Einstein's War

by Matthew Stanley

  Beyond the lack of explicit protest, other reasons emerged to prevent the Germans from being part of scientific organizations. Oxford’s H. H. Turner suggested that scientific communities rested on “the good faith of the contracting parties: can we accept in scientific matters assurances which are, by some of the parties, not considered binding in other connections?” If the Germans, as a people, did not respect the treaties protecting Belgium, how could one take their word on things such as experimental reports and mathematical analysis? Science relied on trust. And now, Turner argued, the Germans had revealed that their racial character made it impossible to trust them. “We have tried to think that the exaggerated and false claims made by Germans today were due to some purely temporary disease of quite recent growth . . . [but one wonders] whether the sad truth may not lie deeper.” Perhaps the apparent success of German science in the past was merely due to “plagiarism and piracy” of more civilized nations.

  Despite the hopefully imminent arrival of the Americans, late 1917 became a desolate time for the war in Britain. Apparently endless political unrest in Russia threatened to knock that ally out of the war just as the new one joined. Other allies were proving of dubious reliability. Some French units were refusing to go on the offensive—it was hard to keep morale up through endless suicidal attacks—though this was not widely known. Everyone heard about the Italian army routed at Caporetto by a combined Central Powers offensive intended to keep the wavering Austria-Hungary in the conflict. Rumors spread that many of the quarter-million Italian soldiers taken prisoner had surrendered eagerly.

  Resources were directed south to support the Italians, just as they were desperately needed in a long-planned attack toward the Belgian village of Passchendaele. Formally known as the Third Battle of Ypres, it was British general Douglas Haig’s plan to strike deep into occupied Belgium to seize German submarine bases. The U-boats were destroying shipping at an alarming rate. Eddington’s lack of tea was a warning that Britain couldn’t hold out much longer.

  The aloof, polo-playing Haig was famously unconcerned with the likely casualties from his offensives. His reputation for being “stubborn, self-righteous, inflexible, intolerant” had not improved since the slaughter of the Somme. Haig was both devoutly Christian and as much a spiritualist as Lodge; there is some sense that he saw himself as having a divine role to play in the world.

  Prime Minister David Lloyd George was deeply unimpressed with the plan Haig presented, but with no military experience of his own had no alternative to offer. Haig retained his confidence in massive barrages and huge attacks—more than 4 million shells were fired in preparation for the assault. Anticipating serious casualties, the Royal Army Medical Corps set up the first blood bank on the western front.

  Unfortunately the start date coincided with some of the worst weather Flanders had seen in decades. Massive rainfall turned the ground to mud, and the artillery barrage destroyed the local drainage systems. Tanks massed to penetrate German defenses quickly sank into the muck. Simply walking became nearly impossible. Boards had to be laid across the oozy ground so units could move forward—not a situation given to tactical flexibility. One Canadian soldier described his experience:

  Gas shells were bursting over me and I couldn’t see where I was going. All of a sudden, my foot slipped on the slippery plank and I went right into a muddy hole. I was up to the neck in mud and couldn’t get out and tore my nails trying . . .

  Bodies floated in the water. The mud not only dragged down the advance, it swallowed shells before they exploded, making the preparatory barrage even more useless.

  If there was one universal experience of the front, it was watching one’s friends die: “A big shell had just burst and blown a group of lads to bits; there were bits of men all over the place, a terrible sight, men just blown to nothing. I just stood there. It was still and misty, and I could taste their blood in the air.” The poets Francis Ledwidge and Hedd Wyn were killed the first day of the battle. Casualties mounted but the front barely shifted. Passchendaele Ridge was supposed to have been seized the first day, but the Germans still held it months in. Haig became obsessed with it and continued throwing more and more troops into the fighting. This battle was the distillation of the idea that the war was fought by lions, led by donkeys. The infantry nicknamed their commander “Butcher Haig.”

