Einstein's Genius Club (15 page)

Now, consider a “fact” about ghosts: They
linger.
If they didn't, would we ever speak of them? But why do they linger? Because (tradition says) they must abide until some higher task is completed: Their sins must be exorcised or their earthly longings abated. Not surprisingly, Gödel also believed in reincarnation, and he thought through some of the implications with philosophic rigor. In 1961, Gödel's mother asked whether he believed in a next world. Gödel said he did. Since the universe and life seemed regularly ordered, there might well be another life in another world:

What would be the point of bringing forth an essence (the human being) that has so wide a range of possible (individual) developments and changes in their relations, but is never allowed to realize one thousandth of them? That would be like laying the foundations of a house with the greatest trouble and expenditure, and then letting the whole thing perish again.
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Thus, the soul (or human essence) proceeds from this world to the next and is reincarnated or reembodied so that it may continue its improvement.

If reincarnation is possible, “time” with its familiar panoply of past, present, and future becomes more mysterious than ever. In 1949, in a volume honoring Einstein, Gödel offered a new twist on Einstein's relativity: rotating universes whose effect is not only time travel, but the disappearance of time itself. Gödel's work on time is the subject of Palle Yourgrau's
A World Without Time: The Forgotten Legacy of Gödel and Einstein
.
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Yourgrau is the first scholar to examine Gödel's philosophizing on time in the depth it deserves.

Gödel's famous incompleteness theorem is ultimately a limiting case for mathematics, demonstrating that mathematics cannot complete its proofs. As we shall see, the confidence that mathematics is a complete system was one of the high water marks of optimistic rationalism in the twentieth century. Incompleteness proved this confidence misplaced: No enterprise of human thought can escape limitation, not even the crystalline structure of mathematics. It might have seemed to Russell that Gödel was mired in Platonism, but on some very fundamental level, it was a Platonism tempered by reasonable doubt.
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On the evening of May 26, 1955, Wolfgang Pauli arrived at the Zurich Physical Society ready to lecture on Einstein. It was the fiftieth
anniversary of the special theory of relativity. He expected to see among the many invited guests his two assistants, David Speiser and Armin Thellung. Both were missing.

So, too, were Ralph de Laer Kronig, in town on his annual trek back to Zurich, and Res Jost, an old friend and associate professor at ETH (Eidgenössische Technische Hochschule, the former Zurich Polytechnic School), Pauli's home university.

Kronig and Pauli were old friends, despite their inauspicious first meeting. In 1924, Kronig, a freshly minted Columbia Ph.D., had gone to the ever-skeptical Pauli, known as the “scourge of God,” with an idea about electron spin. Pauli pronounced the idea “amusing” (“Das is ja ein ganz witziger Einfall”) but unrealistic. He later regretted his words. Discouraged, Kronig gave up. In the months to come, two students of Paul Ehrenfest published very similar ideas on spin, and finally Pauli took notice. Building on these ideas, Pauli proposed a fourth quantum number with two values, one each for clockwise and for counterclockwise spin. Ehrenfest's students were ultimately awarded the Max Planck medal for their discovery. Kronig, quick to forgive, went on to a distinguished career, first at Zurich, where he was hired by Pauli, then at the Dutch University of Groningen. Years afterwards, Pauli, ever the critic even of himself, wrote to Kronig, “I was so stupid when I was young.”
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Res Jost had started out at ETH as Pauli's assistant in 1946, the year Pauli returned from the United States. By 1955, he had risen to the rank of associate professor of theoretical physics. He and Pauli were very close. They spoke to each other in the familiar “du.”

So it was odd that the four had not yet arrived.

Years later, Armin Thellung recollected the incident. The four men had met for dinner at what Thellung remembers as a “teetotal” restaurant. Afterwards, they set off for Pauli's talk. Here is Thellung:

Speiser, discovering that the gasoline tank of his Lambretta [scooter] was empty, went to a filling station. There the Lambretta suddenly caught fire! It was extinguished with the water
from a ewer but was not usable any more, so that Speiser had to walk. I found my bike with flat tires and, hence, also had to walk. Kronig, finally, went by tram—a stretch he had traveled many times already—but he forgot to get out at Gloriastrasse, and noticed it only many stops later.
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They all managed to find their way just in time, despite the instrumental mishaps.

