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Historically Speaking:
The Bulletin of the Historical Society
November 2003

Volume V, Number 2

EINSTEIN'S CLOCKS, POINCARÉ'S MAPS
AN INTERVIEW WITH PETER GALISON, PART I
Conducted by Donald A. Yerxa

Albert Einstein has become an icon of 20th-century science; indeed, he may well stand as the symbol for the entire century. How do historians explain the importance of pivotal breakthroughs of a theoretical nature—like Einstein’s work on relativity— that seemingly change how we view the world? Are these theoretical advances essentially the product of the genius and creativity of heroic individuals? Certainly it is an article of historical faith that context matters. But how much? In the case of Einstein, for instance, does his work in the Bern patent office have anything more than coincidental bearing on his thinking about time and space? Peter Galison’s latest book, Einstein’s Clocks, Poincaré’s Maps (Norton, 2003), explores these themes insightfully and in illuminating detail. Galison, the Mallinckrodt Professor for the History of Science and of Physics at Harvard University, argues that paying attention to the material context of the worlds that Einstein and Poincaré inhabited deepens our appreciation for their significant theoretical work. Donald Yerxa interviewed Galison in his Harvard office on September 29, 2003. We provide the interview in two installments, the first focusing on the particulars of Einstein’s Clocks, Poincaré’s Maps; the second on how historians of science account for how science has worked in the past.

Donald Yerxa: What prompted you to write Einstein’s Clocks, Poincaré’s Maps? 

Peter Galison: For many years I have been captivated by the question of how abstract issues in theoretical science connect to concrete circumstances—machines, laboratories, instruments. I am fascinated by the way people bring ideas into contact with the physical and completely material world. Einstein, for instance, spent some of his formative scientific years working in the patent office—six days a week, ten to twelve hours a day. And yet during this period he wrote some of the most important scientific papers of his day in quantum mechanics, relativity, and atomic theory. Were these connected? Was it just a day job that Einstein had? In a broader sense, beyond the purely biographical, what connection does the development of relativity theory have to the world out of which it came? This mirrors the historian’s eternal question: why did this happen then and there? What I am trying to do in the book is to address that question. Why does relativity happen in different forms, in different ways in Paris and Bern at the turn of the century? 

Yerxa: Can you speak to the book’s subtitle, Empires of Time? 

Galison: In many ways Poincaré and Einstein are after something very similar. Both come to that class of ideas we call the Theory of Relativity, but they reason in very dir II he made no bones about his unhappiness with McCarthyism, nuclear stockpiling, and many other pillars of established politics. Einstein clearly loved to identify himself with dissenting stances inside physics and outside. I think that there is something in this triumphant dissent that appeals widely to people in many walks of life. Add to this appeal the enormous attraction many people have to the particular kinds of problems with which Einstein grappled— the nature of space, the meaning of time, the origin of the universe, its fate, its structure. These were questions that make easy contact with broadly cultural, religious, and philosophical issues that have troubled people for centuries. The confluence of these various public personas is irresistible, creating a figure of Einstein that carries a limitless iconic draw. 

Poincaré was a very different figure. In many ways he was a symbol of a progressive, late 19th-century French establishment. He was somebody, I argue in the book, who should not be seen, as he so often is, as a reactionary, as someone who merely joined the backward-leaning, anti-relativity crowd. True, Poincaré objected to certain commitments of Einstein, but it wasn’t because Poincaré was trying to restore a Newtonian classical order. He was a progressivist in many respects, politically, technologically, scientifically, as well as philosophically. He was for altering things, but it was by repair, by a kind of intervention to fix things that were wrong—an engineer’s progressivism rather than a rebel’s sense of needing to upend. But Poincaré’s meliorism did not mean that he was unwilling to depart, quite radically, from the older science. On the contrary: Poincaré was willing to take up new ideas of space and time. He invented what we now know as chaos theory. There are many respects in which he departed from classical knowledge. He was an advocate of what he dubbed conventionalism and insisted throughout his life that we have enormous freedom in how we choose to structure our scientific laws so long as they are consonant with the experiments. Far from being a reactionary, this was a very progressive figure, somebody who helped free Dreyfus by dismantling the scientific evidence that had been mustered against him. But I think it is harder for people to identify with Poincaré the master craftsman, the engineering reformer, the symbol of an intact French Empire extending its beneficence to lands outside of France. That may have been an ideal cherished by a Third Republic pragmatic reformer, but it is not a vision that seizes hold of each generation of young people from the 1910s to the present. There is surely something very revealing in the way that Einstein functions for people; he plays a useful role for us now and in previous generations that Poincaré has not. 

