Freeman John Dyson (born 15.12.1923) is an American theoretical physicist and a member of the National Academy of Sciences (1964). He was born in Crowthorne (England). He graduated from the University of Cambridge (1945), where he worked in 1946-49. In 1951-53 he was professor at Cornell University and from 1953 at the Institute for Advanced Study in Princeton.
His research concerns quantum electrodynamics, quantum field theory, mathematical physics, low-energy physics, astrophysics (the problem of extraterrestrial civilisations, pulsars, neutron stars) and cosmology. He obtained important results in quantum field theory in connection with the proof of the dispersion relations (the Jost — Lehmann — Dyson representation) and in the theory of the S-matrix, where he derived a formula for the S-matrix (the Dyson formula). To classify the divergences in quantum electrodynamics he developed (1948) the method of canonical transformation (the Dyson transformation). He introduced (1949) the concept of the renormalisability of quantum electrodynamics as a fundamental property of the S-matrix. He showed (1949) the connection between the Feynman formalism of the S-matrix and the more usual form of relativistic quantum field theory (the Feynman — Dyson formalism). Along with J. Schwinger, R. Feynman and S. Tomonaga he is one of the creators of modern quantum electrodynamics.
He proposed (1955) a theory of resonance paramagnetic absorption in metals.
He is developing one of the main lines of the problem of extraterrestrial civilisations, the search for traces of the astro-engineering activity of highly developed extraterrestrial civilisations, and has considered a number of projects for the possible astro-engineering activity of a highly developed civilisation (the Dyson sphere project).
A Fellow of the Royal Society (1952). The H. Lorentz (1966) and M. Planck (1969) Medals.