  Haig swapped subordinates to protect himself from responsibility. He was a master at political maneuvering, if not battlefield strategy. After three months, Allied forces finally captured Passchendaele and he declared the campaign over. The total gains were about five miles, but the submarine pens remained intact. The cost was about half a million dead and wounded on both sides, 4,000 per day or so.

  Passchendaele became symbolic of not knowing where the war was going or whether it would ever end. The grinding combat of the western front aggravated the manpower crisis and there was growing anxiety at home about how to solve it. Conscription was extended to married men, many exemptions were rescinded, and it was made possible for tribunals to impose “finality” (meaning no appeals were allowed). Many men had to present themselves once more at their local tribunal to defend their exemption. During Passchendaele, conscription was extended to British subjects abroad and Allied citizens living in the UK.

  Whatever the level, recruiting was never considered to be enough. The conscientious objectors who refused to fight made little difference in the recruiting numbers, though their resistance became increasingly frustrating for the government. They were made examples of to prevent any further disruption to the war effort. COs were subjected to military discipline, which had a variety of horrible means to crush someone’s spirit. At Lyndhurst military prison Quakers like Eddington were “punched and pelted, knocked down and kicked and sneered at.” Eddington’s friend Ernest Ludlam disappeared into one of the camps. Eddington himself remained free to do science as his conscience allowed.

  * * *

  ON NOVEMBER 10, Eddington attended the first meeting of the JPEC dedicated to discussing the 1919 eclipse. That was three days after the Bolsheviks seized the Winter Palace and two days after Lenin signed the Decree of Peace committing Russia to withdraw from the war. That JPEC meeting went smoothly; it was still high-level planning at this point. Nonetheless, Eddington had been sharpening up his debating skills. Fighting for Einstein was going to take a public presence. The shy boy from Weston-super-Mare would never be able to convert the British Isles. He was getting some good practice at the Royal Astronomical Society, where he had been battling over the nature of the stars.

  As much as we remember Eddington for his work on relativity, his lasting scientific reputation was built on being one of the first astrophysicists to understand why stars shine. He developed the equations that let us peer inside the sun. His great antagonist for this work was James Jeans, a doughy mathematical physicist who played the organ in his spare time. Eddington learned how to debate by clashing with Jeans, and their sparring became legendary (many scientists joined the RAS just to watch). Somehow this mild-mannered Quaker not only became an expert at scientific combat—he came to enjoy it. One of his students later recalled an opponent thinking they had dealt a fatal blow to one of Eddington’s theories, but then “fire suddenly springs into Eddington’s eyes and steel meets steel with sparks flying.” In older years he was known for getting an “impish satisfaction” from anticipating a rival’s entire presentation from their title, or performing their whole calculation before they had even taken the podium. Not everyone appreciated this side of him. The young Subrahmanyan Chandrasekhar, freshly arrived in Cambridge and eager to work with his astrophysical idol, was deeply upset by Eddington’s typically rough-and-tumble treatment.

  But at the end of 1917 he had to focus all his energy on Einstein. To convert the heathen Newtonians he needed to finish his scripture, what would eventually become his Report on Relativity. But he also knew that a scientific essay by itself wasn’t
going to have the impact he wanted. If the eclipse expedition was to restore international science, everyone needed to be watching. Everyone needed to be invested. He had to set the stage for a scientific event that could be seen even through the clouds and smoke of the war.

  Papers given at specialist conferences wouldn’t gather the attention he needed. Instead, he wrangled a spot onstage at the Royal Institution of Great Britain (usually known as the RI). The RI had been the public face of science in London for more than a century. Lecturers there spoke to packed audiences of people from all levels of education and all walks of life. It was where Michael Faraday gave his famous Christmas Lectures, including the classic “Chemical History of a Candle.” There was no better place for Eddington to start taking the case for Einstein directly to the people.

  On February 1, 1918, the RI became Eddington’s pulpit for relativity. His lecture fully embraced all the strangeness of Einstein’s universe (perhaps he was inspired by his recent reading of H. G. Wells’s The War of the Worlds). Listeners heard about wholly new views of space and time, mass, and energy. The speech ignited curiosity among both scientists and laypeople, priming the pump for the appearance of Eddington’s Report on the Relativity Theory of Gravitation in April.