Yerxa: You’re not interested in keeping any scorecard between Einstein and Poincaré? 

Galison: Not at all. Rivers of ink have splashed onto pages denouncing one or the other, offering credit and posthumous accolades. This interests me not at all. On the contrary, there is something bracing about understanding two very different ways of looking at extremely similar situations in physics, philosophy, and technology. I am interested in understanding clearly how each of them saw the world, in making the vision of each as compelling as possible, and yet pitting them against one another. But no, I am repelled by the idea of the historian or philosopher as a prize committee giving first and second honors to the discoverers of relativity. That’s just never interested me, except perhaps as itself a historical subject. That is, we may want to understand how, historically, priority became an issue because some people used Poincaré as a way of discounting what Einstein had done, or conversely of discounting Poincaré as a way to value what Einstein had done. I have no dog in that fight. (But I could find interesting the history of dogfights.) 

Yerxa: Beyond Einstein and Poincaré, why is it that certain scientists achieve such heroic standing?

Galison: Fame is a complicated issue, and standing is not constant over time. The stature of an enormously salient scientist can change in a generation or two, just as it does with politicians, painters, or musicians. William Whewell, for instance, was a figure of major standing in 19th-century Britain and now is largely forgotten. Gregor Mendel was not famous at all and now is a hero. Darwin’s fame has been more unbroken but needs to be understood in terms of larger pedagogical and theological issues—he became a culture hero in the United States by being assimilated to a form of teleological, almost Panglossian progressivism, not because of his advocacy of natural selection. Fame or heroic standing is a historical problem to be cracked, but it has to be approached not as a natural category but as a historical category that must be produced and constantly reproduced. We have an Einstein now, but it’s not the same as the Einstein of 1960, 1933, or 1919. People pick out of these figures different things, and each age establishes fame in its own image. 

Yerxa: To what extent is the popular understanding of Einstein in need of revision? 

Galison: Our contemporary picture of Einstein is dominated by his later years. It is Einstein with his wild, long white hair, his oracular pronouncements, his years in Princeton at the Institute for Advanced Study. This is a person who largely has figured out, if not how to tame, at least how to live with his inner demons, and who represents the very incarnation of a kind of equilibrated calm in his relationship to the world even when he stood as an oppositional figure. The young Einstein is really a very different figure. He is very much in battle with the world: he is unemployed for several years; he wants to establish himself in physics; he is fighting with his elders; he is passionately engaged with material objects, inventions, devices; he takes out patents; he takes on the world in every possible way. In a sense, it’s that younger Einstein that may have been eclipsed by a picture of the “head-in-theclouds” Einstein of his later years. And even in the later years, we forget his hard-edged political stance at the peril of distorting the record. 

Yerxa: Your work raises many fascinating questions about how science works. You advance a reading of the history of science that dispels the erroneous notions that science either proceeds simply from the material to the abstract or the opposite, from the realm of pure ideas to the concrete. And your book describes the “oscillation back and forth between abstraction and concreteness” in the worlds that Poincaré and Einstein inhabited. Is such oscillation generally the case in the history of science? 

