The Perfect Theory

by Pedro G. Ferreira

  Ryle retreated to Cambridge to work on the next generation of his source catalogue. Singed by the debacle of his questionable results, Ryle and his team spent the next three years building a new catalogue, unimaginatively called the 3C Catalogue. The new results would decisively shoot down the nonsense that Hoyle and his team were peddling, or so Ryle thought. In 1958, when the 3C Catalogue was finally revealed to the world, Martin Ryle finally felt he had his pièce de résistance: a collection of radio sources that everyone agreed with. Yet it still wasn’t good enough. Bondi was skeptical and pointed out that Ryle had a tendency to claim that his measurements were better than they actually were; Ryle often claimed to have ruled out the steady-state model when really he had just reached the limits of what could be said with his data. Whenever anyone went back and reanalyzed Ryle’s data and found that the errors were larger than previously claimed, the steady-state model was ruled back in the game. Indeed, as Bondi said publicly, “this has happened more than once in the last ten years.”

  In February 1961, Ryle presented his analysis of what was now the 4C Catalogue at the Royal Astronomical Society meeting. He argued that the results were simply incompatible with those of the steady-state model—there were far too few bright sources relative to the dim ones. The observations, he said, “appear to provide conclusive evidence against the steady state theory.” The newspapers picked up on Ryle’s announcement and came out with headlines claiming that “the Bible was right” about the existence of an initial moment of creation. As other teams in Australia and the United States reproduced Ryle’s results, it seemed that Ryle had finally sorted it out.

  Hoyle and his collaborators were worried but not convinced. As Bondi told the New York Times, shortly after Ryle announced his analysis, “I certainly don’t consider this the death to continuous creation,” adding, “A similar statement has been made by Professor Ryle in 1955 but the observations on which it was based were later found to be incorrect.” There was something irrational about Ryle’s personal quest to kill the steady-state theory, even though the data was improving year by year. To Hoyle, Bondi, and Gold, radio hadn’t killed the steady-state theory, at least not yet.

  The fight between Hoyle and Ryle, centered in Cambridge as it was, may seem like an unnecessary distraction from the inexorable progress of general relativity and cosmology. Few people outside the United Kingdom had any interest in Hoyle’s model. To many, the debate seemed fickle, almost unscientific, driven by personalities and vendettas. Visitors to Cambridge would comment on the poisonous atmosphere between Ryle and Hoyle’s group.

  But their rivalry resulted in significant scientific progress. Fred Hoyle would go on to be lauded as one of the great astrophysicists of the second half of the twentieth century. With William Fowler and Geoffrey and Margaret Burbidge from the United States, he would end up developing a brilliant theory for the origin of the elements in stars. Some might point to his maverick nature and his insistence on supporting the steady-state model to explain why he was not included as one of the awardees of the 1983 Nobel Prize in Physics. In 1973 he left Cambridge to live in the Lake District and write novels.

  Hermann Bondi would end up creating a vibrant general relativity group in King’s College London, and Thomas Gold would end up setting up the world’s largest radio telescope in Arecibo in Puerto Rico. Martin Ryle’s group developed a reputation for secrecy and paranoia, yet they were behind some of the great discoveries in radio astronomy of the following two decades. Ryle won the Nobel Prize in 1974. The rise of radio astronomy and the elusive nature of radio sources would play a crucial role in the advancement of general relativity, which was about to enter a new phase.

  Chapter 7

  Wheelerisms

  JOHN ARCHIBALD WHEELER personally discovered relativity by way of nuclear physics and quantum theory. In the spring of 1952, Wheeler found himself wondering what happened at the end of the lives of stars made of neutrons, the building blocks of nuclear physics that Wheeler had spent his life until then studying. He was puzzled by Robert Oppenheimer’s prediction that the endpoint of the gravitational collapse of such a star could be a singularity, a point of infinite density and curvature at the star’s center. To Wheeler, these singularities didn’t sound right. They couldn’t be truly physical, and there must be some way to avoid them. To understand this bizarre prediction, Wheeler would have to learn general relativity. He figured the best way to do that would be to teach it to the students at Princeton. And so, in 1952, in the home of Einstein, Gödel, and Oppenheimer, John Archibald Wheeler taught the first course on general relativity in the Princeton department of physics. Until then it had been considered an abstract subject more suitable for a mathematics department. It was a momentous departure, one Wheeler would recall years later as “my first step into a territory that would grip my imagination and command my research attention for the rest of my life.”

