Einstein's War

by Matthew Stanley

  While the military did not think much of scientists, the reverse was not true. The Royal Society Council decreed that any scientist who was killed at the front would receive the singular honor of being made a Fellow. Elevation to Fellow of the Royal Society (or “made FRS”) was a mark of enormous distinction normally reserved for scientists making major contributions to their field. They had equated scientific excellence with military service. British scientists wanted them to be interchangeable.

  Those who wanted to use their technical expertise to support the war often had to find their own projects. The father-son Nobel Prize–winning physicist team Lawrence and William Henry Bragg shifted their work from interpreting X-ray waves passing through crystals (similar to Moseley’s research) to interpreting sound waves coming from German artillery. As far as the mathematics goes, waves are waves. They built and operated devices that would use the sounds of cannon fire to locate enemy positions well behind the lines, which could then be targeted by friendly guns. The Braggs were so effective at this that eventually German troops were forbidden from shooting during certain periods, lest they bring down counterartillery fire. Despite their success, the Braggs never stopped complaining about military resistance to scientific ideas. Because they needed to operate the equipment themselves, they actually lived near the front. In an effort to maintain a semblance of scholarly life, they held monthly scientific seminars. By the end of the war about half of British scientists were doing war-related work, even if it wasn’t coordinated with an official military program.

  The sudden appearance of chemical weapons on the battlefield refocused the British government on the importance of science (as did the “shell crisis” of the time, when an ammunition shortage led to political upheaval). Laboratories were set up at the front to take samples of German weapons and develop British equivalents. Their system for weapons development was badly organized and chaotic, which slowed progress. Much of the gas was produced in small academic labs. By July, Britain had her own gas units, though they weren’t used until the Battle of Loos in September. The cylinders were cracked and corroded and the attack wasn’t very effective.

  The biggest problem was simply producing new chemists. The British system of science education was not set up to produce large numbers quickly. Those who were trained often did not have the large-scale industrial expertise necessary. Australia sent about half of their total chemists (about a hundred) to London to help expand the lists. Margaret Turner, a scientist at the Chemical Laboratories at Aberystwyth, asked to help. She was denied; women could work in munitions factories but not as scientists.

  This attempt to make lists of scientists immediately clashed with an attempt to make lists of soldiers. At the same time that scientists were beginning to be recognized for their technical skills, the government created the National Register of all persons between age fifteen and sixty-five. This was an obvious step toward mass conscription. As men were asked to attest that they would be willing to serve, an unusual situation occurred: what if a man attested that he would serve, but his employer wanted to prevent him, say for a crucial munitions job? A series of tribunals were set up to screen these sorts of requests—someone removed from the conscription rolls was said to have received an “exemption.” The usual standard was whether this person’s civilian work was of “national importance.” Soon they found themselves handling a tricky question: was the work of a scientist, by itself, of national importance? There was no clear guidance given for this, and decisions were chaotic and arbitrary. One industrial chemist was not granted an exemption, but a pharmaceutical chemist was. After the system was well under way, of 330 chemists who had sought exemption, 94 were refused.

  Eddington was a good target for any conscription program, so Cambridge University preemptively applied for an exemption for him. They argued that if he were taken as a soldier, the observatory would have to be shut down, which would damage the scientific work of the country. Beyond the scientific value of Eddington’s work, the university was surely engaging in some advance public relations. Eddington’s pacifism was well known and they surely would not have wanted to deal with the embarrassment of having one of their professors publicly refuse to fight.

  The Royal Society received a steady stream of requests for help from scientists looking for exemptions based on their work. They decided not to take any action to support these. The Society was still trying to convince the government that scientists were properly patriotic, and they wanted no part of anything that suggested scientists were not eager to serve in the military. Britain remained deeply ambivalent about whether science was important in wartime.

  * * *

  LIFE FOR SCIENTISTS in Germany was perhaps not quite so rosy as H. G. Wells had imagined. There had been no deliberate effort to mobilize scientists for war work there either. They, too, had no clear guidelines exempting scientists from military service at the beginning of the conflict. As in Britain, many scientists from the Central Powers decided their best contribution would be holding a rifle. We have already heard about Nernst’s and Hahn’s adventures. The Austrian physicist Friedrich Hasenöhrl was killed in October 1915 at age forty. The not-yet-famous philosopher Ludwig Wittgenstein enlisted in the Austrian Army, hoping that “standing eye to eye with death” would bring him some enlightenment. Erwin Schrödinger, bereft of cat, enjoyed watching the electrical discharge of St. Elmo’s fire dance on the barbed wire.

  There was plenty of science-based work to be done near the front, too, like the Braggs’. Lise Meitner, the Austrian physicist who would later go on to introduce the world to nuclear fission, left her positions in Berlin to become a radiological technician at a military hospital. Using X-rays for medicine was still a cutting-edge technology and skilled operators were needed. A year into the war she had taken two hundred X-rays, assisted in the operating room, and fixed the hospital’s electrical system.

