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Photo: The International Astronomical Union/Maique Madeira
The island of Principe in Sao Tome and the Brazilian locality of Sobral on Wednesday mark the 100 years of the proof of Einstein’s Theory of Relativity, a “scientific revolution” and a historical moment in the post-World War.
The solar eclipse on 29 May 1919 allowed two teams of British astronomers, one on the island of Principe – headed by Arthur Eddington – and another in Sobral (Ceará) – led by Andrew Crommelin – to prove the gravitational curving of light theory, proposed four years earlier by the German physicist Albert Einstein.
In Sao Tome and Principe, the centenary celebrations are taking place from Saturday and are to end on Wednesday, with the inauguration of the Sundy Science Space at the Roça Sundy plantation – where the eclipse was seen -, counting on the presence of Portugal’s president, Marcelo Rebelo de Sousa, and Sao Tome’s president, Evaristo Carvalho.
The Space is to “value and recognise the scientific, cultural and historical heritage of the island of Principe,” providing an interactive exhibition on the phenomenon.
On May 29th 1919, during a total solar eclipse, Einstein’s theory of general relativity was confirmed to be correct. Stars behind the obscured Sun could be seen on Earth as the light rays they emitted were deflected due to the Sun’s spacetime curvature within the value of 1.75 arcseconds predicted by the theory.
The observations were carried out at the Príncipe Island, off the western equatorial coast of Central Africa, and in the city of Sobral, in Brazil. Two expeditions, carefully planned by the Astronomer Royal Frank Dyson, left England in early March 1919 and sailed to Lisbon and then Funchal where they separated. Arthur Eddington, the renowned Cambridge astrophysicist, went off with his team to Príncipe and Andrew Crommelin and Charles Davidson, Greenwich Observatory astronomers, were bound for Sobral.
This is one of the most acclaimed events in the history of science with Einstein being made instantaneously a worlwide figure. Science had demonstrated once again that people from different countries could be united in a common goal. At the time, the First World War had just ended and British and German scientists were eager to close hands looking towards a new future.
Since then, general relativity has passed a large number of other impressive tests, the most recent and notable one being the LIGO first detection of gravitational waves generated by the collision of two 30 solar mass black holes.
On May 29, 1919, the young English astronomer Arthur Eddington (December 28, 1882–November 22, 1944) catapulted Albert Einstein into celebrity by proving the most significant scientific model of the universe since Newtonian gravity: the general theory of relativity, completed four years earlier.
For a quarter millennium, Newton’s conception of space as static and absolute had gone unquestioned. According to his instantaneous-action-at-a-distance theory, gravity is a force that, like magnetism, acts through space but not on space, and light travels only in straight lines. According to Einstein’s theory, space and time are one entity — the foundational fabric of the universe — and gravity is a force caused by spacetime: Massive objects don’t merely draw small objects with their gravitational pull but bend the fabric of spacetime itself with their mass, pulling smaller objects into the depressions and bending light along the curvature.
At a time when very few scientists considered relativity plausible, and very few Englishmen would risk their reputation by defending a German’s ideas, Eddington set out to test Einstein’s theory against reality in an ingenious experiment nature herself had furnished. With his small team, he traveled to the remote island of Príncipe off the western coast of Africa to observe the longest total solar eclipse — 6 minutes and 51 seconds — in five centuries. When the Moon curtained the sun, Eddington hoped to see light of the Hyades cluster positioned directly behind the sun from Earth’s vantage point. If Einstein was right and Newton wrong, the sun’s massive gravitational field would warp spacetime itself, bending the path of the light to make it visible from Earth. The Hyades starlight would thus be deflected from its baseline nighttime position, which Eddington had recorded several months earlier.
It was an incredibly ambitious endeavour, both conceptually and practically. After days of heavy rains and overcast skies, resigned to failure, Eddington and his crew watched in awe as the clouds parted just in time for the eclipse, clearing the way for the telescope they had hauled to their cliff side encampment. As totality swept its otherworldly veil over the island, they took several photographic plates. All but two were ruined by the crude technology — but in those two, the Hyades clearly speckled the side of the Sun, matching Einstein’s theoretical prediction and disproving Newton.
“Dear Mother, joyous news today,” Einstein wrote upon receiving word of the triumphant results, which revolutionized our understanding of the universe and shaped the course of modern physics. “New theory of the universe,” the London Times soon proclaimed under the heading REVOLUTION IN SCIENCE, “Newtonian ideas overthrown.”
The scientific triumph was also a heartening, humane moment — just after the close of World War I, a pacifist English Quaker, who had refused to be drafted in the war at the risk of being jailed for treason, and a pacifist German Jew united humanity under the same sky, under the deepest truths of the universe. It was an invitation to perspective in the largest sense — one to which the third annual Universe in Verse was dedicated.
Eddington, unlike some of his compatriots, had no urge to denigrate Einstein’s accomplishments, although he was a citizen of a country so recently a bitter enemy — Einstein, born in Germany, and Eddington, in England. Out of the shadow of the War into the shadow of the Moon, they were citizens of the same Earth and relativity was heralded as one of humanity’s greatest achievements.Source: Lusa / science.esundy / European Space Agency- ESA / brainpicking
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