At the end of the 1904 summer semester, the family made the long-awaited annual pilgrimage to die Hütte. Alfred knew that he was saying good-bye to this period of his life, and he was savoring it to the end. He would return here often in later years, but this was the last summer with his parents, as well as the last long vacation, and he knew it. In mid-August he (and Kurt, of course) took a three-day sailing tour as far as Neustrelitz, 30 kilometers (19 miles) by lake and canal to the north, and wrote up their adventures as a poetic “Edda” for the rest of the family. It was a gentle parody of a great sea voyage, including a survey of the “natural history” of the region and a roster of the expedition’s equipment and provisions (wine, bread, cheese, etc.).56
A week after their return from the first boat trip, they took off once more, this time for a week, armed with a camera and some navigational equipment. They sailed west, as far as they could—about 60 kilometers (37 miles) to Plau on the Plauer See. This voyage produced a longer (seventy pages) and more serious literary effort, illustrated with Alfred’s own photographs and entitled Sieben Tage im Boot (Seven days in a boat). It has the flavor of Theodor Fontane’s popular and reflective travel writing about the same scenes and sights, Wanderung durch die Mark Brandenburg. It is a first attempt at an exploration diary by a young man longing for an expedition—mixing breezy anecdotes with sober disquisitions on when one should and should not unstep the mast, or how one should take bearings from a lakeshore to plan a dead-reckoning course. It is as if he were cutting a template for himself, or producing an explorer’s “apprentice piece” to show his command of the skills, making something that is not a toy, but not the real thing either.57
The Alfonsine Tables
There was one matter still to be seen to before he could (as he ardently wished!) bring his student years to an end: the doctoral dissertation—an apprentice piece of another kind. Having decided to abandon astronomy, he knew that it made little sense (for him or the astronomy department) to pursue dissertation research on a problem in observational astronomy, since he would have to be given valuable observing time at either Berlin or Potsdam in order to make his measurements. The usual dissertation for Berlin astronomy students at this time was an orbital determination for an asteroid or comet; these were the sorts of problems on which Bauschinger was expert. The second most common was some study of the motion of the Moon and planets, or observations of the Sun; Förster supervised these.
Wegener’s (assigned) topic, supervised jointly by Bauschinger and Förster, was quite different and indeed unique in the annals of the department: Wegener was directed to undertake a historical and critical study of a set of astronomical tables—the Alfonsine Tables—commissioned by Alfonso X (“The Wise”) of Castile in the thirteenth century. In the recent past (reckoned from 1900) there had been at Berlin two historical-philosophical theses: in 1903 Abraham Hoffmann had submitted a dissertation on theories of the universe leading up to the work of Descartes, and in 1904 Max Jacobi had produced a thesis on the cosmological theories of Nicholas of Cusa. Neither of these, however, had any substantial technical content. Wegener’s problem required a good deal of historical knowledge, planetary theory, and calculating technique and provided a humorously gratifying, if unexpected, scientific employment for all those years of Latin.58 The latter skill perhaps sealed his fate—as the son of a classical scholar who had drilled him in Latin almost every day for fourteen years, Alfred was perhaps the only student in the history of the department to have his languages still largely intact years after Gymnasium. Though there is no record of collaboration with his father, one can hardly imagine that father and son would not have discussed this work, or that Richard would not wish to have a hand in solving the difficult textual questions that loomed.
As for the work itself, the original (thirteenth-century) purpose of Alfonso’s planetary tables was both astrological and astronomical; they allowed one to find the position of the Sun, Moon, and planets at any hour and minute of any day of any year. Astrologically, the positions were used to cast horoscopes; astronomically, they were used for navigation and time reckoning. The creation of a modernized edition of these tables in the twentieth century was, however, not an antiquarian exercise, though it might appear so today: it actually had applications to a problem in astronomy in which both Bauschinger and Förster were keenly interested.
