In the morning, Bohr had it. When the shutter opens and the photon flies out, the mass of the box goes down. But the weight of the box is being measured. That means it has to be on a scale. When the photon flies out, the scale rises up—very little, but at least a bit. That means it’s ever so slightly higher in the earth’s gravitational field. By Einstein’s own theory of relativity, time is seen to operate at different rates in a stronger versus a weaker gravitational field.
Bohr sketched out the calculations, and once everyone staying at the hotel saw where this was going—Bohr, Heisenberg, probably Ehrenfest, and perhaps others—Einstein, to his credit, helped them fill in the details. Working together, Einstein and Bohr concluded that the uncertainty in the weighing, because of that tiny gravitational shift, was just enough to match exactly what’s predicted by Heisenberg’s uncertainty principle.
Einstein had neglected his own theory of relativity—and Bohr had used it to refute this final attempt to defend causality. It was a crushing blow, made all the more painful by the fact that it was delivered by Einstein’s own instrument—and its implications could not be clearer. Back in 1916, Einstein had assumed that using probabilities to describe how photons operate within a device such as his proto-laser was just a temporary measure and would be put aside once science went further and our knowledge increased. That dream was now over.
Heisenberg was exultant at the outcome. When he saw Einstein’s last bastion crumble, he wrote, “We . . . knew that we could now be sure of our ground . . . The new interpretation of quantum mechanics could not be refuted so simply.”
Bohr was the humbler man, but the gist of his polite, guttural mumblings was clear: He had won. Einstein had lost.
INTERLUDE 4
Music and Inevitability
Einstein never again attended such a meeting; never again attempted to refute Bohr or Heisenberg in public debate. Nor, however, did he change his beliefs. He was still convinced the world’s experimentalists were wrong, their findings incomplete.
For his consolation, he turned to music, as he always had. Einstein loved much of the classical repertoire, even if he took issue with most of its composers. “I always feel,” he wrote, “that Handel is good—even perfect—but that he has a certain shallowness.” Schubert failed the ultimate test, too. “Schubert is one of my favorites because of his superlative ability to express emotion and his enormous powers of melodic invention,” Einstein admitted. “But in his larger works I am disturbed by a certain lack of architectural shape.”
The imperfections went on and on. “Schumann is attractive to me in his smaller works,” Einstein wrote, “because of their originality and richness of feeling, but his lack of formal greatness prevents my full enjoyment . . . I feel that Debussy is delicately colorful but [also] shows a poverty of structure.” In conclusion, he wrote, “I cannot work up great enthusiasm for something of that sort.”
How could these otherwise great composers have missed the large-scale unity that he knew was out there to be found? Only Bach and Mozart had accomplished that. Those two had something that surpassed the others. “It is impossible for me to say [which one] means more to me,” Einstein wrote, but what he knew for sure was that no one else measured up. Beethoven might have been expected to be at that top level, for instance, but though Einstein found him powerful, Beethoven was also “too dramatic, and too personal.” His work had something arbitrary about it, for human emotions depend on our bodies and our personal histories. Mozart, however, went beyond the realm of personal emotions, with a music “so pure that it seemed to have been ever-present in the universe, waiting to be discovered by the master.” Mozart’s work felt more “necessary,” letting us see a Platonic realm of truth that exists far beyond the chance events of anyone’s personal history.
Einstein sought in the music of Bach and Mozart precisely what had eluded him elsewhere. In his emotional life, in his marriages, even more so in his affairs, Einstein had failed to find anything lasting, anything certain. His failure hurt all the more because his dream of certainty, and of contact with the truth, still haunted him.
