IN PRINCETON, DURING THE COLD, wartime winter of 1943–44, four men—scientists and luminaries all, with common interests and uncommon theories—met once a week over the course of several months. These casual meetings took place far from the horrific battlefields of the World War and far from Los Alamos, the (then) secret lair of experimental atomic physicists.
They were extraordinary meetings, although they probably did not contribute to the advancement of the sciences. The four participants were uniquely matched within the adversarial and communal culture of a pure and disinterested science: Albert Einstein (at whose 112 Mercer Street house the men met); Bertrand Russell, the British logician, philosopher, and gadfly; Wolfgang Pauli, the boy wonder of quantum physics, who formulated the “exclusion principle” in 1925 and postulated the existence of the neutrino in 1930; and Kurt Gödel, whose “incompleteness” theory of 1931 shattered the link between logic and mathematics that Russell's monumental work Principia Mathematica had attempted to forge.
We know of these meetings only from passing remarks in Russell's Autobiography:
While in Princeton, I came to know Einstein fairly well. I used to go to his house once a week to discuss with him and Gödel and Pauli. These discussions were in some ways disappointing, for, although all three of them were Jews and exiles and, in intention, cosmopolitans, I found that they all had a German bias toward metaphysics, and in spite of our utmost endeavour we never arrived at common premises from which to argue.1
Eventually, the conversations seem to have sputtered out. Russell gives us no other details about what was said, and perhaps nothing worth reporting was said.
That such exemplars of our scientific age had occasion to chat in the cloistered world of Princeton's Institute for Advanced Study might seem fodder for yet another London stage play set in the world of physics—Heisenberg and Bohr had met in Copenhagen in 1941, and from that meeting, with its uncertainties and relative perspectives, can be seen, in retrospect, angled perspectives into the collision of particles that is war.
Indeed, it was war and Hitler that had brought all four to Princeton. Einstein, Pauli, and Gödel, having fled the chaos of Europe, found refuge at the Institute (Einstein in 1933, Pauli and Gödel in 1940). Russell was in temporary exile from England, yearning to return, but as yet unable, owing to travel restrictions. Solidly entrenched in the small-town atmosphere, the four men spent their days thinking, writing, and, periodically, lecturing, either within the Institute or elsewhere at professional meetings.
For years, Einstein had enjoyed world fame. Princeton was no different. Shop owners hoarded his signed checks, children pleaded for help with homework, strangers approached him on the street or in museums. He and his second wife, Elsa, had moved to the modest white house at 112 Mercer Street in 1935, just a year before Elsa's death. During Elsa's illness and after her death, Elsa's daughter, Margot, and Helen Dukas, Einstein's secretary, who had been part of the family since 1928, ran the household. They were joined by Maja, Einstein's gifted and beloved sister, in 1939. By 1943, then, Einstein's household consisted of himself and three exceedingly intelligent women. One of the three would surely have served tea to the guests.
The colonial-style house (which Einstein paid for by selling a manuscript to the Morgan Library) was filled with solid German furniture rescued from the couple's apartment in Berlin. Typically Biedermeier, a style associated with the pretentious nineteenth-century German bourgeoisie, the cumbersome, clumsy, outmoded furniture was relegated to the first floor at 112 Mercer—Elsa's domain. His own study, on the upper floor, was furnished in much plainer fashion, with tall bookshelves and a paper-strewn table.2 It was there that Einstein often entertained colleagues, and there, presumably, that the four men met.
Clearly, the meetings did not make history. But they certainly embodied it. Einstein's special and general theories of relativity had reshaped modern physics; Pauli's exclusion principle helped launch the revolution in quantum physics; Russell's early eminence as a logician resulted in the towering Principia Mathematica (written with Alfred Whitehead), which laid out the foundations of symbolic logic; Gödel's incompleteness theorem quashed any hope (including Russell's) of mathematics as a universal, consistent, and complete system.
A more illustrious scientific group of friends probably never gathered, at least not in such a relaxed and intimate setting as Einstein's study. After all, Einstein was Einstein, and Gödel was considered the most important logician since Aristotle. In terms of stature, their only equivalents would be Newton and Leibniz in the seventeenth century, two geniuses who never met. Of course, conferences and congresses were typical meeting places, with their rituals of podium, prepared papers, and hallway talk. But the conversations Russell alludes to would have had nothing in common with academic conferences.
It was an intimate little group. Gödel and Pauli were among Einstein's closest friends in Princeton. Einstein was fond of Russell, who, as the only nonmember of the Institute for Advanced Study, might have seemed a bit of an interloper. Later, Russell would develop a friendship of sorts with Wolfgang Pauli.
