The Perfect Theory

by Pedro G. Ferreira

  Oppenheimer and Snyder’s paper was published on September 1, 1939, in the Physical Review, on the day Nazi troops marched across the Polish border. In the exact same issue was another paper, this one by a Danish physicist named Niels Bohr and his young American collaborator, John Archibald Wheeler. While they were also interested in neutrons and how they interact in extreme situations, the topic of “The Mechanism of Nuclear Fission” was completely different. Bohr and Wheeler were interested in modeling the structure of very heavy nuclei, such as those of uranium and its isotopes. If they could get this right, it might be possible to figure out how to extract the enormous amounts of energy locked up inside.

  Throughout the 1930s, the zoo of atomic nuclei had begun to be understood in ever-increasing detail. Eddington had proposed that hydrogen nuclei could fuse together to form helium in the cores of stars, fueling starlight. This is known as nuclear fusion. On the other end of the range, it was believed that very heavy nuclei could be split into smaller nuclei, also releasing energy—in this case the process is known as nuclear fission. A question that was on everyone’s mind was how to make nuclear fission efficient. Would it be possible to trigger nuclear fission in a clump of heavy atoms with a small amount of energy so that as each individual atom split, it would trigger yet another split? In other words, was it possible to trigger a chain reaction?

  Bohr and Wheeler’s paper pointed the way to nuclear fission and helped other physicists understand why uranium-235 and plutonium-239 might be the elements of choice to work, the sweet spot in the periodic table where fission might actually be easier to accomplish. Nuclear fission would dominate physics during the years that followed, eclipsing almost all other fields. An army of brilliant scientists turned their intellects to trying to understand how to harness fission, and Robert Oppenheimer was among them.

  Oppenheimer, during his stay at Berkeley, had built a stunning group of young researchers and students who were willing to tackle any problem. He had developed a formidable reputation as an organizer and group leader and would deploy his leadership skill to marshal his team to solve problems that were of interest to him. His colleagues at Berkeley were beginning to synthesize the heavier, unstable elements in the cyclotron up on the Berkeley Hills. In 1941, one of his colleagues, Glenn Seaborg, discovered plutonium, opening one of the routes to fission. Oppenheimer was being caught up in the whirlwind of events and discoveries that characterized the development of nuclear physics during the Second World War.

  Oppenheimer was also outraged. The reported treatment of Jews in Germany and the diaspora of brilliant scientists fleeing Nazi oppression who were washing up on American shores shocked him. As he developed his group at Berkeley, he also started to look around him, tentatively engaging with the teeming intellectual activity of the influx of European refugees. Although he refrained from being too active politically, he began paying attention. And with the onset of the war, nuclear fission became one of Oppenheimer’s main concerns.

  In 1942, Oppenheimer was asked to lead a task force of physicists based in Los Alamos, New Mexico, whose sole purpose was to produce and control a chain reaction of nuclear fission. The task force included a host of young and not-so-young brilliant minds, from John von Neumann, Hans Bethe, and Edward Teller to the young Richard Feynman. The Manhattan Project focused its resources on producing the first atomic bomb, and in just under three years they had achieved their goal. When the two atomic bombs, “Little Boy” and “Fat Man,” were dropped on Hiroshima and Nagasaki in August of 1945, around two hundred thousand people were killed. These devastating consequences were a harrowing testament to Oppenheimer’s ability to harness the nuclear force in such a short period of time. With the success of the atomic bomb, the quantum firmly took center stage in the world of physics.

  With so much attention focused on the war and the nuclear project, Oppenheimer and Snyder’s seminal paper on black holes was kicked into the long grass, to be ignored and forgotten for years to come. What could have been the auspicious birth of one of general relativity’s greatest concepts was indefinitely put off. The two grand old men of general relativity, Albert Einstein and Arthur Eddington, did nothing to save Oppenheimer and Snyder’s finding from obscurity.