In letter after letter now, he went over the many ways in which his previous work had ostensibly proved that his beautiful dream was valid. E=mc2 from 1905 showed there was certainty in the universe, since it described in as much detail as one could wish exactly how mass and energy could change into each other. The great G=T of his 1915 equation had been just as clear. Mass made space curve. Curved space guided mass along. How could there be any random chance involved, given that this equation, too, was so clear? The sheer simplicity of G=T was impossible to ignore. “Hardly anyone who has truly understood it will be able to escape the charm of this theory,” Einstein had written, exhausted but content, that Berlin winter when he’d first completed his work on the equation. He himself was still trapped within its orbit.
It’s true that Einstein himself had once questioned the simplicity at the heart of G=T—during the years between 1917 and 1929, when his lambda mistake still stood—but ultimately this questioning had proved unnecessary. Moreover, although Einstein may have been humiliated in Brussels in 1930, he also took heart in the fact that his contemporaries had validated his other work time and time again, in ways that lent support to his belief in the inherent certainty of the universe. Humason had measured distant galaxies through the giant telescope in the mountains of California and found that billions of stars were hurtling away from us. There was no ambiguity about it, and it was exactly what the original, simple G=T predicted. Such reinforcement helps explain why almost a decade after the 1930 conference, Einstein still felt comfortable telling a close assistant, “When I am judging a theory, I ask myself whether, if I were God, I would have arranged the world in such a way.”
Einstein’s faith in his own ability to judge the architecture of the universe was powerful, but also potentially dangerous. The more esteem a great man gets, the easier it is for him to deny reality—just as Einstein was now doing, and in a manner of which his younger self would have disapproved.
Einstein had once drawn for his old friend Maurice Solovine—the enthusiastic Romanian who’d first responded to his 1902 advertisement for private lessons in math and physics in Bern—a picture of how he felt creativity worked. We start with the reality around us, Einstein wrote: the empirical world, where we experience our ordinary sensations. In a burst of imagination, thinkers can ascend from that foundation to loftier general principles. Then, in order to be sure that those principles are true, we must work out detailed propositions that follow from those principles and test them against the empirical world.
That was the procedure Einstein had followed with E=mc2, whose predictions—after he’d conceived of them on paper—he’d proposed testing with the radium salts the Curies were using in Paris. It was the procedure he had followed with general relativity as well: a great jump in imagination—using the thought experiments about the falling room—to create a clear, abstract theory, and then from that drawing detailed testable conclusions, such as the ones about space curving that Eddington had checked during the 1919 eclipse.
Although Einstein often wrote that this was still proper, he also increasingly expressed a contrary belief. As he wrote in 1938 to an old colleague, “I began with a skeptical empiricism . . . But the problem of gravitation converted me into . . . someone who searches for the inky reliable source of Truth in mathematical simplicity.” As his work went on, Einstein increasingly ignored his original, more empirical approach. “[Quantum theory] says a lot,” he wrote, “but does not really bring us any closer to the secret of the ‘Old One.’ I, at any rate, am convinced that He is not playing at dice.” God, he felt sure, followed a rational plan when He designed the universe. Experimental results were not going to rebut that.
Nothing at the Brussels conferences, apparently, had changed his mind. His whole belief system would have been crushed if something had. But when he said “God does not play dice with the universe,” Niels Bohr
would reply, effectively, “Einstein, stop telling God what to do!” The two men held utterly different views—not just about how the universe worked, but also about their own abilities to discern its divine functions.
Only one of them could be right.
Part VI
FINAL ACTS
Einstein in Princeton, early 1950s
EIGHTEEN
Dispersions
BY 1950, TWENTY years after the final Brussels conference, Bohr’s institute in Copenhagen was at the center of the world’s physics research. Despite his victory over Einstein in 1930, the towering Dane had managed to avoid the lure of dogmatism, and his broad-mindedness had attracted some of the brightest new minds. Young people from Harvard, Caltech, and Cambridge eagerly went to Copenhagen for a year or two during their graduate studies or after, to join in the exciting atmosphere and share ideas with the respected, approachable Professor Bohr. Conversations with him demanded as much concentration as ever, for Bohr’s accent still rarely strayed far from Danish no matter what language he tried to speak. But that didn’t matter. The bright young people at the institute came from so many countries that they happily described its official language as “Broken English.”
