The Hunt for Vulcan

by Thomas Levenson

  Except—there’s a story that bears on this from within Eddington’s decisive photographs. The announcement of those results propelled Einstein to the worldwide fame he still enjoys, sixty years after his death. That celebrity came only after Eddington and his colleagues became convinced that they hadn’t deceived themselves into finding what they had expected to see. Remember that second team taking measurements during the eclipse at Sobral? The weather had been fine there, and the team made several more useful photographs than Eddington. When they were analyzed, they seemed to show only half the deflection claimed at Principe: Newton’s answer, not Einstein’s. Eddington was convinced there had to be some error with the Sobral images. But the mistake, if that’s what it was, didn’t show itself easily. As late as September, he wouldn’t commit himself further than to say that the observed deflection lay between the two predicted values.

  That was a holding action. The next month, Eddington and his colleagues confirmed that the primary Sobral instrument had an optical defect that systematically produced errors in its results. They found seven more images that had been taken with a second instrument at the Brazil site that consistently showed the Einstein value, confirming the best data from Principe. With that, Eddington felt justified in ignoring the contradicting images, and alerting the Royal Society.

  Eddington was right, of course, which is all the defense one needs. The main Sobral instrument was flawed; his best images were the most nearly correct; and, of course, general relativity has survived every challenge since. It is thoroughly implicated in everything from the birth and evolution of the universe to the accuracy of the GPS system in your phone. Black holes, gravitational lensing and gravity waves, the expansion of the universe, even speculation about time travel (vanishingly unlikely, but not quite completely foreclosed)—all these belong to the general theory’s bestiary. And more: the theory is not just richly explanatory. It has generated new ways of seeing—not just in physics, but in that broader culture, of which science is a part.

  The New York Times headline on Monday, November 10, 1919.

  Just remember one human truth: the astronomers and physicists and the ordinarily curious in the mid-nineteenth century who peered longingly at the face of the sun could have said something very similar about their theory of the universe and all that it implied for the reality of Vulcan.

  What moral to draw, then, of the nonexistence of an innermost planet and the universal triumph of general relativity?

  At the least this: Science is unique among human ways of knowing because it is self-correcting. Every claim is provisional, which is to say each is incomplete in some small or, occasionally, truly consequential way. But in the midst of the fray, it is impossible to be sure what any gap between knowledge and nature might mean. We know now that Vulcan could never have existed; Einstein has shown us so. But no route to such certainty existed for Le Verrier, nor for any of his successors over the next half century. They lacked not facts, but a framework, some alternate way of seeing through which Vulcan’s absence could be understood.

  Such insights do not come on command. And until they do, the only way any of us can interpret what we find is through what we already know to be true. Vulcan itself, with its fifty years of stubborn possibility, is a measure of just how hard it was to see past its phantom, how genuinely powerful an achievement it was to create both Newton’s account of gravity and its successor, the general theory of relativity.

  —

  Give Einstein (almost) the last word. In 1918, he spoke at the German Physical Society. There, he tried to describe what goes on inside the mind of someone attempting to interrogate nature at the edge of understanding. He didn’t speak of logic, or rigor, or some exceptional mental talent. Instead, the driving force behind great work turned, he said, on “the longing to behold…preexisting harmony.” Getting there required the usual work of the researcher, of course, mathematics to learn, calculations to perform, the endless cat-and-mouse with errors of thought and execution. All that had to be done. But to do it, day after day, there was a certain way one had to be: “the state of mind which enables a man to do work of this kind” he said, “is akin to that of the religious worshiper or the lover; the daily effort does not originate from a deliberate intention or program, but straight from the heart.”

  For more than two centuries humankind lived in the cosmos Newton discovered. Vulcan’s nonexistence did not demolish that dwelling place; rather it is the marker on which its passing is written.

  Now, strange as it once seemed, beautiful as it is, Einstein’s universe is our home.

  For Katha and Henry, ever-renewing gifts,

  and in remembrance of my uncles

  Daniel Levenson and David Sebag-Montefiore,

  who stood up through the hard years

  and the fine ones

  Acknowledgments

  First among those who have made this book into a reality: my editor, Sam Nicholson, who had actually signed me up to write something quite different. To Sam’s and Random House’s great credit they welcomed my shift to pursue what became this volume. Sam’s editing was meticulous, firm, always kind, and measurably improved the manuscript through each draft. My agent, Eric Lupfer, skillfully guided the project through its unlikely gestation and birth, and continues to be an exemplary shepherd to my writing career. My deepest thanks to them both.