  Eddington continued to insist that Chandra’s calculation was wrong and misguided and that white dwarfs were the quiet endpoint of stellar evolution for stars of any mass. The continued unfettered collapse of a star until “gravity becomes strong enough to hold in the radiation” was simply absurd. Chandra recalled, almost half a century later, “For my part I shall only say that I find it hard to understand why Eddington, who was one of the earliest and staunchest supporters of the general theory of relativity, should have found the conclusion that black holes may form during the natural course of evolution of the stars, so unacceptable.”

  Einstein himself continued resisting the idea that the extreme form of Schwarzschild’s solution—black holes—had any place in the natural world. He reacted in much the same way as he had to Friedmann and Lemaître’s proposal of an expanding universe: it was beautiful mathematics but abominable physics all over again. After more than twenty years dismissing the more outlandish features of Schwarzschild’s solution, he finally sat down and tried to come up with a reasoned argument for why they were of no physical significance in nature. In 1939, the same year Oppenheimer and Snyder devoted to determining the consequences of gravitational collapse, Einstein published a paper in which he worked out how a swarm of particles would behave as they collapsed through gravity. He argued that particles would never fall too close to the critical radius. He was too stubborn, setting up the problem in such a way that he got the answer he wanted: no black holes. He was wrong, once again, and just like Eddington he missed an opportunity to explore the full glory of his general theory of relativity.

  Almost everyone’s attention was elsewhere now, enthralled by the triumph of quantum physics. Most of the talented young physicists were focusing their efforts on pushing the quantum theory further, looking for more spectacular discoveries and applications. Einstein’s general theory of relativity, with all its odd predictions and exotic results, had been elbowed out of the way and sentenced to a trek in the wilderness.

  Chapter 5

  Completely Cuckoo

  DURING HIS FINAL YEARS, Albert Einstein lived a simple life. He would wake up late in his white clapboard house on Mercer Street near the heart of Princeton, New Jersey, where he lived with his sister, Maja. (His wife, Elsa, died in 1936, shortly after his arrival.) During the week, he would walk to Fuld Hall at the Institute for Advanced Study, where he had been based since 1933. Over the years he had become a familiar presence on the Princeton campus. Yet while he was more famous than ever before, he cut a lonely figure.

  Einstein had been recruited to be one of the first permanent members of the institute, a privately funded haven for brilliant minds that had been set up by the Bamberger family. Einstein was surrounded by illustrious colleagues. There was John von Neumann, a mathematician who had worked on the atomic bomb and was one of the inventors of modern computers, and for a while the mathematician Hermann Weyl, one of David Hilbert’s protégés, who had been one of the first to take up the banner of Einstein’s theory of spacetime. Then there was Kurt Gödel, the philosopher and logician who wreaked havoc in twentieth-century philosophy with his incompleteness theorem. And of course there was Robert Oppenheimer, who had become the director of the institute in 1947. In the corridors Einstein might encounter distinguished visitors, architects of the quantum or of modern mathematics. But mostly he would retreat to his office.

  After a few hours, Einstein would head back home for lunch and a nap. He would then wander over to his study and sit in his favorite chair with a rug around his legs, calculating, writing, and dealing with the multitude of letters that encroached on his life from the outside world. Letters from heads of state and dignitaries were interspersed with requests from aspiring young scientists and fans. At the end of th
e day, he would have an early supper, then listen to the radio and read for a bit before going to bed.

  It was an unusually quiet life for a man who had reached such colossal fame. He wasn’t forgotten. His name was just as recognizable to the public as Charlie Chaplin or Marilyn Monroe. He was a member of countless learned societies and had been awarded the keys to many cities. The cover of Time magazine featuring his picture became one of the iconic images of the new technological era. Every now and then, celebrities would still make their way to his door for a few hours with the great man. Jawaharlal Nehru and his daughter, Indira Gandhi, stopped by, as did the premier of Israel, David Ben-Gurion. The Juilliard String Quartet once came to play an impromptu concert in his front room.