It was also a pot simmering with outsized personalities. Pauli, then aged forty-three, was famously intimidating, given his brilliance and rough sarcasm—and he looked the part: florid and barrel shaped, with strangely slanted eyes in a moonface. (George Gamow, the mathematician, once sketched Pauli as a plump devil, an allusion to his reputation as an intense critic, as well as to his devilish wit.) Gödel, aged thirty-seven, a mathematical Platonist happily married to a former cabaret dancer from Vienna, was a notorious recluse, shadowed by bad health and nervous breakdowns. He was thin and intense, his eyes shielded by horn-rim glasses with tinted lenses—he might be staring at you, but it was hard to tell. The seventy-two-year-old Russell, small and bony-featured, was famous for his lightning mind, malicious wit, and boundless energy; he was now the third Earl Russell and one of the world's leading philosophers, but he was also impoverished and had been in America since 1938 trying (vainly) to find a paying job. Then there was Einstein, his hair wild as ever, wearing a sweatshirt with a handy pen clipped to its neckline.
German accents mingled with upper-class British tones: Einstein talked very softly, Russell in a snapping high pitch, Pauli in a growl, and Gödel quietly and precisely. It would have been a smoke-filled room as well: Einstein, Russell, and Pauli were incessant pipe smokers.
One fascinating topic probably never came up. Two of the four scientists dabbled in the realm of the irrational. Pauli the physicist was a scourge of any idea that did not meet the most rigorous, objective standards of proof. But privately he subscribed to Carl Jung's psychology, with its archetypes and archaic myths. Indeed, he had been Jung's patient in the early 1930s, and Jung had mined his client's rich dream life in several lectures and articles, suppressing Pauli's name, of course. Among Jung's writings on Pauli's dreams is the chapter “Individual Dream Symbols in Relation to Alchemy,” which alludes to another of Pauli's extrarational interests: medieval alchemy. Pauli found in alchemy a model for how matter could be joined to spirit—a task he felt urgent for the modern mind. As for Gödel, the astringent logician was highly sympathetic to telepathy, reincarnation, and the existence of ghosts—not despite being a logician, but because of it: He thought such phenomena rationally justifiable. The young Gödel may have attended a séance; certainly he read widely on parapsychology throughout his life.
Had they been aired, Pauli's Jungian affinities and Gödel's excursions into the paranormal would have startled the two elder scientists. Einstein and Russell both adhered to more conventional metaphysical views. Einstein, though close to both Pauli and Gödel, seems to have been unaware of their otherworldly interests. Perhaps it is no wonder, as Russell complained, that the group could not find common premises, at least when it came to philosophizing about science.
Besides tangled friendships and rivalries, the four men who met in Einstein's living room shared something else: the common fate of being past their prime. By 1944 each had already done his important scientific work. Einstein had already spent the last twenty years pursuing his hope of a grand unified theory for physics—a pursuit destined for failure. Russell's creative years in logic lay more than thirty years in the past; now, he was busily churning out popularizing books to earn badly needed money. (The History of Western Philosophy, which he was finishing up, surprised him by becoming a runaway best seller the following year.) Pauli's many achievements included his 1925 discovery of the exclusion principle, one of the great clarifying insights in physics, and his daring prediction in 1930 of the neutrino; but there were no more such triumphs ahead. Gödel's startling theorem of 1931 proved that mathematics must remain incomplete—the “most significant mathematical truth of this century,” as his honorary degree from Harvard later put it; but by 1944, he had shifted from logic to make a new start in philosophy.
The history of science is a long procession of figures, some famous, many forgotten, who come forward, work their special wonders, make their mark, lose the power of genius, and make their exit. That scientific careers peak early is, of course, a commonplace—some might say a myth. Yet it would seem that those exits are, on the whole, earlier than those of poets and artists. Aging genius has been a topic of much discussion among scientists and their anatomists. Like any myth, that of the coupling of youth and scientific discovery is both exaggerated and compelling. Indeed, those to whom scientific genius is ascribed have done as much as any to propel the myth. G. H. Hardy, a numbers theorist who continued to produce well beyond middle age, nevertheless wrote in his memoir, A Mathematician's Apology, “No mathematician should ever allow himself to forget that mathematics, more than any other art or science, is a young man's game.” And we have Russell's own account of his dogged work on the Principia to remind us that scientific creativity requires immense energy:
So I persisted, and in the end the work was finished, but my intellect never quite recovered from the strain. I have been ever since definitely less capable of dealing with difficult abstractions than I was before.3
Mathematical theorizing seems especially suited to the young, nor is theoretical physics a country for old men. Thus, we have John Nash at twenty-two (equilibrium and game theory); John von Neumann at twenty (a definition of ordinal numbers); Carl Friedrich Gauss at twenty-one (the fundamental theorem of algebra); Evariste Galois at twenty-one (recognized posthumously for his algebraic theories); Alan Turing at twenty-four (the Turing machine). Arguably, the average age of discovery has risen in recent years. Jordan Ellenberg reminds us that modern mathematics is itself a mature field, requiring years of study well beyond that of an eighteenth or nineteenth or even early twentieth century prodigy.
