Why was the question of the nature of light limited to the wave theory or the particle one ?

Question

The question is in the title. I'm obviously refering to the 17/18 th century somewhere around this era.

Answer 1

A possible simple answer is that experiments on light manifested only the wave aspect of light behaviour or the particle one. These two aspects were not compatible, in the sense that light behaved as waves or behaved like particle depending on the nature of the experiment done. Heisemberg attributed this duality to the insufficience of our language to capture the real sense of the phenomena. By his point of view both aspects of light behaviour have to be treated as two different "representation" of the same phenomenon. More explicitly He remind us that already the category to which the terms "particle" and "wave" belong is the category of "a model"! He underlines that the products of radioactive emission going trough a Wilson Chamber shows themselves via a hyperfine-line of micro-droplets of condensend water supporting the "saying" that the radiation manifest itself as made of small particles moving at high velocity. On the contrary in the experiment of Davisson, Germer, Rupp, where one assume the particulate nature of radiation, since they also are products of redioactive decay, as a matter of fact they behave like waves giving rise to interference shapes similar to the one already known made by the X-Ray. In this case is appropriate "saying" that particulate radiation (see the source: radioactive decay) are indeed wave propagations. .... Heisember concludes that: "Matter cannot behave at once as particles and as waves and that the two "representations" are deeply diferent. The solution of this problem must be found in the sense that both are "models" i.e., they are simply similarities, that sometimes seams to validly apply, and in other occasions just fail. ... For instance, about the electron is simply proven in certain experiments that it behaves like a particle, but there is nothing saying that the electron possess all properties of the corpuscular model. "Mutatis mutandis", one can say the same thing about the undulatory model.". Up to now we dealt whith what we can say intuitively and using ordinary language. Heisemberg will take this, in accord with Bohr, as a starting point of the criticism of such level of knolwdge in order to found a proper logic reduction of the model theory and of the introduced analogous concepts.This in order to gain a mathematical coherent axiomatic from wich build the description of the new and unique nature of these phenomena. (from "Die physikalischen Prinzipien der Quantentheorie" 1930, in Italian "I principi fisici della teoria dei quanti" the text I used, and translate the best I could). I hope it can be of some use :-) ...