  Despite his global fame, Einstein kept mostly to himself. While he had a few younger assistants working with him, he chose to spend his time working alone. His general theory of relativity was still his pride and joy, and he would every now and then delve into it, moving beyond the solutions of Friedmann, Lemaître, and Schwarzschild and trying to find new, more complicated, but possibly more realistic ones. General relativity still had so much to give, but not many people were spending time on it, preferring instead to invest their efforts in quantum theory. Even Einstein himself chose to spend most of his time on a new, more ambitious theory that had been consuming him for almost three decades. And he would be shunned for it.

  The Einstein of the 1950s could not be more different from the Einstein of the 1920s. Following his early scientific successes, Einstein had traveled the world, being treated like royalty, giving public lectures, debating other physicists, resisting and then embracing the discovery of the expanding universe. He was rewarded with the construction of the Einstein Tower on the outskirts of Berlin, in Potsdam, where observational research into his theory could be carried out. He was lauded at international meetings, where he was invited to opine on the newest developments in physics.

  He had also seen the crescendo of anti-Semitic feeling in his homeland and, as the 1930s arrived, had felt the hard realities of the rise of the Nazi Party and its followers. His travel became more constricted, the death threats started to multiply, and even though his fame continued to grow, he became more wary of traveling through Europe to fulfill his many engagements.

  Although he was somewhat shielded from the turmoil around him, a national treasure spared from the ugliness, Einstein had felt the dark underbelly of anti-Semitism early on. Shortly after his discovery of general relativity, a band of scientists, officially known as the Working Party of German Scientists for the Preservation of a Pure Science, took it upon themselves to campaign against his new theory. The Working Party smeared relativity as an example of “mass delusion” and attempted to build a case of plagiarism against Einstein. The movement recruited a world-renowned scientist as a vocal opponent to relativity: Philipp Lenard.

  The Hungarian-born Philipp Lenard had won the Nobel Prize in 1905 for his work on cathode rays, and his experimental work had been at the heart of Einstein’s early work on light quanta. His relationship with Einstein had been courteous throughout the lead-up to the discovery of general relativity. But he violently objected to Einstein’s relativity—it was far too obscure and went against what he considered the “common sense” of any physicist. Lenard proceeded to write articles, dismissing Einstein’s theory in the Yearbook, the same journal where, in 1907, Einstein had first presented the ideas that would lead to his general principle of relativity. A war of words ensued, in which Einstein dismissed Lenard as an experimentalist, not particularly capable of understanding his ideas. Lenard took offense, demanding a public apology. The public affray reflected badly on Einstein as well as Lenard and the “anti-relativists.”

  By 1933, Einstein had had enough of Germany. When the Nazi Party came to power, he decided to cut his ties with Berlin. He left Germany as it was entering its darkest days, and his theory became a target for the Deutsche Physik, or German Physics, movement. With the rise of the Nazi Party, Philipp Lenard’s case, now with the vociferous support of another physicist and Nobel Prize winner, Johannes Stark, was much easier to make. According to Lenard and Stark, Einstein’s theory was simply part of something insidious that was poisoning German culture: Jewish physics. In line with the grand plans of Nazi ideology, Jewish physics had to be eradicated from the system.

  The years following Einstein’s departure saw the systematic destruction of physics in the scientific community in Germany, which had been responsible for most of the greatest developments of the early twentieth century. By the time the Second World War broke out, all Jewish professors of physics had been removed from their university positions. Some of the most visionary thinkers in modern physics, instrumental in the creation of the new quantum physics, such as Erwin Schrödinger and Max Born, abandoned Germany. Some of them ended up contributing to the Allied atom bomb projects during the Second World War.

  With the physics community seriously crippled, Johannes Stark set about establishing himself as the leader of the new Aryan physics. One of the fathers of the modern quantum theory, Werner Heisenberg, stood in his way. Heisenberg wasn’t Jewish, but this didn’t stop Stark. He wrote a piece for the official magazine of the SS labeling Heisenberg a “White Jew,” as much a part of the decay of German science as all the others who had been ousted. Yet, surprisingly, Stark failed. Heisenberg had been at school with Heinrich Himmler, the commander of the SS. Himmler protected Heisenberg from further vilification. Indeed, Heisenberg ultimately ended up running the German atom bomb project, much to the consternation of his colleagues who had fled Hitler’s Germany.

