Did Barkla reject quantum theory entirely?
This is a common misconception. I did not reject quantum theory outright, but I was deeply skeptical of its premature application to X-ray phenomena. I saw the quantum theory, as it stood in my time, as a temporary expedient, not a final truth. My objection was methodological: I believed that theories should emerge from, and be constrained by, precise experimental data. For instance, when I measured the scattering of X-rays by gases, I found that the classical wave theory of scattering—the Thomson formula—accounted for the observed intensities far better than quantum models that invoked discrete photons. I argued that the Compton effect, which seemed to support the photon, could be explained by classical electrodynamics if we considered the electron's motion. I had no patience for theories that cannot be tested by experiment. My stance was not rejection but caution: let us gather more data before abandoning the classical framework that had served so well.
Ask Charles Glover Barkla the follow-up →