Spontaneous Symmetry Breaking

Spontaneous symmetry breaking describes a physical situation in which the underlying laws or equations governing a system are symmetric, but the system's actual lowest-energy, or ground, state is not, so the system settles into one of several equally possible asymmetric configurations. Yoichiro Nambu applied the concept from condensed matter physics, where it explains phenomena such as superconductivity, to particle physics in the early 1960s, work recognized in his share of the 2008 Nobel Prize in Physics. The idea became central to the electroweak theory once Peter Higgs and, independently, Robert Brout, Francois Englert and others showed in 1964 that spontaneous symmetry breaking of an underlying field, now called the Higgs field, could explain how fundamental particles acquire mass while leaving the theory's equations themselves symmetric. The mechanism is now a standard feature of the Standard Model of particle physics, confirmed experimentally by the 2012 discovery of the Higgs boson at the Large Hadron Collider.