Alfred Wegener

by Mott T. Greene

  The Royal Friedrich-Wilhelms University of Berlin was, at the time Alfred enrolled in it, one of the largest universities in the world. It had a student body of almost 7,000 and a faculty of 450 professors, 227 of them in the Faculty of Philosophy—what we would now call the School of Arts and Sciences; the remainder were in law, medicine, and theology. The true size of the teaching faculty was larger, since the German system usually specified only one salaried full professor, called the Ordinarius, and one associate professor, the Extraordinarius, for each subject. The rest of the faculty was composed mostly of Dozenten, a composite group of what would in an American university be the assistant professors and the instructors, though their positions were more precarious and their incomes much lower. The university’s place on Unter den Linden, between the State Library and the Royal Arsenal across the way from the Palace of Wilhelm I, testified to the importance of the learned professions in the Prussian scheme of things. The late-century transformation of Germany into an empire and a wealthy industrial state, ruled by an education-minded kaiser, flooded the university system with new resources and brought students in great numbers, especially into the sciences.

  The Physics Institute at the University of Berlin, where Alfred Wegener began his university career in October 1899. From a contemporary postcard in the author’s collection.

  Alfred’s first-year academic program at Berlin must bring a smile of recognition to anyone who has pursued—or thought about pursuing—a vocation in natural sciences: analytic geometry and calculus, physics, and chemistry.2 This is “year one” of most scientific careers then and now, all over the world. To these fundamental preparatory studies Alfred added a course in “practical astronomy” and a series of inspirational and nontechnical lectures in astrophysics, aimed at a popular audience. This is the program he would pursue until the following April—the end of the “winter semester”—a period of study roughly the length of a North American academic year. The topics of the basic courses were generic, and so was the content. That was the point: in classical physics and astronomy generic content and methods really existed as shared foundations on which one could build. Indeed, in spite of the many revolutions in physical theory since that time, the basic subject matter and contents of these entry-level studies have remained remarkably constant.

  If the content of Wegener’s first year was generic and ordinary, not so the instruction. Berlin was in 1899 the summit of not just the Prussian but the Imperial German university system; it was the top of the profession, the pinnacle of advancement and promotion. The professors were giants of international reputation, men who ruled their departments like feudal baronies and held their professorial chairs like thrones. Their appointments were for life, and when they died or retired, there were no applicants for their jobs—the ministry of education formed a committee to rank the three current leaders in a given field, and based on this ranking a “call” went out to a specific person, named as the successor. The resulting concentration of talent in science and mathematics was awe inspiring. More extraordinary, however, and in contrast to the image of the lofty and indifferent German professor, Wegener’s roster of teachers (in his first year and thereafter) was dominated by men devoted to teaching. Among these were a few individuals equally famous for their easy familiarity, their lack of ceremony, and their concern for their students’ welfare and progress. The culture of physics, astronomy, and mathematics at Berlin, like that of the Wegener household, was of one of cooperative work, of mission, of participation, and of community. There was, of course, a hierarchy—where is a there a community without one? The professors were also severally quirky, imperious, abrupt, demanding, and tedious: it was, after all, a university. These reservations notwithstanding, the institutional culture demanded careful attention to the instruction of students, whose intellectual welfare was a real consideration.

  The course that introduced Alfred to university mathematics was analytic geometry and the theory of limits, taught in a large lecture hall to an audience of 200 or so by Hermann Amandus Schwarz (1843–1921). Schwarz, famous for his work on conformal mapping and Riemann surfaces and in the calculus of variations, was well known in Berlin for his lectures and his relationship to his students. When Wegener first heard him lecture, Schwarz had been in Berlin for eight years and had thrown himself completely into his teaching. He shared Karl Weierstrass’s (1815–1897) conviction that the theory of functions had to be established on simple algebraic truths and that the foundations of the theory should be available to students without a knowledge of complex techniques of differentiation.3

  Schwarz took his time in lecture, not reading from notes or rocketing through the designated material, as did some of his colleagues. His explanations were detailed and discursive. To illustrate his points, he drew beautiful diagrams in colored chalk, completely unhurried. He stuck to the fundamentals of analytical geometry, not moving rapidly to those topics that the advanced mathematics students were waiting to hear about. The slow pace reinforced the importance of the basic algebraic and trigonometric concepts, of logarithms and exponents, sequences and series, rehearsing the linkage between the world of algebra and that of geometry, and returning again and again to the basic concept of the limiting value—the discovery of the point at which some mathematical function or physical quality reaches a maximum or a minimum.4 Schwarz tried to get all of his students to join the Mathematical Society, urging them to come to the meetings and get to know and meet with their Dozenten—a means to learn mathematics and to develop a sense of community in a large and impersonal university.5