Here is the problem that Wegener’s work was intended to solve. About thirty years before, in 1870, the great American astronomer Simon Newcomb (1835–1909) had discovered that the set of tables he was using to predict the position of the Moon showed increasing deviations from the Moon’s actual position. This was disturbing to Newcomb because the tables in question had been prepared by the German astronomer Peter Hansen (1795–1874), probably the greatest master of celestial mechanics since Laplace, and one of Newcomb’s heroes. Hansen had worked by matching his theory of the Moon’s motion to observations stretching back to 1750, and he had extrapolated earlier positions by calculations based on theory. To figure out what had gone wrong with Hansen’s predicted positions for the Moon, Newcomb traveled to Europe to study even older tables of the Moon’s motion. He found that the farther he worked back before 1750, the greater the discrepancy became. He conceived the notion, based on his absolute confidence in Hansen, that the reason for the discrepancy had to be a variation in Earth’s rate of rotation. Newcomb worked steadily on this problem until the end of his life, assembling astronomical records back into preclassical antiquity to try to get the longest possible series of lunar positions, so as to determine the pattern of rotational variation.59
The Alfonsine Tables figure into such investigations because they were the tables of reference throughout Europe from about 1330 until 1551, the year in which Erasmus Reinhold’s Prutenic Tables appeared—the latter being the vehicle whereby Copernicus’s theory first appeared in print. The Alfonsine Tables quickly fell out of use once the more accurate tables became available, having by 1900 been out of general use for almost 350 years. With the growing interest, around 1900, in what we would now call “long time series” of observations of celestial motions, there was now a good reason to refer to and correct these tables to establish the Moon’s position in the middle of the thirteenth century. Moreover, by looking at fifteenth- and sixteenth-century editions of the tables, one could examine the corrections introduced by later astronomers to overcome emerging divergences between predicted and observed positions of the Moon. This might also provide valuable hints about the Moon’s actual (vs. predicted) position and therefore information about Earth’s rotation.
The difficulty, as Wegener himself explained in his introduction, was that these Alfonsine Tables were now rare books available only in great university libraries. They were written in a difficult form of Medieval Latin and couched in terms of the Ptolemaic (Earth-centered) solar system, with its immense geometrical complexities and unfamiliar terminology. Moreover, the numerical values in the planetary tables employed the sexagesimal system (base 60) rather than the decimal system both for angular measurement and for date and time reckoning. The modern system uses the sexagesimal system for degrees, minutes, and seconds (and minutes and seconds of time) but then proceeds decimally. In brief, the Alfonsine Tables were generally unavailable, and where they were available, the difficulties of calculating or even reading them rendered them nearly useless.60
Wegener began his work in September 1904, comparing the (six) existing principal Latin editions to eliminate printer’s errors. He then translated the text from Latin to German. Then (in October and November) he converted the tables from sexagesimal to decimal values, a task involving about 9,000 calculations. That was the heart of the task, but there was a good deal more. He had to provide extensive notes to give astronomical calculators the means to use them. The calculators in question were not machines, of course, but observatory staff whose job it was to perform the actual calculations.
Alfred provided a correction for the difference between Toledo Sp
ain, the 0° of longitude in the tables, and Greenwich, England, the 0° of longitude for modern astronomy. He uncovered a systematic sixteen-minute offset in the tables resulting from a discrepancy between the Alfonsine way of calculating the “mean time” of a transit and the modern method of doing so. Finally, he devised a formula to eliminate a correction in the tables meant to account for the precession of the equinoxes which employed a (nonexistent) celestial motion called a “trepidation,” which the modern user must discount.
Wegener also had to show the calculators how to calculate using the tables, and he gave worked-out examples of such calculations. It required several explanations: the tables for the Sun are used differently than the tables for the Moon, and there are separate sets of tables for each of the planets. Latitudes are calculated in a way quite different from the calculation of longitude and distances, and these require separate tables and figures showing the geometry of the relationships (Wegener drew fourteen figures for his text). A sample calculation for the use of the Mars Tables and a copy of Wegener’s first page of figures give the flavor of the work.61
He also drew up a concise glossary of Latin technical terms for which there were no German counterparts, since the concepts in question had vanished from astronomy before German had become a scientific language.