  That this book made it past the “sounds interesting” phase of an idea comes down to two conversations with deeply valued friends. A couple of years ago Neil Belton, who had edited the British edition of my previous book and is publishing this one at his new home, allowed me to commandeer a dinner conversation to lay out Vulcan’s strange history. He was the first to tell me that this tale should be a book. That made me think, but it took another encounter to launch the project. In the spring of 2014, Ta-Nehisi Coates talked me through the idea and after two or three afternoons he told me just to start writing, never mind what might happen with any accumulating pile of words. Without those marching orders, the work you hold would not exist. I owe Ta-Nehisi and Neil both thanks and, at the next chance, a glass or more of really good stuff.

  My largest intellectual debts are to the writers and researchers who have preceded me in our collective obsession with the planet that wasn’t there. You will find the works by Richard Baum and William Sheehan, N. T. Roseveare, Robert Fontenrose, and James Lequeux in the Bibliography. I’ve argued with interpretations found in some of those works, but as a much greater thinker once put it, I’m standing on their shoulders.

  In the here and now, special thanks to my MIT colleagues David Kaiser and Allan Adams, Caltech’s Sean Carroll, and Cornell’s Paul Ginsparg, all of whom read the manuscript at various stages of completion—in David’s case, with a gluttony for punishment sufficient to review repeated attempts to get things right. An author could not have more generous colleagues. They each made this book better; any errors that remain exist despite their best efforts and are down to me alone. Professor Matt Strassler gave me pointers to sources on the history of the problem of Mercury. In the longer term, conversations over many years with Abraham Pais, Simon Schaffer, Gerald Holton, and Peter Galison have sharpened my understanding of the history of physics and the roles played by its most notable heroes. I’m as grateful as I can be for the help of such accomplished and busy scholars.

  Three cheers to all those who helped me research this book. Cara Giaimo gave valuable assistance working with newspaper archives. Archivists at the American Heritage Center and at the Hebard Historic Map Collection at the University of Wyoming were welcoming and generous with time and knowledge. The staff of the Carbon County Museum produced unexpected treasures with equal kindness. And I must also thank the Carbon County sheriff’s department, who extracted my rental car from a snow-and-ice bank encountered on a too-reckless attempt to find the exact spot where Separation once stood. Yup, I was that much of a city slicker.

  My gratitude as well to everyone at Random House who helped
bring this book into being—with special shout-outs to associate publisher Tom Perry, copy editor Leda Scheintaub, cover designer Joseph Perez, book designer Simon M. Sullivan, and to publishing intern Lily Choi, who worked with me on picture rights and permissions.

  Deep thanks to my overlapping posses of family, friends, and coworkers who nurtured this project—and me—from start to finish. My MIT colleagues were great throughout, encouraging, smart, and supportive. My thanks to Marcia Bartusiak, Alan Lightman, Seth Mnookin, and Shannon Larkin; to my department head, Ed Schiappa, and to all my other departmental colleagues there—with an extra nod to Junot Díaz and Joe Haldeman who talked me through several of the steps of the work. John Durant, director of the MIT Museum, has been a friend and intellectual goad for years. I’ve benefited from the encouragement of a host of friends and colleagues from across the spectrum of science and science writing and publishing, here in no order but that of recollection: Carl Zimmer, Lisa Randall, Nikki (Veronique) Greenwood, Sean Carroll, Rose Eveleth, Neil deGrasse Tyson, Jennifer Ouellette, Brian Greene, Rebecca Saletan, David Bodanis, Ann Harris, Ed Yong, Deborah Blum, John Rubin, Ben Lillie, John Timmer, Maryn McKenna, Ian Condry, Rebecca Saxe, Ed Bertschinger, Nancy Kanwisher, Steve McCarthy, Alok Jha, Virginia Hughes, Steve Silberman, Maggie Koerth-Baker, Kevin Fong, David Dobbs, Annalee Newitz, Eric Michael Johnson, Maia Szalavitz, Tim de Chant, Tim Ferris, and Amy Harmon. A special thanks all their own goes to my students in the MIT Graduate Program in Science Writing, and especially those of the class of 2015, present at the creation: Rachel Becker, Christina Couch, Cara Giaimo, Michael Greshko, Anna Nowogrodzki, Sarah Schwartz, and Josh Sokol.