  In sharp contrast to Schwarz’s lectures were those of Johannes Knoblauch (1855–1915), who taught Wegener introductory calculus. He was a clear lecturer but moved very rapidly and developed the differential calculus with a very abstract and arithmetical approach that was too sophisticated for most of his young students. Knoblauch was at pains to give them exercises and problem sets in order to apply the principles, but the problems were generally too hard.6 Alfred had worked diligently at his school mathematics in the Gymnasium, knowing that he would be going on to the university for astronomy and physics, but he found Knoblauch’s course hard sledding. He had no special gifts in mathematics—something he knew early on and freely acknowledged to family, friends, colleagues, and later his students. Neither had he any taste for the sort of mathematical abstraction that gives some physicists such intense aesthetic and intellectual pleasure; in later years he exhibited a strong antipathy toward it, and one may suspect that this antipathy was born here.7

  More compelling and exciting were the lectures in experimental physics given by Emil Warburg (1846–1931). Warburg lectured to audiences of 300 or more, crammed into the largest hall in the institute. His lectures were formal and showy demonstrations in which the experiments were performed by the professor and the instructors before the class, rather than a laboratory-based study in which the students performed the experiments themselves; there was no opportunity for discussion. But Warburg put tremendous energy into this teaching, and some of the demonstrations were wonderful and are still performed today, all designed to be as striking as possible and to link the phenomena under examination to a unified mechanical picture of the world through the laws of motion. This bringing of physics together under the concepts of mechanics had been the goal of Berlin physicists in the previous generation under Helmholtz and Kirchhoff, and it had been affirmed by their successors, including Hertz and Boltzmann.8

  The lectures by Julius Scheiner (1858–1913) on “Popular Astrophysics” had the merit of being about the subject that Wegener had come to the university to study. Scheiner had come to Berlin as “Extraordinary Professor of Astronomy” in 1894, though Berlin was not a center for astrophysics, but rather one for classical observational astronomy. Scheiner was a somewhat distant figure who spent a good deal of his time in the observatory at Potsdam, where he was part of an international project to create an “astrographic chart” of the heavens, and where he worked
in developing practical techniques for celestial photography and spectrography.

  Given Wegener’s intense excitement about moving on to the university, there was something very unsatisfactory about all of this. The classes were huge, and the course work consisted in listening to lectures, taking notes, looking at demonstrations, and reading the professors’ textbooks. There were no real laboratory exercises, and the problem sets were limited and unsatisfactory, or too hard. The professors were clearly well-meaning and abstractly concerned for students, but they were not available for consultation outside of the Sprechstunde, the one office hour per week that each professor was required to keep. Even for that minimal contact, one had to stand in line to get one’s name on the sign-up sheet when it was posted, and one would be lucky to speak to the professor for a few minutes in the course of an entire semester. Wegener’s studies were interesting and necessary, but it was not scientific work; it was schoolwork.

  There was one wonderful exception: the course taught by Adolf Marcuse (1860–1930). Marcuse had come to the university only two years before, as Privatdozent in astronomy.9 His course for the 1899–1900 year—small, intense, and pragmatic—was entitled “Practical Astronomy,” and it was exactly that. Finally, there was something to do rather than to listen to. The course had three segments, and each of them had a profound effect on Wegener’s thinking and his plans for a career. The very first part was “Theory and Use of Astronomical Instruments, Especially for Geographical Position Finding.”

  Marcuse, at thirty-nine, was the youngest of Wegener’s teachers in that first year, and he was an expert on the use of astronomical observations to make precise determinations of latitude and longitude. In connection with this work, he was a leading observer throughout the 1890s in a program to measure the amount and direction of the very slight oscillations of Earth’s axis of rotation, now known as the Chandler wobble (after Seth Carlo Chandler, 1846–1913). These motions had first been detected in Berlin in 1884–1885, though they had been predicted theoretically by Leonhard Euler in 1765. In the years 1889, 1890, and 1891 Marcuse worked at the Royal Observatory (Berlin-Potsdam) with a universal transit instrument—a telescope mounted in such a way that it could rotate in any direction and swivel so that it could look straight up, and equipped with vernier scales and micrometers capable of extremely delicate adjustments and very fine scaled measurements of angles. Marcuse was looking for repeated, minute variations in the apparent positions of pairs of stars. These variations could be interpreted as indications of slight variations of the latitude of the observatory and were what one would expect if Earth’s pole of rotation was slightly and continuously displaced. The phenomenon was very interesting in its own right, but it also provided a necessary correction when preparing maps of star positions, and the Royal Observatory was at that time preparing such a map. Finally, it was a technical tour de force involving both instrument design and observational precision.

  In 1891, Marcuse had traveled to the Hawaiian Islands and made the same observations. Hawaii lies between about longitude 155° and 160° west and is nearly halfway around the world from the Berlin Royal Observatory (Potsdam), at longitude 13° east. If Earth’s pole were wobbling in an irregularly circular path over a period of months, the same latitude variations should be seen in Hawaii that were seen in Berlin, but they should be in the opposite direction. Marcuse showed that this was the case: the measurements confirmed an oscillation of Earth’s axis of 0.3 arcseconds over a period of fourteen months. With 60 nautical miles (111 kilometers) for each degree of angular measure, this was a displacement of the pole of just under 10 meters (31 feet).10

