Instruments and history

When we think about the history of physics, we usually think about theories – the magisterial sweep of relativity, quantum mechanics, current algebra, SU(3), and gauge theories seems to subsume and dwarf the details of experiments. And if experiments appear small, how much less significant are instruments? The great breaks and continuities of physics are typically defined by the epochal accomplishments of Maxwell's equations, Einstein's special relativity, nonrelativistic quantum mechanics, and quantum electrodynamics. Such a “theorocentric” view has become ingrained in our pedagogical, physical, and historical literature. Most textbooks attach only a passing section on the devices of experimentation. The subfields of physics are classified by the theories they lead to – not by all the results one can get from instruments.

But it is hopelessly one-sided to let theory stand in for all of physics when we want to understand the past sympathetically, to capture the felt continuities of physicists in the day-to-day practice of their discipline. Experimentalists frequently move between theoretical areas linked only by a continuity in the experimental skills and instruments they have at hand. Here I want to examine some of the “instrumental” continuities – and discontinuities – that existed in the 1950s, for that decade saw a proliferation of instruments unparalleled in the twentieth century. Necessarily, only a few can be discussed here, as it is hardly possible to cover the multitude of detectors that arose in that decisive decade. Regrettably, I shall not discuss developments in nuclear emulsions or scintillators.