Quantum Legacies: Dispatches From an Uncertain World

by David Kaiser

  Gravitation focuses on the general theory of relativity, Albert Einstein’s remarkable theory of gravity. Einstein completed the theory just over a century ago. He had toiled for nearly a decade up to that point, stumbling through a series of false starts and working at a frenzied pace. Throughout the month of November 1915, he delivered regular updates on the emerging theory to the Prussian Academy of Sciences—one presentation each Thursday, four weeks in a row—adjusting details between each presentation. By the end of that month, he had arrived at a form of his equations that physicists still use today. Elegant and crisp, they are brief enough to tweet. Einstein’s major insight was that space and time were actors in the story of nature, not merely a fixed stage on which all other activity played out. Space and time, on Einstein’s account, were as wobbly as a trampoline—they could bend and distend in response to the distribution of matter and energy. That warping, in turn, affected objects’ motion, diverting them from the straight and narrow path.2

  One year after the armistice that ended the First World War, a British team, led by Arthur Eddington, announced that they had confirmed one of Einstein’s key predictions: that gravity could bend the path of starlight. The dramatic announcement propelled Einstein and his general theory to instant stardom. Yet interest in the theory waned over the 1930s. Einstein himself noted plaintively, in a preface for a colleague’s textbook in 1942, “I believe that more time and effort might well be devoted to the systematic teaching of the theory of relativity than is usual at present at most universities.”3

  Years passed, but eventually some charismatic teachers began to heed Einstein’s call. Among the first and most influential was John Wheeler, who began to offer Physics 570, a full-length course on general relativity, at Princeton University in the mid-1950s. He quickly attracted world-class graduate students to the subject, including Charles Misner and Kip Thorne. Fifteen years later, concerned that textbooks on general relativity had failed to keep up with modern developments, Misner, Thorne, and Wheeler teamed up to write Gravitation.4 Upon publication, Gravitation joined several other new books about general relativity, including Steven Weinberg’s Gravitation and Cosmology (1972) and Stephen Hawking and George Ellis’s The Large Scale Structure of Space-Time (1973).5 Unlike those other books, however, MTW defied many people’s expectations for a textbook. Some just didn’t know what to make of it.

  Misner, Thorne, and Wheeler clearly intended Gravitation to be a textbook, pitched at advanced physics students. Wheeler’s notes from an early planning meeting with his coauthors made clear that they would write the book with “the committee planning graduate courses in U. of X” in mind. While certainly thinking in terms of a textbook, however, from the start they treated the project as an experiment in the genre. They developed a rather complicated structure for the book, dividing material into two tracks: a core of introductory material occupying less than a third of the book, surrounded by extensions, elaborations, and applications.6 The two tracks were not sequential; many chapters were divided, section by section, into one track or the other. Even more novel was the extensive use of “boxes” for complementary material. The boxes were set off from the main text by heavy black lines, interrupting the flow of ordinary chapter exposition, often for several pages at a time. Some of the boxes resembled the “sidebars” that had long been a staple of science textbooks aimed at younger students and featured short biographies of famous physicists or brief descriptions of important experiments. But most of the boxes in Gravitation served a different purpose. According to Wheeler’s notes, the boxes were meant to constitute “a third channel of pedagogy,” beyond the two tracks. “They are distinguished from the main text by untidiness” and included “the kinds of things we would like to present in lecture hour to students who can be relied upon to learn tightly organized material and computational methods on their own from a systematic text.” Their pedagogical aspirations were clear: as each author drafted a section of the book, the coauthors would “test a write up by asking if a student could use it to lecture from.”7

  Figure 15.1. Top left, Charles Misner. (Source: AIP Emilio Segrè Visual Archives, Physics Today Collection). Top right, Kip Thorne in 1977. (Source: Courtesy of the Archives, California Institute of Technology). Bottom, John A. Wheeler in his office, late 1970s. (Source: Photograph by Frank Armstrong for The University of Texas at Austin, courtesy of AIP Emilio Segrè Visual Archives, Wheeler Collection.)

