Hunt, Pursuing Power and Light

Reviewed by Jacob Darwin Hamblin in Physics in Perspective 13:1 (2011), 117-118.

Bruce J. Hunt, Pursuing Power and Light: Technology and Physics from James Watt to Albert Einstein.  Baltimore: Johns Hopkins University Press, 2010, 182 pages. $20.00 (paperback).

About a third of the way through Bruce J. Hunt’s marvelous little book on nineteenth-century physics, I stopped thinking about it as a book reviewer.  Instead, I began to imagine ways that I could use it to re-tool my classes in the history of science and technology.  Surely this is a good sign.  Part of the Johns Hopkins Introductory Series in the History of Science, Pursuing Power and Light packs in an extraordinary amount of material in just 167 pages of lucid, entertaining, and (most importantly) comprehensible text.  It is an ideal historical primer for students (and teachers), not only because of Hunt’s gift of scientific explanation, but because of his convincing portrait of how closely scientific ideas developed in relation to changes in technology.

Although Hunt does not argue that technology always preceded science, he makes clear that it often did, and rarely neglects an opportunity to disown the twentieth-century idea that scientific ideas typically are the building blocks of new technology.  As other historians have noted, the steam engine did more for science than science ever has done for the steam engine.  The science of thermodynamics owes a great debt to the industrial revolution, just as electrical science developed under the pressures of expanding telegraph lines and submarine cables.  When William Thomson was raised to the peerage in 1892, his friends joked that he should take on the mantle of “Lord Cable” rather than Lord Kelvin.  This message comes across loud and clear in Hunt’s telling, and it is a powerful theme for explaining the development of the physical sciences in the century prior to relativity, quanta, electrons, X-Rays, and radioactivity.

One of the strengths of Hunt’s narrative, for instructional purposes, is that it sets up clear conceptual dichotomies that are easy to follow.  The reader comes away understanding why the Laplaceans favored the particle interpretation of light (rather than waves), for example, or why Carnot’s disciples thought that heat was a real substance—caloric—that flowed through a steam engine (rather than a measure of energy, as later physicists believed).  This approach conveys the scientific ideas in an intelligible way, and it also helps to identify the personal, social, or financial stakes in any given approach.  Such stakes are especially evident later in the book as Hunt discusses the corporate battles over alternating electrical current and direct current.

The book also succeeds in highlighting the genuine conceptual dilemmas posed by nineteenth century physics—not just for scientists but also for laypersons.  For example, the notion of heat death, the ultimate running down of the universe, was a consequence of entropy that many observers found deeply troubling.  Also, the notion that energy can neither be created nor destroyed did not spring merely from the weight of evidence; it was a powerful idea that resonated with many scientists.  In particular Michael Faraday, a sincerely religious man, saw the forces of nature as something only God had the power to make or erase.

The book’s structure contains no great somersaults of innovation, but it is logical and extremely helpful in separating out several key areas of study.  It begins with a discussion of the steam engine and the questions about heat efficiency that its use provoked, connecting James Watt’s ingenuity with Sadi Carnot’s early attempts to explain in mathematical terms what occurred.  Then Hunt focuses on the efforts to devise a more thoroughgoing theoretical basis for the movement of heat, leading to concepts such as energy and entropy.  Here he gives a detailed account of James Joule’s paddle-wheel experiments, in which he attempted to show that work could be converted into heat, before going on to discuss how William Thomson, Rudolf Clausius, and others worked out the laws of thermodynamics.  Another chapter is devoted to kinetic theory, including a very clear discussion of “Maxwell’s demon” and its importance in pointing out some of the consequences of entropy.  Hunt’s chapter on electricity is especially good.  Not only does it include a superb overview of how Faraday came upon his “lines of force,” but also it reveals how intertwined this research was with the early days of telegraphy.  If the narrative stumbles at all, it is only a slight bump in his discussion of electromagnetism—a topic Hunt knows quite well, as demonstrated in a previous book, The Maxwellians (Cornell, 2005).  His close reading of Maxwell is at times fascinating, but even the best students may struggle to comprehend all the implications of spinning vortex cells.  On the other hand, such dedicated students will be grateful for the helpful diagrams.

Other than the chapter on electromagnetism, the book is remarkably (and fortunately) light on equations, and Hunt leaves little doubt about what concepts are at stake and what personalities play important roles.  This is particularly so toward the end of the book, when Hunt provides a riveting tale of how electricity came to be so pervasive in society, powering light bulbs and motors.  Hunt tells the story of the acrimonious disputes between Edison and Westinghouse about alternating current and direct current, as electrical grids began to spring up all over the United States. The book finishes with the events that usually begin the tales of twentieth-century physics: the Michelson-Morley measurements of the speed of light, Einstein’s theory of relativity, and Planck’s quantum.  In keeping with his theme, he notes that despite Einstein’s fame as a theoretician, he gained many of his insights while poring over technological designs in a patent office.

Throughout the narrative, Hunt has helpfully encapsulated some of the key ideas in separate textual inserts, usually next to a graphic to illustrate the idea.  These are short and to the point, invariably adding further clarity.  Although Hunt has included some diagrams of his own (as in his discussion of kinetic theory), most of them are drawn from contemporary sources, a nice touch that helps to communicate not only the ideas but also how scientists and others might have visualized them at the time.

This book has three extraordinary merits: it is clearly a product of fine scholarship, it is a pleasure to read, and it has great pedagogical value.  I plan to assign it in my classes.  When William Thomson chose one word to sum up his five decades of research on the foundational principles of the physical world, it was “FAILURE.”  The same could never be said of Hunt’s book, which succeeds in expressing the frustrations, motivations, and conceptual problems of nineteenth century physics with erudition and style.

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