  My debts of gratitude to my family extend well beyond this book. In extended form, my siblings, Richard, Irene, and Leo, and spouses Jan and Rebecca; my siblings-in-law Jon, Kricket, Judy, Gay, Heinz, Neva, and Zeph; and my nieces and nephews (and my grandnephew and niece!) have sustained me with love and insight across a lifetime. I’m deeply thankful, and not only because they have mastered the art of not asking (too often) how the book is going.

  Of the last I need to thank, well, words are insufficient, but they are what we have. Year in and year out, they give me patience, tolerance, laughter, distractions offered as needed, and above all love—each of these gifts and so many more. This book and its writer would not be as we are without them both. How lucky I am to owe so much to my son, Henry, and my wife, Katha.

  Notes

  Abbreviations

  CRAS: Comptes Rendus hebdomadaires des séances de l’Académie des Sciences, available online at http://​gallica.​bnf.​fr/​ark:/​12148/​cb343481087/​date.​langEN.

  CPAE: Collected Papers of Albert Einstein, available online at http://​einsteinpapers​.press.​princeton.​edu/.

  Preface

  “subjecting matter to number” Here I must acknowledge Alexander Koyré, who coined the notion of matter subject to number to describe Galileo’s achievement. It’s too wonderful a phrase to employ only once.

  “When he completed the calculation” Einstein to Paul Ehrenfest, CPAE 8, document 182, 179, and Einstein to Adriaan Fokker and to Wander Johannes de Haas, quoted in Abraham Pais, Subtle Is the Lord, 253.

  1. “The Immovable Order of the World”

  “That miserable business” Cook, Edmond Halley, 140; 148.

  “Wren didn’t believe him” Ibid., 147–48, and Westfall, Never at Rest, 402–3.

  “had he died in the spring of 1684” Westfall, Never at Rest, 407.

  “ ‘I have calculated it’ ” Ibid., 403.

  “Newton went further” Ibid., 403–6.

  “Finally, in 1687” There are many translations of Principia available in English. I recommend I. Bernard Cohen and Anne Whitman’s: Isaac Newton, The Principia (Berkeley: University of California Press, 1999). It’s meticulous, and the edition includes Cohen’s invaluable—and book length on its own—reading guide.

  “ ‘a sort of nebulous spot’ ” Gottfried Kirch, quoted in Gary Kronk, “From Superstition to Science,” 30–35.

  “a parabola” J. A. Ruffner, “Isaac Newton’s Historia Cometarum,” 425–51.

  “ ‘The theory that corresponds exactly’ ” Newton, The Principia, trans. Cohen and Whitman, 916. Italics added.

  “ ‘But we are now admitted’ ” Edmond Halley, “Halley’s ode to Isaac Newton” Newton, The Principia, trans. Cohen and Whitman, 379–80.

  2. “A Happy Thought”

  “a nearly circular orbit” Baum and Sheehan, In Search of Planet Vulcan, 50–51.

  “When he applied his new approach” For background on Laplace’s work on Uranus, see Roger Hahn, Pierre Simon Laplace, 1749–1827: A Determined Scientist, 77–78, on which this account is based.

  “to the limits of the accuracy” Gillispie et al., Pierre-Simon Laplace 1749–1827: A Life in Exact Science, 127–28.

  “ ‘when subjected to rigorous calculations’ ” Laplace to Le Sage, April 16, 1797, quoted in Hahn, Pierre Simon Laplace, 142.

  “Every event” This argument is taken from Hahn, Pierre Simon Laplace; see especially page 158. The definition of determinism offered is a variation of common short-form statements of the idea; this one draws from several of them, first from the Wikipedia entry titled “Determinsm.”

  “ ‘failed to find his name’ ” This version of the contested tale comes from Roger Hahn, “Laplace and the Vanishing Role of God in the Physical Universe,” in Harry Woolf, ed., The Analytic Spirit: Essays in the History of Science (Cornell University Press, 1981), 85–86.