  The authors devoted spectacular attention to the physical appearance and production of the book. Thorne traded detailed letters with the artists and layout designers at the original publisher, W. H. Freeman in San Francisco, going over everything from the thickness of lines setting off the box material to arrow styles and shadings to be adopted in the hundreds of illustrations. Early on, Thorne alerted an editor at Freeman that “several features of the manuscript will require special typesetting problems.” Beyond the extensive figures, tables, and boxes, the authors anticipated the need for at least six distinct typefaces, perhaps as many as eight, to properly distinguish the plethora of symbols and equations they would be treating.8 (Before the book had even been published, Thorne worried that “the extreme complexity of the typography” would bedevil foreign-language publishers. He recommended that they simply photograph the equations from the English edition once it became available rather than attempt to re-typeset them.)9 Given the book’s unusual organization, the authors also inserted thousands of marginal comments throughout the book. Some comments summarized the material under discussion, but many others were “dependency statements”: a road map spelling out at each point in the massive tome which other sections a given discussion depended upon, and which others would in turn depend upon it.10

  Having tackled every detail of composition and typesetting, imagine the authors’ surprise when—two years into the process, and just three weeks before they submitted their final, edited manuscript—they learned that the publisher held a rather different conception of the book than they did. After meeting with their editor from the press, Thorne shot off a letter to his coauthors. “I was rather shocked to learn from Bruce [Armbruster, the editor] that the people at Freeman are so out-of-touch with our book that they have not been regarding it as a textbook, but rather as a technical monograph. I suppose that the enormous size of the book has something to do with it.” The publisher’s plan had been to produce an expensive hardcover edition, intended primarily for purchase by libraries: “Freeman had not been expecting to pick up the textbook market with this book” at all. Thorne worked hard to convince the editor that “there might be some hope of picking up student sales” as well, but that would require a complete overhaul of the publisher’s printing and pricing plans.11

  Was Gravitation a reference monograph for libraries or a textbook for classroom use? From that ontological difference sprang more immediate considerations. For example, how could they keep such a fabulous concoction from crumbling under its own weight? The book’s unusual trim size—each of its nearly 1,300 pages was more than an inch wider and taller than standard textbooks at the time—suggested hardcover rather than paperback binding. Hardcover binding seemed all the more appropriate to the authors, for whom Gravitation was self-evidently a textbook, since (as Thorne explained) “it seems to me that paperback editions cannot hold up well enough with the heavy use that a student in a full year course would give the book.” But hardcover binding threatened to price the book beyond the reach of a student market.12 After assurances from the publisher that paperback binding could hold up just as ruggedly as hardcover, the authors struck a deal with the publisher: in exchange for reduced royalty rates on the paperback edition, the press would aim to keep the price of the paperback lower than the hardcover price of the recent textbook by Weinberg, Gravitation and Cosmology. Upon publication, the paperback edition of Misner, Thorne, and Wheeler’s Gravitation sold for $19.95 (about $110 in 2020 dollars), and the hardcover for twice that price. With the publisher now treating the book as a tex
tbook rather than a reference monograph, and with the compromise pricing plan in place, Thorne was confident that the book could “capture one hundred percent of the textbook market in this field—or as nearly so as possible.”13

  Like the authors and publisher, reviewers recognized the book as unusual. “A pedagogic masterpiece,” announced a reviewer in Science; “one of the great books of science, a lamp to illuminate this Aladdin’s cave of theoretical physics whose genie was Albert Einstein,” crowed another in Science Progress. A third reviewer challenged his readers: “Imagine that three highly inventive people get together to invent a scientific book. Not just to write it, but invent the tone, the style, the methods of exposition, the format.” Many reviewers lauded the rich set of illustrations and the innovative use of boxes.14 Others complained that the two-track-plus-box organization introduced too many redundancies. “This is a difficult book to read in a linear, progressive fashion,” concluded one reviewer; “there is needless repetition (indeed, almost everything is stated at least three times),” noted another. “The variety of gimmicks is bewildering—framed headings with quotations, marginal titles, ‘boxes’ sometimes extending over several pages, heavy type, light type, large type, small type,” reported a reviewer in Contemporary Physics. “Clearly the book is an experiment in presentation on a grand scale.”15

