sentences:  He continued this line of work after receipt of his Ph.D. on a National Research Council Fellowship at the California Institute of Technology (Caltech) during the period 1925 to 1927.Max Born, Director of the Institute for Theoretical Physics at the University of Göttingen and co-developer of the matrix mechanics formulation of quantum mechanics with Werner Heisenberg, came to Caltech in the winter of 1925 and gave a lecture on his work.Born’s lecture gave Eckart the impetus to investigate the possible general operator formalism for quantum mechanics.