In 1919, it seemed almost possible to chart the year by tracking the movement of ships across the Atlantic Ocean. The ship that brought President Wilson back to America in February crossed on the same days as the one that took seventy deported immigrants out of America. And when the president’s ship sailed back to France, it passed two transports coming from France with thousands of American soldiers returning home. Shortly after the president arrived in Brest, W. E. B. Du Bois left Brest on his return voyage to America. The cruiser Chattanooga and the converted yacht Yanta crossed the Atlantic in the early days of spring, taking American soldiers to Archangel, moving eastward as the Leviathan, the largest transport then afloat, sailed westward with 12,059 American soldiers on board, the largest number of troops to come home on a single ship since the Armistice. In April, the USS Princess Matoika landed five thousand American troops in Charleston, South Carolina, and picked up 2,200 German prisoners of war to take them to Rotterdam. The USS Agamemnon, known as Rolling Billy for having withstood fierce North Atlantic gales in 1918, would cross the Atlantic, back and forth from France, nine times in 1919 to bring back 41,000 American soldiers.
On cruisers, giant transports, and yachts sailing the high seas in every season of the year, there were soldiers, statesmen, journalists, Red Cross workers, deported aliens, prisoners of war, crusaders of all sorts—and there were scientists.
In March and early April, two ships sailed into the Atlantic from Portugal bound for two separate destinations, the village of Sobral in northeast Brazil and the Isle of Príncipe in the Gulf of Guinea, off the coast of West Africa. Both shared the same purpose: to observe the total eclipse of the sun on May 29. The passengers, however, were hardly the usual eclipse chasers ready to pop champagne corks at the first sight of the sun’s brilliant corona highlighting the far-off edges of the moon. Rather, they were British physicists and astronomers embarking on a mission to test a German physicist’s concepts about the relationship of space, time, and matter. The physicist’s name was Albert Einstein, and the concept the general theory of relativity.
This was a scientific expedition imbued with all the excitement and stirrings of venturing to the shores of the unknown with the hope of discovering something meaningful, something new, something that might even change the world, or at least perceptions of the world. It was all about the thrill of “seeing physical science on the march in a new direction,” Arthur Stanley Eddington, the renowned astronomer on the Príncipe expedition, would later write. And as Eddington well knew, it was about even more. Because of its timing, its purpose, and its participants, this expedition was about demonstrating the value of international peace and cooperation: British scientists and British money dedicated to proving the findings of a scientist in Germany. It was about sailing far enough away from the shores of postwar strife and international differences that the drumbeat of nationalism could no longer be heard. What the peace conference in Paris was seeking, the Einstein-inspired expeditions might find. Rolling across the unpredictable seas of new thought, these ships and their passengers were destined for greatness.
Eclipses, whether solar or lunar, partial or total, have always been marvels of a sort, viewed throughout the ages as spectacles of horror and magnificence, once feared as supernatural omens and later used as ways to probe the mysteries of the universe. The total eclipse of the sun on May 29, 1919, would be a marvel of the most memorable sort. To begin with, solar eclipses occur less frequently than lunar eclipses—roughly every eighteen months—and their totality, that is the time when the moon is directly in front of the sun, is far shorter. The 1919 eclipse was exceptionally long compared to most solar eclipses—more than five minutes—and it was a rare event because late May is the time when the sun passes through the constellation of Taurus crossing what is known as the Hyades, a rich concentration of very bright stars. For the sun to be covered for so many minutes on this date was an extraordinary opportunity for the scientists. With a cluster of bright stars close to the sun during the totality, the scientists could better measure the distance between the stars and the sun, thus providing a unique opportunity to test Einstein’s calculations regarding the relationships of matter, space, and time. Measuring the distance between the stars and the sun during the eclipse and then comparing the positions of the same stars later could prove, or strike down, Einstein’s theory that a massive body such as the sun could actually bend light and thus warp the geometry of space and affect the progression of time.
