Richard Feynman made significant contributions to both field theory and particle physics throughout his career, and he had important thoughts on the interplay between these two areas of physics.
Feynman was one of the pioneers in the development of quantum field theory, particularly through his work on quantum electrodynamics (QED). QED is a field theory that describes the interactions between charged particles and the electromagnetic field. Feynman's Feynman diagrams and his path integral formulation of quantum mechanics were instrumental in the development of QED, and he received the Nobel Prize in Physics in 1965 for his contributions.
Despite his profound contributions to field theory, Feynman also recognized the importance of particle physics. He understood that field theory provides a powerful framework for understanding the fundamental forces and particles of nature. However, he also emphasized the significance of experimental observations and the need for particle physicists to study individual particles and their interactions.
Feynman famously said, "Nature uses only the longest threads to weave her patterns, so that each small piece of her fabric reveals the organization of the entire tapestry." This statement reflects his view that both field theory and particle physics are essential for a complete understanding of the laws of nature. Field theory provides a unified description of the underlying symmetries and interactions, while particle physics allows us to study and discover the individual building blocks of matter.
Overall, Feynman's thoughts on field theory vs particle physics can be seen as a recognition of their complementary nature. He believed that both fields of study are necessary to fully grasp the fundamental workings of the universe, and his own contributions spanned both domains.