When the tale was recounted, Pauli was quite amused, perhaps even gratified. The notorious “Pauli effect”—his peculiar and negative influence on all things instrumental—had struck again.

As a theorist, Pauli was on the other side of the divide from experimental physics. Rarely did theorists venture into the laboratory, certainly in the early days of quantum theory. Pauli, though, represented an extreme case, especially among the highly superstitious experimental physicists. It was said that no instrument or laboratory apparatus was safe when Pauli was near. Mechanisms ground to a halt, experimental data disintegrated, glass beakers tumbled to the floor. Thus, “the Pauli effect.” The great Otto Stern, who developed the molecular beam for use in studying molecules, forbade Pauli to enter his lab when the two worked in Hamburg. If Pauli came by for a chat or on the way to lunch, he was obliged to knock on the door, to make sure he never set foot within.

By 1940, when Pauli came to Princeton, he had established his name in quantum theory. He remained active, but, as with Einstein, his great discoveries lay in the past. He, too, fit the definition of protégé. At nineteen, at Arnold Sommerfeld's request, he wrote the relativity article for the
Encyclopädie der Mathematischen Wissenschaften,
a project that ultimately turned from an article into a book and garnered praise from Einstein himself. At twenty-two, as an assistant to Max Born, Pauli was invited to the Bohr Festival, his initiation into the vibrant international society of nuclear physics. At twenty-four, he discovered how electrons gather energy levels in
the atom—the exclusion principle. Nine years later, he published his paper on what would later be called the neutrino. For his exclusion principle, Pauli was awarded the Nobel Prize in Physics in 1945. The neutrino was another matter. It remained in the realm of theory until 1956, when its existence was confirmed by experiment.

But Pauli's genius, however creative, was circumscribed by his critical acumen. From the mid-1930s to the end of his life, he functioned as the “conscience of physics”—a critic whose often acerbic tongue was widely respected for its impartiality and clarity. He stayed abreast of all the advances and developments; he knew everyone, wrote to everyone, and traveled widely. But after 1933, he made no singular discovery. His contributions to meson theory (the interaction of subatomic particles that “glue” protons and neutrons) and spin (the angular momentum of subatomic particles) were numerous and valuable. Yet Pauli himself seemed unsuited to revolutionary advancement. While he labored over the exclusion principle, his close friend Werner Heisenberg published in 1925 an early formulation of quantum mechanics without fully understanding his own theory. Heisenberg published his “uncertainty principle” in 1927, against the advice of Niels Bohr. Pauli was too cautious and too much of a perfectionist to leap at speculative theories. As collaborators, Pauli and Heisenberg may have combined into the yin and yang of quantum physics. “Pauli's whole character was different from mine,” wrote Heisenberg in 1968.

He was much more critical, and he tried to do two things at once. I, on the other hand, generally thought that this is really too difficult, even for the best physicist. He tried, first of all, to find inspiration in the experiments and to see, in a kind of intuitive way, how things are connected. At the same time, he tried to rationalize his intuitions and to find a rigorous mathematical scheme, so that he really could prove everything he asserted. Now that is, I think, just too much. Therefore Pauli has, through his whole life, published much less than he could
have done if he had abandoned one of these two postulates. Bohr had dared to publish ideas that later turned out to be right, even though he couldn't prove them at the time. Others have done a lot by rational methods and good mathematics. But the two things together, I think, are too much for one man.
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A year before his death, Pauli, diffident and critical as ever, quarreled with Heisenberg over a paper on the theory of elemental particles. Heisenberg wanted to publish, despite many doubts; Pauli refused, cautious to the end. The paper remained unpublished.

With his cherubic face and high-spirited demeanor, Pauli stood out among his peers. In a photograph of the 1927 Solvay Conference (a highly selective physics conference held in Brussels), three rows of eminent figures including Einstein, Marie Curie, Bohr, and Max Planck all face dutifully front toward the photographer—all except Pauli, who is looking down and to our left, staring inquisitively elsewhere as the camera clicked.

