Einstein's Clocks and Poincare's Maps

by Peter Galison

  By the time Poincaré and Lorentz put these worries on paper, both saw the essentials of their physics in mortal danger—their hunt for an explanation of the microphysics of the electron, their long struggle to instantiate the relativity principle, and their never-ending quest to specify the status of the ether. In the early years after 1905, some physicists assimilated the new theory to an older ambition to find an electrical explanation for all physics. Others seized the mathematics, ignoring the reformation of time. But in the end, the greatest threat did not emerge from the magnets, tubes, and photographic plates of Kaufmann’s study of how fast electrons were deflected by electric and magnetic fields or work at any other laboratory. Though the “true relations” of his physics survived, in the long term Poincaré’s vision of the time and space of modern physics—one that prized the ether as an ineliminable framework for intuitive mathematized understanding, one that sharply split true from apparent time—lost its place in the canonical presentation of physics. An unknown twenty-six-year-old physicist at the Bern patent office was to offer a different path to understanding, one that threw aside electron structure, the ether, and the distinction between “apparent” and “true time.” Instead he wired a coordinated clock into the theory not as an aid to the physical interpretation of local time but as the capstone of the relativistic arch.

  Chapter 5

  EINSTEIN’S CLOCKS

  Materializing Time

  IN JUNE OF 1905, the contrast between Einstein and Poincaré could not have been greater. Poincaré was an Academician in Paris, fifty-one years old and at the height of his powers. He had been a professor at France’s most illustrious institutions, run interministerial commissions, and published a shelf of books—volumes on celestial mechanics, electricity and magnetism, wireless telegraphy, and thermodynamics. With over 200 technical articles to his name, he had altered whole fields of science. His best-selling volume of philosophical essays had brought his abstract reflections on the meaning of science to a huge audience, including Einstein. Einstein, at twenty-six, was by contrast an unknown patent officer, living in a walk-up flat in a modest section of Bern.

  Unlike France or Britain, Switzerland was not a colonial power. Unlike the United States or Russia, it had no vast longitudinal spread, nor did it have even a hectare of unsettled land to be colonized by railways, telegraphs, and time links. In fact, Switzerland was late to adopt the telegraph and, relative to other European countries, late in the construction of a rail network. But when rails and telegraphs did come to this mountainous country in the latter part of the nineteenth century, the movement to synchronize clocks quickly gained momentum—not surprising in a nation in which the production of precise timepieces was, by century’s end, an urgent matter both of national pride and economic significance.1

  The clock-world famous Matthäus Hipp found welcome in Switzerland. Blacklisted in his native Württemberg for his republican and democratic advocacy around 1848, his trade was in time machines of every sort. He developed electrically maintained pendula so regular that they far surpassed mechanical ones: a heavy pendulum swung freely except when it needed an electromagnetic boost. Alongside such electrical timepieces, Hipp perfected recording clocks that radically altered experimental psychology. Collaborating with physicists and astronomers, he tracked the transmission speeds of nerves, telegraphs, and light, thereby inventing, altering, and producing new ways to use electricity and clocks to materialize time. Though he worked closely with scientists (especially Swiss astronomer Adolphe Hirsch), Hipp was more artisan-entrepreneur than mathematician-savant. Founder of telegraph and electrical apparatus factories in Bern and later Neuchâtel and Zurich, Hipp took his company from the establishment of the first network of public electric clocks in Geneva (1861) to ever greater prominence. In 1889 Hipp’s firm became A. De Peyer and A. Favarger et Cie; from then to 1908 the concern extended the range of their mother clocks beyond the dominion of observatories and railways to steeple clocks and even to the wake-up clocks inside hotels.2 With the march of time into every street, engineers needed methods to extend indefinitely the number of units that could be branched together. A flood of patents followed, perfecting relays and signal amplifiers.

  If you wanted to display time on a major building, you needed more than one clock before time unification. The Tower of the Island in Geneva boasted three around 1880: a big clockface in the center showed middle Geneva time (about 10:30); the face on the left showed Paris time for the Paris-based “Paris-Lyon-Mediterranean” line (10:15); and the right-hand clock boasted Bern time, a handsome five minutes in advance of Geneva (10:35). Clock synchronization in Switzerland was public and eminently visible. So, too, was the chaos of uncoordinated time.

  Bern inaugurated its own urban time network in 1890; improvements, expansions, and new networks sprouted throughout Switzerland. Not only was accurate, coordinated time important for European passenger railroads and the Prussian military, it was equally crucial for the dispersed Swiss clockmaking industry, which desperately needed the means for consistent calibration.3 But time was always practical and more than practical, material-economic necessity and cultural imaginary. Professor Wilhelm Förster of the Berlin Observatory, which set the Berlin master clock by the heavens, sniffed that any urban clock that did not guarantee time to the nearest minute was a machine “downright contemptuous of people.”4

  Figure 5.1 Three Clocks: Tower of the Island of Geneva (circa 1880). Before time unification, a fine clock tower like this one publicly registered the multiplicity of times. SOURCE: CENTRE D’ICONOGRAPHIE GENEVOISE, RVG N13X18 14934.