  Nearly all reviewers commented on the writing style. Wheeler was already well known among physicists for his catchy slogans and engaging prose. (Among other memorable contributions, Wheeler had coined the term “black hole.”) Wheeler’s early planning notes for the book insisted that he and his coauthors must “make clear the idea itself. But soberly, factually, no hyperbole, no enthusiasm.”16 If that had been the intention, not all reviewers agreed on the outcome. The book featured a “prose style varying from the unusually colloquial to the unusually lyrical,” wrote one reviewer. But one person’s lyricism was another’s doggerel. “There is a commendable attempt at informality, but this reviewer found the breeziness irritating at times,” came one verdict. “A ‘poetical’ style is understandable if one deals with such [speculative] topics as ‘pregeometry.’ However, ‘poetical’ passages in differential geometry, for example, may obstruct the understanding of an ascetic reader,” concluded another.17 One reviewer huffed that the informal writing style “comes dangerously close to being patronisingly simplistic, to the point of insulting the reader’s intelligence.” Another reviewer was even more scandalized by the book’s tone. The intended reader, he scoffed, would be most at home with the book “if he is a regular subscriber to Time magazine—the writing of these authors has much in common with its breathless style.”18 Subrahmanyan Chandrasekhar, the Nobel-laureate astrophysicist who had grown up in India, trained in Britain, and settled in the United States, likewise noted that the book’s “style fluctuates from precise mathematical rigor to evangelical rhetoric.” He closed his review with the memorable observation: “There is one overriding impression this book leaves. ‘It is written with the zeal of a missionary preaching to cannibals’ (as J. E. Littlewood, in referring to another book, has said). But I (probably for historical reasons) have always been allergic to missionaries.” (Thorne wrote to Chandrasekhar that the closing paragraph had left him “chuckling for about ten minutes.”)19

  While acknowledging the book’s unusual organization, writing style, and pedagogical innovations, most reviewers treated the book as the authors had intended: as a textbook primarily for graduate-level coursework in the technical details of gravitational physics. The authors had set out to corner the market for textbooks on the topic, and they largely succeeded. A few years after publication, their book was still selling between four thousand and five thousand copies per year, while their main competitor, Weinberg’s Gravitation and Cosmology, had dropped to around one thousand copies per year. Thorne noted to the publisher—with fanfare but not much hyperbole—that by the late 1970s, “a large fraction of the physics graduate students in the Western world bought a copy of Gravitation.”20 The book sold fifty thousand copies during its first decade, at a time when institutions in the United States graduated about one thousand PhDs in physics per year, and no other country came close to those annual totals.21

  Yet from the start, some readers saw much more in Gravitation than a vehicle for training soon-to-be specialists. The publisher, for one, reversed course in a dramatic way. A decade after having written off the book as merely a reference work for library purchase, the editors decided to advertise a specially reduced price on the book—nearly 25 percent off list price—to subscribers of the popular magazine Scientific American. Thorne countered that a better way to test “the elasticity in the demand” for the book would be to offer that reduced price to “that portion of the market which concerns me most”: students and young academics. He urged the publisher to offer the reduced price to university bookstores rather than Scientific American devotees.22

