Optics in the Age of Euler: Conceptions of the Nature of Light, 1700–1795 by Casper Hakfoort

Abstract

968 Book Reviews TECHNOLOGY AND CULTURE his major contribution may be to remind us that inventions are the creation of discrete content as well as cognitive process, of local knowledge as much as blinding insight. William S. Pretzer Dr. Pretzer, director of educational programs at Henry Ford Museum & Green­ field Village, recently completed a term on the National Commission for Technology Education, a K-12 educational standards project. Optics in the Age ofEuler: Conceptions ofthe Nature ofLight, 1700-1795. By Casper Hakfoort. Cambridge: Cambridge University Press, 1995. Pp. 243; figures, tables, notes, bibliography, index. $64.95 (hardcover). There is a considerable literature on the debate on the nature of light, and historians of science agree that until the 19th century the corpuscular (or emission) theory of light had the upper hand. The main purpose of this book, as stated by its author, is to “enrich and qualify” this picture by showing that in Germany in the second half of the 18th century Leonhard Euler’s wave theory was preferred to the corpuscular theory. This conclusion is based on a comprehensive study (apparently the first one) of the dispute on the nature of light in Germany. This is the strongest part of the book and provides a wealth of informa­ tion little known even to historians. Hakfoort also attempts to revise the generally accepted outline of the controversy on the nature of light, in particular, the view that the opposition between “the emission and medium traditions” de­ veloped in the second halfof the 17th century. In his view this oppo­ sition emerged after Euler. To prove this point, the author gives a detailed account of Euler’s theory, which he believes to be the first wave theory of light (however, see below), and discusses the German response to it. Finally, Hakfoort offers a new classification of the methodological components of science. In addition to mathematics (“classical tradi­ tion”) and experiment (“Baconian tradition”), used by Thomas Kuhn and others, he suggests a third, “theoretical natural philoso­ phy,” which refers to a qualitative explanation of phenomena. Hak­ foort claims that 18th-century optics was “torn among the three tra­ ditions” (p. 182), each of which developed different methods and objectives. In his view, only Huygens synthesized all three method­ ological components, while Newton’s optics was short on mathemat­ ics and Euler’s, on experiment. In the early 19th century, French researchers revived Huygens’ methodology so that “equal attention was given to all three of these elements” (p. 184). The author uses this scheme to account for the reception both of Newton’s theory TECHNOLOGY AND CULTURE Book Reviews 969 ofcolors and ofEuler’s theory and concludes that the lack ofcontact among “theory, mathematics, and experiment” (p. 188), prevented a more complete mathematization ofphysical optics in the 18th cen­ tury. In his view, the problem was not in applying mathematics but in finding “an integrated method” (p. 189). The book provides interesting observations about the work of Eu­ ler and others, although readers may disagree with some of the au­ thor’s conclusions, based on his own interpretations of terms or his­ toriographical issues. In particular, he treats optics before 1800 as dealing primarily with colors, and he begins the story of the wave theory with Euler because the only “true” waves, in his view, are the periodical ones. While Hakfoort is correct about Euler’s theory as the best contri­ bution to the “medium tradition” in the 18th century, to say that it was a “full-fledged alternative to the emission theories” (p. 115) is an exaggeration. Euler’s theory could not explain even phenomena already accounted for by Newton, such as rectilinear propagation of light, diffraction, colors of thin films, double refraction, and polar­ ization. For this reason, some historians do not consider Euler’s the­ ory to be an equal alternative to Newton’s emission theory (see, for instance, the paper by L. Minchenko in Physics at the Turn ofthe 17th18th centuries [in Russian] [Moscow, 1974]) While a formal mathe­ matical introduction of periodical waves was an achievement in it­ self, it remained useless for optics until the discovery of the principle ofinterference by Thomas Young, who borrowed the idea ofperiodi...