  Einstein’s patent-office window on this electrochronometric world opened a crucial moment in the synchronization of Swiss time. For despite General von Moltke’s resounding support for a pan-German time unification and the undamped enthusiasm of the North American advocates of one-world time, Albert Favarger, one of Hipp’s chief engineers and the man who effectively succeeded Hipp at the helm of his company, was not at all satisfied with the rate of progress. He intended to say so, very publicly, at the 1900 Exposition Universelle in Paris. Here, the International Congress on Chronometry met to discuss the status, inter alia, of clock-coordination efforts.5 At the outset of his speech to the congress, Favarger asked how it could be that the distribution of electrical time was running so distressingly far behind the related technologies of telegraphy and telephony? First, he suggested, there were technical difficulties; remotely coordinated clocks could rely on no obliging friend (“ami complaisant”) to oversee and correct the least difficulty, whereas the steam engine, dynamo, or telegraph all seemed to run with constant human companionship. Second, there was a technician gap—the best technical people were staffing power and communication devices, not time machines. Finally, he lamented, the public was not funding time distribution as it should. Such lagging boosterism baffled Favarger: “Could it be possible that we have not experienced the imperious, absolute, I would say collective need of time exactly uniformly, and regularly distributed? . . . Here’s a question that borders on impertinence when addressed to a late 19th century public, laden with business and always rushed, a public that has made its own the famous adage: Time is money.”6

  Figure 5.2 One Clock: Tower of the Island of Geneva (after 1894). After time unification, the same tower shown in figure 5.1 needed but a single clock: time unification was visible for all to see. SOURCE: CENTRE D’ICONOGRAPHIE GENEVOISE, RVG N13X18 1769.

  As far as Favarger was concerned, the sorry state of time distribution was out of all proportion with the exigencies of modern life. He insisted that humans needed exactitude and universality correct to the nearest second. No old-fashioned mechanical, hydraulic, or pneumatic system would do. Electricity was the key to the future, a future that would only come about properly if humankind broke with its past of mechanical clocks: a technical era riven by anarchy, incoherence, and routinization. In place of the pneumatic chaos of Paris or Vienna, the new world of electrocoordinated clocks would be
based on a rational and methodical approach. As he put it,

  You don’t have to run long errands through Paris to notice numerous clocks, both public and private, that disagree—which one is the biggest liar? In fact if even just one is lying one suspects the sincerity of them all. The public will only gain security when every single clock indicates unanimity at the same time at the same instant.7

  How could it be otherwise? In terms reminiscent of time struggles in the United States some years earlier, Favarger reminded the assembled exposition attendees that the speed of trains roaring through Europe was mounting to 100, 150, even 200 kilometers per hour. Those running the trains and directing their movements, not to speak of the passengers entrusting their lives to such speeding carriages, had to have correct times. At 55 meters per second, every tick counted, and the prevalent but obsolete mechanical systems of coordination were bound to be inferior. Only the electric, automatic system was truly appropriate: “The nonautomatic system, the most primitive yet the most widespread, is the direct cause of the time anarchy that we must escape.”8

  Time anarchy. No doubt Favarger’s reference recalled in his listeners the anarchism that had taken a powerful hold among the Jura watchmakers (or for that matter it might have reminded Parisian listeners of French anarchist Martial Bourdin’s detonation outside Greenwich Observatory). Peter Kropotkin had broadly publicized the clockmakers’ anarchism just a year before in his 1898–99 Memoirs of a Revolutionist:

  The equalitarian relations which I found in the Jura Mountains, the independence of thought and expression which I saw developing in the workers, and their unlimited devotion to the cause appealed even more strongly to my feelings; and when I came away from the mountains, after a week’s stay with the watchmakers, my views upon socialism were settled. I was an anarchist.9

  Favarger was, however, more concerned about an anarchism signaled by a broader disintegration of personal and societal regularity. Not for him the older pneumatic system—those steam-driven, rigidly framed branched pipes that had pulsed compressed-air time to fixed public clocks and private timepieces in Vienna and Paris. Only electrical distribution of simultaneity could provide the “indefinite expansion of the time unification zone.”10 Favarger’s unwavering support for distant simultaneity issued from many sources, from the practicalities of train scheduling and the entrepreneurial ambitions of his company to a sense of what time would mean for the inner life of the modern citizen. Time synchronization was all at once political, profitable, and pragmatic.

  Should we escape this dreaded anarcho-clockism, Favarger assured his listeners, we could fill a great lacuna in our knowledge of the world. For even as the Paris-based International Bureau of Weights and Measures had begun to conquer the first two fundamental quantities—space and mass—Favarger insisted that the final frontier, time, remained unexplored.11 And the way to conquer time was to create an ever-widening electrical network, bound to an observatory-linked mother clock that would drive relays multiplying its signals and send automatic clock resets into hotels, streetcorners, and steeples across the continents. Affiliated with Favarger was a company determined to synchronize Bern’s own network. When, on 1 August 1890, Bern set the hands of its coordinated clocks in motion, the press hailed the “Revolution in Clocks.”12

  Even today, from many places in Bern you can clearly see the faces of several grand public clocks. In that August of 1890, when they all began running in step, the order of coordinated time was written upon the architecture of this city of arcades and churches. Swiss clockmakers publicly joined the worldwide project of electric simultaneity.