  Einstein’s departure left work on his theory in Germany in the doldrums. He had been lauded as a national hero during the Weimar Republic, but he rapidly disappeared from German culture during the Nazi years. Some of the ideas that had led up to the formulation of his special theory of relativity were included in textbooks, but the main physics textbook, Grimshels’s Lehrbuch der Physik, made no mention of his name. Only after the war would Einstein’s general theory of relativity be taken up again in Germany.

  It wasn’t only in Germany that Einstein’s ideas were taking a battering. On the opposite side of the political spectrum, in the Soviet Union, relativity and quantum mechanics had occasionally run into trouble with the officially adopted philosophy, dialectical materialism, an integral part of Marxism. Based on the ideas of the German philosophers Friedrich Hegel and Ludwig Feuerbach, dialectical materialism was developed by Karl Marx in the mid- to late nineteenth century and was further refined by Friedrich Engels and numerous followers, notably Vladimir Lenin. In his 1938 article “Dialectical and Historical Materialism,” Joseph Stalin defined, explained, and effectively canonized dialectical materialism as part of the official Soviet ideology. In this philosophy, the basis of everything was matter, and everything else emerged from that. Reality was defined by the way the material world behaved and was interrelated, preceding any form of thought and idealization. As Marx stated in his magnum opus, Das Kapital, “The ideal world is nothing else than the material world reflected by the human mind, and translated into forms of thought.”

  A practitioner of Marx’s philosophy strove to explain everything in terms of the different constituents of the natural world and their interactions. Everything in the natural world contributed to a universe that was in a constant state of flux and evolution, punctuated by the most dramatic transformations that could arise from the gradual accumulation of the smallest changes. Crucially, the existence and evolution of matter were viewed as an objective reality whose laws were independent of observers and interpretations. Human knowledge was capable of approximating this objective reality faithfully and closely in a series of converging iterations, but the process would never be exhaustively complete and would never come to an end.

  Most if not all physicists in the world would have no problem with materialistic views per se, and in fact in their work they all were practicing materialists without bothe
ring to call themselves such. But the same physicists would definitely view with disdain and vehemently oppose any attempt by the philosophers to teach them how to do their research using the “correct methodology” advocated by a particular philosophical school. Marxism-Leninism was not just a particular philosophical concept; it was a powerful, all-reaching doctrine fully supported by the Soviet state. In the tense political atmosphere of the 1930s, 1940s, and 1950s, philosophical debates on the interpretation of quantum mechanics or relativity had the potential of deteriorating into accusations of disloyalty, sometimes with dangerous consequences.

  Admittedly, the relativistic physics of Einstein as well as the emerging new radical ideas on the quantum, with their complexity and endless and often vague philosophical musings, were easy prey for Soviet philosophers of science. There was much that could be attacked in Einstein’s theory of spacetime as well. First and foremost, it was the ultimate example of idealization. It had arisen from Einstein’s now-famous thought experiments, with little or no input from the tangible, natural world. Furthermore, it was couched in the most abstruse mathematical language, a set of rules and principles that obscured interpretation, especially by the people who, like many philosophers, were not experts in sophisticated mathematics. Finally, to crown it all, Einstein’s theory gave rise to an absurd universe with a defined origin, too close to the religious viewpoint that Soviet thought was so keen on eradicating from society. It didn’t help that one of the lead contributors was a priest, the Abbé Lemaître, another corrupt foreigner from a decadent bourgeois society in its final throes. In fact, in a fierce rejection of non-Soviet thought, it was conveniently forgotten that the expanding universe had in fact first been proposed by the brilliant Russian and Soviet physicist, Alexander Friedmann. The debate smoldered for years, flaring occasionally, yet it would be too simplistic to view it as an ideological battle between brilliant physicists and ignorant orthodox philosophers. A number of physicists and mathematicians, some of them well known, joined the philosophers’ ranks, and the dispute was severely aggravated by group allegiances and other factors not related to the subject of the discussion.