Still, Gödel was only twenty-five when in 1931 he proved the “incompleteness” of mathematics. And the early days of quantum physics saw a procession of theorists remarkable for their youth as well as their genius: Wolfgang Pauli and Werner Heisenberg were both twenty-five, and Paul Dirac was twenty-four, when they published their landmark contributions. Newton's insights into gravity and optics came when he was twenty-three, “in the prime of my age for invention” or his “annus mirabilis.” Einstein published his special theory of relativity at the age of twenty-nine in his own annus mirabilis of 1905. In the last four centuries, only Newton and Einstein among major theorists were able to surpass their earliest work—Newton with his universal law of gravitation in 1686 and Einstein with his general theory of relativity in 1916.
But even Einstein's gifts finally failed. In the late 1920s, while in his late forties—an almost Methuselah-like age for topflight creative work in theoretical physics—Einstein began his exit.
Why such a “running down” of energy happened to him, or happens to other scientific theorists, is a puzzle, as mysterious as the initial outburst of genius that occurs early in such careers. Explanations range from the physiological (a decrease in testosterone, according to the psychologist Satoshi Kanazawa) to the sociological (math and physics reward brash, revolutionary discoveries, and thus brash, youthful thinkers) to the biohistorical (age statistics are affected by life expectancy or the relative “age” of the field).4 Despite a mountain of studies, we know very little about why such supreme gifts appear or disappear.
“Genius” is a word that only gives a local habitation and a name to an unfathomable phenomenon: Would we call it genius otherwise? Genius eludes definition partly because it points not to a single ability, but to a web of abilities and coincidences that must hang together delicately yet powerfully to work at all. In physics and logic, mathematical prowess is obligatory; but so are audacity and courage, penetrating insight, imaginative vision, tenacity—and luck. And luck must occur not only within the arena of study—for instance, finding the right equations—but in a larger sense as well: In order to ponder gravity, Newton must first have survived the plague; in order to develop his general theory of relativity, Einstein must first have had the leisure and salary offered by the Kaiser Wilhelm Institute of Physics and must first have accepted the post in late 1913, before World War I had barred him from entering Germany. Accident not only historical, but emotional can loose creative genius. Take, for instance, Einstein's separation from his first wife, Mileva, in the year prior to general relativity, and Gödel's serendipitous marriage to a cabaret singer who kept him sane.
At some point, however, one or another of these powers—or the way they join together—changes, and “genius” departs. Perhaps insight fails, or else ambition or energy, or the theorist becomes too cautious, or is surpassed by students (as the great physicist Max Born confessed of Pauli, his onetime assistant), or can't keep up with new ideas. (Paul Ehrenfest, Einstein's cherished friend, committed suicide at fifty, an act Einstein attributed in part to the “difficulty that adaptation to new ideas inevitably imposes on a man of fifty.”5) Or perhaps the theorist simply finds physics no longer quite so important—as with Newton, who in middle age took up theology.
The “middle-aged” scientist often seems to his or her colleagues to be a flawed version of that younger, more brilliant self. Those phenomenal gifts are still evident, but something seems “off” or amiss.
Einstein's seeming failure to produce theoretical insights after the mid-1920s is an example. In 1916, when he published his theory of general relativity, he was thirty-eight, still at the height of his powers. His last contributions, on wave theory and quantum statistics, came in 1925. By then, Einstein was launched on his quest for a unified theory—as quixotic a journey as that of any hapless knight. Many critics think that Einstein misjudged the problem of a unified theory as he would never have done before. But even so, something slowed him down. He was stymied at every step. Only his old boldness and tenacity kept him doggedly going, decade after pointless decade. Some crucial power seems to have left that marvelous mind, and Einstein eventually became resigned to it.
