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Description
The concept of the photon is often presented in physics education without highlighting the historical and epistemological processes that led to its development. To clarify the current understanding of the term “photon,” the present study traces its evolution from Einstein’s “light quantum” hypothesis till the development of quantum radiation theory and quantum optics.
Two main conceptual issues are identified. The first concerns the need for a quantized description of electromagnetic radiation, which provides the theoretical foundation for the light quantum. The second concerns interference phenomena, traditionally interpreted as evidence of the wave nature of light. During the past 50 years, single-photon interference and correlations between distinct detection events showed that the photon cannot be reduced to classical models such as wave or particle.
This analysis highlights how the meaning of the photon emerges within the formalism of quantum radiation theory and through experimental detection procedures, blending its definition. From this perspective, the history of the photon does not appear as a linear sequence of discoveries, but rather as a process of a series of conceptual reformulations. Such an approach may contribute to a more critical understanding of the foundations of physics and to a more effective integration of these perspectives in teaching/learning processes.