successfully applied to models in biology and economics. I will focus on a specific example.

The Fisher-Stauffer scaling method has been applied to models of percolation and the Ising model. I generalize the Fisher-Stauffer cluster scaling to study the avalanches in the nearest-neighbor stochastic Olami-Feder-Christensen (OFC) model, which is believed to be a non-equilibrium system. The OFC model is a two-dimensional lattice of leaky integrate-and-fire sites. The strength of the noise determines if the model is effectively ergodic or non-ergodic. I show that the limit of vanishing dissipation corresponds to a critical point. I show that the Fisher-Stauffer scaling holds when the OFC model is effectively ergodic. The scale invariant behavior is consistent with the derived scaling laws. I derive universal scaling functions for the avalanche distributions and dynamics. However, Fisher-Stauffer scaling breaks down when the OFC model is non-ergodic. These results indicates that effective ergodicity may be a sufficient criterion for the validity of certain equilibrium tools such as cluster scaling.

https://bostonu.zoom.us/j/95421155441?pwd=c2p2WWZBRHdjdUVxQy9TWGVTZi9idz09

Meeting ID: 954 2115 5441 Passcode: 112015