It was Pauli's first Solvay Conference. At twenty-seven, already famous, he stands in the last row. Front row center was Einstein, then only forty-eight years old, but with white hair, winged collar, and a solemn look. Positioned as they are, one in front and the other at the rear, they embody in that image the course of their working lives. Pauli's entire career coincided with the last half of Einstein's life. Like others of his generation, Pauli moved in the wake of Einstein's epochal discoveries. In spite of their profound disagreement over quantum physics, Pauli and Einstein remained friends. During thirty years of affectionate exchanges, neither wavered, and the great man and the brash youngster never hesitated to voice disagreement.

Certainly, Pauli would have been most welcome in Einstein's living room during that winter of 1943–44. Theirs was something of a transfigured father-son relationship. It was Einstein who nominated Pauli for the 1945 Nobel Prize. At the celebration party, held in Princeton, Einstein declared Pauli his scientific heir apparent.

The usually acerbic Pauli was immeasurably touched. At Einstein's death, he wrote to Max Born:

Now, that affectionate, fatherly friend is gone. Never will I forget the speech that [Einstein] gave about me and for me in Princeton in 1945, after I had received the Nobel Prize. It was like a king who abdicates and installs me, as a kind of chosen son, a successor.
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Still, Pauli was famous for his sharp tongue and combative presence. Even Einstein was not immune to Pauli's verbal assaults. At one lecture, Einstein had just finished making a point when the very young Pauli remarked to the assembly, “What Professor Einstein said is not entirely stupid.” One theory, advanced unwisely in Pauli's presence, was so poorly conceived that it was, said Pauli, “Not even wrong!” For the most part, colleagues and students seemed to accept his sledgehammer approach as a reflection of his passion for truth and clarity, at whatever personal cost. Others felt vulnerable. Hans Bethe, for one, gave Pauli a wide, respectful berth after their first meeting at a 1929 conference, when Pauli introduced himself by saying, “Bethe, I was quite disappointed by your thesis.” No wonder Pauli earned the nickname “the scourge of God.”

Yet he was also a self-effacing colleague and supportive teacher. He fed insights to others, but never thought to claim credit. His letters to colleagues were brilliant small monographs that helped clarify and extend their ideas.

Pauli was born in 1900 in Vienna. But his familial roots—both maternal and paternal—lay in Prague. His maternal grandfather, Friedrich Schütz, was born in Prague, but moved to Vienna, where, as a journalist and playwright, he was active in Jewish political and cultural life. His maternal grandmother, Bertha Schütz-Dillner, was a famed mezzo-soprano, born in Vienna, who sang at the Cologne and Prague opera houses before moving back to Vienna, where she met and married Friedrich. Pauli's own mother,
also Bertha, was born in Vienna in 1878. Intelligent and well educated, she was a feminist and a pacifist. She was actively involved in socialist politics. Her writings included theater reviews, essays, and a book on the French Revolution. (Her suicide, in 1927, was one of the precipitating events of Pauli's breakdown in 1931.) Her daughter, Hertha, Pauli's sister, took part in the French Resistance and later became a professional writer.

Pauli's father, Wolf, was descended from Jewish intellectuals who had lived in and around Prague since their expulsion from Spain. At Prague's Carl Ferdinand University, Wolf worked with Ernst Mach, the physicist and philosopher (“Mach” speed was named in his honor), whose works would later directly influence Einstein. After receiving his degree in 1893, Wolf was appointed to the medical staff of Rudolf Hospital in Vienna. There he remained until 1898, when, only months after his father's death in 1897, he changed his name from Pascheles, converted to Catholicism, and married Bertha Schütz, Pauli's mother. He took the name “Pauli” probably in honor of Saint Paul, that earlier convert. The conversion was a prudent and fairly typical step for a professional amid the growing anti-Semitism of Europe. It meant that Wolf, whose specialty was colloid chemistry, would be able to rise to the rank of director of the Biological Experimental Institute and, eventually, full professor and director of the Institute for Medical Colloid Chemistry at the University of Vienna.
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Contradictions presided over Pauli's cradle. His father was a Jew who converted to Catholicism to advance his academic career. Young Wolfgang was not a Jew, according to Jewish tradition, since his mother was not (Bertha's mother was Christian, though her father was Jewish). Still, the Nazis would later deem him Jewish (in a 1940 letter to Frank Aydelotte, director of the Institute for Advanced Study, Pauli noted that he was “75 percent Jewish”
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), and thus his exile to Princeton in 1940.