Galison: Let me respond in two steps. First, I think that very often what we consider to be the most abstract ideas can be located within a set of much more particular concerns that are associated with them. I actually don’t think that it is rare for abstract and concrete developments within science to be associated. What I think is rare is the simultaneous crossing of broadly philosophical, importantly technological, and centrally physical ideas. That does not happen very often. More recently, we see another example of the crossing of philosophy, technology, and fundamental science in the nexus of issues around cognitive science, cybernetics, computers, the building of computers, abstract ideas about computer functioning and proof. Think, for example, of John von Neumann. He was a mathematician who became interested in practical problems of computation during World War II and afterward was one of the co-inventors of the stored-program computer. When he thought of the computer, he patterned it on the faculties of the mind. He reasoned, “How does our mind work? Well, we have memory, we have input, we have output, processing.” And then he began to identify the functional elements of what we call the stored-program computer in terms of this quasi-faculty picture of the mind. But then the computer itself became a model of the mind, and people began to draw on the computer to better understand how cognition works. Around a fluctuating picture of model and modeled has arisen a complex of philosophical ideas, very practical issues around computer design, and abstract notions of computational science. That sort of oscillation seems to be somewhat analogous to the story I am pursuing in Einstein’s Clocks, Poincaré’s Maps. The computer becomes a kind of governing metaphor for our times—and of course through its consequences far more than a metaphor. It is that kind of centrality and multiplicity that I think is unusual, and it’s that triple intersection of practical, abstract, and philosophical issues that becomes a governing sign of an era. I’ve called this a kind of critical opalescence. 

Yerxa: Could you explain the metaphor of critical opalescence and discuss how it helps us better understand the simultaneous convergence of questions at multiple scales? 

Galison: By critical opalescence I have in mind this: it is easy enough, as we think back historically, to reason in terms of a kind of ascension from the concrete to the abstract. One way of thinking of that progression is as a kind of Platonic ascension—we make a stick model of a triangle, then we draw it on paper, then we imagine it as a pure idea, abstracted from all instantiations. Or we might think of the progression from material to abstract in terms of a vulgarized Marxist picture (I don’t actually think this is what Marx had in mind at all). But such a view would argue that in the beginning are the relations of people to specific means of production and from those relations come, univocally, the epiphenomenal superstructures of the world, including jurisprudence, religion, and perhaps science. According to this way of thinking, science or the abstract ideas of science become nothing but surface phenomena that are projected by the functional relations of labor. So in either the Platonic model or (over-simplified) Marxism the movement from materiality to abstraction is a process of sublimation: all that is solid melts into air. 

On the other side is a more idealist picture, one that says: in the beginning are ideas, and our ideas become more concrete or applied—mathematics or mathematical physics is converted into applied science or engineering and eventually written into concrete, wires, and stone in the factory. In a sense the idealist picture is an exact reverse of the materialist picture, and we think of it as a kind of condensation. On the one side, a kind of sublimation; on the other, a condensation. I’m not happy with either of those images on both philosophical and historical grounds. And I don’t think that either begins to capture what is going on in situations like those in which Poincaré and Einstein found themselves. In fact these people were moving very quickly back and forth between practical questions and abstract questions. Poincaré would give a talk on relativity and then work on turning the Eiffel Tower into a timesending station; then he’d go back and attend a philosophy conference. Back and forth this went. 

A better metaphor, it seems to me, is the phenomenon—a little less well known perhaps than sublimation or condensation— that physicists call critical opalescence. If you put water and vapor in a vessel under such pressure and temperature that the water thrashes back and forth between tiny droplets, bigger droplets, and vapor and then you shine in blue light, you get blue light back because it reflects off the droplets that are the wavelengths of blue; if you shine in green, then you get back green. Whatever size droplet you want, you will find. In critical opalescence there is no privileged scale, no single length that is more fundamental than all others. There simply is no natural scale to water and vapor in critical opalescence. And it is something like that that I’m after in the story I am looking at here with Poincaré and Einstein. There isn’t one scale at which this story is grounded or founded. There isn’t an originary or fundamental scale. It is all at once about philosophy, technology, and physics. And the fluctuations of scale between the abstract ideas of conventionalism and a new kind of knowledge and the practical exigencies of wiring up continents so that they’ll tell the same time are very rapid and an essential aspect of this story. Is this a story of social history? Yes. Look at the coordination of cities, trains, markets, and maps. Is this a story about the intellectual history of physics? Yes. Relativity is one of the epochal changes in the discipline. Is this a question about the history of philosophy? Again, yes. Conventionalism reshaped modern philosophy. Moreover, it is not just a story about those things, but central stories to each of those. It is a crucial piece of late 19th-century technology. It is one of the founding pieces of 20th-century physics. And it is a transformative moment in the philosophy of science, indeed a model for the philosophy of science for the next hundred years. 

Yerxa: How does critical opalescence—which presumably is highly transformative— relate to the notion of scientific revolution?