Something similar happened to Pauli in physics and to Russell and Gödel in logic. In his thirties, Pauli was already becoming more of a critical than a creative force within physics. In their thirties, Russell and Gödel both began to abandon logic for philosophy.
Why do physicists and mathematicians seem more susceptible to this fading of creative energy and genius than, say, artists and composers and writers? Johann Sebastian Bach, after all, kept building incomparable structures of abstract musical symbols until his death at seventy-five; Yeats wrote great poems into his seventies. Goethe's artistic maturation continued until his death at eighty-three. Picasso worked successfully into his nineties, DeKooning into his eighties, Braque until his death at eighty-one. No such example of late-stage genius and production can be found in the sciences.
This striking difference between the worlds of science and art was noted by the eminent astrophysicist S. Chandrasekhar, who, musing on artistic genius, thought of Beethoven's words: “Now, I know how to compose.” At forty-seven, Beethoven had already written eight symphonies, five piano concertos, eleven quartets, and twenty-five of his thirty-two piano sonatas.
Scientists do not develop this way, suggests Chandrasekhar. Their genius flowers young and does not “mature.”6 No major scientist has continued to grow through life as did Beethoven, or Shakespeare, or Rembrandt—not to mention Verdi, Titian, Picasso, or Thomas Mann. To paraphrase F. Scott Fitzgerald, there are a great many triumphant third acts in art and literature, but even second acts are rare in science.
Something systemic—peculiar to scientific endeavor—seems to be involved. Genius is an individual matter—one that varies from person to person and is expressible in a myriad of forms. But science is a collective enterprise. It progresses and builds, dependent on a process of incremental contribution. Even revolutions in science—Thomas Kuhn's paradigm shifts—require structures to build upon (or tear down).7
Scientists thus often live to see their greatest work superseded, modified, or refuted. None escapes the relentless march: Immortal Newton was displaced by Einstein, and Einstein fully expected that his work would be corrected or surpassed. In 1949, he wrote to a friend:
You imagine that I look back on my life's work with calm satisfaction. But from nearby it looks quite different. There is not a single concept of which I am convinced that it will stand firm, and I feel uncertain whether I am in general on the right track.8
Einstein's humble reflection reveals from within what can be called “the pathos of science.” Neither artists nor philosophers are prey to this pathos: Nothing can “improve” upon Socrates’ Oedipus Rex or Mozart's Don Giovanni or Plato's Republic, though these works are subject to the vicissitudes of changing tastes and interpretations. Indeed, poets are especially caught up in intimations of immortality, as distinct from mere fame. Milton invokes the “Heavenly Muse” to ensure that his Paradise Lost would “soar / Above th’ Aonian mount, while it pursues / Things unattempted yet in prose or rhyme.”
Scientists, on the other hand, create only to be superseded. The greatest scientific achievements will be scrutinized and, eventually, proven inadequate. After two thousand years, Euclid's geometry was shown to be limited and was augmented by the non-Euclidean geometry of Carl Friedrich Gauss. Within twenty years, a fellow German, Georg Friedrich Bernhard Riemann, improved on Gauss—and Riemann's geometry helped lead Einstein to his general theory of relativity.
Science is a community of interlocked, perpetual, cumulative effort. No one can be successful except by working within its common premises and rules of procedure and proof—however “revolutionary” the work. But the cumulative nature of science also means that each individual effort will be supplanted. Discoveries keep occurring—and every discovery means that some previous finding becomes modified or discarded. Thus, most productive scientists become half-forgotten figures in the public mind, existing in textbooks as abbreviations, symbols, and identifiers: Boyle's law, the joule, the fermi, Planck's constant. The incessant construction of science provides new and exalted triumphs (Einstein, after all, can build on Newton), but also ensures one's own “defeat” or limitation—sometimes within a few years.
The four men in Einstein's study provided striking examples of this “pathos of science.” Here were two aging scientists paired with upstart revisionists: Einstein and Pauli, Russell and Gödel. At stake were none other than the fundamental structures of modern physics and logic.
Wolfgang Pauli was only sixteen when Einstein's general theory of relativity turned physics upside down. Within four short years, Pauli was to write a definitive explanation of relativity for the Encyclopädie der Mathematischen Wissenschaften—an account so clear that forty years later, Niels Bohr lauded it as “still one of the most valuable expositions” of Einstein's theory. Five years later, Pauli presented his “exclusion theory,” the first in a number of successive discoveries by Pauli and Werner Heisenberg that defined the nascent field of quantum mechanics.