Einstein’s theory refuted Isaac Newton’s belief that space was rigid and time was absolute. Newton had recognized the gravitational pull of large masses, but Einstein’s degree of deflection was twice as large as Newton’s, large enough to significantly affect space and time in the universe, making space and time relative to matter. Time, according to Newton, was an absolute property, measured at the same rate for everyone and for everything. But under Einstein’s principle, a clock in close proximity to a large mass slows its measurement of time. And if the clock is moving through space at a high speed, time also moves more slowly. Time and space, according to Einstein, were dependent on the presence of massive bodies.
If Einstein was right, then Newton, whose definitions of an absolute universe had been the foundation for scientific inquiry for more than 250 years, was not. And if space was indeed flexible, there were endless possibilities for bodies orbiting the universe. Could it be true that the formulaic and absolutely knowable tenets of the world were about to change and that ours was a world of barely visible fields of force for which there were no formulas to predict behavior? What new ideas, questions, possibilities would be raised by a new physics? What was at stake was a new concept of the universe in which Einstein, moving beyond Newton, effectively said that the presence and distribution of matter could change the shape of space and alter time.
There had been other expeditions to study eclipses with the hope of testing the deflection of light but none had succeeded. In 1912, Argentine scientists in Brazil were rained out. In 1914, Gustav Krupp, the German arms manufacturer, funded a large expedition to the Crimea led by a German astronomer, Erwin Finlay Freundlich, who had worked closely with Einstein. But a week before the August 21 eclipse, World War I broke out. The German expedition shut down and some of its members made it out just in time to avoid arrest. Those who didn’t, including Freundlich, were interned briefly in Russia. Although observers from neutral and Allied nations, including the United States, were allowed to stay, the weather was too cloudy for any useful photos. Because of the war, another chance to observe an eclipse, in 1916, was missed, this time in Venezuela. And because the U.S. team at the Crimea site could not bring home all its equipment—due to the difficulty of getting home after war was declared—observations of the June 1918 eclipse were stymied.
The eclipse of May 1919 was so favorable that every astronomer and every eclipse chaser on every continent must have been aware of it. But at a time when a large portion of the planet’s population was consumed with war and hatred, who would have dared to plan an expedition to observe an eclipse that might prove the theory of a German scientist? Not the Germans, rationing all resources for the war. Not the Russians, in the midst of civil war. Not the Americans, having just entered the European war. Not the French, filled with enough hatred for the Germans to create a light-bending force of their own. Not the Italians, Spaniards, or Portuguese.
The answer was the British scientific community, largely because of two individuals: Britain’s astronomer royal, Sir Frank Watson Dyson; and Arthur Stanley Eddington, the Plumian Professor of Astronomy and Experimental Philosophy at the University of Cambridge, the most prestigious astronomy chair in England. Eddington was also the director of the Royal Observatory in Greenwich and the world’s leading exponent of Einstein’s general theory of relativity.
Eddington was passionate about the theory and Dyson deeply respected Eddington. In fact, Dyson had been Eddington’s mentor. Although he was not as confident about the theory as Eddington was, Dyson recognized the importance of testing it and he identified the 1919 eclipse as the ideal test. To this end, in 1917 Dyson urged the Royal Society and the Royal Astronomical Society of London to appoint a committee to plan the expedition. Although the war cast a spell of skepticism on the Eddington-Dyson dream, the Joint Permanent Eclipse Committee proceeded. Dyson applied for grants to fund it. And he put Eddington in charge of the committee. Eddington had read Einstein’s theory for the first time in 1916. Despite the cessation of communication between scientists in England and in Germany during the war, he had acquired a copy of Einstein’s 1915 paper on the general theory of relativity from Willem deSitter, an astronomer in neutral Holland. Immediately upon reading it, Eddington was impressed with the theory and saw its significance. At a dinner, years later, a colleague of Eddington’s would compliment him by saying, “You must be one of three persons in the world who understands general relativity.” Eddington was silent. The colleague then hastened to add, “Don’t be modest, Eddington.” Eddington said, “On the contrary, I am trying to think who the third person is.” Eddington was so dazzled by Einstein’s work that in 1918 he published the first account of the theory in the English language, Report on the Relativity Theory of Gravitation. “One of the masterpieces of contemporary scientific literature,” one reviewer wrote. And in the preface, Eddington wrote: “Whether the theory ultimately proves to be correct or not, it claims attention as being one of the most beautiful examples of the power of general mathematical reasoning.”
