The Contributions of Other Disciplines to 19th Century Physics

Summary

My objective here is vulnerable to some spurious semantics. I aim to delineate how the development of physical theory in the later 19th century was essentially dependent on the reflections and discoveries of Chemists, Biologists and Mathematicians. But when one alludes to some professional Chemist or Biologist as having affected the history of physics, it can always be countered “to that extent he was doing physics, he was being a physicist”. Thus when Urey helped to separate U²³⁵ from U²³⁸, and when he invoked theoretical thermodynamics to determine the age of the solar system, he might be said then to have been doing physics — despite being a Nobel laureate in chemistry. And when Pauling applied quantum theory to studies of complex substances, and when he considered the rotation of molecules in crystals — he too was apparently being a physicist, although, again, a Nobel laureate in chemistry. So also of great moments in the work of Nernst, Boltzmann, Helmholtz, Faraday, Young… and so on. That is, one can always say that whatever helps physics is physics. But this is 20–20 hindsight focused to the point of tautology. For it suggests that a Biologist might one day awaken with the pronouncement “Ithink I’ll do some physics today”; a Chemist or Mathematician might muse “this problem will put demands on the physicist in me”. The history of science can be thus chopped up only by destroying the organic interplay between disciplines, an interplay which constitutes the very pulse of scientific research. The picture of disciplines rigidly fixed as to content, and of scientists as compartmentalized thinking machines — both pictures are unreliable reflections of the ways in which problems and their solutions have actually shaped the history of science. Just as being a ‘natural philosopher’ in the 17th century was not identical with being a theoretical physicist in the 20th, so also the divisions between biology, chemistry and physics in the 19th century may not always have been drawn along the same lines as we should sketch them today. In short, one must be an historian when tracing the lines of development through 19th century science. Not everything that is embraced today in physics texts began in physics labs, or in the minds of professional physicists. Therefore, I propose to correlate the contributions of scientists now known to us as important in the histories of chemistry and biology — with moments in the development of 19th century physics. Should one then choose to dub all such individuals as really physicists, à la bonne heure.