Physics Colloquium: Emergent phenomena—from starlings to spin liquids

Some of the most exciting problems and phenomena in physics today come not from the fundamental interactions of a few particles, but the novel collective behavior of many particles. While we understand the behavior of a single electron extremely well, the behavior of 10^23 electrons is more readily described by collective modes of all of the electrons, which themselves behave like novel types of fundamental particles. Spin liquids are one such emergent phase of matter; at high temperatures, these phases can be described as an independent magnet sitting at each site of a lattice, but at low temperatures they develop strong correlations, leading to exotic critical collective behavior. In this talk, we will explore several examples of critical collective behavior, from starlings to the critical point of water to spin liquids.