Born on December 20, 1882, Eddington was 36 years old for most of 1919. A man of average height and quite physically fit, he was by then known for his prowess at cricket, at bicycling long distances, at mathematics, and at writing about science in an accessible way. He understood the difficulty of conveying profound thoughts in science and philosophy to the layman, who, he believed, had a right to know the sometimes abstruse discoveries of scientists and philosophers. He was a sensitive man, quiet almost to the point of shyness, and a lover of great literature, with a fondness for William Shakespeare, Charles Lamb, and William Blake. He was particularly inspired by Blake’s vision: “To see a World in a Grain of Sand, And a Heaven in a Wild Flower, Hold Infinity in the palm of your hand, And Eternity in an hour.” Eddington routinely worked the crossword puzzles in the London Times, The New Statesman, and The Nation, rarely taking more than five minutes per puzzle. And he was a devout scientist.
Eddington would one day be considered the greatest British astronomer of the first half of the twentieth century. Credited with laying foundations in cosmology and astrophysics, he would make a number of remarkable discoveries regarding the evolution and energy of stars—for example, that atomic energy was the source that could keep stars shining for such immensely long periods of time. On a visit to Tivoli Gardens in Copenhagen, Eddington once told a friend that it wasn’t just the beauty of the gardens that attracted him, it was the amusement park, because the merry-go-rounds and the swings were practical applications of two of his favorite subjects, mathematical probabilities and gravitation. It wasn’t surprising then that from the time he first read Einstein’s theory, Eddington was nearly possessed by it. While the pervasive mentality of war that gripped the Allied nations and the hateful campaign against all that was German would have caused most people to drop a campaign promoting a German scientist, Eddington was not deterred. His devotion to science and his sense of Einstein’s importance to the future of science drew him to the theory and to its creator. However, what most allowed Eddington to transcend the prevailing prejudices of his times was his religion.
Eddington was a Quaker. His parents were Quakers. His grandparents were Quakers. On his mother’s side, his lineage extended to the founders of the first religious Society of Friends in seventeenth-century England. He was as deeply devoted to the values of his Quaker faith as he was to science, always seeking truth in both and exploring the ways each affected the other. “In science as in religion the truth shines ahead as a beacon showing us the path,” he wrote in his book Science and the Unseen World. And in his pursuit of truth, he ventured beyond science and religion to what he called the realm of mysticism. “If I were to try to put into words the essential truth revealed in the mystic experience, it would be that our minds are not apart from the world; and the feelings we have of gladness and melancholy and our yet deeper feelings are not of ourselves alone, but are glimpses of a reality transcending the narrow limits of our particular consciousness—that the harmony and beauty of the face of Nature is, at root, one with the gladness that transfigures the face of man.”
Eddington spent his life trying to relate his religious experience and his scientific work. The Einstein expedition was one time when both came together. As a scientist he was able to see the groundbreaking significance of proving the bending of light rays passing near the sun, and he could not resist the chance to explore a theory that might reveal a scintilla of truth in the universe. As a Quaker he was able to rise above the intolerance of the world around him. Eddington knew the dangers of jingoism in science and so for him, bringing Einstein onto the international stage was just as much about advancing internationalism in science as it was about space, matter, and time. For Eddington, it was about forcing humanity to fly above the clouds of war and hatred on the wings of scientific discovery. “The lines of latitude and longitude pay no regard to national boundaries,” he wrote in 1916. “The pursuit of truth, whether in the minute structure of the atom or in the vast system of the stars, is a bond transcending human differences.”