  Wheeler was, as one of his students summed him up, a “radical conservative.” He definitely looked conservative, always dressed impeccably, in a dark suit and tie, hair perfectly groomed, his shoes shined, the perfect image of a traditional, somewhat conventional gentleman. Devoted to his students and collaborators, he was courteous and polite with an old-fashioned sense of propriety. Yet he would say the most outlandish things, often spouting out cryptic phrases about cosmic enigmas that made him sound more like a New Age guru or an enlightened hippie.

  As a scientist, Wheeler saw himself as both a dreamer and a “doer.” His interests ranged from the esoteric to the practical. He was just as fascinated by explosives and mechanical devices as he was by the magical new rules of atomic theory. At university, Wheeler studied engineering and discovered the full glory of mathematics. One of his mathematics teachers had given him advice on how to tackle problems; as Wheeler recalled, he “liked to tell us in class while teaching us new mathematical tricks that an Irishman gets over an obstacle by going around it.” This advice affected Wheeler’s approach to solving problems throughout his life. He would fearlessly jump into problems, learning whatever he needed, when he needed it. In 1932 he was only twenty-one and already had a PhD in quantum physics.

  John Wheeler came of age as a quantum physicist when all the great discoveries of Schrödinger and Heisenberg were bearing fruit. As a young faculty member at Princeton, he worked with the Danish physicist Niels Bohr on the quantum properties of nuclei and how they interact. Wheeler and Bohr’s work on nuclear fission was published on exactly the same day as Oppenheimer and Snyder’s work on gravitational collapse and played an important role in the lead-up to the Manhattan Project.

  Wheeler’s conservatism came out in his passionate belief in the American way of life, its institutions, and its defense. He joined the atomic bomb project immediately after Pearl Harbor, working on the giant reactors that were needed to create plutonium for the bombs. His brother died in combat in 1944, and for the rest of his life Wheeler felt that he hadn’t done enough in pushing more actively for the development of the bomb much earlier. As he would later tell his colleagues, if the bomb had been developed earlier, it could have been used sooner, in Germany. The loss of life would have been tremendous but not, in his view, as terrible as in the last year of the war. His patriotism sometimes put him at odds with his colleagues. In the early 1950s, he was invited to work with Edward Teller on the Matterhorn Project, an attempt by the United States to develop the H-bomb, a thermonuclear weapon that would work with nuclear fusion. He did so even though many of his colleagues, including Robert Oppenheimer, were firmly against it. Wheeler was one of the few physicists to stand back from supporting Oppenheimer when he faced charges of breaching national security.

  Though conservative politically, he couldn’t resist being a maverick, or radical, in science, following outlandish ideas that went against the physics establishment at the time. Among Wheeler’s students at Princeton was Richard Feynman, a brilliant young man from New York who would come to be the poster boy of postwar quantum physics. Unde
r Wheeler’s supervision, Feynman would come up with a completely revolutionary way of explaining and calculating how particles and forces played against each other in the arena of spacetime. It was Wheeler who encouraged Feynman to think differently and be bold.

  Wheeler was the perfect person to pick up the pieces of general relativity. He was both practical and visionary. He was conservative and respectful of the physics and astrophysics that had led up to the theory but at the same time keen on trying different, new, untested approaches. And above all, he was an inspiring mentor who would train and support a new generation of physicists who would breathe new life into the general theory of relativity.