Galison: Scientific revolution has a long and complicated history within my discipline. Sometimes it means the Scientific Revolution of Descartes, Galileo, and Newton. The problem is that people have found it increasingly difficult to bound this notion of “The Scientific Revolution” in any coherent way. Driven by the difficulty of bounding this “event,” historians of science started writing books decades ago on the Scientific Revolution from 1550 to 1750. But then it is really not clear what conceptual meaning can be derived from a revolution lasting two centuries. And because of difficulties like this, many historians today refer now to early modern science, with all the complexities that you would expect from what we know about early modern history more broadly conceived. I think, for instance, of Lynn Hunt’s excellent work on the French Revolution where she looks at how different strata of life are broken or continuous across the events of the French Revolution. She shows that if we look in one plane, so to speak, we see continuity; whereas in another we might see breaks. So what represents a break in terms of representative government may not in terms of family structure and much else besides. I think something like that has become more typically the way we see things in the history of science. For as historians of science have attempted to engage the content of science and its embedding in the world together, it becomes more and more problematic to see a particular doctrinal change as a universal break that cuts all the way through everything. In that sense, Thomas Kuhn’s image of the shattering of a world by responses to a stubborn scientific anomaly becomes harder to accept. Take a simple example from my How Experiments End. Part of what I was interested in was that experimenters typically don’t change their practices in lock step with theoretical changes. So if you look at what happened to experiments during the time of quantum mechanics and relativity, it’s not a major change for the experimentalist. Conversely, the big changes to the experimentalist are not the most major changes for the theorists. Because I find periodization to be intercalated in this way (rather than global continuity followed by global discontinuity), I find the idea of a scientific revolution too clumsy to capture what interests me. 

Now, you have asked how the idea of critical opalescence relates to this. In Einstein’s Clocks, Poincaré’s Maps, I am not saying that there is a break in all of the different strata simultaneously. It is obviously not that all of electrodynamics, cartography, or train scheduling is broken at once. But there is a coincident transforming event (around time and simultaneity) that takes in theoretical physics, practical aspects of technology, and philosophy. So I am interested in a break that takes place across many different scales, but it is not my claim that this shatters practices all at once everywhere. 

Consequently, the argument against scientific revolutions is not based on the notion that everything is continuous; it is rather that the breaks and continuities are not all lined up. This suggests that the hopeless question of whether science is continuous or discontinuous needs to be replaced by precisely where scientific practices are continuous and precisely where they are discontinuous. Because of these more complex questions we need to ask, I find allusions to the Scientific Revolution (singular) or scientific revolutions (plural) to be unhelpful. 

Yerxa: You have terminal degrees in the history of science and particle physics. How important is it for historians of science to have that sort of dual professional expertise? 

Galison: In the history of science, the particular mix of training is really specific to the kind of problem that interests you. I have a colleague here at Harvard, Katharine Park, who is a great historian of Renaissance science. For her and for her students, it is much more important to know the pertinent languages, to be familiar with the broader issues of Renaissance history, of Renaissance painting, and of the development of perspective. She’s interested in anatomical drawing and representations of dissection, so medical knowledge becomes crucial. For someone training with her, particle physics, quantum field theory, or condensed matter experimentation are all really pretty irrelevant. So what was appropriate for me is not necessarily appropriate for everyone. Those who study with me pursue a variety of mixes of historical, philosophical, and technical work. Two of my students have done Ph.D.s in physics in addition to their Ph.D.s in the history of science. Some have done masters’ degrees in physics, chemistry, or astronomy—others have studied sociology or philosophy. There is no universal solution to such questions; it depends essentially on the historian, the problem, and questions asked. 

Yerxa: Did you pursue particle physics in order to address specific questions in the history of science?

Galison: It would never be worthwhile to do a Ph.D. in physics in order to just ask one set of questions. It’s too big a commitment for that. But it is true that the problems I worked on in my physics dissertation (electroweak theories) grew out of historical questions that arose in writing my history dissertation (“How Experiments End”). For me, one of the advantages of physics training was that it opened up the literature in a way that would not have been possible otherwise. Second, and this might seem paradoxical, my physics training allows me to write less technically because I am in a better position to know which technical ideas are central and which are secondary. Einstein once said that we must do everything as simply as possible —but not simpler. I have always liked that view. 

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