As a Quaker, Eddington believed in the existence of the divine in everyone. People must follow their Inner Light, the voice of God’s Holy Spirit, which is within each person. He believed that hatred and violence only begat more hatred and violence. He did not believe in war. In the Great War, he was an avowed pacifist and believed in maintaining a relationship whenever possible with the people of the “enemy” nations. Humanizing the enemy would weaken the hatred that fueled the war. He was not pro-German, as he did not approve of German militarism, but he was sympathetic to the German people and believed that pacifism was the best strategy for confronting German militarism. To the Quakers, the true enemy was war itself and the misery that came out of it. At the beginning of the war, Eddington and the Quakers of Great Britain issued a public statement: “We find ourselves today in the midst of what may prove to be the fiercest conflict in the history of the human race. [We reaffirm that] the method of force is no solution of any question [and] that the fundamental unity of men in the family of God is the one enduring reality. Our duty is clear: to be courageous in the cause of love and in the hate of hate.”
When Britain instituted conscription in March of 1916, Eddington, though prepared to declare himself a conscientious objector, was exempted automatically because his work as an astronomer was considered war work with potential military value. Over the next two years, Eddington advocated the release of Britain’s pacifists, including the writer, mathematician, and social reformer Bertrand Russell, despite the fact that the stands and beliefs of his fellow Quakers were shunned by the majority of his countrymen as nothing less than treasonous. This did not stop him from protesting the harsh treatment of conscientious objectors, many of whom were Quakers interned in camps or prisons. Nor did he hesitate to support the Emergency Committee for the Assistance of Germans, Austrians, and Hungarians in Distress, which was organized to help enemy citizens detained in Britain after the war broke out.
In the spring of 1918, when the Allies appeared to be losing ground almost daily and casualty lists were higher than ever imagined, Britain, in desperate need of more troops, raised the draft age limit to thirty-five and canceled many exemptions, including Eddington’s. Eddington immediately declared himself a conscientious objector. At his hearing he testified, “I cannot believe that God is calling me to go out to slaughter men,” and he said he would continue to refuse to fight no matter what the risk in doing so. His stand stirred several Cambridge officials to beseech the British Home Office to defer him again because of his importance as one of Britain’s preeminent scientists. If he had to resort to the status of being a conscientious objector, it would damage his reputation, as those who protested the war were viewed as vermin. And he would go to prison. In response, the Home Office sent a letter to Eddington offering an exemption as long as he did not claim his religious objection to the war. All Eddington had to do was to sign the exemption. But he would not.
The only exemption Eddington would sign was one in response to his own request to be deferred as a conscientious objector. He would not sign a deferment based on his post at Cambridge while fellow Quakers were interned at camps in northern England peeling potatoes all day or worse, for objecting to the war. The Home Office was caught between deferring him based on his religious beliefs, as he asked them to do, or rejecting his application, which meant he would be sent to a camp. His colleagues at Cambridge were vexed and concerned.
Knowing that Eddington would refuse to fight and thus was headed for prison, Dyson intervened with a possible solution. He asked the government to defer Eddington for the purpose of organizing the eclipse expedition to Africa. If the government would exempt him with this stipulation, a requirement of duty to the Crown, Eddington might not see the deferment as a result of his privileged post, but rather an obligation to his nation. Dyson, who commanded a good deal of respect in political as well as scientific circles, was certain that he could persuade the government to do this and that Eddington would agree to it. In his presentation, he compared Eddington to Charles Darwin and other stellar British scientists. He talked about the grant he had just received to study the May 1919 eclipse and said that Eddington must be the one to make the observations. He did not tell them that the exciting new theory that the eclipse might prove came out of the mind of a scientist in Berlin. The government granted Eddington the exemption to prepare for the expedition and to participate in it, if the war was over by the date of the eclipse. If the war was not over by May of 1919, and if he still refused to fight, then he would face the consequences of his beliefs.