This was indeed the work of an apprentice: straightforward and, though useful, much less valuable for itself than for what it revealed about its maker—self-discipline, attention to detail, a spirit of repetition, stoicism in laborious calculation, and an interest in rationalizing, modernizing, and easing access to data and theory, especially where long historical time series of measurements were involved. It was yet another practicum for Alfred in understanding the deep penetration of theory into scientific observation and, more importantly, by understanding the theory, how one learned to extract and discard it—an extremely useful scientific acquisition. Wegener’s The Alfonsine Tables was not scientifically important and led to no program of research for its author, though its technical proficiency was admirable, its explanations models of clarity, and the tables themselves still useful today for the purposes they were meant to serve. It was a parting gift to his mentors, Bauschinger and Förster, and also a gift to his parents and the classical world they inhabited, as reflected in its dedication: Meinen Eltern (To my parents).62
From another perspective, though, it was a serious underemployment of an exceptionally able and well-trained scientific intelligence. Wegener’s research produced a great deal more material than could be fitted into the scope of an edition of the tables, and he also found a good deal of error and sloppiness in the work already done on the tables. He wrote in his introduction,
It is worth while emphasizing that, on the other hand, the 1863–67 edition of the “Libros del saber de astronomia del Rey Alfonso X. de Castilla etc.” edited by the Madrid Academy of Sciences were completely useless for the present work. In the fourth volume of this work the Castilian original text of the [Alfonsine] Tables is included, but all that appears in the very place where the tables themselves are supposed to be is (erroneously identified as “numerical fragments of the Alfonsine Tables”) a special kind of Ephemeris for the tabulation of dates, later known as a “perpetual almanac,” which has nothing whatever to do with the original Alfonsine Tables. For the most part the contents of the Spanish publication are dedicated not to the planetary tables, but to a newly discovered edition of the work of Alfonso X on astronomical instruments.63
Wegener’s impatience with a careless error, combined with a too-limited project, seemed momentarily ready to project him into a new edition of the works of Alfonso of Castile, but he soon recalled that he was trying to get out of astronomy, not into the history of astronomy. After all, it could not have been lost on him that no one had remarked on the error in the forty years since its publication, so this was clearly no “hot corner” in astronomy or its history. The experience with the bungled Spanish edition resulted instead in a publication (nearly as long as the dissertation itself) in a leading journal of the history of mathematics, cataloging and analyzing Alfonso’s astronomical works.64 Wegener was taking the opportunity, limited as it was in subject matter, to develop an approach to research in general, finding what for him would be a comfortable depth of understanding of a text or a topic. This depth, here and afterward, turned out to be quite great, as we shall see.
Explanatory figures from Wegener’s dissertation to help the reader visualize the relationship of Earth to the Sun and other planets. The Earth-centered Ptolemaic system, on which the Alfonsine Tables are based, requires a number of extra geometrical devices to explain the observations while preserving the demand for perfectly circular orbits. In this illustration Fig. 1 is the orbit of the Sun; Fig. 2 is the orbit of the Moon, with the Moon’s epicycle centered on A; Figs. 3–5 are aspects of the changing distance of the Sun, Moon, and Earth from one another; and Fig. 6 is a composite picture of the geometric relationships among Earth, Jupiter, Mars, and Saturn. From Alfred Wegener, Die Alfonsinischen Tafeln für den Gebrauch eines modernen Rechners: Inaugural-Dissertation zur Erlangung der Doktorwürde genehmigt von der philosophischen Facultät der Friedrich-Wilhelms-Universität zu Berlin (Berlin: E. Eberling, 1905).
