1. Introduction

The appeal of symmetry is deep. It conveys ideas of perfection, balance, and equilibrium. It makes reality seem rational and understandable. It soothes our spirits and provides a notion that the world is perfectly equitable and unbiased. And so, humans have searched for symmetry everywhere, and when nature did not abide, we imposed symmetric ideals. Mountains, rivers, and planets are irregular and asymmetric. But the human imagination has proven itself powerful and, through amazing conceptual jumps, attempted to impose symmetry onto nature. Triangles, circles, squares: all are completely imaginary figures, idealized concepts that have no connection to reality. Physics—as we will see—created several theoretical symmetries based on beautiful mathematical theories. But all these theories require the establishment of numerous symmetry-breaking events to be compatible with the known universe. So, while people search for symmetry, the key to existence is asymmetry.