Nearly a century ago, Hendrik Lorentz described the problem of studying the motion of an electron when subjected to reflections as it traverses a field of massive particles.
Probability theory plays a role in the distribution of the point process of massive particles.
The extreme difficulty of the original problem is attenuated when the motion of the electron is itself subjected to random fluctuations. Under certain conditions one may prove results concerning localisation and central limit behaviour. A key source of techniques is percolation theory. In this talk, versions of the physical problem will be formulated in simple ways accessible to anyone with experience of tossing coins. Links with percolation theory will be described, and some basic properties of the percolation model will be presented.