Description
The nearly 80-year-old correlated electron problems remain largely unsolved; with one stunning success being BCS electron-phonon mediated "conventional" superconductivity. There are dozens of families of superconductors that are "unconventional" including the high-T cuprates, iron-based, and heavy fermions. Although these materials are disparate in many properties, some of their fundamental properties are strikingly similar, including their ubiquitous phase diagram; with intriguing correlated-electron phases above the superconducting transition. These remain among the greatest unsolved problems in physics, today; and a fun analogy stressing this will be presented.