Soon after the war Dyson was the first physicist who realised Q.E.D. theory has 2 different faces. One face was researched by Richard Feynman alone and the other one by Julian Schwinger[?] and Sin-Itiro Tomonaga.
From 1957 to 1961 he worked on the Orion project, which demonstrated the possibility of space-flight using nuclear propulsion: a prototype was demonstrated using conventional explosives, but a treaty banning the use of nuclear weapons in space caused the project to be abandoned.
In one of his papers, he made the observation that it was possible that a growing technological society would increasingly surround its native star so as to maximise the capture of available energy. The end point of this process would be the complete enclosure of the star; all wavelength from visible light downwards being intercepted and waste heat being radiated outwards as infrared radiation. Therefore, one method of searching for extraterrestrial civilisations would be to look for suspiciously large objects radiating in the infrared. Dyson actually conceived of such a structure as being a cloud of asteroid-sized habitats, though science fiction writers have preferred a solid structure: either way, such an artifact is often referred to as a Dyson sphere.
He has published a number of collections of speculations and observations about technology, science, and the future:
His daughter is the well-known Esther Dyson.