Wegener’s simplified explanation of how to use his modernized tables. The text reads, “Example: Find the true longitude of Mars for September 20, 1477 at 6:01:36 [a.m.] M[ean] T[ime] Toledo, decimal 1477.0+ 263 days, 6 hours, 1.6 minutes or 1477.72. We draw from the table the Mean Motions IV and V … [calculations follow yielding the true Mars astronomical longitude of 140.38°].” From Wegener, Die Alfonsinischen Tafeln (1905).
Alfred Wegener at age twenty-four in the summer of 1905, in a portrait made to accompany his dissertation on the Alfonsine Tables. From Wegener, Die Alfonsinischen Tafeln (1905).
It is also fair to say that Wegener could not resist the temptation to show off a little. He did not like to work without publishing, then or later, and almost every piece of work he ever did found its way into print somewhere and somehow. In a burst of festive file clearing in 1905 as he prepared to leave the university, Wegener collected his preliminary background studies on the relationship of observation to theory in cosmology from the pre-Socratics down to the time of Laplace and published them in the Berlin scientific monthly Mathematisches-Naturwissenschaftliches Blätter.65 He concluded that a survey of the history of cosmology shows a constant repetition of a few ideas—a disk, a vortex, nested spheres, or hemispherical heavens. The “right answer” appears again and again, but only as speculative philosophy. What separated modern (here Descartes and Newton) cosmology from the ancients was not new ideas, but the harvesting of fruitful conceptions—especially those of Anaxagoras—and then treating them mathematically.66 Newton would probably have agreed with and approved of this judgment: he held originality of conception to be of little weight and the mathematical explication to be the real scientific accomplishment. Wegener was defending his own work on the Alfonsine Tables and stating a credo.
The Last Classical Physicist?
Wegener’s university studies came to an end just as a number of profound changes swept through physics, astronomy, and cosmology. Einstein’s work on special relativity, the photoelectric effect, and Brownian motion—all in 1905—changed the meaning of space and time, divided light into discrete packets, and made the statistical interpretation (as opposed to determinate interpretations) of atomic behavior inevitable. Between 1905 and 1906 a number of stunning developments in quantum theory, physical chemistry, and microscopy drove even the most outspoken opponents of the atomic theory into accepting the reality of atoms and therefore of the granular character of the universe—putting back into basic physics what Planck had worked so hard to remove a few years before.
In astronomy, the work of J. C. Kapteyn (1851–1922) in 1904–1905 and that of Ejnar Hertzsprung (1873–1967) in 1905–1907 opened the door to the study of the evolutionary history of stars and of the dynamics of the univer
se and completely revitalized observational astronomy, albeit, as Alfred recognized, only for those with access to giant telescopes and those with great mathematical talents.
One is tempted to tell a story about a “fateful timing” in which Wegener was born at the very end of classical physics and, like a Lohengrin missing the swan boat, was left in the backstage of physics to smoke and think while the action went on without him, under the dramatic stage lighting of history. This would have a spark of tragic poetry, but it is too falsely theatric to contemplate for more than a moment. For one thing, there were other equally powerful and fundamental developments in these same years which created a great deal of new theoretical and practical turmoil in the regions of science Wegener was moving into, among them radioactive transmutation, a new theory of the formation of the planets, and other developments we shall discuss. But even had there not been these changes, it would have come out the same for Alfred. He began his adult scientific career in a world of observation, experiment, and data collection, in a world of macroscopic, thermodynamic physics, and this world remained virtually untouched in its character and practice by these fundamental changes in the view of the microscopic world—just as Planck had predicted. Timing had nothing to do with it. Had he been born a little later, had he taken those courses in stellar evolution, it would have made no difference; he still would have wanted to be outdoors. We need not divide up physicists into “theorists and experimenters” to explain his decision to abandon astronomy because we have recourse to another equally valid partition of humanity: those who do not need to feel the wind in their faces, and those who do.
4
The Aerologist
Alfred Wegener Page 13
