Early in 1919, two teams of British astronomers embarked on a journey to the far reaches of the planet to observe a solar eclipse. Nearly eight months later, on Nov. 6, 1919, the teams presented their findings before a packed audience of scientists in London. Their announcement changed forever how humans view the universe.
The teams’ report, coming less than a year after the end of World War I, was noteworthy for another reason: It may have helped heal the wounds of war. The British eclipse expedition was designed to test a new theory of gravity proposed by Albert Einstein, a German-born scientist who had published his work behind enemy lines. If the British proved him right, his theory would topple that of Isaac Newton, a founding father of modern scientific thought and a national hero in Britain.
Newton had viewed gravity as a force that acts across space, pulling massive bodies together. Einstein replaced that notion with the radical proposition that gravity is space. Rather than stiff and immutable as the floorboards of a stage, space and time, he said, jiggles like jelly. A massive body dents this jiggly space-time much the way a lead weight sags a sheet of rubber. Earth is attracted to the sun not because of a force but because the sun has dimpled the space-time through which our planet must travel.
As early as 1911, Einstein had suggested a way to verify his outlandish proposal, known as the general theory of relativity. If a body is massive enough — like the sun — scientists should be able to observe the curved or bent path of all objects traveling in its vicinity, even particles of starlight. Through a telescope, the bending of starlight would show up as a change in the apparent position of the star compared with its position when the sun was in another part of the sky.
Under ordinary conditions, attempting such an observation would be folly. The blinding light of the solar disk would completely swamp the much fainter light from surrounding stars. But the stars pop into view during those rare times and places when the clockwork motion of the solar system places the moon directly between the sun and Earth.
Beginning in 1912, several attempts to search for Einstein’s gravitational light-bending during a solar eclipse had failed, mainly because of bad weather. But the Great War also played a role. The German astronomer Erwin Finlay Freundlich had just arrived in the Crimea to study the solar eclipse of Aug. 21, 1914, when the war broke out. He and his associates were promptly interned in Russia as spies and their equipment was confiscated.
Einstein himself hated the war. In October 1914, 93 German scientists signed a proclamation giving their unqualified support to the German military. Einstein refused to sign the “Manifesto of the Ninety-Three” and instead was one of just four scientists to endorse a proclamation protesting Germany’s aggression.
Although Einstein blocked out the war as best he could, sometimes it was too close to be ignored. His office was in the Kaiser Wilhelm Institute for Physical Chemistry in Berlin. To aid in the war effort, the institute’s director, Fritz Haber, and his collaborators had begun experiments with chlorine, a poisonous gas. On Dec. 17, 1914, a test tube of cacodyl chloride, an unstable substance, caught fire in Haber’s laboratory. The subsequent explosion blew off the right hand of one researcher and killed another. Fortunately for Einstein, he was unharmed.
By 1916, Einstein had a new and unexpected champion of his work — the British astronomer Arthur Eddington, a lifelong Quaker who was nearly jailed for his refusal to serve in the British Army. Eddington became enamored of Einstein’s work after reading several of his seminal papers, smuggled into Britain through the Netherlands, which had stayed neutral. He exhorted his colleagues at scientific conferences to embrace the theory, published review articles on Einstein’s mysterious concept of curved space-time, and defended the work when critics tried to disparage it.
Story Credit : Ron Cowen, Published in the New York Times.