The discussion centers on the relationship between amplitude, intensity, and energy in electromagnetic (EM) waves, particularly visible light. It explains that the intensity or brightness of an EM wave is determined by the number of photons, while amplitude is linked to intensity in the classical view. In the quantum perspective, a photon represents energy carried by the wave, complicating the relationship between wave and particle models. The conversation highlights that amplitude is not independent and that the wave nature predominates, especially during interactions with materials. Ultimately, the mixed model of photons and waves presents challenges in understanding EM wave behavior.