Behind it all was Einstein, who, using Planck's concepts, “launched” quantum physics in 1905. But Einstein's quantum physics was built on classical physics. No “uncertainty” there. The new quantum mechanics, formulated by Bohr, Heisenberg, and Pauli, no longer postulated an objective reality that could be observed and measured. To Einstein's horror, physics had become a matter of statistical laws rather than certainty. “God does not play dice with the world!” he exclaimed.
Pauli and the quantum physicists had triumphed, however. At the Fifth Solvay Conference in 1927, quantum physics took on classicism from the lectern and in the corridors of discussion. Einstein, who did not present a paper, spoke against the new world of physics heralded by Niels Bohr and his young followers, among them Pauli and the German wunderkind Werner Heisenberg. Stubbornly, Einstein held out against the tidal wave of quantum physics. All indeterminacy was temporary, he insisted, a passing stage within the history of physics. Sooner or later, with more knowledge and insight, physicists would be able to lay aside uncertainty. He never gave up that belief.
But quantum physics, argued Bohr and his quantum conscripts, was here to stay. Uncertainty was not an imposition of humanity onto nature, but a fundamental state. However distressed the Solvay participants might have been by Einstein's vehement opposition, the conference shifted the ground so vigorously that, during the three years between the Fifth and the Sixth Solvay Conference, Einstein found himself in a rearguard position. He was by far the most visible and vocal critic of quantum physics. He devoted the remainder of his life to the search for a unified theory, in hopes of proving Pauli and his quantum mechanics wrong. But in the intervening years, Einstein's position had gained no ground. Pauli and his quantum associates held sway in a world of physics that had passed Einstein by.
Russell and Gödel were also scientific rivals. Russell's pioneering Principia Mathematica won him fame as a logician and was the basis of his philosophic authority and later reputation. Written with Alfred Whitehead and published in three volumes beginning in 1910, the Principia tackled the entire domain of mathematics. Its purpose was to demonstrate that “all pure mathematics follows from purely logical premises and uses only concepts definable in logical terms.”9 The impulse to subsume mathematics into pure logic (called “logicism”) began with Gottfried Leibniz, who, in the seventeenth century, yearned for a universal language based on logic. Not until the late nineteenth century, however, did logicians develop the tools (in the form of definitions and methods) needed to place mathematics more or less within the realm of logic. In 1879, the German logician Gottlob Frege began his life's work on a system to formalize logic and to develop a logical foundation for mathematics. In their Principia, Russell and Whitehead solved inconsistencies that Frege and others could not. (Indeed, Russell had to solve his own “Russell's paradox,” which demonstrated inconsistencies in Frege's axioms, before he could complete his Principia.) In its three lengthy volumes, the Principia devised a comprehensive and very usable notation system; by demonstrating the power of logic, it inaugurated the field of metalogic; it placed logicism comfortably within the realm of traditional philosophy and even made it fashionable.
But the underlying premise of the Principia—that mathematics was a complete and thus a universal language and logical system—was thoroughly demolished by the upstart Gödel. In 1931, Gödel published his infamous proof known as the “incompleteness theorem.” In it, he demonstrates that no mathematical system that depends on axioms can be thought of as complete, for in any such system, some propositions can be neither proved nor disproved. In extinguishing the dream of a consistent mathematical system, Gödel became, in the eyes of many, one of the two most important logicians of the twentieth century—the other being Russell himself.
Pauli and Gödel were simply following in the tracks of Einstein and Russell. Einstein built upon and upended Newton; Russell built upon and upended the pioneering mathematical logician Gottlob Frege. So science marches on.
As Einstein, Russell, Pauli, and Gödel sat talking in Princeton, Robert Oppenheimer and his fellow physicists in Los Alamos were trying to build an atom bomb that could decide the course of World War II. They believed—and it is certainly argued—that Werner Heisenberg and his fellow physicists were doing the same in Germany.
Physics was a small world. Einstein and Pauli had direct links to these projects, both personal and professional. Fearful of a German bomb, Einstein had written to President Roosevelt in 1939, urging him to begin an atomic project. Pauli had been Oppenheimer's teacher in the early 1930s and had been Heisenberg's close friend and collaborator in the 1920s when, together with Niels Bohr, they had built the foundations of quantum mechanics. In this tightly knit world, Einstein and Pauli were aware of what was at stake, if not in detail.
