Diffusion is pervasive in the natural world. Over one hundred years ago Einstein created a remarkably simple and powerful theory describing the behavior of a single diffusing particle. That theory has since been applied countless times to successfully model widely disparate systems. In this talk, Ivan will explain a failure of this theory when applied to systems with many particles diffusing in the same environment. In particular, in such systems, the particles that move the furthest (the extremes of the diffusion) are governed by behaviors much different than would follow from Einstein's theory.