  Once Wheeler had taught himself general relativity, he embraced it. It was too elegant, and the experimental facts, meager as they might be, too compelling, for the theory not to be true. But that didn’t mean he was opposed to testing its limits. He believed that “by pushing a theory to its extremes, we also find out where the cracks in its structure might be hiding,” and so he set out to discover just how strange general relativity could be. In the process he often assigned pithy, simple one-liners to his outlandish ideas, popularly known as Wheelerisms.

  One idea, developed with his talented student Charles Misner, was to incorporate electric charges into general relativity without actually having any charge whatsoever. “Charge without charge” was the Wheelerism he came up with to describe the concept. The thought experiment used a series of mathematical tricks to poke holes in two distant pieces of spacetime and connect them with a tube of spacetime they called a wormhole. Through these tunnellike wormholes they could thread electrical field lines. Field lines emerging from one end of the wormhole would make it act as if it had a positive charge, attracting negative charges toward it. The field lines entering at the other end would make it appear to have a negative charge. The wormhole would act like a pair of positive and negative charges very far apart, but, in fact, no charged particles were involved. It was an ingenious idea, easy to visualize but fiendishly difficult to work with in practice.

  “Mass without mass” was another Wheelerism. Einstein’s theory explains how objects with mass interact, but Wheeler wanted to find a way to derive Einstein’s results without involving any mass at all. In Einstein’s theory, light can bend space just like mass, so Wheeler proposed that if he could compress a bunch of light rays in a way that warped space and time enough, they would look just like a mass. The bundle of light, or geon as he called it, would have weight and attract other geons. The light rays would have to be wrapped up into a doughnut-shaped coil and could be easily taken apart, but they would have the effects of mass without actual mass. With another student, Kip Thorne, Wheeler set out to determine if these objects could exist in nature without immediately becoming unstable.

  And then there was, of course, the problem of marrying the quantum to general relativity. It was too good a problem, and too extreme, for Wheeler to resist an attempt at solving it. Once again, he made things up. Wheeler postulated that if you were to observe spacetime on the smallest scales, you would start to see strange effects emerge. While spacetime might look smooth at large scales, mildly warped by the presence of massive objects (including Wheeler’s geons and wormholes), at smaller scales you would see a roughness that you hadn’t realized was there. With a really powerful microscope you might find that spacetime is a turbulent mess, all jumbled up. In fact, quantum uncertainty should make spacetime look like a roiling foam on the smallest scales. It is only because we see the world with blurry vision that we are unable to observe its fundamentally rough nature.

  Yet while Wheeler embraced the outlandish and was happy to propose bold scenarios, he felt deep unease about the singularities lurking at the core of the work of Schwarzschild, Oppenheimer, and Snyder on collapsing massive stars, which had first sparked his interest in general relativity. To Wheeler, the strange singularities must be a strange mathematical artifact that wouldn’t arise in nature. As Wheeler recalled, “For many years this idea of collapse to what we now call a black hole went against my grain. I just didn’t like it.”

  So he set about trying to fix the problem by inventing new physical processes that would come into play when collapse pushes matter into the obscenely high densities at a star’s core. This was new territory for him, for although Wheeler had become one of the world’s experts in nuclear physics, the physics that described neutrons at the center of gravitational collapse was a completely different matter. He needed to figure out what would happen when neutrons were packed far more densely than in Landau’s or Oppenheimer’s neutron stars or in any bomb he might have come up with during his work for the American military. It was a form of guesswork and imagination at which he excelled. But despite his creativity, and like Landau and Oppenheimer before him, Wheeler and his group also found that there was a maximum mass above which not even their detailed, speculative proposals for the end state of matter would compete with gravity. Whatever they did, it simply wasn’t possible to avoid the formation of a singularity at the end of gravitational collapse. Yet Wheeler simply couldn’t stomach the singularity and refused to give in.

  As Wheeler grew more and more fascinated with general relativity and his quest to rid it of singularities, he cajoled his students and postdocs to join him on his journey. Like their mentor, they were seduced by the power of the theory, intrigued by what could be done. Year after year, Wheeler’s group came up with new ideas, some outlandish, some sensible, but all of them captivating. Wheeler’s influence on general relativity extended well beyond Princeton. One of his greatest contributions was his quiet support for Bryce DeWitt at the University of North Carolina at Chapel Hill.

