EINSTEIN AND POINCARÉ (p2)

(PETER GALISON:) When the Einstein centenary was celebrated in 1979 the speakers at all of these great events spoke about physics only as theory. It seemed odd to me that somebody like Einstein, who had begun as a patent officer and who had been profoundly interested in experiments, had left such a thoroughly abstract image of himself. My interest in Einstein began in that period, but beyond Einstein I was intrigued by the startling way that experiment and theory worked together, fascinated by the abutting of craft knowledge hard against the great abstractions of theoretical physics.

For quite a number of years I have been guided in my work by the odd confrontation of abstract ideas and extremely concrete objects. Science history, sociology, and epistemology are for me very connected, and the kind of work that I do in the history of science is always propelled and illuminated through philosophical questions. For example, I am interested in what counts as a demonstration. What does it mean to be done with a demonstration? How do experimenters distinguish between a real effect and artifacts of the apparatus or the environment? We think we know what it means to conclude a mathematical deduction, but what does it mean when I’ve shown something with a computer simulation? If I do a simulation and show that the tail of a comet forms into islands, have I demonstrated that, or is my result just the beginning of an explanation that then needs a more analytic mathematical derivation? These are questions that even today puzzle across a myriad of fields. They are questions that are, inevitably both historical and epistemological — that is they are about ordinary scientific practice and yet fundamentally philosophical. When I choose to work on a problem it is usually because it is illuminated by these different beams of light, so to speak.

When I and a few other historians, sociologists, and philosophers began looking at instruments and laboratories back in the late 1970s, emphasizing experimentation in the history of science seemed rather odd. Most historians and philosophers were keen (in the aftermath of Thomas Kuhn’s work) to show that all of science issued from theory. I suppose it was a kind of reaction against all those years of positivism from the 1920s through the 1950s when philosophers insisted that all knowledge came down to perception and observation. In any case, there wasn’t really a body of serious work on what a laboratory was, where the lab came from, or how it functioned. Since then, inquiry into the history and dynamics of experimental practice has grown into much larger domain of study. I am interested not just in the laboratory itself, however, but also in the most abstract kinds of theories. Recently, for example, I’ve been writing about string theory—specifically the confrontation between physicists and mathematicians as they try to sort out what ought to be a demonstration—in what is without doubt the most abstract form of science ever pursued.

But in every instance I’m above all intrigued by how philosophical questions illuminate and are illuminated by very the practices of science, sometimes material, sometimes abstract. And I suppose that I am always interested in blasting away the mid-level generalizations, and to explore, as in Einstein’s Clocks, Poincaré's Maps, at the way the most abstract and the most concrete come together. Instead of thinking of a kind of smooth spectrum that goes from ultraviolet to infrared with everything in between, I’m interested in bending the edges of the spectrum to make the abstract and the concrete hit one another more directly.

When I began my work quite a number of years ago, the history of science was focused almost exclusively on the history of ideas and theories. Experiments and instruments, to the extent that they were of interest to anybody, were peripheral helpmates to the production of theory. I began by being interested in the way that certain kinds of instruments, or the way that instruments were used, shaped the way knowledge worked and the kinds of questions that people were asking. My first book, How Experiments End, was about how experimentalists decide that they’re looking at something real, whether it’s using a small scale table-top device or a huge experiment involving hundreds of people.

Then I turned to another subculture of physics, if you will, a sub-culture of people who are really interested in the machines themselves, not just in experimentation. I wanted to know how certain kinds of devices have carried a philosophy with them. For example, how did machines like cloud chambers and bubble chambers, which produce pictures, become the standard of evidence for a whole group of physicists across most of the 20th century? Or how did funny little objects like Geiger counters, which click when they’re near something radioactive, produce a kind of statistical argument for new effects? What interested me was the contrast between the tradition of scientists who wanted to take pictures — who wanted to see in order to know — and another computing group who wanted to combine information more quantitatively — digitally, if you will — to produce a logic of demonstration. My second book, Image and Logic is about these two huge, long-standing traditions within modern physics.