2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206513The connection between the Gupta-Bleuler formulation and the Coulomb gauge formulation of QED is discussed. It is argued that the two formulations are not connected by a gauge transformation. Nor can the state space of the Coulomb gauge be identified with a subspace of the Gupta-Bleuler space. Instead a more indirect connection between the two formulations via a detour through the Wightman reconstruction theorem is proposed.9 pages. Based on talk delivered at: "Symposium on Rigorous Quantum Field Theory", Saclay, July 2004High Energy Physics - TheoryMathematical PhysicsQuantum Physicstext