Bohr was a hero in his own country. After the outbreak of World War II, he’d kept the institute operating during the first years of the German occupation, staying until 1943, before being spirited off—by secret RAF transport from Sweden—when his Jewish ancestry and political significance made staying any longer too dangerous. Excessively tall, and excessively polite, Bohr had nearly died during the RAF flight, for he’d been secreted away in the bomb bay and was supposed to speak into a microphone to tell the pilots if anything was wrong. When his oxygen failed—the mask not fitting around his head—his mutterings and polite gasps seemed no less incomprehensible than his previous communications, and he fell unconscious, only recovering when the pilots, realizing it was odd that there was such silence, swooped lower into denser atmosphere, where there was enough oxygen to keep Bohr alive.
Brought in to aid the Manhattan Project in building an atomic bomb, Bohr had tried, albeit unsuccessfully, to alert both Churchill and Roosevelt to the dangers this weapon posed. He suggested there should be a demonstration of it first, or arrangements set up for international control, but to no avail. When the United States dropped the bombs on Hiroshima and Nagasaki in the final days of the war, it was the first time the world had been treated to a public showing of these terrible machines—weapons that had been born, ultimately, in the theories of Einstein as much as in the practical efforts of Bohr and many others.
Bohr always felt, as he once put it, that we should be both “spectators and actors in the great drama of life.” With the support of his thoughtful wife, the openness of his personality, and the general safety of Denmark, he’d managed to be both an onlooker and a participant—in politics as well as in science—all while keeping in line with Europe’s noblest ideals. He emerged from the conflict not only unscathed but stronger in his public standing, at least, than ever before.
The German physicist Werner Heisenberg, by contrast, had disgraced himself during the war. More worldly physicists had sometimes teased him for his years of rambling over the countryside with exuberant youth groups. But those hikes hadn’t been as innocuous as they’d seemed. Ever more of their participants felt this was a way to get close to the Fatherland’s soil and to help preserve it from dangerous outsiders, such as Jews and foreigners. Although Heisenberg did try to stand up for a few of his colleagues who were being ousted from their academic positions for being Jewish, later he clearly relished being brought into commanding positions within the technocratic parts of the new Nazi state. There were new research groups to run, large budgets to control, and visions of a miracle weapon that could ensure Germany’s triumph over its enemies forever.
At one point during the war, with black-jacketed SS officers not far away, Heisenberg had even stormed into Bohr’s institute in Copenhagen, explaining with great assurance now—in these early days, when Germany was on the rise—on which side the future lay. Bohr was still there, and he was appalled. Already he’d begun preparing the institute against German depredations, including hiding the gold Nobel Prizes of two Jewish members. (By German law, what was owned by Jews could be stolen, and if the owners tried to keep their possessions, such as by shipping the medals abroad, they or anyone who helped them could be arrested and quite legally tortured.) Bohr’s ingenious friend de Hevesy from their Manchester days, now in Copenhagen, had worked out the ideal hiding place. The lustrous gold medals were dissolved in a mixture of nitric and hydrochloric acids, creating an innocuous brown sludge that was stored on a back shelf until the war was over.
That was the German state the excited Heisenberg now so happily represented. His brilliance in creating the uncertainty principle had given him the respect within the Nazi establishment to do almost whatever he wanted. Bohr didn’t know that Heisenberg would soon be working female slaves to death at the Sachsenhausen concentration camp by forcing them to produce toxic uranium powder for his experiments. But Bohr was a civilized man. He now recognized, with disgust, that Heisenberg, despite his music, his education, his mathematical brilliance, was not.
