What theory was cited in Feynman's 1965 Nobel Prize work?

What theory was cited in Feynman’s 1965 Nobel Prize work? It was quantum electrodynamics.

Quantum electrodynamics, usually abbreviated QED, is the quantum theory of electromagnetism. It describes how charged particles such as electrons interact with light, treating electromagnetic forces through exchanges involving photons. QED became one of the most precisely tested theories in modern physics.

Feynman shared the 1965 Nobel Prize in Physics with Julian Schwinger and Shin’ichirō Tomonaga for their fundamental work in QED. Their formulations were not initially presented in the same mathematical style: Feynman emphasized space-time methods and diagrams, while Schwinger and Tomonaga developed more formal field-theoretic approaches.

Freeman Dyson later demonstrated that the methods were equivalent and helped make Feynman’s diagrammatic techniques broadly usable. The answer is not general relativity, which describes gravity, or string theory, a later speculative framework. Plate tectonics belongs to Earth science, not particle physics.