Because this theory explain all of chemistry and the reason for the various properties of substances, it was hailed a success, but there was still no answer to the interaction between light and matter: Maxwell's Electrodynamics had to be altered to align with quantum theory, which began to be developed in 1929 by Dirac.

Electrodynamics

This departure is necessitated by the results of experiment: it is known that the forces of Electrodynamics are not sufficient to describe the observed stability of atoms and molecules, which provides definite physical and chemical properties to all material/matter.

If there is a beam of light, shone through tourmaline, which has thqe property of letting through only light which is plane polarized perpendicular to the axis, classical Electrodynamics indicates what will happen with the incident beam with any polarization.

The earliest field theory, is gifted to us via James Clerk Maxwell, who developed the formula forElectrodynamics, but while this contained a gauge symmetry, it went unnoticed.