|3/9||Duality of particle and wave
According to the ideas of classical physics, light had to be either waves or particles. The incompatibility of these two concepts caused major difficulties even for experienced physicists.
The most popular solution to overcome this problem is based on the hypothesis that both the particle and the wave model provide a correct description of light. Depending on the experiment either one could be used, although the number of available concepts was not limited to the two mentioned above. This explanation, however, did not meet the criteria of modern physics, because it was based on an unrelated co-existence of models, not connected by an overarching theory.
Quantum dynamics joined the two models. In addition to describing the creation and absorption of light, quantum electrodynamics explained the change of radiation in matter through the creation of particle-antiparticle pairs.