  Meitner returned to Berlin in the middle of the war. She had overcome tremendous obstacles as a woman in science (she was once denied entry into a chemistry lab on the grounds that her hair was too flammable). She complained that she had been in the field for so long that she “no longer knew what physics is.” Meitner felt strongly that it was the duty of German science to support the war, and was pleased to attend the patriotic evening gatherings of professors common at the time.

  One of these gatherings was at Planck’s house, where Einstein happened to be in attendance. He shared his views on the war and Meitner was not impressed: “Einstein played the violin and, in passing, offered such deliciously naïve and peculiar political and military opinions. The very fact that an educated human being exists who, during this time, does not consult a single newspaper, is surely a curiosity.” No one was impressed with his pacifism. It read not as idealistic but foolish.

  He was still active in the BNV. He and Elsa regularly attended meetings that spring. It is an interesting note of Einstein’s pre-fame life that no one recognized him. Walther Schücking, a prominent pacifist at one of the meetings, wrote himself a note to remember who the eccentric physicist was—apparently he had discovered some law regarding the unity of time.

  The group had smuggled a censored book, Richard Grelling’s J’accuse, into Germany. It explained Germany’s responsibility for the war in seditious terms. They ran a kind of lending library for it—a member could borrow it and then return it within forty-eight hours. Einstein took it out, read it, and returned it promptly. He might have hesitated had he known that he was being investigated by the police for his political loyalty after he sent a poorly phrased postcard through the mail. The police decided that he had been “until now not politically active” but was now “a supporter of the peace movement.” He was left alone—politically unreliable but not dangerous.

  Einstein had been growing closer to Elsa, though her bourgeois lifestyle still did not seem very inviting. After Mileva left, he moved to an apartment on the Wittelsbacherstrasse, near where his
cousin lived. He knew she wanted to marry—the role of the professor’s wife was appealing to her in a way it never was to Mileva—but he was wary of entering into a new marriage so soon after his last. She fulfilled wifely duties nonetheless, trying to get him healthy food despite the privations of the blockade. When she was out shopping for him she would have been one of many women on the streets. As men were drawn away to the battlefields women increasingly took on the everyday tasks of running the city. Many saw this sudden visibility as a kind of empowerment—Marlene Dietrich called wartime Berlin “a woman’s world.”

  Liberated women were not the only unusual sights on the capital’s streets. Some 70,000 Eastern European Jews had fled the fighting and taken shelter in Berlin. These orthodox Jews were very different from the largely assimilated communities already there, who rarely ate kosher food or visited the mikvah. Many of these secular Jews, including Einstein, were somewhat taken aback by these kinsmen who seemed so unfamiliar and alien. They were also shocked by the rising anti-Semitism that greeted the refugees (anti-Semitism increased in every country involved in the war). Right-wing groups accused the refugees of bringing crime and shirking their duty to fight; in fact, Jews were overrepresented in the German military, using the war as an opportunity to demonstrate their wholehearted citizenship. Even within a country’s borders, citizenship could be complicated.

  Planck, Einstein’s mentor, had begun having more complicated thoughts about the war as well. We can see the hand of Lorentz, Einstein’s other father figure, in his evolution. Everyone trusted Lorentz, so when he contacted Planck about conditions inside German-occupied Belgium, notice was taken. They met in person in 1915 and he persuaded Planck to repudiate the Manifesto of 93. Planck wrote an open letter doing so, which Lorentz had printed. In the letter Planck demurred that signing the manifesto had been only a defense of Germany and not any specific actions taken by any individual German. He pleaded that international values were compatible with love for one’s own country, and that perhaps the scientific community could come together once again. This should not be mistaken for a turn to pacifism, though—he wrote that scientists should withdraw from the field and let cannons speak instead of manifestoes.

  Lorentz tried to similarly soothe the fiery Wilhelm Wien, to less success. Trying to build on his moderate victory with Planck, Lorentz sent copies of the repudiation to physicists in enemy countries—the elder Bragg, Joseph Larmor, Oliver Lodge—to help calm their anger. It was not well received. With the bodies of prodigies like Moseley constantly coming home, it was not a time for healing.

  CHAPTER 6

  A Vital Victory

  “An unscrupulous opportunist.”

  EDDINGTON LOVED A good puzzle. Not just crossword puzzles, though his obsession with them was legendary. He felt puzzles—mysteries—were the real heart of science. Science wasn’t about celebrating what we knew, it was about exploring what we didn’t know. It wasn’t about being sure you were right; it was about finding a new puzzle to solve.

  So when he became co-editor of the Royal Astronomical Society’s journal The Observatory in 1913, he instituted a new feature titled “Some Problems in Astronomy.” Each issue had an astronomer present some “perplexing” part of the field—something that was not well understood, or for which there were no satisfactory explanations. Eddington wanted everyone talking about the exciting puzzles, not the stuff we already understood well. These included the nature of the spiral nebulae, why some moons orbit counterclockwise, whether the dark spots in the Milky Way are actually gaps, and the precise shape of the Earth.

