Two Minutes of Eclipse for Einstein. Ups and Downs of an International Astronomical Collaboration in 1914

I had read that a group of scientists undertook a long voyage from the port of Buenos Aires to Crimea at the time of World War I in order to gather evidence for Albert Einstein to prove his special theory of relativity. It was 1914, a century before Vladimir Putin undertook the annexation of that peninsula of the Black Sea.

They were astronomers who had to measure a total solar eclipse that would last two minutes. That was the reference I read in the biography Einstein: His Life and Universe by Walter Isaacson. I imagined a handful of men with porteño accent sharing a mate bombilla as they sailed the Atlantic in a wood-veneered cabin with skylights from which they watched the sea tussle. The whole scenario and the minuscule time margin to accomplish the feat in Crimea seemed worthy of a novel to me. So I decided to write it. 

The first thing I found out about the expedition broke the oceanic vision I had: it was not done by Argentinians, but by Americans from the National Observatory, an institution founded in Córdoba by Domingo Faustino Sarmiento in the second half of the 19^th century, 50 years after an Argentinian had proclaimed the independence of my country, Peru, in 1821. My horizon of documentary and literary research was incited by numbers and displacements, old dates and migrations such as the one I myself had undertaken: I had gone from Lima to Barcelona and was looking for a way to fly to Buenos Aires. 

I wrote to the institution that today bears the name of Astronomical Observatory of Córdoba, and inquired about their archives on Crimea and what of it was digitalized. After a few months, the distance from one country to another turned into the distance from one city to another because I managed to move to Argentina; but still, the distance. My query was referred to the Documentation Center of the National University of Córdoba’s Main Library. By then, I had a clear journalistic reference: the person in charge of the scientific trip had written a chronicle in the local newspaper Los Principios under the title “El eclipse de sol del 21 de agosto. La expedición astronómica argentina” (The August 21 solar eclipse. The Argentinian Astronomical Expedition). According to my database revision, the publication was dated October 12, 1914—three years later, President Hipólito Yrigoyen would decree the date as a national holiday. The colleagues requested my personal data and academic affiliation to begin the documentary search of documents from a century ago, which they solved with admirable speed. 

It was 2019, one hundred days before the World Health Organization declared the coronavirus a pandemic. By then I had obtained a research stay for my doctoral thesis on a character from the 19^th century who split his life of exile between Cusco, Ceuta, and Buenos Aires, the latter being from where I exchanged emails with the Documentation Center in Córdoba. The colleagues corrected my perspectives and inquiries: the chronicle of the expedition to Crimea had been published in Los Principios in three parts, but not on October 12, but on October 11, 14, and, apparently, 23, in 1914. They had only been able to find copies of the newspaper corresponding to the first two dates. They scanned and sent the strong yellowish documents to me as attachments; they also suggested to contact the Archives of the Archbishopric about the missing part. 

Of course, I listened to them. 

Signed by the then director of the observatory, Dr. Charles Perrine, the chronicle has the following subtitle: “Interesting account of the voyage related to the European conflagration” and was written at the request of the newspaper. A “valuable scoop” is mentioned, since the expedition left Córdoba on June 16 and sailed from Buenos Aires to Genoa on the 20^th of the same month. Eight days later, Archdukes Sofia Chotek and Franz Ferdinand, heir to the Austro-Hungarian crown, were assassinated in Sarajevo by a Serbian extremist. 

At the end of the 19^th century, German Chancellor Otto von Bismarck foretold: “One day the great European War will come out of some damned foolish thing in the Balkans”. And so it happened. As the expedition went from South to North and from East from West, the Great War that would last from 1914 to 1918 began. This is how the author told it on Sunday, October 11: 
   
After reading the first and second parts of the testimony written by the protagonist of the expedition, I decided that I had to go from Buenos Aires to Córdoba, not only to try to find what was missing from the chronicle scanned by the colleagues, but also to carry out the search for scientific reports and archive photographs of the eclipse. Perhaps even to find the references that would direct the astronomical event to Albert Einstein. From the coast of Río de la Plata, I rode 700 kilometers in a night bus through the Pampas Plain. Perhaps because I spent the trip asleep from beginning to end, all that now seems to me like a dream of pre-pandemic life. 

I had arranged the trip to Córdoba with the offer to conduct a workshop at the Astronomical Observatory on persuasive and inclusive uses of language. Once the opportunity to visit the institution was secured, I began to dream about the possibility of visiting the Black Sea in the future. I imagined the longest route from Barcelona: a flight to Helsinki in Finland and arriving in St. Petersburg in Russia through the Baltic by ferry; then, a full day overland to Crimea. It seemed like an unfeasible goal for the imminent 2020, but I did find it feasible for the following year: to celebrate my forty-fifth birthday in those far-fetched lands during the summer of 2021. It was not a great excuse, but it was mine. What was Charles Perrine’s reason in 1914 to have the same destination? The author explains it in the chronicle: 
   
Everything at the Astronomical Observatory of Córdoba was at hand since in addition to being an institution specialized in observing and studying the cosmos, it also fulfilled a museography mission. Director David Merlo and his team guided me through the exhibition they had set up about Crimea in the corridors and halls. This way, I gained access to a handful of learning that was essential to understand the 1914 expedition: a letter from Albert Einstein’s secretary and the request he made to his colleagues in Argentina to take measurements in Brazil. 

The letter was kept in a display case in the exhibition; I later received a scanned version to give it an extra revision. It alluded to the need to provide rigorous and contrasted findings to Professor Einstein’s theory of relativity, the one he had published in a series of articles in 1905. Regarding the essential question of light, the most effective way was to measure it during an astronomical event that would allow comparing its curvature: a total eclipse, in which the stellar masses exert a determining influence on the phenomenon. 

