Herman Weyl first developed this technique in his attempts to unify relativity and electromagnetism.  
Herman Weyl first developed this technique in his attempts to unify relativity and electromagnetism.  The first theory to make use of it in its general form addressed the effect of an electromagnetic field on a charged particle. For a principal bundle whose base space is spacetime and structure group is a Lie group, the space of smooth sections of this bundle form a group of these, and in Yang-Mills theory, the Wilson loop is invariable under them. Taking its name from acting on a degree of freedom whose change does not influence physical observable, FTP, identify this operation, whose best-known application is in picking the divergence of the vector potential.
Herman Weyl first developed this technique in his attempts to unify relativity and electromagnetism.  
gauge transformation (prompt on ”gauge”)