Electromagnetic pion production: From Yukawa to Goldstone

The evolution of electromagnetic pion production is presented. The early experiments verified that the reaction mechanism of pion production in nuclei was understood; some open issues which can now be studied with CW electron beams are discussed. Emphasis is given to the present studies which measure meson production from the nucleon. The impact of spontaneously broken chiral symmetry and Goldstone's theorem on pion-nucleon physics is sketched. Present and future experiments to measure quark mass effects such as isospin breaking are described. The role of the new generation of beam and target polarization experiments are stressed, including such future possibilities at Bates as virtual photon tagging