The event could be captured very well from a location near Rio de Janeiro and the observatory made the mission its own. Charles Perrine—the director at the time and whose desk I even got to see because of the institutional exhibition of his works and belongings—formed a team of professionals who perfected their instruments for the mission in Brazil. At that time, the Bondinho, the Sugarloaf mountain Cable Car—iconic cable car of the carnival city—was being assembled. 

The expedition to Crimea was intended to accomplish what had been impossible in 1912 as weather conditions in the Brazilian sky prevented the four professionals from the Argentine National Observatory from obtaining the missing measurements. I have not been able to access the letter with explanations that the meticulous Perrine probably prepared for Einstein’s secretary. In 1914, with the equipment reduced by half, they also reduced the budgets and the instruments, which were made lighter, more portable, and dismountable. At the Cordoban institution, in addition to archival photographs and some extra correspondence, I was able to access the 18 pages of the scientific report the director typed. With a title made up of 23 underlined words, the document addresses in its first paragraph a primordially earthly question in the perspective of an expert in contemplating the firmament: “it was noted that there were several moral obligations to overcome”. 

The first five pages of the report are a synthesis of the expedition, which is detailed by its author in the following sections. Written with poise and precision, the document helps to comprehend how astronomy was understood more than a century ago and what the task of measuring an eclipse entailed. And so Perrine expresses it (he clearly elaborated his chronicle in the Córdoba local press based on this institutional document): 
   
From the Atlantic to the Mediterranean, from the ship to the railroad, the expedition of the Argentine National Observatory continued its way for several weeks to the East. They were only two observers carrying a load, according to the scientific report, of one and a half tons. Just as they had considerably adapted the instruments for the latitude in Crimea, they also had to adapt to environmental conditions, financial struggles and the effects of armed conflict for their movements: Perrine and his colleague Mulvey went overland, while their large wooden crates circulated by sea, which was the most economical, yet risky route. 

The scientific report remarks, again and again, the solidarity with which colleagues from other expeditions and customs personnel in Genoa, Odessa, Feodosia… acted, which allowed the instruments, that traveled from one steamer to another without supervision by the experts, to arrive on time and in perfect conditions for the eclipse measurements. The research plan was to obtain “Large-scale photographs of the corona with a fixed telescope of 12 meters of focal length to show especially the fine structure details in the inner and middle regions,” just to begin with, since the purpose “is to reveal any variation in the amount of light in the corona that may be due to variation of solar activity.” When the day came, they set up the camp, the tower for the telescope, and the foundations for the instruments they had brought from the other side of the world at the beginning of World War I. However, at that geographic point of the planet, belligerence was suspended or considered to be removed from reality in the name of the common task, peaceful coexistence and healthy camaraderie, of an astronomical discovery. 

On the morning of the eclipse, the location of the instruments was ideal and none failed, despite the complexity involved in transporting them. Moreover, the duo from the Argentine National Observatory had spent days rehearsing the taking of photographs and measurements, for which they also had the support of people from outside the expedition, such as locals or other teams. However, what they could not fully calculate or predict were the weather conditions. Although they had studied the sky at dawn and dusk the previous days, with great results because of how clear and cloudless it had been, on August 21, 1914, the total eclipse was covered by clouds in the firmament. Specifically, a small cloud was responsible for obscuring the corona and prevented them from achieving the feat for which they had traveled no less than thirteen thousand kilometers from the city of Córdoba. 
   
Neither those who had arrived from Argentina nor those from England or Russia—the German expedition had been intervened much earlier for war reasons—were able to take the images and measurements they wanted. Of course, they still took photographs, just without getting significant results. Just as it had been impossible in Brazil, it was impossible in Crimea two years later too. In the scientific report, Perrine details everything they intended to capture and what they obtained. Day after day, they revealed and analyzed, contrasted and debated. In the end the director states: “It is possible, but by no means certain, that, in some as yet unknown way, some very valuable information may be derived from these photographs”. 

The way back home was marked by an anecdote that only takes up a two-line paragraph in the report. Instead of making the return journey with the instruments, the Argentine National Observatory expedition opted to leave them behind and only paid customs duties for the wood from which they were made. Perrine and Mulvey returned to South America by longer and more complex routes because of the European war. The last section of the report is subtitled “Acknowledgements” and offers a horizon of gratitude filled with names of people and institutions that made it possible for the mission to reach its goal. 

The book and audiovisual sources about Einstein’s life highlight that the Argentinians—who were not Argentinians but Americans—did not get the measurements needed for the special theory of relativity, and happily so. There was a mistake in the numbers worked by the most famous physicist of the 20^th century, a fact that would have led to a wrong result with the data of the eclipse. It would be years later, when the general theory of relativity was already formulated in addition to the special one, that a mathematician with no great affection for Einstein made the correction in the calculations and, therefore, a further collection of astronomical data provided enough information to support his equations. 

There were two expeditions to achieve a goal that, had it been reached, would have led scientific expectations to a setback, which is not a minor deal. However, it may be before the major experience of looking at the sky to search for an answer in the infinite. This is what Perrine and Mulvey did, and so many human beings before and after them. Before leaving Córdoba on the brief visit I made at the end of November 2019, I asked the director of the observatory what had been the most beautiful day of his work with a telescope. I inquired about his work, but also about the emotion and sensitivity involved in performing his duties. After smiling at me and describing the way in which a device of such magnitude is used, he evoked a very early morning in which he contemplated the clearest and most lyrical Milky Way of his life. All that I could remember of the Milky Way in documentary records and films, all the colors and shapes that animate in my visual memory and imagination appeared before his eyes. He told me he was alone, and in solitude he experienced the endless beauty of the cosmos. 

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