For just now, we can summarize the wave-particle puzzle by saying that when we do a wave-type experiment, light behaves like a wave. When we do a particle-type experiment, light behaves like a particle. When the two are combined, as in the Compton scattering experiment, the behavior of the light switches back and forth according to the demands made on it by the actual apparatus used. The key new point here is the fact that the measuring apparatus seems to affect the physical system, instead of just recording some pure reality.
For just now, we can summarize the wave-particle puzzle by saying that when we do a wave-type experiment, light behaves like a wave. When we do a particle-type experiment, light behaves like a particle. When the two are combined, as in the Compton scattering experiment, the behavior of the light switches back and forth according to the demands made on it by the actual apparatus used. The key new point here is the fact that the measuring apparatus seems to affect the physical system, instead of just recording some pure reality.