  “Herschel noted in his diary” William Herschel, quoted in Roger Hahn, Pierre Simon Laplace, 86.

  “ ‘He merely ignores it’ ” Hahn in Harry Woolf, ed., The Analytic Spirit: Essays in the History of Science, 95.

  “ ‘We may regard the present state’ ” Pierre Simon Laplace (trans. Truscott and Emory), Essai philosophique sur les probabilités, 4. Laplace proposed the idea of a comprehensively knowledgeable intellect in his 1812 Théorie analytique des probabilités—and had been thinking and occasionally writing about the notion at least since encountering a similar formulation in the work of his friend and colleague Condorcet in 1768.

  3. “That Star Is Not on the Map”

  “In the guidebooks” Galignai, Galignani’s New Paris Guide, 367, and Baedeker (firm), Paris and Environs, 7th ed., 276.

  “ ‘I must not only accept’ ” Lequeux, Le Verrier—Magnificent and Detestable Astronomer, 4.

  “ ‘Laplace’s inheritance’ ” Jean Baptiste Dumas, Sept. 25, 1877, quoted in Lequeux, Le Verrier, 5.

  “It took him just two years” Le Verrier, “Sur les variations séculaires des orbites des planètes,” CRAS 9 (1839), 370–74. Discussion in Lequeux, Le Verrier, 7–8, and Baum and Sheehan, In Search of Planet Vulcan, 70–71.

  “ ‘In recent times’ ” Le Verrier, “Détermination nouvelle de l’orbite de Mercure et de ses perturbations,” CRAS 16 (1843), 1054–65, quoted in Lequeux, Le Verrier, 13.

  “Mercury’s mass” Lequeux, Le Verrier, 13.

  “He called out ‘Now!’ ” Baum and Sheehan, In Search of Planet Vulcan, 73.

  “reality and calculation diverged” Airy, “Account of Some Circumstances Historically Connected with the Discovery of the Planet Exterior to Uranus,” 123.

  “Newton’s gravitational constant itself might vary with distance” Grosser, The Discovery of Neptune, 44; also discussed in Baum and Sheehan, In Search of Planet Vulcan, 80.

  “ ‘perturbing Uranus’ ” Eugène Bouvard, “Nouvelle Table d’Uranus,” 525. Cited in James Lequeux, Le Verrier, 24.

  “across the channel to England” Lequeux, Le Verrier, 25.

  “ ‘several successive revolutions’ ” Airy, “Account of Some Circumstances Historically Connected with the Discovery of the Planet Exterior to Uranus,” 124–25.

  “Arago pulled the younger man away” Le Verrier, “Première Mémoire sur la théorie d’Uranus,” 10
50, translation in Lequeux, Le Verrier, 26.

  “Le Verrier instead recalculated” Grosser, The Discovery of Neptune, 99.

  “some as-yet-undiscovered object” Ibid., 100.

  “an as-yet-undiscovered trans-Uranian planet” For a contemporaneous account of this line of thinking, see John Pringle Nichol, The Planet Neptune, 65; 84.

  “ ‘the action of a new planet’ ” Le Verrier, “Recherches sur les mouvements d’Uranus,” 907–18, translation in Lequeux, Le Verrier, 28.

  “3.3. arcseconds in diameter” Le Verrier, “Sur la planète qui produit les anomalies observées dans le mouvement d’Uranus,” 428–38. To reiterate my intellectual debt: I’ve relied in this brief account very heavily on James Lequeux’s 2013 biography of Le Verrier, and on Baum and Sheehan’s In Search of Planet Vulcan. Like them, I found the 1962 work by Morton Grosser invaluable.

  “But none did” Lequeux, Le Verrier, 33.

  “ ‘a planet to discover’ ” Le Verrier to Galle, September 18, 1846, quoted and translated in Grosser, The Discovery of Neptune, 115.

  Part One Interlude: “So Very Occult”

  “ ‘I do not feign hypotheses’ ” Newton, The Principia (trans. Cohen and Whitman), 943.

  “ ‘changeless supernatural beings’ ” Benson, Cosmigraphics, 144.

  “something Newton called a force” For an idea of just how strange “force” as a concept was to Newton’s peers (and how strange in some ways it remains), see physicist Frank Wilczek’s essay “Whence the Force in F-ma?”