Light Without Duality: A Semiclassical Model for Electrical Engineering Education

AbstractWave–particle duality is often presented as an intrinsic property of light, a fundamental enigma of quantum mechanics that requires accepting light as both wave and particle depending on the experiment. This paper challenges that narrative by demonstrating that duality is not a law of nature but a didactic artifact — one that obscures a far simpler and more consistent physical reality. Light behaves as a classical electromagnetic wave, while the discreteness observed in interactions arises exclusively from the quantised nature of matter, not the field itself. The semiclassical model, in which a classical electromagnetic field interacts with quantised detectors, fully explains all optoelectronic phenomena relevant to electrical engineering, from the photoelectric effect to the behavior of CMOS sensors, without ever invoking the concept of light as a particle. Historical and experimental evidence supports this view: Fowler’s 1931 measurements revealed that the photoelectric threshold smears at temperatures above absolute zero due to the Fermi–Dirac statistics of electrons in metals, not because of any quantisation of light. Hübel’s 1987 school experiments confirmed these findings in an accessible educational setting, while Herrmann’s 1994 framework demonstrated that the external photoelectric effect can be described as a three-step process — penetration depth of radiation, escape depth of electrons, and the work function — none of which require the existence of photons. A simple and inexpensive experiment, costing around 150 euros and fitting on a kitchen table, illustrates this clearly: a laser pointer, a precision double slit, and a lensless digital camera separate the three phases of the process — emission as a quantised matter process, propagation as a classical Maxwell wave, and detection through the band structure of the silicon sensor. The only limitation of this model, second-order intensity correlations, lies far beyond the scope of typical electrical engineering applications. In conclusion, for electrical engineers, the photon is best understood as a finite electromagnetic wave train. The discreteness of interaction with matter does not originate from the wave train but from the matter itself. This paper argues for replacing the duality narrative with a semiclassical model that is physically precise, didactically clearer, and professionally essential for understanding modern optoelectronics.