Goldstone's Theorem

Goldstone's Theorem states that when a system's underlying symmetry is spontaneously broken—meaning the system's lowest energy state no longer exhibits that symmetry—massless particles called Goldstone bosons naturally emerge. These particles can be thought of as ripples or excitations resulting from the broken symmetry and are fundamental in understanding phenomena in particle physics and condensed matter systems. Essentially, the theorem links the breaking of symmetries at a fundamental level to the appearance of these unique, massless particles, highlighting how symmetry principles shape the behavior of physical systems.