The Impact of Photography on the Centennial of Einstein’s General Theory of Relativity

I have often written and spoken about the impact of photography and its invention on the course of history and its transformations. Photography has played a major role in bringing about many of these transformations and significant changes in historical events. It has influenced various artistic, scientific, political, and social fields, becoming a fundamental pillar and cornerstone of these disciplines.

Photographic images have supported numerous in-depth studies and written research, adding an unparalleled level of credibility and serving as a highly valuable visual reference. They have also created a visual astonishment by capturing what was previously transmitted orally or considered theoretical assumptions.

Einstein and the General Theory of Relativity

On November 24, 1915, Einstein published his General Theory of Relativity, challenging Newton’s law of universal gravitation and several other physical and cosmic laws. He proposed that space and time are deeply interconnected and influenced by gravity—asserting that they are, in fact, a single entity called "spacetime." However, he was initially unable to provide practical proof of his theory.

Despite completing all the mathematical and physical aspects of his theory, including formulating cosmic hypotheses to support it, the scientific community remained skeptical and demanded practical evidence to verify its validity.

The Hypothesis of Starlight Bending and Its Photographic Proof

Einstein hypothesized that light rays could bend if they passed through a gravitational field. Even before publishing his theory in 1915, he devised an experiment to test this hypothesis. The idea was that if light rays from a group of stars behind the Sun passed through the Sun’s gravitational field, the light would bend due to gravity, allowing the stars to be seen from Earth—even though they were actually behind the Sun.

Einstein concluded that the best time to observe this phenomenon would be during a total solar eclipse when the Sun’s surroundings would become visible. While this idea seemed logical, relying on the naked eye to observe the eclipse was problematic due to potential discrepancies in individual observations. Thus, it became essential to document the positions of stars and their light paths using photography, which would enable scientists to calculate the distances and shifts in starlight caused by gravitational bending.

The First Attempt to Photograph the Eclipse

Einstein announced his hypothesis about light bending nearly a year before publishing his theory, calling on astrophysicists to photograph the solar disk during a total eclipse, as this would provide the only practical proof of his theory.

Two physicists responded to the call: German astrophysicist Erwin Freundlich from the Berlin Observatory and William Campbell, director of the Lick Observatory in the United States, a pioneer in astrophotography specializing in photographing comets and nebulae.

The two scientists coordinated their efforts and identified the best locations to observe the total eclipse—Crimea and Kyiv, both under Russian control. Freundlich headed to Crimea, while Campbell traveled to Kyiv as a contingency in case of poor weather conditions in one location.

However, when World War I broke out on July 28, 1914—just 24 days before the eclipse—Russian forces confiscated Freundlich’s astrophotography equipment and imprisoned him as a German prisoner of war. Meanwhile, Campbell, though allowed to remain in Kyiv as an American, was unable to capture any images due to heavy cloud cover that obscured the Sun during the eclipse. He eventually had to leave Kyiv without his expensive equipment due to the ongoing war.

With no photographic proof, Einstein decided not to delay publishing his theory, fearing that someone else might claim the discovery. He published the General Theory of Relativity in 1915, sparking intense debate and increasing demands for empirical verification.

The Second Attempt to Photograph the Eclipse

In 1916, British astrophysicist Arthur Eddington learned about Einstein’s theory and the only possible method to confirm or refute it—photographing a total solar eclipse and capturing the stars around the Sun. Enthusiastic about the project, Eddington immediately began studying astrophotography, learning how to capture solar eclipses. He familiarized himself with photography fundamentals, camera operation, preparing glass negative plates, exposure timing, and image development.

The next total solar eclipse was scheduled for June 8, 1918, and would be visible in its entirety from Washington, D.C. However, due to the ongoing war, Eddington was unable to travel. Thus, Campbell, still committed to the project, was the only one able to attempt photographing the eclipse.

Although Campbell managed to capture some images in Washington, they were somewhat blurry due to recurring cloud cover, similar to his experience in Kyiv. Nevertheless, he believed the images were sufficient to analyze Einstein’s theory.

The Third Attempt and Campbell’s Announcement

Campbell spent an entire year analyzing the few eclipse images with his colleagues.

By late 1918, the war had ended, and Campbell announced that he would reveal his findings in 1919. Meanwhile, Eddington identified another upcoming total eclipse on May 29, 1919, which would be visible off the western coast of Africa, and planned to capture it.

The Fourth Attempt and Eddington’s Announcement

Eddington traveled to the African coast and took numerous photographs of the eclipse. In July 1919, as Campbell prepared to present his findings at the Royal Astronomical Society in London, Eddington sent a telegram stating that his results might contradict Campbell’s and that he needed two more months to complete his analysis.

In November 1919, Eddington held a session at the Royal Astronomical Society, revealing his photographic evidence supporting Einstein’s hypothesis that light bends due to gravity. He presented historical photographs showing multiple stars behind the Sun that appeared visible due to the bending of their light around the solar disk.

The Photographic Revolution in Astronomy

Eddington’s findings ignited a surge of interest in astrophotography across Europe, the United States, Australia, and Canada. Astrophysicists eagerly awaited the next total eclipse in September 1922, visible off the western coast of Australia, to further examine Einstein’s hypothesis.

Many astronomers began learning astrophotography, making it an essential tool in celestial observations. Numerous observatories worldwide incorporated astrophotography as a fundamental skill, even requiring it for employment applications.

Determined to re-examine Einstein’s hypothesis, Campbell redesigned his astrophotographic telescope, developing an advanced camera known as the "Einstein Camera."

This camera measured 13 meters in length, with a glass negative plate measuring approximately 35 cm by 50 cm, offering unprecedented image resolution—far superior to Eddington’s 15 cm by 20 cm plates.

After capturing images of the eclipse in Australia, Campbell meticulously analyzed them with fellow physicists and astronomers. Their calculations confirmed that Einstein’s hypothesis was correct. Instead of announcing his findings to the media or the Royal Astronomical Society, Campbell first sent a personal telegram to Einstein stating: "Your hypothesis and theory are correct, and Eddington was right."

Photography as the Ultimate Proof

Without photography, it would have been impossible to empirically prove a theory of this magnitude—one that overturned 200 years of established physical and astronomical laws. Despite thousands of pages of mathematical equations and calculations by Einstein and other physicists, photography provided the final, irrefutable proof of the General Theory of Relativity and its cosmic implications.

By Mohammad Hannon / originaly written in Arabic and published in Arabic newspapers.

Palestinian-Jordanian Photographer