In physics, a global symmetry is a symmetry that holds at all points in the spacetime under consideration, as opposed to a local symmetry which varies from point to point. Global symmetries require conservation laws, but not forces, in physics. An example of a global symmetry is the action of the (for a constant – making it a global transformation) group on the Dirac Lagrangian: : Under this transformation the wavefunction changes as and and so: :