Heisenberg’s old teacher, Max Born, being Jewish, could not ride out the war like his pupil; he had to escape Germany. Even at the time of the 1930 conference, the youth groups that Heisenberg relished had been getting stronger, and in the quiet university town of Göttingen, about a third of the adults voted for the Nazi Party in elections that year. One especially energetic student group began working through baptismal records and town registries to see which professors were actually Jewish. Detailed lists were drawn up, and The Jewish Influence in German Universities, vol. 1, University of Göttingen appeared. Just a few years later, lists like that would be used for extermination.
Life became impossible for Born, especially as almost all his faculty colleagues turned away when he tried to get their support. Eventually he ended up in Scotland, where he became a benevolent teacher of generations of students. (His daughter, marrying a British man and taking his last name, Newton-John, later moved to Australia, where one of their own children, Olivia, had noted success as a singer and actress.) It was a good thing he got away when he did, for during the rise of the Nazi state, it became clear that intellectuals and other prominent Jews were under particular threat.
In 1933, when Born was still in Germany, Hitler gained effective control of the Reichstag, and the great number of students who were Nazi supporters could beat up Jews with impunity. Born’s daughters were threatened on the street. And then, on May 10—in a scene unimagined since the Middle Ages—throughout the country, including the old university towns, great pyres were made of books.
The largest book-burning crowds assembled in Berlin at the Opernplatz, just near the Opera House. Students had eagerly been collecting cartloads of volumes seized from libraries or private homes. Propaganda Minister Goebbels arrived at midnight to begin a nationally broadcast speech: “German men and women! . . . You do well in this midnight hour to commit to the flames the evil spirit of the past!” Goebbels’s photographers were standing by, ready to capture the images that would be shown across the country: the joy before flames, the exultation in the crowds. Student crowds in Göttingen had engaged in their own burnings the same night.
Einstein’s books had been hurled into the flames with especial glee, for he was the most famous of all Jewish intellectuals and represented a spirit of liberalism and rational inquiry that was the opposite of what the new state insisted was right. “The age of Jewish intellectualism has come to an end!” Goebbels announced to the nation from Berlin’s Opernplatz. It was easy to tell what was coming.
LATE IN 1932, the year before the Opernplatz rally in which his books would be burned, Einstein had gone to his country home outside Berlin with Elsa—that place of the affairs that had tormented her; of the friendly walks and mushroom hunting and family di
nners she had loved. Now they were there to collect his papers, as well as her most important belongings. Caltech, in Pasadena, California, had offered him a position, while Princeton’s new Institute for Advanced Study in New Jersey looked set to propose a better one.
Elsa was good at reading people, but her intuition failed her about what was happening to her country. She and Einstein had gone to America before, for visits or even longer stays when he was a months-long lecturer. Surely this would be just the same?
Einstein shook his head. She understood very little. “Look around you,” he reportedly said. “It’s the last time you’ll see this.”
After Einstein and Elsa had left their home, and after the book burnings the following year, mobs broke in, ransacking what possessions the hated Professor had left. Elsa only found out about that later. She was in Belgium at the time, having been under armed protection with her husband before they sailed to America.
NINETEEN
Isolation in Princeton
EINSTEIN SPENT THE rest of his life, from 1933 to 1955, in Princeton, a university town then far from the sophisticated, egalitarian haven it has become today. There were few Catholics, fewer Jews, and no blacks allowed to teach or attend when Einstein was first there. The faculty thought highly of themselves, even though for most of them the prestige that Princeton afforded was not close to that which they would have enjoyed at the genuinely important institutions of the day—such as those in Zurich, Berlin, or Oxford—which unlike Princeton were home to world-class scientists who produced essential work. Faculty parties were especially ridiculous, and certain professors put on airs that even Elsa’s socialite friends would have found excessive: making blue-collar New Jersey men dress up as liveried footmen and bow as they served champagne on fine trays. Writing to a friend in Belgium, Einstein described the whole setting as “a quaint and ceremonious village of puny demigods, strutting on stiff legs.”
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