Against the Impossible Picture: Feynman's Heuristics in his Search for a Divergence-free Quantum Electrodynamics

Abstract

I review three early steps of the development of Feynman's proposal for a divergence-free quantum electrodynamics and identify the characteristic feature of his heuristics: the search for alternative formulations of the existing theories. Feynman's reformulations always had precise goals, and in each of the three steps one of them was particularly important. Through reformulation, he tried (1) to extend the domain of application of an existing theory, (2) to provide a model to justify the theory's equations, or (3) to reveal assumptions problematic for the existing theory and in this way find amendments to it.