Spontaneous symmetry breaking is a mode of realization of
symmetry breaking in a physical system, where the underlying laws are
invariant under a
symmetry transformation, but the system as a whole changes under such transformations, in contrast to
explicit symmetry breaking. It is a
spontaneous process by which a system in a
symmetrical state ends up in an asymmetrical state. It thus describes systems where the equations of motion or the Lagrangian obey certain symmetries, but the lowest-energy solutions do not exhibit that
symmetry.