Turner on Cahan, 'Helmholtz: A Life in Science'

David Cahan
R. Steven Turner

David Cahan. Helmholtz: A Life in Science. Chicago: University of Chicago Press, 2018. 944 pp. $55.00 (cloth), ISBN 978-0-226-48114-2.

Reviewed by R. Steven Turner (University of New Brunswick) Published on H-Sci-Med-Tech (December, 2018) Commissioned by Kathryn Olesko (Georgetown University)

Printable Version: http://www.h-net.org/reviews/showpdf.php?id=53173

At his death in 1894, Hermann von Helmholtz was arguably the most acclaimed natural scientist in the world. Today his achievements still awe even specialist historians. The son of a high school (Gymnasium) instructor in Potsdam, Helmholtz studied medicine at the University of Berlin. There he joined other students of physiologist Johannes Müller in an anti-vitalistic commitment to physicalist approaches to the study of life. Self-taught as a mathematical physicist, and inspired in part by his physiological interests, he formulated the definitive theoretical statement of the Conservation of Energy in 1847 at the age of twenty-six. His early experimental research dealt with animal heat and muscle energetics, and in his first professorial position, at the University of Königsberg, he measured the velocity of the nerve impulse. In 1851 Helmholtz won international renown after inventing the opthalmoscope, a diagnostics instrument which revolutionized opthalmology. His interests soon gravitated to sensory physiology, and in successive positions at the Universities of Bonn and Heidelberg, he published the three volumes of his epic Handbuch of Physiological Optics. This work synthesized all existing research on the physiology and psychology of vision and laid out the major theoretical interpretations that would dominate those fields (not uncontested) for sixty years. In 1861 his no-less-epic work On the Sensations of Tone did much the same for the physiology and psychology of hearing, especially as it referred to musical perceptions.

In 1871, at the height of his fame as a physiologist, his native Prussia brought Helmholtz back to Berlin, now as professor of physics. In that role he became the chief intermediary in introducing James Clerk Maxwell’s field theory of electrodynamic action to Continental physicists (as one variant of his generalized potential theory) and inspired the experimental work of his student, Heinrich Hertz. By now the living symbol of German scientific dominance in Europe, he was appointed president of the new Physikalisch-Technische Reichsansalt and represented Germany in numerous international conferences on electrical standards. Along the way, he became a leading figure in the formulation of non-Euclidean geometry, contributed to hydrodynamics, and published research seminal to the emergence of whole new disciplines, including meteorology, physical chemistry, and electron theory.

Throughout his career Helmholtz lectured and wrote prolifically on epistemological issues, integrating classical British empiricism with the most up-to-date scientific findings from sensory physiology and psychology. He propounded a widely influential, Kantian-flavored “empiricist theory of perception,” anchored by his insistence that “unconscious inferences” underlie all human perceptual processes. His widely read popular lectures also contain his ideas on the relationship of science to art, the place of science in modern culture, and the origins and destiny of the solar system. He was, by any standard, one of the best-known science popularizers of the century.

To produce a definitive biography of a protean figure like Helmholtz is a major scholarly achievement, and that is what David Cahan of the University of Nebraska has accomplished. Cahan’s formidable new biography runs to 764 pages of text, 74 pages of footnotes, 56 pages of bibliography, and six full pages to list the many archives through which Cahan has exhaustively tracked every surviving record of Helmholtz’s life and work. The treatment is richly detailed, judicious, quietly conservative, and eminently readable. Cahan has long been the recognized doyen of Helmholtz studies internationally, and his biography has been eagerly awaited by scholars in the field.

Cahan has had to overcome obstacles to produce this work. Earlier studies of Helmholtz offer few attractive models for a biographer. Leo Königsberger’s classic three-volume biography (1902-03) is not only hagiographic, but consists mainly of long extracts from the published scientific works and popular lectures. More serious, the large Helmholtz literary estate held in the archive of the (now) Berlin-Brandenburgishe Akademie der Wissenschaft was largely closed to scholars outside East Germany until the later 1980s. Even that Nachlass contains mostly letters to Helmholtz; letters by him are scattered among some 120 other depositories around the world. Cahan’s research for this biography has been a work of exploration as well as interpretation.

Nor is the secondary literature on Helmholtz entirely helpful to the would-be biographer. Helmholtz has attracted less scholarly attention than other comparable historical figures of the nineteenth century (Goethe, Humboldt, Darwin, Pasteur). The literature that exists has focused on his epistemological and philosophical views rather than his research science per se. Topics that dominate the Helmholtz literature include his empiricist theory of knowledge and perception, the extent of his debt to Kant, his influence on later philosophers and the Vienna Circle, and his understanding of the foundations of geometry and mathematics. Cahan has navigated the biases built into the secondary literature with aplomb, while not neglecting the vexed question of Kantian influences.

