Spontaneous symmetry breaking
Suppose we have some laws describing how possible states ought to behave and they are symmetric
under a certain group
. But suppose, however, the lowest energy solution, i.e. the stable solution is not symmetric
under that group. This obviously means the lowest energy state is degenerate
and performing a symmetry transformation on any such state would just lead to another such state. However, from the point of view of an observer in a state close to one of these states, it looks as if the symmetry of the dynamical laws are broken.
This article is a stub. You can help Wikipedia by fixing it.