In 1982, the Nobel Prize in physics was awarded to Ken Wilson for his contribution to understanding what goes on in certain materials as they undergo a phase transition—like the transition between liquid water and steam. For certain kinds of phase transitions, it turns out that the governing laws of physics conform to a very peculiar, fractal symmetry. That is, the physical laws are the same whether considered at small scales or large scales. The consequences of this odd scale-change symmetry are profound. It turns out that quite diverse systems—not just water—exhibit the same, universal behavior as long as they conformed to the same scale-change symmetry.