Our third class was devoted to exploring random processes through random walks. Many physical processes in nature – diffusion, radiation, conduction, current flow, fluid dynamics – can be modeled as a random process. This is certainly true at the quantum mechanical level, where there is inherent uncertainty in the position-momentum of a particle due to its wave-like nature (modeled as a probability wave function); this is Planck’s Uncertainty Principle. But even in “deterministic” classical mechanics, randomness plays a role in modeling complexity; it is simply too hard to measure the precise state of every particle in a system and all of the forces involved. This is where statistical mechanics and thermodynamics become important.