  Theory-Machines

  During the 1890s Einstein was not yet concerned about clocks at all; but as a young man of sixteen, in 1895, he was very much concerned with the nature of electromagnetic radiation. That summer Einstein put on paper his reflections of how the state of the ether would alter in the presence of a magnetic field; for example, how its parts would distend in response to a passing wave. Even his untutored imagination was uncomfortable with the “customary conception” of radiation as a wave in static, substantial ether. Suppose, he later recalled thinking, that one could catch up to a light wave and ride it, so to speak, as classical physics might imply. Then one would see the electromagnetic wave unfold before him, the field undulating in space but frozen in time. But nothing like such a frozen wave had ever been observed.13 Something was wrong with this way of thinking, but Einstein did not know what.

  After a first unsuccessful application, Einstein began his training at Switzerland’s (and one of Europe’s) great technical universities: the Eidgenössische Technische Hochschule (ETH), founded in 1855. Certainly the ETH of 1896 was a very different place from the Ecole Polytechnique that Poincaré had entered in the early 1870s. To be sure, both stressed engineering. But Ecole Polytechnique’s fame had long rested on its schooling the elite in a concentrated mix of pure mathematics and scientific training, a foundation on which its graduates would then build at places like the School of Mines. For the French ever since Napoleon, the ambition had been to educate an elite in high mathematics that would be (in due time) able to meet the demands of the practical world they would control. Founded in the mid-nineteenth century in a Switzerland short on natural resources and long on desire to catch up with the rapid industrialization of France, Britain, and Germany, ETH was very different. ETH wanted an immediate link between theory and praxis. There was never a moment when the demands of road, railroad, water, electrical, and bridge construction were lost to sight or even put in the background.14 Take mechanics. At Ecole Polytechnique, Poincaré celebrated the subject as the “factory stamp” for all students, from those striving to become abstract mathematicians to those whose ambitions would take them into administrative or military service. Mathematics was the queen of the university, structuring the teaching of mechanics so that its abstractions were only gradually specified to the point where it met application. By contrast, in Zurich, it was a mining engineer with little interest in abstract mathematics who had set the tone of the mechanics course back in 1855. Built more along German pedagogical lines than along French ones, the Swiss insisted that the abstract should not wait for an eventual union with the applied in a next stage of education. Swiss industrialists needed help building everything from telegraphs and trains to water works and bridges. From the start (and throughout its history) the applied and abstract entered ETH together.

  So, while Poincaré and his contemporaries learned about experimentation by watching demonstrations at the front of the amphitheater, Einstein spent a great deal of time learning hands-on in the well-appointed physics laboratory at ETH. Formal treatments of the principles of devices were typical of the work at Polytechnique; when Cornu wanted to study synchronized clocks, he wrote down an elegant theory of the physics that underlay them. Instead, when Einstein’s physics teacher Heinrich Friedrich Weber taught, he spoke about the precise heat-conducting ability of granite, sandstone, and glass. Thermodynamics at ETH oscillated back and forth between the basic equations and detailed numerical calculations and laboratory arrangements of glass, pumps, and thermometers, as Einstein carefully recorded in his notebooks.15 Indeed, differences between the two institutions reflected their views about what theories said about the world. In Poincaré’s Ecole Polytechnique, he would have found a proud agnosticism toward atoms (or many other hypothetical physical objects). At ETH, Weber and his colleagues had no time for such fancy dancing, no interest in exploring, for its own sake, the myriad ways one could account for a collection of phenomena. After introducing “heat” without concern for its “true nature,” Weber argued that the connections among physical quantities led directly to a mechanical picture in which heat was nothing more than molecular motion. Then he calculated numbers of molecules and fixed their properties. No metaphysical realism, just a matter-of-fact engineer’s assessment that atoms let the work proceed.16

  In the summer of 1899, Einstein still was agonizing over the ether, moving
bodies, and electrodynamics. To his beloved Mileva Mari, he recalled that back in Aarau (in secondary school), he had thought up a way to measure, and perhaps to explain, how light traveled in transparent bodies when these transparent bodies were dragged through the ether.17 Now he conveyed to her his sense that naive, material ether theories, ones that proposed bits of ether here and there moving this way and that, would simply have to go. No doubt he had absorbed some of this austere attitude toward theory through the emphasis on measurement at ETH. Still, the school clearly frustrated Einstein by not offering more about the relatively new Maxwellian theories of electricity and magnetism. So he began teaching himself, and one clearly important source was the work of Heinrich Hertz. Hertz had stripped Maxwell’s complicated theory of electricity and magnetism down to its bare-boned equations and, to general astonishment, demonstrated experimentally the existence of electric (radio) waves in the ether. Throughout his short life, Hertz paid extraordinary attention to the different ways of formulating theories of electricity and magnetism, doubting out loud that the “name” electricity or the “name” magnetism corresponded to anything substantial in its own right. Einstein then turned Hertz’s critical sword against the still-vibrant ether: