The theory used to describe the phenomena of infinite smallness arose early in the twentieth century. Quantum mechanics produced a coherent description of the atom and of the interactions of its constituent parts; better yet, it provided a standard model that unified three of the four forces at work in nature. Unfortunately, it conflicted with gravitation. In this program, the methods of particle physics are detailed by, among others, Murray Gell-Mann, Steven Weinberg, Burton Richter, Ugo Amaldi, and Pierre Dariulat. (26 minutes)