  There was something formidable about Bryce DeWitt. He had a towering, stern presence, like an Old Testament prophet, and when he walked into a room, backs straightened. He had no time for sloppiness—things had to be done properly, so when ideas finally made their way to paper and publication, they were set in stone.

  DeWitt was also a traveler, a “space traveller,” as he liked to call himself. As a young man, he was a pilot in the Second World War, and following his graduate studies at Harvard he hopped around the globe, working at Princeton, Zurich, and the Tata Institute in Bombay, the latter of which a colleague later described as “a sojourn [that] did not make good professional sense, but . . . suited his roving spirit.”

  DeWitt settled in California with his wife, Cécile DeWitt-Morette, a French mathematician he had met at Princeton, and found work at the Lawrence Livermore Laboratory developing computer simulations for modeling nuclear artillery shells. But the family needed more money to buy a house, so one evening, DeWitt decided to enter an essay competition that offered a first prize of $1,000. The essay would change everything—not just for the DeWitts, but for general relativity.

  The Gravity Research Foundation competition was the brainchild of Roger Babson, a businessman who was passionate about gravity. He made his fortune playing the stock market by applying his own version of Newton’s laws of physics: “What goes up will come down. . . . The stock market will fall by its own weight.” It wasn’t rocket science, but Babson was a man with an obsession. His older sister had drowned when he was a young child, and he blamed gravity. In his version of the tragedy, “she was unable to fight gravity, which came up and seized her like a dragon.” Throughout his life Babson invested in gravity in one way or another, collecting Newton memorabilia, promoting outlandish ideas, and, most significantly, creating the Gravity Research Foundation.

  Babson originally envisioned the Gravity Research Foundation as the sponsor of an annual essay-writing competition. Candidates would submit essays of no more than two thousand words suggesting ways to harness gravity and achieve Babson’s ultimate goal: antigravity. The foundation would lead to the development of antigravity devices: contraptions that could insulate, absorb, or even reflect gravity. The atom was being harnessed, and Babson thought it was time for gravity to be brought under control as well. He intend
ed for his essay competition to bring out the best in postwar physics.

  The initial response to Babson’s challenge was lackluster. From 1949 until 1953, essays trickled in with a few muted suggestions. The topics were scattered, and the contestants were a mixture of academics, graduate students, and amateurs racking their brains to come up with something that might fit Babson’s requirements. But the topic was too outlandish, bringing cranks out of the woodwork instead of inspiring real science.

  Babson’s challenge certainly wasn’t respectable—no right-minded physicist actually believed that it would be possible to build an antigravity machine—but it did echo a wider growing interest in the potential of gravity. After the Second World War the US economy was booming and optimism was infecting everyday life. It was the beginning of the atomic era, the birth of a new technological age. With money to invest, organizations and business people placed substantial bets on gravity as the next big thing after nuclear energy. There was something truly appealing and revolutionary about a goal that, in essence, came directly out of a science fiction novel. For it was, if anything, an attempt to do what H. G. Wells had written into his 1901 novel The First Men in the Moon, to discover the magical substance “cavorite” that could reverse gravity and take people to the moon.

  Throughout the mid-1950s there were routine references in the broadsheets to a new form of space travel that could beat gravity. Articles with headlines like “Space Ship Marvel Seen If Gravity Is Outwitted,” “New Air-Dream Planes Flying Outside Gravity,” and “Future Planes May Defy Gravity and Air Lift in Space Travel” marveled at a future with “gravity propulsion systems.” The popular press imagined airplanes or spacecraft that would use gravity instead of jet engines to propel them forward. A New York Herald Tribune article with the headline “Conquest of Gravity Aim of Top Scientist in the U.S.” described how aviation companies like Convair, Bell Aircraft, and Lear, Inc., were looking into gravity, which just might “eventually be controlled like light and radio waves.”