V. A. Fock and gauge symmetry

V. A. Fock, in 1926, was the first to have the idea of an Abelian gradient transformation and to discover that the electromagnetic interaction of charged particles has a gradient invariance in the framework of quantum mechanics. These transformation and invariance were respectively named Eichtransformation and Eichinvarianz by H. Weyl in 1929 (the German verb zu eichen means to gauge). The first non-Abelian gauge theory was suggested by O. Klein in 1938, and in 1954, C. N. Yang and R. L. Mills rediscovered the non-Abelian gauge symmetry. Gauge invariance is the underlying principle of the current Standard Model of strong and electroweak interactions.