He first worked on
plasma oscillations and took a postdoctoral position at Harvard with
Edward Mills Purcell. His interests evolved toward cosmology and the physics of the interstellar medium of galaxies. He was briefly on the faculty at Princeton before joining the faculty of the Department of Astronomy at the
University of California, Berkeley where he remained until 1973. He left to become the founding director of the
Center for Astrophysics (CfA) Harvard & Smithsonian, an organizational structure that unified the
Smithsonian Astrophysical Observatory (a government agency) and the
Harvard College Observatory (a private institution) under a single management. Field served as Director until 1982, after which he remained the Robert Wheeler Wilson Professor of Applied Astronomy at Harvard until retirement. He was succeeded in the CfA Directorship by
Irwin I. Shapiro. In the early 1980s, Field chaired an influential
National Academy of Sciences decadal study that recommended priorities for US astronomical research. It was the third of what has become an extended series of
Astronomy and Astrophysics Decadal Surveys, with format and goals now emulated by similar surveys in other disciplines. After his incumbency as CfA Director, his research focused on the theory of accretion disks in active galactic nuclei; cosmic
birefringence;
magnetohydrodynamics and magnetic fields in astronomy; and the structure of molecular clouds. == Doctoral students ==