  The Report was a remarkable document: less than a hundred pages to introduce an entirely new view of the cosmos (and to set up Eddington as an expert on it). It was the culmination of eighteen months of Eddington’s work to understand, digest, and translate relativity for an audience that was actively hostile to German science. He had little of Einstein’s actual work to model it on. Instead, the Report is distinctly Eddington’s take on relativity. He had the same equations as Einstein, de Sitter, and Hilbert. But a theory is more than just the equations. It needs a framework: to be interpreted, given meaning, and connected to everyday life. Most of the world’s first encounter with relativity would not be through Einstein’s framework; it would be through Eddington’s.

  He explicitly wrote the document to make it as accessible as possible. The powerful but opaque Hamiltonian and Lagrangian methods, along with the complicated tensor mathematics, were exiled to a special section. Everything was laid out to get to the experimental consequences as quickly as possible. As fascinating as the theoretical aspects were, he knew that his audience needed to be persuaded that relativity was not mere speculation. It could, and would, be checked with that most powerful tool of science: looking closely at nature. That would be what determined whether, as Eddington put it a couple years later, “Albert Einstein has provoked a revolution of thought in physical science.”

  The Report began with the Michelson–Morley experiment. Its strange null results gave Eddington a chance to question precisely what it meant to measure time or space. Once the question was open, he then presented Einstein’s positivist arguments for length contraction and time dilation. The Report was where Eddington first tried out the vivid illustrations that would push his later books to the top of the bestseller lists. In one of those, Space, Time, and Gravitation, he asked the reader to imagine someone moving near the speed of light. When she consulted a mirror on board her own ship, everything looked normal. But looking out on us on the street she saw “a strange race of men who have apparently gone through some flattening-out process; one man looks barely 10 inches across the shoulders.” Even harder than accepting this strangeness, though, was the realization that those of us on the street saw her flattened in precisely the same way.

  How to get his readers to understand this fundamental paradox? With Gulliver’s Travels, of course:

  Gulliver regarded the Lilliputians as a race of dwarfs; and the Lilliputians regarded Gulliver as a giant. That is natural. If the Lilliputians had appeared dwarfs to Gulliver, and Gulliver had appeared a dwarf to the Lilliputians—but no! that is too absurd for fiction, and is an idea only to be found in the sober pages of science.

  There was no confusion for Gulliver about who seemed big and who seemed small. In Einstein’s terms he might try to declare himself to be a privileged reference frame. But under relativity, no observer could be privileged over any others. So the Lilliputians could come to the same conclusion as Gulliver about the other’s strange size—each seemed absurdly small to the other. Length contraction was an inherently odd thing.

  Similarly, Eddington said, time dilation meant that two people could disagree about how long a cigar would burn for (perhaps there was some bitterness over blockade shortages hiding in that example). Clocks ran slower and slower the closer one moved to the speed of light, so “if man wishes to achieve immortality and eternal youth, all he has to do is to cruise about space with the velocity of light. He will return to the earth after what seems to him an instant to find many centuries passed away.”

  The temptation upon hearing such outrageous claims was to try to dismiss them as, perhaps, not real. But they were fundamental to understanding relativity. Eddington appreciated that the frequency with which Einstein presented such ideas meant that “the relativist is sometimes suspected of an inordinate fondness for paradox.” It was not mere fondness, though. Einstein’s universe was genuinely different from our traditional one, and we needed to get used to it: there was no person, no place, no orientation more fundamental than any other. There was no Newtonian “super-observer” who was always right. It was only the laws of nature themselves that were absolute.