  Nonetheless, the publisher was on to something. Upon the book’s publication, reviews had run not just in venues such as Science and Physics Today; the Washington Post devoted a full-page review to the book, and a daily newspaper in San Antonio, Texas, likewise recommended it. The reviewer in the Post, himself a physicist at Williams College, acknowledged, “Perhaps it is strange to review here a textbook full of mathematics, a book, moreover, whose 6.7-pound bulk the young, the old and the infirm can scarcely lift. But,” he declared, “those who read like to know what is being published and discussed.” And Gravitation certainly warranted discussion. The book’s engaging prose “awakens hope that the fuzzy and lugubrious ‘style’ that still spreads its gloom over so much of American science may not be in fashion forever.” The book’s unusual organization, moreover, seemed akin to recent trends in avant-garde filmmaking, such as the French nouvelle vague. “There are very few stories that should be told sequentially,” the reviewer avowed. All the better that Gravitation, like the hip filmmakers, had discovered “strategies for breaking up a linear narrative.”23 The San Antonio reviewer likewise encouraged his readers. “I am not a mathematician, and the 200 or so pages I’ve read are not all that formidable,” he explained. “If you’re curious and have an imagination, you won’t be cowed. The challenge is stiff, but fascinating.” The organization of the book was “phenomenal,” and the topic inspiring. He concluded, “This is a fabulous, rewarding book.” Novelists could scarcely hope for a more enthusiastic review.24

  Fan letters also streamed in to the authors from a wide assortment of readers. Many came from colleagues who reported how much they enjoyed teaching from the book in their formal classes.25 But others came from further afield. One reader wrote from a hospital in Italy—it is not clear whether the handwritten letter came from a patient or a physician—to press the authors whether their views about the cosmos had changed during the three years since the book’s publication. (The letter writer had been keeping up with more recent discussions in the field by reading the Italian-language edition of Scientific American.) He had more specific questions, too. In particular, what was the fate of life in a universe that cycled from big bang to big crunch? He was so desperate for a response that he promised $200 to anyone (the authors or their graduate students) who might take the time to answer. “Don’t be offended by my proposal. Time = Money.”26

  An engineer in Brussels turned to the book for a different reason. He decided to pick up Gravitation to help him learn English before beginning military service. “My hopes have been completely fulfilled: Gravitation is worth reading to learn English because it makes enjoy Physics!” The book so inspired him that he drew seven full-page, whimsical cartoons in the style of Antoine de Saint-Exupéry’s The Little Prince to illustrate concepts he had learned from Gravitation.27

  Readers closer to home wrote to the authors as well. Especially poignant was a letter that Thorne received from a reader in Portland, Oregon. “I stumble here, fall down there, and generally make a fool of myself as I wander about your textbook,” the correspondent
explained, “but I am gaining a sense of balance and a few tools with which to deal with the subject.” His dedication to the book was impressive:

  When friends ask me about what I am doing I have made the mistake of telling them the truth [about his attempts to read Gravitation]. Sometimes I think they are right, I feel as though I am on the brink of madness. I go out to have a beer and listen to someone talk about his love affairs, the clutch in his pick-up truck, the problems with his children, the plumbing, the bus service. I look at him and see him dealing with all these important issues and I ask myself why do I care if I ever understand the difference between leptons and leprosy?

  Yet still he could not shake his “obsession” with Einstein’s own question, “whether or not God had any choice in the creation of the Universe.” He needed to know: “Could God be a traveling technician whose responsibility is to supervise gravitational collapses and big bangs?”28

  Six years after publication, with annual sales still brisk, John Wheeler tried to assess the reasons for the book’s success. Writing to his editor, Wheeler surmised that “many people buy the book who are attracted by the mystique, the boxes, the interesting illustrations, the ideas but who don’t expect to and never will get deep into the mathematics.” He figured about half the purchasers fell into that category—and he was eager not to lose them. In thinking about revising and updating the book, Wheeler concluded that “I think we can add a few things and take away a lot of things to keep this group ‘on board.’”29 Those plans fell through—Misner, Thorne, and Wheeler never did undertake a revision of their massive masterpiece—but Wheeler’s observation nonetheless rang true. In their effort to write a specialized textbook they had produced a hybrid work, as attractive to Scientific American subscribers for its “mystique” as to doctoral students struggling to enter the field.