Einstein's Greatest Mistake

by David Bodanis

  Even with Einstein’s help, there was a shortfall, but Freundlich managed to secure extra funds from the immensely wealthy Krupp family: the world-terrifying arms merchants. The Krupps’ cannons and other military equipment were sold around the world, and they were the backbone of the German army.

  Toward the end of July 1914, Erwin Freundlich arrived in the Russian peninsula of the Crimea. A few days later, World War I began. Germany and Russia were on opposite sides. Freundlich was by then camping in the wilderness, outfitted with exceptionally powerful telescopes, not far from the headquarters of Russia’s Imperial Battle Fleet. It’s hard to imagine how one could make a German national seem more suspicious, especially as all his documentation showed that the Krupp Foundation was behind his mission. Freundlich’s party was quickly surrounded by armed Russians, and his beautiful, lovingly prepared equipment was confiscated. When the eclipse took place as predicted, on August 21—the surrounding stars serenely distanced from the furious cannon flashes all over Europe—Freundlich was in a Russian prison camp.

  Einstein and others managed to get Freundlich out of lockup, as part of a prisoner exchange not too much later. Characteristically, Freundlich wasn’t downhearted. He simply had to engineer more opportunities to find fresh proof! The next really good solar eclipse wouldn’t be for several years, which was too long to wait. But what if, instead of being so fixated on the sun, they thought of measuring starlight falling into one of the invisible gravity valleys that had to exist near the planet Jupiter? The deflection would be smaller than from starlight falling into the big curves in space near our sun (just as small pebbles on a trampoline surface make it sag less than heavier stones do). But Jupiter was certainly easier to photograph than the sun.

  It wasn’t a terrible idea, but by the time Freundlich began racing to get the right equipment together, his Hamburg Observatory director had had enough of this underling’s exuberance. Einstein wrote to the Ministry of Education, encouraging administrators to bypass any bureaucrats who got in the way and give support to Freundlich. The minister passed the request on to the observatory director, who was not just a professor but a privy councilor who prided himself on being addressed by the title Geheimrat, or in a pinch “Your Excellency.” He certainly didn’t think of himself as a bureaucrat to be bypassed, and in his estimation Freundlich was a mere junior, of questionable competence and unacceptable insubordination. The director wrote a firm, and barbed, response to Einstein: “Even a ‘multitude of the most sophisticated measurements’ by expert observers, let alone by those who do not come under this heading, will not yield any useful results and merely cause a needless expenditure of time and effort.”

  The obstruction from Freundlich’s boss was only one of the problems. As the war dragged on and Britain’s naval blockade of Germany hardened, it proved impossible for Einstein and the loyal Freundlich to carry out their astronomical test. Einstein’s bold new theory, it seemed, was dead in the water—that is, unless there was someone else to whom he could turn for help.

  TEN

  Totality

  IN MAY 1919, a lean, sweaty Englishman stepped out of a hut on a small island off West Africa and looked up anxiously at the sun. A solar eclipse was coming, and he had spent two years readying for it. But if the threatening storm from the Congo coast didn’t blow away, the expensive telescope he’d shipped down from England and lugged overland would be useless.

  He had his team set them up anyway, despite the misty rain, and covered the lenses with his own jacket. It was a good thing, too, because suddenly, just a few minutes before totality, the clouds blew clear.

  The sun’s edge was shockingly bright. A previous generation of astronomers had imagined that somewhere within that glare, a fast-circling planet they’d named Vulcan existed. They had proposed that because something had seemed wrong with the orbit of Mercury. Newton’s theory of gravitation predicted a very precise orbit for Mercury, but that didn’t match what had been observed, even after correcting for the slight tugs the other planets in the solar system would exert on Mercury. An additional planet, orbiting closer to the sun, might be pulling Mercury into that uneven path.

  Other telescopic surveys had failed to find this imagined new planet. If the large photographic plates ready to be installed in the Englishman’s telescope showed what he expected, he would be able to disprove its existence beyond a doubt. He would do so not by documenting its absence on film, but by capturing evidence that would verify the theories of this still scarcely known German theorist, the gentle Berliner he’d never met, whose work had led to his presence on this distant island.

  From his later records, we know what happened next. He gave a quick glance up. The clouds were coming back. There were going to be a lot of plates to change, and quickly. The Englishman bent back down, undeterred by the swarms of mosquitoes. He’d have time to speculate on the theory later, once he’d taken the pictures.

  If, that is, the plates’ emulsions could survive the tropical heat.

  IN 1917 THE colleagues of the Cambridge astronomer Arthur Stanley Eddington were at an impasse. They knew that Eddington was a determined man, as those who tried to keep up with him on bicycle rides soon discovered. He always dressed properly, with neat suit trousers tucked in his equally neat socks, but with a nearly wild look on his face, he would speed through the countryside, ever faster, for hours on end, leaving his colleagues behind.

  They knew that Eddington’s determination came out in his religious views as well. Eddington was a devout Quaker, with principles that made him unwilling to defend the British Empire in the Great War that was still dragging on, so many years after it had begun. Many Cambridge men had died in the struggles on the Continent, including one of the university’s greatest young physicists, Henry Moseley, meaninglessly facing Turkish machine gunners in the Gallipoli campaign. Eddington was showing signs of being one of his generation’s leading astronomers. His colleagues at Cambridge were not going to have another of their own end up the same way.

  When the Cambridge administrators tried to obtain an exemption from service for Eddington, however, by writing to the Home Office, stating that the contribution he could make while remaining at the university was necessary for the war effort, everything had unraveled. The Home Office had written to Eddington with the appropriate exemption form. All he had to do was sign his name. Eddington conscientiously did that, but then even more conscientiously he added a postscript explaining that as a good Quaker, even if he wasn’t deferred on the stated ground, he would claim it on the ground of conscientious objection anyway. As one friend of Eddington later put it, “This postscript naturally placed the Home Office in a logical quandary, since a confessed conscientious objector must be sent to a [prison] camp.” Eddington’s colleagues were “very much piqued.”

  Luckily for him, and for Einstein, Eddington’s friends landed on a solution that didn’t involve war or a prison camp. Rather, it involved Britain’s enemy Germany and the strange scientific theories that had been leaking out of that country even at the peak of the war.

  Direct contact with German scientists had closed down since the war began. Censors didn’t like telegrams with obscure formulas and lists of numbers traveling between the two countries. There was also a general distaste in England for all things German, leading at times to riots and even to some anxious immigrant families changing their last names. But hints of Einstein’s new ideas had made their way to England through trusted intermediaries in the Netherlands.

  Eddington’s main protector, Astronomer Royal Sir Frank Dyson, couldn’t understand all the details of Einstein’s theories—and wasn’t even convinced they were necessarily valid—but he did recognize what a coup it would be if a Cambridge man could find out for sure whether this strange German scientist was right. Not only would Eddington be able to demonstrate that science could transcend the barbarity of warfare; he’d also be able to preserve a few precious links between his nation and Einstein’s.

  Dyson spoke
with his contacts at the Admiralty and came away with an arrangement so securely signed and sealed that even an earnest Quaker couldn’t get around it. Eddington would be engaged in important government business and under no circumstances could be sent to the deadly front, or even relegated to a prison camp. Instead, Eddington would be involuntarily volunteered to run an astronomical expedition to test Einstein’s theories, once and for all.

  The idea of a scientific, rather than a military, mission was fine with Eddington. Perhaps even more than Dyson, he appreciated the salutary effect science could have during wartime. One of Eddington’s noted contemporaries in England’s Quaker community, Ruth Fry, wrote that “one person who heads an expedition to heal the wounds and desolation of war is stronger than a battalion of men under arms.” For Eddington, a voyage to promote the views of a thinker working in the capital of Britain’s gravest enemy would be perfect. “The lines of latitude and longitude pay no regard to national boundaries,” Eddington wrote. The hunt for truth would bring mankind together.

  Eddington as a young man, c. 1914

  And so, in the midst of wartime Britain—with shortages of almost all materials and the seas around the island nation stalked by deadly German U-boats—Eddington began to plan how to succeed where Einstein’s helper, the unfortunate German astronomer Freundlich, had failed.

  Eddington knew that an eclipse was expected on May 29, 1919, so he determined to use it to test Einstein’s theory. Eclipses are only visible from specific regions, and this one was expected to follow a trajectory across the Atlantic from northern Brazil to Africa. Eddington and Dyson arranged for two teams, one to view the eclipse from the town of Sobral, in the Brazilian jungle, and the other to try to reach the island of Principe, a Portuguese colony just off the coast of West Africa, right near the equator and along the course of the eclipse.

  No one—not even the shipping insurers at Lloyd’s of London—had any account of steamers that went to Principe, so the second team would have to get as close as they could and then hope they could work out the details from there. Complicating things further, Eddington’s limited funds would only allow four Englishmen to go on the expeditions that he had planned: two of Eddington’s colleagues would observe the eclipse from Brazil, and Eddington himself plus a mechanically gifted technician from the Greenwich Observatory he’d chosen, Mr. E. T. Cottingham, would watch it from Principe.

  Experimentalists from another country were sometimes brought along on such expeditions to help researchers from the sponsoring country, but in this instance one obvious foreign candidate was left out. While the war was still on, it would have been impossible for Freundlich to accompany either team, and even after the Armistice was signed in November 1918, such transnational collaboration proved to be a bridge too far for the poor man. Freundlich no doubt knew that May 1919 was his one big chance, for no other eclipse where the sun passed through such a dense star field would occur for many years. Because most communications between the two sides were still blocked, he might have continued to hope that an invitation would arrive. He spoke English well enough and could get Einstein’s own recommendation. But by February 1919, the month the expeditions were scheduled to depart, he’d have known that wasn’t going to happen and he would be left behind.

  IN ENGLAND, PREPARATIONS for the two expeditions went distressingly slowly at first but picked up pace once the war wound down. “It was impossible to get any work done by instrument-makers until after the armistice,” Eddington wrote. Once fighting did end, in November, they only had three months to get ready. Just before the British team left England, an astronomer who’d originally been written in for the Brazil leg but couldn’t make it—one Father A. L. Cortie—suggested that along with their main equipment, the men also take a relatively small four-inch telescope as a backup in case something went wrong. Eddington already had a lot to pack, but Cortie was insistent, and so the telescope ended up with the luggage of the team going to Brazil.

  In February 1919, with telescopes, crates, canvas, mirrors, cigarettes, two metronomes, no doubt plenty of tea, and other essential items securely packed, the four men gathered in the port of Liverpool. They found there the Anselm, a ship at their beck and call, which would prove particularly well suited for crossing a dangerous sea only recently cleared of German U-boats. They departed England on March 8, 1919.

  At Madeira, the Portuguese island off the coast of Morocco, they split up, with the Brazil team continuing on, while the pair bound for Principe stayed ashore, as Eddington hunted for a ship they could get space on the rest of the way. That took nearly a month. Cottingham was bored, but Eddington, though sadly without his bicycle, used his time to scale the local mountains, and also to visit Madeira’s casino—writing to his mother that this was not for any gambling, but simply because word was out that they served quite good tea there. If Eddington had chosen to gamble, his mathematical quickness would likely have added considerably to the expedition’s coffers.

  Eventually, in early April, he found a transport that would take them down to the tropics. The world was only slowly recovering from the war, and as they left the harbor, they passed sunken ships with twisted metal masts leaning out of the water. On the open sea, passengers weren’t informed of their daily location, for despite the Armistice, no peace treaty with Germany had yet been signed, and officially a state of war still existed.

  Dyson hadn’t entirely understood Einstein’s new idea, but he knew enough spherical geometry to be able to chart, back in his rooms at Greenwich, the approximate route that Eddington and Cottingham would have to follow. This, too, demonstrated what geometers had learned. If the earth could be opened up, a straight line from Madeira to Principe would, of course, be a far shorter path. But since that was impossible, they’d have to take the longer route, along the curved surface of the planet.

  Eddington knew that, too, but since the earth is so big, from his position on the ship, so close to the surface, the horizon always seemed to be straight ahead, oscillating only from the waves that lifted and dropped them. There was the smell of burnt fuel as the engines pushed them forward, and the tedium went on for day after day until—from his private notebook ​—“on the morning of April 23, we got our first sight of Principe.”

  The island shot out of the sea, with central mountains a half mile high seeming to drag heavy masses of cloud over them. There were dense forests everywhere. In places wild surf hit the bases of cliffs that climbed up five hundred feet, but there also were coves where the ocean had worn away the volcanic rock, and in one of these the researchers put ashore.

  At about 80 degrees Fahrenheit, Principe wasn’t as hot as one might expect the equatorial tropics to be, but it was humid, and they’d arrived just before the end of the rainy season, so tremendous storms were still constant. In between storms, the island was rich with clouds of mosquitoes. Eddington and Cottingham had to cover themselves, despite the heat, to avoid being bitten to distraction. They took quinine daily, had local laborers build huts that were at least partly waterproof, and chased monkeys away, sometimes with rifles. A more poignant reminder of how far from home they were came when one of the island’s plantation owners invited them over and casually put out full bowls of sugar. They did something of a double take: because of wartime rationing, they had scarcely seen sugar for five years.

  A little over three weeks after they arrived, it was time to prepare for the eclipse. The worst of the rains had stopped several days before, and to be extra sure of avoiding clouds, they had moved as far from the central mountains as possible, to a plateau on the northwest tip of the island. The violent Atlantic lay a steep several hundred feet below. The forest was so thick that their equipment couldn’t be transported by mules for the last kilometer, and only native porters could help them. They found a clearing, and from there, on April 29, they finally were in position for what they had come for.

  Eddington recorded the beginning of the eclipse in his journal, calmly recalling the morning’s
meteorological phenomena. “[In] the morning there was a very heavy thunderstorm from about 10 a.m. to 11.30 a.m.—a remarkable occurrence at that time of year.” Then the sun appeared, but only briefly before the clouds rolled back in. As the day proceeded they had tantalizing glimpses of the sun, and by 2 p.m. the drifting clouds only lightly covered it.

  There would be no more than five minutes of totality, and that was going to start precisely at five seconds after 2:13 p.m. Eddington must have been eager for the obstructing clouds to drift away quickly. If Einstein was right, the sun was already distorting the space overhead—like the rock on our taut trampoline—so that light from the stars in the distant Hyades cluster would bank hard as it took that curve. The starlight would have been traveling for trillions of miles by that point. Yet if it were blocked by clouds just a few hundred feet above Eddington’s telescope, he would never be able to prove anything.

  Cottingham had the all-important metronome ready and began to give warning to Eddington at about 58 seconds, 22 seconds, and 12 seconds before totality. When the last visible crescent of the sun disappeared and the forest beyond their clearing fell into near-complete darkness, he called out the single word “Go!” Eddington had been holding the first photographic plate and now quickly slotted it in, as gently as possible so as not to jar the telescope. Cottingham kept on counting, calling out every tenth or twentieth beat, so that Eddington would know when to pull out each plate to ensure that the exposure was right.