Einstein's War

by Matthew Stanley

  Readers of the Report at this point would have been struggling with abstractions such as space-time and worldlines, so Eddington brought them back to more normal experience with Einstein’s elevator thought experiment. Like Einstein, he used that mental image to show how gravity and acceleration were the same (or more properly, indistinguishable). Unlike Einstein, he used some classic science fiction to make sure his readers understood it. Eddington reminded them of Jules Verne’s Around the Moon, in which some intrepid explorers build a gigantic gun with which to shoot themselves to the moon. In the book the proto-astronauts experience a moment with no gravity when the pull of the moon equaled that of the Earth (what Verne called the “dead point” and what astronomers call the Lagrange point). Eddington pointed out that Einstein had shown this to be wrong: the bullet riders would have felt intense acceleration/gravity while in the gun’s barrel, but the equivalence principle says that once they were no longer being pushed they would have felt no gravity at all. They would have been floating inside their craft as it moved from the end of the gun barrel all the way to the moon. Once he finished the correction, Eddington immediately apologized. “Pedantic criticism of so delightful a book is detestable.”

  From the equivalence principle it was a short jump to the three classic tests of general relativity. Einstein’s precise explanation of Mercury was presented as a powerful reason to take the theory seriously. The gravitational redshift was more complicated. Eddington noted that the best attempts to find the shift had returned nothing. He was willing to concede that it might be actually disproved. But the difficulty of the test was so great that “we may perhaps suspend judgment; but it would be idle to deny the seriousness of this apparent break-down of Einstein’s theory.” As Eddington saw it, the redshift was a necessary consequence of the equivalence principle. If it were never found, every part of relativity that depended on that principle would have to be discarded.

  That left the gravitational deflection of light. This was the climax of the Report—the empirical test to which everything had been building. He told his readers that he hoped to look for this phenomenon at the solar eclipse in 1919. He claimed that what was really being asked was not an obscure question of theory—it was simply asking whether light had weight. Einstein said it did—specifically that energy had a mass equivalence. Eddington later joked that this meant the electric company could charge for power by the pound. He estimated that the rate would be something like £140,000,000 per pound of light (1918 currency values, of course). If you could catch all the light falling on the Earth each day, it would come to about 160 tons.

  The nature of the deflection test was not quite that simple, though. Without mentioning Lodge by name, Eddington commented that there were nonrelativistic theories that also predicted a deflection of a different value. The test would need to be precise enough to decide between the two theories, two versions of reality—Einstein’s or Newton’s. To find the truth about the universe would require the highest level of skill, dedication, and international cooperation. Could it be done? Could it even be considered, in these darkest days of the war?

  The Report was carefully written to achieve exactly this goal—to capture the imagination of the English-speaking world, to evoke passion for a great clash of scientific ideas. He demurred that it did not even really matter which one triumphed. It was about investigating a new kind of science: “Whether the theory ultimately proves to be correct or not, it claims attention as one of the most beautiful examples of the power of general mathematical reasoning.”

  He closed the document with a brief suggestion of the philosophical implications of relativity. Relativity, he offered, had taught us a great deal but had given no “ultimate explanation” of forces like gravity. The theory’s positivist emphasis on measurement and events suggested that a full picture of reality could not be achieved by science. Things beyond “the purview of physics” were needed for that. The human mind and spirit still had a role, Eddington hinted, in a world of non-Euclidean geometry and mass-energy equivalence.

  Eddington’s first epistle to the Newtonians was certainly a success. There were not many immediate converts, but that wasn’t really what he needed. He needed people to pay attention; to wonder about the theory; to want to know the answers to the questions Einstein had raised. And by that standard it worked. The Report flew off the shelves (by the standards of a science paper anyway) and one reviewer called it “the most remarkable publication during the war.” Most people were still cautious, though, and worried about relativity’s complexity and seeming split from common sense. Regardless of skepticism, the Report allowed conversations about relativity in a way that had been impossible before.

  We shouldn’t overemphasize the public interest, though. Einstein was still obscure and German. The war commanded all the attention of the newspapers; the food shortages commanded the attention of every family. By the time the Report was published, food controls in Britain had become strict. Milk was the first item controlled. Sugar was the first to require ration cards. Children at boarding schools had to bring their ration cards with them. It was forbidden to throw rice at weddings or use starch in the laundry. It was an offense to feed stray dogs. Wheat flour became rare. “Flour” purchased at the store was adulterated with oatmeal, barley, and potato to stretch scarce reserves. Bread became mealy. The greatest offense, though, was the disappearance of the muffin and its teatime cousins. Virtually impossible to make with the ingredients available, the normally ubiquitous muffin’s absence felt like a blow to national identity. On the other hand, one housewife reported, “We consoled ourselves for our muffinless, crumpetless state by owning gloomily that when we had neither butter nor ‘marge’ . . . of what use to us was the muffin?”