  Astronomers greeted these measurements with great interest, and the amplitudes of the oscillations were exactly confirmed by those measured by Seth Chandler at Harvard Observatory. Chandler had also made such measurements in 1884–1885, but he published them only in 1891. He also made an interesting and successful attempt to confirm the motion historically by going back to look at observatory records of the past 150 years indicating similar shifts of star positions, including the observations of James Bradley (1693–1762) at Greenwich Observatory, an astronomer renowned both for his accuracy of observation and for his strenuous efforts to remove every source of error. These historical researches uncovered a twelve-month variation superimposed on the fourteen-month period and set off a controversy even more absorbing than the measurements themselves. Euler had predicted an oscillation of 305 days, and Chandler’s period was considerably longer, at 434: what could be causing the variation? Since it was a “free motion,” it should ultimately “damp out” and cease, unless re-excited, but 150 years of records showed no damping, and there was no candidate mechanism for the excitation to keep the motion active. The phenomenon was of sufficient interest that in 1899, the same year Alfred entered the university in Berlin, an agreement was reached to establish the International Latitude Service, with four observatories to be constructed in the Northern Hemisphere 90° of longitude apart from one another, all four at the same latitude, to measure continuously the shifting of the pole.

  Wegener had landed not just in an astronomy course in which he could do astronomy, but in one that implied that doing astronomy sometimes involved expeditions to distant places, and signifying a kind of work where a relatively short series of very precise measurements could be decisive in a long-standing controversy—and in this case could open new questions not only about the sky but about the earth as well. Marcuse took Alfred and the other students on field trips and taught them to level and orient the transits, telescopes, alt-azimuths, and other instruments. He taught them how to calculate instrument errors and how to correct observations for temperature (expansion and contraction of the instrument itself) and for the relative humidity, since the amount of water vapor in the air changed the way the light was refracted, causing a measurable (and correctable) angular displacement. He regaled them with stories of expedition science, both from his work in Hawaii and from his more recent trip to German Samoa.11

  In the second wing of the course Marcuse took the students through a general survey of the fundamental ideas and achievements of modern astronomy, and here again was a pleasant novelty—the lectures were illustrated with lantern slides. Marcuse was a prolific and expert photographer, with a missionary zeal on the subject of photographic illustration. He taught every course using slides and believed that all subjects benefited from profuse illustration.12 When he published a popular travel book about Hawaii, written while on the latitude expedition, he illustrated it abundantly with his own photographs, even including a color frontispiece.13 Marcuse’s use of photography in the classroom on this scale was as great and powerful an innovation in 1899 as classroom projection of computerized images directly from the Internet became 100 years later. The use of photographic illustration in science teaching is so uniform, and the slide format so ubiquitous (the most commonly repeated phrase at any gathering of scientists was, for some decades, “next slide please”), that it is interesting to remember that this approach to teaching was something that had to be pioneered and defended.

  Wegener was entranced by the photographs, and he immediately and completely embraced both the technology itself and Marcuse’s passionate advocacy of its use. There was certainly a scientific case to be made for the intellectual impact of visual images unfiltered by profuse verbal description. In a textual presentation of some aspect of the world, the author reveals the object of study in a series of steps and is in control of the unveiling. Even if the verbal text is accompanied by drawings, these inescapably reflect both deliberate and unconscious selection of detail. A photographer can do this too, of course, by selecting the illumination, angle, film speed, exposure, and so on, but the editing of a photograph is a matter of filters and thresholds. In a drawing, only what is put in goes in; in a photograph, everything goes in that is not screened out.

  Marcuse made it clear to Alfred and the other students that photography was not solely an illustrative and pedagog
ic device but also a potent means of scientific discovery. In the third wing of the course, the first-year astronomy students accompanied Marcuse to the Royal Observatory, where they watched him and the other staff astronomers demonstrate the photographic methods used to document their observations. The students were put to work with practical exercises of observation, photography (including the preparation of photographic plates and darkroom work), and measurements of the shifts in the plates thus produced. These were not part of the institute’s regular documentation; they were practice exercises—but they were nevertheless real observations and real calculations based on real measurements.

  Wegener liked this approach to the world—he liked the small groups, the tactile and practical character of the work, and the emphasis on standardizing methods of doing things, as opposed to the standardized manipulation of abstract principles. He was exhilarated by the direct connection of observation and discovery and found that the emphasis on repetition gave him a certain advantage because of his habitual tenacity. By this route he had discovered much from the telescope on the Gymnasium roof which was new to him; now he was moving into a situation where really new discoveries were actually possible and even likely.

  The summer semester of the year 1900 was coming soon, and with it a chance to alter his academic program. It was typical at that time for Berlin students to leave for the summer term, from May to August, especially during their first years. Consequently, enrollment at Berlin dropped by about 2,000 in the summer. Students headed generally for smaller and rural universities, like Göttingen, the choice of Alfred’s student friend Walther Lietzmann (1880–1959), who wanted to pursue higher mathematics but also wanted to have a chance to hike and do some field botany and geology.14 For his own first semester away Alfred settled on the university in Heidelberg, and he looked forward to it with great anticipation—not least because he was nineteen years old and had never been more than a few miles or a few days away from his parents.