Geometrization in the Yang-Mills,extended supergravity,and Klein-Kaluza versions

We relate personal encounters of three kinds with geometrical approaches in the development of a relativistic quantum field theory of the fundamental interactions—including interactions with Nathan Rosen. We characterize the geometrical structures involved and discuss the more recent attempts to develop a unified theory based on a Klein-Kaluza contraction of the eightfold extended supergravity.Publisher's note: The full paper will appear inFoundations of Physics, Volume 15, Number 3, March 1985.