  Eddington wrote several of these columns himself (more than any other contributor). He speculated about cometary orbits, why stars were certain colors, and, in February 1915, the nature of gravity. He remarked that gravity remained as much of a mystery as it had been in the days of Newton. They had the formula, but still no one had any idea what gravity really was. Many possible explanations had come and gone—electrical inequalities, particle bombardments, ether squirts. Eddington was disappointed that none had led anywhere. Gravity still seemed to have no connection to any other force of nature. Most frustratingly, none of the theories had a way to test them and decide whether they were worthy of further investigation.

  Except, he noted near the end of his essay, that there was a prediction that light would change its speed in a gravitation field. This suggestion had been offered by a German professor named Einstein. Eddington knew about it from the 1912 eclipse expedition, where C. D. Perrine had failed to test it. Eddington’s brief discussion here referred only to Einstein’s 1911 paper, suggesting that he was completely unaware of any of the work done since then. He had learned almost nothing about Einstein since he first heard the name in 1912.

  Eddington’s ignorance of what had been happening in Berlin was not at all unusual. It is hard today for anyone to remember a time when Einstein’s name would not have been immediately recognized. Einstein’s name appeared only once more in the whole “Problems in Astronomy” series, when he was mentioned in the same breath as Lorentz with the comment that neither of their theories were well supported by observational evidence. One of the “Problems” columns even focused on whether there was a redshift in the solar spectrum—one of the primary tests of general relativity—without a single mention of Einstein or his theory.

  The handful of British scientists who knew about Einstein before the war generally thought of his ideas as contributions to well-established electromagnetic theory, not a revolutionary reworking of the fundamentals of knowledge. One of these was Ebenezer Cunningham, a physicist at St. John’s College in Cambridge. Cunningham was for the most part trying to elaborate on Einstein’s 1905 theory, and was actually working on a textbook on relativity when the war broke out. We don’t know whether Cunningham and Eddington discussed relativity in this early period—they were interested in it for very different reasons, in different contexts, and wouldn’t have had much to say to each other. Interestingly, Cunningham was also a pacifist (though not a Quaker). As with Eddington, the arrival of the war changed his work completely.

  So, by mid-1915, a handful of people in Great Britain were vaguely aware of Einstein. They didn’t really know what his ideas were about. What they did know was between four and ten years out of date. Einstein was a footnote in other people’s projects. Eddington’s attention had been caught by how empirical evidence for relativity “would mean that gravitation has been pulled down from its pedestal, and ceases to stand aloof from the other interrelated forces of nature.” But as far as he knew, nothing interesting had been happening with the theory. In any case, there was a war on.

  * * *

  BY THAT SUMMER Einstein’s personal war was not unlike the western front. It had been in a stalemate for some time. His early advances, like the Germans’ into France, had stalled. While he held ground, there were no signs of a breakthrough. He wasn’t sure whether total victory was possible—was there a brilliant maneuver that would lead to triumph? Was there more beyond the Entwurf?

  It is not always obvious when a piece of science is finished. The crisp form of a theory you see in a textbook usually only appears decades after its discovery. The classic laboratory experiment you do in school, with its clear right and wrong results, was profoundly confusing to the first person who performed it. Everything makes sense when you look back—but if you’re not sure if your theory is complete right now, how would you know?

  One of the things you do with a possibly complete theory is try to use it to solve problems. Does it give a better explanation for old problems than the theories we already have? Does it help solve a problem that we haven’t made any headway on? Does it tell us about a problem that we didn’t even know was a problem? Einstein was trying all of these. It’s much like when you have a new wrench in the workshop—you try it on all the stuck bolts that you have sitting around. Hopefully it works better on them than the old wrenches and still works just as well as
them on the old projects. Most of all, it should let you build something new that you couldn’t before. Did the Entwurf do all these?

  The stuck bolt of physics was the orbit of Mercury—a known problem that couldn’t be solved by the old tools. The Entwurf didn’t do much better. The old projects were showing that relativity was similar enough to the Newtonian theory and the laws of conservation of energy and momentum. The new projects were covariance and the equivalence principle (which could hopefully be demonstrated through Einstein’s equations), and the deflection of light and the gravitational redshift (which had to be tested empirically, impossible from wartime Germany). So one of the things he spent the summer of 1915 doing was revisiting the old and new projects. Did the Entwurf in fact do everything he wanted it to?

  He was expecting reassurance that the work he had already done was sound. A great breakthrough wasn’t really on his mind. But that summer he made a new friend, a moment that would set in motion a chain of events that would completely reframe all the work he had been struggling with for a decade. That friend was David Hilbert, a distinguished professor at the University of Göttingen and one of the most influential mathematicians of the twentieth century. His close-set eyes gazed out from behind a pince-nez and above a neatly trimmed beard. His somewhat informal dress (by the standards of German professors) meant that in his early years of teaching, students often did not realize he was the instructor.

  Hilbert came to general relativity through a roundabout route. His early career focused on geometry, which he originally thought of as being just an elaboration of sensory experience—Pythagoras’s theorem should come from actually inspecting triangles, for instance. He gradually became interested in an “axiomatic” approach, in which the actual physical referents of geometric statements were irrelevant, and only their logical relationship mattered. So when Euclid said “two points define a line,” points and lines didn’t actually matter—you could replace them to get “two jabberwocks define a cromulence,” and the logical structure of the laws of geometry would still be true.