Abstract

In 1928, George Paget Thomson measured the wavelength associated with an electron in his experiments on refraction. This was the first proof of a principle that the French physicist Louis de Broglie had proposed five years earlier in his doctoral dissertation, according to which all particles had a wavelength associated with them. Thus, electrons were the first corpuscles to prove the wave-particle duality. Ironically, it had been his father, Joseph John Thomson, who, in 1897, had first attributed a corpuscular nature to the undulatory phenomenon of cathode rays, in a suggestion that is commonly seen as the discovery of the electron. In this paper I want to discuss the possible influence of J.J. Thomson on his son’s early career.

After graduating in Cambridge, G.P. Thomson moved to Aberdeen where he had to start a new laboratory of Physics from scratch. J.J. had been in a similar situation when, being a young graduate from Cambridge, he was appointed director of the recently created Cavendish Laboratory, and it is justified to imagine some advice from father to son. Furthermore, the specific direction G.P. gave to his research is not alien to his father’s theoretical interests. While he was the first to bring forward evidence for the existence of what he called corpuscles, J.J. always believed that electrons were a corpuscular manifestation of some dynamical process taking place in the ether. The measurement of the wavelength associated with the electron and the dual nature of the particle probably appealed to J.J. as much as to G.P., but for different reasons. To the father, as a proof of the ethereal nature of the electron. To the son, as a contribution to the incipient quantum mechanics.