“QED” , the short popular text by Richard Feynman was published 30 years ago. Yet, we still hear the literate public talk about the “wave-particle duality” of light as if that is part of 21st Century quantum theory. Rather, it is this out-dated concept, acting like a dogmatic religion, that will demonstrate itself to be a roadblock in further understanding of photon entanglement and quantum computing. Unfortunately, old thinking doesn’t leave the scene of its own accord.
“For many years after Newton, partial reflection by two surfaces was happily explained by a ‘theory of waves’*, but when experiments were made with very weak light hitting photomultipliers, the wave theory collapsed: as the light got dimmer and dimmer, the photomultipliers kept making full sized clicks – there were just fewer of them. Light behaves as particles.” – (Richard Feynman, 1985)
“* This idea made use of the fact that waves can combine or cancel out, and the calculations based on this model matched the results of Newton’s experiments, as well as those done for hundreds of years afterwards. But when experiments were developed that were sensitive enough to detect a single photon, the wave theory predicted that the clicks of a photomultiplier would get softer and softer, whereas they stayed at full strength – they just occurred less and less often. No reasonable model could explain this fact. This state of confusion was called the wave – particle duality of light.”