2.5 A GATHERING STORM OF FAILURE
The process of implementing the corpuscular program which attempts to explain the inside through an outside has led the scientific community to the introduction of molecules, atoms, electrons, and protons. In time, this family grew to include neutrons, positrons, and a growing collection of other elementary particles. These particles were assumed to influence each other through mechanical and electromagnetic forces. During the 19th Century, the program proved to be brilliantly successful in constructing a growing structure able to explain the phenomena related to the inside of matter.
There were however a few signs of difficulty with the corpuscular program, all but neglected in the rush to extension. Thus, concerning the corpuscular structure itself, there was the persistent need for statistical arguments which, despite the generally accepted point of view, remained mysterious. Indeed, while it is true that one could not practicably ascertain the whereabouts of each molecule, the theory took it for granted that one could do so in principle without considering the manner in which one could experimentally approach one of them to do so. Then, there was the electromagnetic field: Maxwell clearly went beyond the electric and magnetic laws empirically established by Faraday when he introduced into his equations the displacement current in ether. The fact that the displacement current was also formally required by the continuity equation does not illuminate the mechanism through which such current would be produced once the luminiferous ether was abolished from physics. And, lurking around, there were the failures to explain the temperature dependence of the specific heat of solid objects and the behavior of electrons emitted by the photoelectric effect.
These long-neglected signs of difficulty with the corpuscular program, while unable to slow down the scientific progress, have eventually gathered together into a series of spectacular failures generated by the unexplored manner in which particles and fields fitted together in explaining the inside of those things which man encounters in his experience. In what follows we shall recall only three of these failures: the program’s inability to explain the observed spectral energy distribution of black body radiation, the program’s inability to account for atomic stability and spectra, and the program’s inability to describe the scattering of an electron off a crystalline structure.
In discussing all these illustrative examples we shall go back to the original source in the literature rather than rely upon current textbooks. The effort to understand where and how the scientific project took the specific turn which has inevitably led it to quantum mechanics is helped by locating ourselves at the time when fundamental questions were first asked rather than at the much later time when the answers were already well settled in. For at such later time, the incentive in the literature is to clarify and support the accepted answers with arguments and experimental evidence, while at the beginning other alternative answers were still possible.