  Once the reader had grasped (or at least accepted) this fundamental malleability of measurements, Eddington introduced them to the four dimensions of space-time. The basic unit of measurement in the universe was now the interval, that strange combination of space and time that all observers would agree on no matter what. The interval marked the 4-D distance between events (things interacting with each other in some way). These intervals could be warped and curved by the presence of large masses, and those curves were perceived by us as gravitational forces. He warned that while words like “curvature” were extremely helpful (they allowed us to avoid phrases like “differential invariant”), one needed to remember that they were only analogies to familiar three-dimensional space. When we say that gravity is like the puckering of a rubber sheet caused by a bowling ball, that’s a helpful image—but remember that there is no giant rubber sheet out in space. It is merely an image to aid us in visualizing an inherently unvisualizable four-dimensional surface.

  Eddington described how the surface of space-time stretched across the entire universe. He presented Einstein’s and de Sitter’s cosmological models, their attempts to describe mathematically the cosmos as a whole. He emphasized a particular detail about Einstein’s closed universe (the one with finite Starbucks). Just as you, exploring that universe, would eventually come back to your starting point, light from a star would eventually bend around and return to itself. This meant that most of the lights in the night sky would not be actual stars but only light trapped in the curvature of space-time. He called these “anti-stars”: “It suggests that only a certain proportion of the visible stars are material bodies; the remainder are ghosts of stars, haunting the places where stars used to be in a far-off past.” De Sitter’s model, on the other hand, had any and all objects flying apart. Eddington speculated that this might be related to then-recent observations that the spiral nebulae (what we now call galaxies) seemed to be hurtling away from one another. Indeed it was—he had spied the earliest evidence for what we now know as the Big Bang.

  Eddington empathized with the reader at this point. He suspected they had a voice in the back of their head whispering that the fourth dimension was “nonsense”—he certainly did. But he pointed out that much of modern science could be seen as similarly absurd. “I fancy that voice must often have had a busy time in the past history of physics.” Was it nonsense to say that this solid table is a collection of moving atoms, or that the air was trying to crush you, or that the Earth was moving even though you couldn’t feel it? “Let us not be beguiled by this voice. It is discredited.”<
br />
  The reality of the fourth dimension could not be directly seen, but that wasn’t a reason not to believe in it. Imagine that you are looking at a circular object with a flat portrait on it, and someone else on the other side sees a different flat image. A third observer sees only a thin rectangle. These disparate points of view can all be reconciled if the observers are all looking from different angles at the same three-dimensional object—a penny. No reasonable person could doubt that the penny is real, even if it looked different to different people. Doubting the fourth dimension was like doubting the penny.

  The four-dimensional world had further strangeness in store. According to general relativity, all the objects in the universe, from cookies to badgers to every atom in your body, have a path through space-time called a worldline. Your worldline bounces from event to event—intersecting with the worldline of the coffee shop before intersecting with the worldline of your boss before intersecting with the worldline of your ride home before intersecting with the worldline of your bed. You ride your worldline from event to event, encountering each like a train coming into a station. We humans, limited three-dimensional creatures as we are, only experience those events one by one. But the full four-dimensional fabric of space-time doesn’t—it “sees” all those events at once. A being who could perceive the true nature of space-time would see their future and past stretched out along their worldline. Past, present, and future would be only relative terms.

  Now imagine, Eddington said, the worldlines for every particle in existence. The lines would be tangled and twisted, but this enormous skein would give us “a complete history of the configurations of the Universe for all time.” General relativity presents us with a universe that is sometimes called deterministic. That is, the future is already set. We only see one little part of our worldline, so we think the future is not set. Our 4-D friend, though, can clearly see that the future already exists. A deterministic universe doesn’t seem right to many people—surely I can decide what I will have for breakfast in the morning, and therefore change the trajectory of my worldline from intersecting with a doughnut to intersecting with oatmeal? Relativity says no. There is no free will. This sense that you can alter your future is an illusion, one caused by our incorrect perceptions. Eddington was not very happy with this conclusion—he certainly felt able to affect his own destiny—and he spent many years later in life trying to analyze the nature of free will and human sensation of the passage of time in his books such as The Nature of the Physical World.