Throughout, David Cahan has had to wrestle with the fundamental questions that the authors of scientific biography must face. One is the balance to strike between the subject’s life and the subject’s science. Here the biography maintains a fine equilibrium, perhaps with some inclination toward the personal and professional. In Cahan’s pages we meet Helmholtz the son, husband, and father, immersed in family and often benefiting from the advantages that marriage and family connections opened to him. Although by no means a gregarious individual, the calm and placid Helmholtz was an inveterate networker who loved to travel and could rarely turn down a conference or an invitation. We find in Cahan’s study a Helmholtz constantly on the road, whether hiking in the Alps, guest-lecturing all over Europe, starring at international conferences, or cultivating his always-close ties with the British community of physicists, especially John Tyndall and William Thomson. The biography is rich with information about intrigues over appointments and promotions, Helmholtz’s work habits and schedules, teaching and administrative duties, awards received, and the many students who flocked to study with the most famous scientist in Europe (and were usually disappointed by the great man’s dearth of teaching skills). The work concludes with an intriguing chapter tracing the political uses made of Helmholtz’s historical memory during the century after his death.

Biographers of scientists must also decide how to present the thought and the research of their subjects: in how much detail, and with how much attention to context, impact, and competing interpretations. Here Cahan is typically balanced, but on the whole he lets Helmholtz’s scientific contributions speak for themselves. The scientific contents of projects and papers are cogently and accurately summarized, but the biography eschews detailed descriptions, equations, and abstruse technical matters. Context, however, is richly provided, especially in the coverage of the controversies Helmholtz’s writings sometimes provoked. These included not only significant disputes with figures such as Ewald Hering, Rudolph Clausius, and Wilhelm Weber’s students, but also attacks by ideologically driven cranks such as Eugen Dühring and Johann Zöllner. Cahan is particularly thorough in his discussion of Helmholtz’s work on musical perception, and judicious in his coverage of Helmholtz’s participation in the disputes over priority for the discovery of the conservation of energy.

Good biographies paint pictures of individual lives, and Cahan does that vividly, especially for the later, Berlin years. Despite his bourgeois origins, Helmholtz and his second wife, Anna von Mohl (1834-99; his first wife, Olga von Velten, had died in 1859), moved among the Prussian elite. Their acquaintances included Crown Prince Frederick William of Prussia, and Anna was a personal friend of the Crown Princess Victoria. During the Berlin years, Anna operated a prominent learned salon in Berlin, one of a distinct liberal tinge (Bismarck was never invited), which attracted Berlin’s artistic and intellectual elite. Their other close acquaintances beyond science and academia included Richard Wagner, the Steinway family (which gifted Helmholtz with five pianos), and Thomas Edison.

The biography also presents a picture of an aging individual worked almost to exhaustion: in Berlin Helmholtz lectured two hours a day, taught introductory and advanced courses, oversaw his laboratory Praktikanten, carried out extensive administrative duties as (sometimes) rector of the university, managed the construction and operation of the new university physics institute (and later that of the Reichsanstalt), was a mainstay of the Annalen der Physik und Chemie, and attended weekly meetings of and made frequent presentations to the Berlin Academy of Sciences and the Berlin Physical Society. He greeted the presidency of the Reichsansalt, endowed in part by admirer and industrialist Werner von Siemens, as a welcome means of escaping some of his exhausting teaching duties. Yet to his death, Helmholtz’s scientific productivity never flagged. During his last years he undertook a far-reaching program to ground all physics on the concept of least action, and so to create a “physics of principle” in which “hypothetical elements would be unnecessary or at best a heuristic aid” (p. 702).

To read David Cahan’s biography is to be drawn into meditation about the ironies of scientific fame and the varieties of scientific creativity. Helmholtz, especially through his lectures on theoretical physics and his work on least action, came to personify “classical physics.” That edifice was soon to be undermined by the revolutions in relativity and quantum theory, and with it some of Helmholtz’s standing in the history of science. A similar fate, to a lesser extent, befell his work in sensory physiology. In the twentieth century new experimental techniques—electronic instrumentation, electrode implantation, and direct measurements of neural impulses—would partly supplant his own methodology and findings, based as they were on introspective and psychophysical principles.       

Helmholtz’s scientific creativity did not consist, as Cahan astutely observes, in his ability or desire to challenge the conceptual foundations of the fields in which he worked. For him, the ideal of “the unity of sciences” was not mere rhetoric. He was a brilliant synthesizer, dedicated to using his mathematical, physical, and experimental expertise to knit together the entire front of human knowledge, including the fine arts, philosophy, and the various natural sciences. Cahan quotes Emil du Bois-Reymond at the time of Helmholtz’s death as questioning “whether a figure like him can ever appear again” (p. 738). Cahan, too, rightly calls Helmholtz “the last great generalist” (p. 738). His fine biography amply testifies to Helmholtz’s noble, if ultimately impossible, aspirations.

Citation: R. Steven Turner. Review of Cahan, David, Helmholtz: A Life in Science. H-Sci-Med-Tech, H-Net Reviews. December, 2018. URL: http://www.h-net.org/reviews/showrev.php?id=53173

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