Abstract :
In 1927, George Paget Thomson, professor at the University of Aberdeen, obtained
photographs that he interpreted as evidence for electron diffraction. These photographs were
in total agreement with de Broglie’s principle of wave–particle duality, a basic tenet of the
new quantum wave mechanics. His experiments were an initially unforeseen spin-off from a
project he had started in Cambridge with his father, Joseph John Thomson, on the study of
positive rays. This paper addresses the scientific relationship between the Thomsons, father
and son, as well as the influence that the institutional milieu of Cambridge had on the early
work of the latter. Both Thomsons were trained in the pedagogical tradition of classical
physics in the Cambridge Mathematical Tripos, and this certainly influenced their understanding
of quantum physics and early quantum mechanics. In this paper, I analyse the responses
of both father and son to the photographs of electron diffraction: a confirmation of
the existence of the ether in the former, and a partial embrace of some ideas of the new
quantum mechanics in the latter.
