Understanding Statistical Mechanics and Biophysics Using Excel

A new approach to teaching statistical mechanics and biophysics is presented using the classic two-box system from statistical mechanics as an example. This approach makes advanced physics concepts accessible to a broad audience including undergraduates with no calculus background. Students develop a simple Excel spreadsheet that implements a kinetic Monte Carlo (kMC) simulation algorithm ``from scratch''. The students discover for themselves the properties of the system by analyzing the simulation output in a directed, activity-based exercise. By changing the number and initial distribution of the particles, students see how the system approaches equilibrium and how system variability changes with system size. A finite difference solution is also implemented in Excel, and students compare its predictions with the kMC results. This approach is quite different from using ``canned'' computer demonstrations, as students design, implement and debug the simulation themselves -- ensuring that they understand the model system intimately.