  * * *

  BY THAT POINT, Einstein had been without proper baked goods, much less anything to smear on top of them, for three years. With or without jam, though, the German academic bureaucracy marched onward. In October, Einstein was informed that it was time for him to receive a reward that he would have just as soon forgotten about. When he was first lured to Berlin, one of the promises Planck made was that Einstein would be made director of his own Kaiser Wilhelm Institute. It took four years for the Institute to actually be created, which was fine by Einstein. He was in no hurry to have administrative duties, though the extra money would be nice.

  Initially his institute consisted of a board of trustees composed of Einstein and four of his friends . . . and that was it. It was run out of his apartment, and he was able to hire a secretary to handle his official correspondence (letters to him were addressed “Your Honor”). He hired Elsa’s twenty-year-old daughter, Ilse, for the job. He was essentially clueless about how to handle even minor administrative tasks. Planck hovered constantly, helping him through. Control of the institute’s meager funds, though, allowed him to—finally!—hire Freundlich to work full-time on relativity.

  It is perhaps not a coincidence that shortly after he took on these new duties, Einstein suffered a slew of new stomach attacks. He was increasingly skeptical of his doctor’s diagnoses. With typical cheek he complained, “I do not believe in the new medical magic with X-rays. I am at the point where I only trust post mortem diagnoses, nothing else.” His friends wondered if there were better places than Berlin for finding treatment. By the end of 1917 he was bedridden again.

  It was hard for him to do much science, though it gave him some time to think about what the postwar world might look like. He imagined a “pacifist union” with an international court and favored trade networks, restrictions on conscription, enforced democratic principles, and guarantees of territorial integrity for all members. He speculated that the economic benefits of such an arrangement might help bring in otherwise wavering nations. He tried to convince Romain Rolland, still sheltered in Switzerland, that this was worth striving for. Intellectuals in Germany, he wrote, have become subservient to “a kind of religion of might” and could only be �
��steered by hard facts.”

  Rolland thought Einstein was being rather politically naïve (he was not the first to make that accusation, nor would he be the last). Einstein seemed to think that only German intellectuals had been corrupted by the war, and that other countries would surely be more receptive to internationalism. Rolland, much more in tune with the wider European situation, warned that scholars in other lands were just as bad: “Evil spreads like a splotch of oil.” Perhaps suggesting one opening, though, he asked if Einstein had seen any of Bertrand Russell’s pacifist writings? Einstein had not.

  Einstein was still confined to bed as 1918 started. He had been trying, unsuccessfully, to invite Gunnar Nordström (his earlier rival in gravitation theory) to visit. When Haber heard that the military authorities were making that difficult, he saw a perfect opportunity to help out his friend. Using his many contacts in the military, he tried to smooth out some of the bureaucratic difficulties. When Einstein heard about this, he exploded. He wanted nothing to do with the military, and he certainly did not want to benefit from Haber’s morally compromised position! Haber apologized meekly after his friend’s outburst. Einstein, as always valuing his close colleagues over almost everything else, apologized too.

  Perhaps his stomach ailments were affecting all his personal relationships, because around the same time he also managed to make his home life even more complicated. He had been living with Elsa and her two adult daughters for several months (he liked to call them his “small harem”) when he had some kind of romantic or sexual encounter with the twenty-year-old Ilse. We don’t know the details of what happened, only that Ilse was suddenly unsure whether Einstein wanted to marry her or her mother. Einstein, astoundingly, told them that he was indifferent—the two women should sort it out among themselves and he would marry whomever. As one of Einstein’s biographers has pointed out, he did not really connect sex and marriage (a lifetime of his mistresses could confirm). He did not consider the whole episode particularly important. Ilse quickly decided to step aside. We can only imagine how painful this incident must have been to Elsa. Very soon after, though, Einstein finally agreed to marry her. Perhaps this was his attempt to make up for that enormous embarrassment. The problem was that Einstein was still technically married to Mileva. For an official divorce, Einstein had to ask her for an exquisitely painful favor. He needed her to make a formal accusation of adultery against him. Then a divorce could proceed on those grounds. Mileva, finally having some leverage, was in no rush to make the process easy for him. Negotiations went back and forth—her asking for more money, him threatening not to send any more. Finally she decided she was willing to accept a kind of gamble on Einstein’s success in science. If Einstein were to be awarded the Nobel Prize, she would receive the prize money. On that condition, the deal was made.

  * * *

  AS WINTER RECEDED Einstein was feeling a little better and was allowed by his doctor to venture out for a half hour at a time. He immediately went to visit Planck for much longer than that. Elsa scolded Planck (who, of course, was blameless) for disrupting Albert’s rest. Planck then chided Einstein for not telling him about the doctor’s guidance. It seems the patient was beginning to chafe against his restrictions. He also tried to play the violin for an hour (he wasn’t going out, so the doctor couldn’t complain, right?). This immediately resulted in another painful stomach attack.