When the Bomb exploded over Hiroshima, science lost its innocence, irrevocably. In return for the ultimate weapon, physicists tasted dizzying political power. Yet that power was poisoned fruit. Indispensable to their government's survival in the atomic age, physicists were enlisted as guardians of the state—guardians who were kept under strictest guard. Their knowledge was dangerous, and their loyalty was constantly questioned. Oppenheimer's security hearing of 1954 is often thought to have inaugurated the era of atomic suspicion. In fact, distrust and surveillance followed almost immediately from Einstein's letter to Roosevelt. By the time Oppenheimer was staking out Los Alamos, spying on physicists was widespread—even obsessive. Most scrutinized of all, perhaps, was Einstein, whose FBI file eventually numbered some fifteen hundred pages. A new age of suspicion was emerging.
The four men came to Princeton from a continent wracked by war. Each made his way to Princeton as much by luck as by any clear design. There they waited as the world changed. And change it did. In 1945, after the Bomb was dropped, Pauli, critical and prescient as always, lamented:
The Atom Bomb is a very evil thing, also for physics, I think. The politicians, of course, are at a complete loss and talk in a demagogic way of a secret which, evidently, does not exist (the true secret is the nature of the nuclear forces). Although most people say that I see ghosts, I am afraid that physics gets more or less subdued by military censorship and that free research, in principle, is gone.10
If Einstein and his friends spent the war sidelined and isolated, they were not idle. Of the four, Einstein and Russell were the most outwardly political. Both had abandoned their early pacifism in the face of Hitler and the threat of Fascism. Of the four, only Einstein made any direct contribution to the war effort, working in a minor capacity for the Navy, despite his status as a security risk. Pauli offered his services, only to be told by Oppenheimer to “keep those principles of science alive which do not seem immediately relevant to the war.”11 Pauli was too acerbic and independent to fit into regulated teamwork and had no taste for the applied science useful in military research. Gödel was unfit physically and mentally. Russell was trapped in the United States, unable to secure sea passage to England, where he hoped to contribute to the war effort.
Thus it was Princeton, for better or worse. Einstein described the town “as a wonderful bit of earth, and a most amusing ceremonial backwater of tiny demigods on stilts.”12 As for its intellectual life, “[a]part from the handful of really fine scholars, it is a boring and barren society that would soon make you shiver.”13 Einstein shunned the public spotlight as much as possible. Yet he could never escape the notice of town and gown alike. He was besieged by requests for appearances, statements, appeals, signatures, speeches, and interviews. But he avoided making political statements and reserved his energy for Jewish causes.
Generally, he kept his distance from Princeton's colony of German and European exiles. He was always in the public eye, yet he remained apart, even from the nexus of intellectual life: “I live like a bear in my den.”14 From 1938 to 1941, the great German novelist Thomas Mann taught at Princeton and lived only a few blocks away. But the two men saw little of each other. Mann's wife, Katia, thought Einstein an “enormously specialized talent” but “not particularly stimulating” and “not a very impressive person.”15 A certain cultural snobbery seemed to have migrated to the American shores. Then again, the Manns’ grand style of living—in a mansion with a staff of servants—did not appeal to Einstein, who lived simply, without fuss. One can scarcely imagine the dandyish Thomas Mann in Einstein's trademark sweatshirt. Einstein's few close friends in Princeton were outsiders and mavericks, like Gödel and Pauli.
Of the four men who met in Einstein's living room, Gödel, Pauli, and Einstein held appointments at the Institute for Advanced Study. Established by Abraham Flexner in 1930, the Institute offered fellowships (without teaching requirements) to eminent scholars in the natural and social sciences and in physics and mathematics. Einstein was Flexner's first recruit—and his fame fortified the Institute's prestige. Gödel joined in 1933, though only as an assistant; Pauli, after a visit in the mid-1930s, arrived in 1940 to take up residence until the end of the war.
Gödel and Pauli were not only Einstein's intellectual peers, but also, thankfully, spoke German. Einstein's spoken English was never strong; he was really at home only in German. In Princeton, his old friendship with Pauli deepened, and a new one with Gödel flowered. Pauli was superbly knowledgeable about relativity theory, and, when they were not arguing about quantum theory, he and Einstein collaborated on a paper. Gödel and Einstein saw each other daily for years; their walks to the Institute gave Einstein an intellectual equal with whom to discuss his unfashionable unified theory, though Gödel remained skeptical. Russell, whom Einstein had met years before, showed up in Princeton at the end of 1943, at loose ends, scheduled for periodic lectures in New York, desperate for a ship to take him back to wartime England.
Four more varied—and difficult—people would be hard to find.