After the war, in August 1945 Sachs enrolled in the Navy Eddy program in Chicago learning about electronics and radar equipment.

In July 1946, Sachs spoke with the executive officer of the ship, explaining that he wanted to go to college and study physics and received an early honorable discharge from the Navy in August 1946.

During that time Columbia's physics department was chaired by Isidor Isaac Rabi and was home to two Nobel laureates (Rabi and Enrico Fermi) and seven future laureates (Polykarp Kusch, Willis Lamb, Maria Goeppert-Mayer, James Rainwater, Norman Ramsey, Charles Townes and Hideki Yukawa) While at Columbia Sachs was taught by Willis Lamb and Hideki Yukawa.

In his new job Sachs intended to get in contact with Albert Einstein at his office at the Institute for Advanced Study, Princeton to arrange an appointment to discuss his research program.

While at Lockheed Sachs began developing with Solomon Schwebel a field theory of quantum electrodynamics that included broken symmetries that did not require recourse to renormalization or perturbation techniques – the "Schwebel-Sachs" model.

Sachs argued that the work of Albert Einstein and Erwin Schrödinger in general relativity did not yet take account of the inertia of matter, which required consideration of the Mach principle.

In the summer of 1966 Abdus Salam invited Sachs to spend a few months at the International Centre for Theoretical Physics, in Trieste, Italy.

During this time Sachs published the details of his formal structure of quantum mechanics from a generally covariant field theory of inertia in the Italian journal, Il Nuovo Cimento.

[8] A symposium was held in Sachs honour to mark his retirement, the event was attended by Nobel laureates Willis E. Lamb and Herbert A. Hauptman and a subsequent festschrift was published.

Sachs described how quantum mechanics, first in relativistic two-component spinor form, and then under low energy-momentum as Schrödinger's equation emerges therefrom.

[8] Through general relativity, he instead produced a myriad of theoretical results without resorting to arbitrary parameters or renormalization, some in closer agreement with experiment than derived from quantum field theory, e.g. for the Lamb splitting with N = 4.