AbstractThis paper argues for a Work-Centric, Transactional interpretation of electromagnetic radiation (EMR) grounded in operational physics and the Operational Threshold Principle (OTP). It maintains that while field evolution describes potential, physical reality is instantiated only when energy crosses an interaction threshold. Without realized work, the 'photon' remains a non-event in the thermodynamic ledger of the universe, properly described as quantum excitations of the electromagnetic field, their physical meaning becomes operationally significant only at irreversible interaction events.The manuscript distinguishes between:• Propagation as mathematical description • Interaction as physical instantiation of energy transfer • Energy as capacity for work • Work as realized transfer across a system boundaryThe central claim advanced here is:All causal efficacy attributed to light occurs at interaction. Version 2