ABSTRACT
One of the most fundamental notions of physics is that of symmetry: the idea that certain systems, or properties of a system, or laws governing a system, remain unchanged when people do something to them. Invariance is the term used to describe properties of a system that do not change when a symmetry transformation is performed. Symmetries can be either continuous or discrete. In particle physics the most common thing that is transformed under a symmetry operation is the wavefunction of a particle or set of particles. The symmetries of the system are transformations that act on the wavefunction via multiplication by complex matrices. Lie groups are important in physics because most of the symmetries people consider are continuous symmetries. The action of any group on a wavefunction multiplet will result in a rearrangement of multiplet components.