Eddington agreed to the plan though he continued his advocacy for conscientious objectors and his own objections to the war—a stand Einstein in Berlin shared. For Einstein too was a pacifist. To discover a pacifist in the German science community during the Great War was nothing less than a miracle to Eddington, who wrote to deSitter in 1916, “I’m interested to hear that so fine a thinker as Einstein is anti-Prussian.” But Einstein’s pacifism was not a response to any political, religious, or intellectual theory. It was for him a matter of instinct, he told a group of Americans in Berlin after the war, “a feeling that possesses me because the murder of men is disgusting.” It was based, he said, on his “deepest antipathy to every kind of cruelty and hatred.” Einstein had been in Germany for only four months when the war began, having returned to his homeland in April of 1914 to teach at the University of Berlin, after years of study and work in Switzerland. By 1918, he was the director of the Kaiser Wilhelm Institute of Physics. And with a tight focus on his work, he rejected the Prussianism, militarism, and nationalism that brutally defined his country.
During the war, the German intellectual community was deeply offended that the world press had made all things German synonymous with barbarity so much so that leading intellectuals wrote, signed, and sent to the press “The Manifesto to the Civilized World,” defending their nation and its culture in the face of Germany’s “severe struggle for existence which has been forced upon her.” Twenty-two of the ninety-three who signed it were scientists and doctors. Einstein refused to sign, and with several others who disagreed with the Manifesto of Ninety-three, as it was called, wrote a counter-declaration: “Never has any previous war caused so complete an interruption of that cooperation that exists between civilized nations…. educated men in all countries not only should, but absolutely must, exert all their influence to prevent the conditions of peace being the source of future wars.”
After the Armistice, in the international community of science, Einstein would still feel the pinpricks of prejudice, scorned as a German during the war, and now as a Red or Bolshevist. Some even described his general relativity theory as “Bolshevism in physics.” One astronomy professor at Columbia University, upon learning of Einstein and his theory, declared: “When is space curved? When do parallel lines meet? When is a circle not a circle? When are the three angles of a triangle not equal to two right angles? Why, when Bolshevism enters the world of science, of course.”
As a pacifist, as a Jew, and as a suspected Red, Einstein represented the “other,” for whom the postwar world was not a kind place. The prejudices that dominated both Britain and Germany intensified the challenges of putting together the eclipse expeditions, making the observation of the May 29 eclipse all the more remarkable. The extraordinary confluence of people and events surrounding the 1919 expeditions seemed almost miraculous. Here were two scientists, one in England and the other in Germany, unknown to each other, living in nations at war with each other. However, both opposed the war and both were ardent advocates of internationalism in science at a time when opposition to nationalism was tantamount to siding with the enemy. Their beliefs allowed them to transcend the prejudices of their warring nations and to form a bond in the name of humanity. As a result, the scientist in Cambridge read the findings of the scientist in Berlin, and despite the damning of all things German he embraced the theory and promoted it. This happened at a time when Britain’s astronomer royal (Dyson), the mentor of the British scientist and a man connected to high-level government officials, helpful for fund-raising, was aware of the importance of testing Einstein’s theory. And it all happened at just the right moment in the vast history of the universe: before an eclipse that was ideal for testing the theory and that would not occur again for many years.
Fund-raising and basic preparations for the expeditions began in earnest during the autumn of 1917. Eddington, Dyson, and the Joint Permanent Eclipse Committee knew that the path of the totality of the eclipse, that is, where it would be the most complete—and where it would last the longest—was across the open seas of the South Atlantic. There would be few landfalls, including the Portuguese-owned Isle of Príncipe just north of the equator and 150 miles off the coast of Africa; the western shore of Lake Tanganyika in Africa; and northern Brazil. The committee chose two locations: Sobral, a small village in northern Brazil, and Príncipe. Dr. Andrew Crommelin, an astronomer at the Royal Greenwich Observatory, would lead the observation at Sobral along with C. Davidson, also of the Greenwich Observatory; Eddington would head up the African expedition with E. T. Cottingham, a British astronomer.