  His condition was bad enough that he worried he might miss the scientific event of the season: Planck’s sixtieth birthday. Despite the tumultuousness of the war years, Planck remained universally beloved in Germany, and a huge party was planned for April 26, 1918. Einstein rallied and he gave one of his finest speeches. It was a love letter not just to his mentor and friend, but also to their shared passion of theoretical physics.

  Einstein presented his audience with a bold metaphor. Imagine, he said, the “temple of science.” If we cast out those who pursued science just for personal ambition or for utilitarian application, so few would be left—and Planck would be foremost among them. He offered a meditation on what might motivate Planck and his ilk, if not some form of personal gain: “The state of mind which enables a man to do work of this kind is akin to that of a religious worshipper or the lover; the daily effort comes from no deliberate intention or program, but straight from the heart.”

  It is not hard to see Einstein describing himself here, evoking what he would later call the “cosmic religious feeling” that he saw as the core of both true science and true religion. This was not religion in the conventional sense—Einstein had no interest in organized faith or belief in a personal God—rather a kind of awe and reverence toward the laws of nature themselves. We can see more of this reverence as he explained what Planck’s great contribution to science was:

  The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them.

  Planck’s gift, and clearly what Einstein was trying to achieve himself, was to find the “pre-established harmony” of the world. It was to find the fundamental principles on which the universe was organized. He wanted universal laws—like relativity. Theories were supposed to reach across the chaos of ordinary life and show the hidden rules that governed everything. They organized reality for us with invisible laws and abstract concepts, revealed only by patient thought and laborious investigations.

  Einstein saw relativity as being precisely in this tradition, and as being one more contribution to the theoretical physics created by Newton, Maxwell, Lorentz, and Planck. He saw it as a natural extension of the work that had come before him, not a radical break with those traditions. As one of Einstein’s biographers, Albrecht Fölsing, phrased it, he saw himself as perfecting classical physics, not overthrowing it. Ironically, it was Planck who was the first to talk about relativity as revolutionary. He emphasized its boldness and willingness to discard accepted notions.

  Like Planck, Eddington wanted relativity to mark a new era, a new kind of science. He wanted a scientific revolution, a great moment that would draw the world’s attention. He needed to present the theory as thrilling and exciting enough to capture attention even across the trenches. So the theory was both revolutionary and conservative, depending on whom you asked. It would remain to be seen which way relativity would be remembered.

  CHAPTER 10

  Angels of the Revolution

  “The Director is the sole remaining member of the staff.”

  AT PLANCK’S BIRTHDAY party in April 1918, everyone was happy. Einstein was happy to celebrate his mentor and friend. Those who opposed Einstein’s politics were happy too. The party came just a few weeks after the beginning of the Kaiserschlacht—the Emperor’s Battle. This massive offensive was war-weary Germany’s last chance for victory before the Americans began flooding in. Nearly a million of the kaiser’s troops had been freed up by Russia’s collapse. Those fifty divisions were moved to the west for a decisive attack. By moving at night and staying far behind the trenches until the last moment, they achieved complete surprise. A brief (by Great War standards) barrage of a few hours was followed by infantry using the new “storm trooper” tactics. The attack fell on a section of the trenches only recently taken over by British troops, who had not yet had time to fortify properly. The defense collapsed. The long-awaited breakthrough had finally begun. Patriotic fervor was reignited across Germany in a way not seen since the early days of the war.

  R. C. Sherriff’s famous play Journey’s End takes place in a bunker in the days leading up to the Kaiserschlacht. It captured the daily banality of poor food and pointless conversations about prewar rugby juxtaposed with the constant threat of overwhelming violence. George Bernard Shaw called it “a ‘slice of life’—horribly abnormal life.” One of the protagonists, Lieutenant Osborne, passed the time with Alice’s Adventures in
Wonderland, which was also one of Eddington’s favorite books. Eddington used Wonderland to illustrate the strangeness of Einstein’s space-time; Sherriff used it to show the otherworldliness of no-man’s-land. Both were completely alien to ordinary life; both would lead to revolutions that would shake the world.

  The shattering conclusion to Journey’s End captured well the experience of the British troops on the receiving end of the onslaught. The breach of their lines completely changed the character of the war—from long periods of not even seeing the enemy to a terrifying war of movement. The Germans advanced twelve miles in two days (farther than four months of fighting had gained the British at the Somme). The British fell back to protect their supply lines connecting them to the coast. If the Germans managed to capture the strategic railways there, the British could be knocked completely out of the war. One soldier recalled the frantic retreat: