Light is quantized into photons, and the Doppler effect for light can be explained through the frame-dependent nature of photon frequency and energy. The frequency of a photon changes based on the relative motion of the source and observer, which does not violate conservation of energy, as energy is also frame-dependent. An analogy is made with kinetic energy, where an object's energy varies depending on the observer's frame of reference. The discussion emphasizes that while energy can change with motion, it remains conserved within the appropriate frame. Understanding the Doppler effect in light requires acknowledging these principles of relativity and energy conservation.