Challenges were numerous. Raising money for such an expedition while the war was on seemed almost impossible. Because of the demands of the war, it was difficult to line up transportation. The destinations were not on well-traveled routes and there were no ships to spare for undertakings unrelated to the war. The equipment must be exceptional because the test would require a level of precision on the cutting edge of what was possible at that time. There would be four or more long and heavy telescopes lying in a stable horizontal position with pivoting mirrors called coelostats. These would reflect the image of the stars into the telescope, moving to compensate for the rotation of the earth and keeping the eclipse in the center of the photographic plate. The equipment must be able to with-stand the humidity and heat of equatorial weather. In fact, several brands of photographic plates would be purchased from different companies to assure that there would be enough with a composition that operated in the tropics. The observatories at Greenwich and Oxford would supply the telescopes and coelostats, and Cottingham would recondition the ones that needed work. While the war was on, however, such work could be done only with a special government certificate from the Ministry of Munitions, and eclipses were not a high priority.
Ships could not be confirmed until after the Armistice and even then a steamer to Príncipe was not assured. Much of the work on the telescopes and coelostats was on hold until then. However, Dyson did obtain a £1,000 grant, and on the day of the Armistice the Committee was confident enough to announce publicly its plans for the great expeditions: the scientists, crews, and instruments for both tests would leave together on one ship from England in mid-March, sailing to Portugal and then on to their separate destinations, to arrive at least a month in advance of the eclipse.
The night before setting sail from England, Eddington and the three other eclipse observers met with Dyson at his Greenwich study. They talked about the calculations for the deflection of light and described their visions and expectations for the May event. To communicate weather conditions and results as quickly as possible to Dyson, Eddington had developed a telegraphic code. Weather was the major worry and there was concern about the condition of the equipment. Not one to dwell on fears, Eddington spoke confidently about his belief that the deflection would match Einstein’s prediction. Cottingham then asked, “What will it mean if we get double the Einstein deflection?”
“Then Eddington will go mad and you will have to come home alone!” Dyson said.
The next day, like explorers of centuries past, the eclipse observers set sail from Liverpool on the SS Anselm, arriving in Lisbon on March 14, which happened to be Albert Einstein’s fortieth birthday. Two days later, the Sobral group left for Brazil, landing first in the town of Para, where they learned that preparations in Sobral were not yet completed and thus decided it was best to postpone their arrival at the site for another few weeks. They were also informed that there was a severe drought in northern Brazil and they were reminded that the war with Germany was still fresh in the minds of Brazilians. A local Para paper wrote: “Instead of trying to establish a German theory, the members of the expedition who are well acquainted with the heavens, should rather try to obtain rain for the country which has suffered from a long drought.” A few days later it began to rain in northern Brazil.
For the next few weeks they explored hundreds of acres of Amazon rain forest, taking note of things they had never before seen, such as plants that snapped shut upon being touched and leaf-cutting ants that marched in masses of thousands with slivers of leaves on their backs, like a green field in motion. On April 29, they arrived in barren, dry Sobral. A friendly group of local authorities, including two men who spoke English and one who had studied agriculture in America, greeted them. Soon they learned that their quarters had access to a permanent water supply, a local meatpacker would give them ice when needed for developing photos, and that during their stay they would have access to an automobile, sent from Rio de Janeiro and the first that the citizens of Sobral had ever seen.
Back in Portugal, Eddington and Cottingham waited weeks for their steamer to Príncipe and were unable to leave until April 9, finally pulling into the dock on the Isle of Príncipe on April 23. Eddington described the island as “very charming” in a letter on the 29th and he was startled to see sugar bowls full to the brim, after years of war rations back home. He was also eager to hear about world affairs. “[I wonder] whether the peace had been signed,” he wrote in one letter. The island was covered with thick forests and hordes of mosquitoes. Malaria was clearly a problem, making the use of quinine and mosquito netting a part of the men’s daily regimen. Very quickly, they began to build waterproof shelters for their equipment, working with local laborers from a nearby plantation.
Now was the time to build structures, test equipment, run preliminary photos, and rehearse every remarkable moment of the 302-second drama that would play out on May 29—what Eddington would describe as “the most exciting event, I can recall, in my connection with astronomy.” But soon after arriving at Sobral that April, Crommelin and his cohorts discovered a serious optical defect on the coelostat mirror for the biggest and the best of the telescopes. And on the Isle of Príncipe it began to rain. The locals said the rain would surely stop sometime in the next several weeks—perhaps by June.