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Testing Einstein Theory: Error in Calculation of Speed of Light Reported by German Expedition to Sum

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Something of a sensation has been created in the world of science here by a report which has just been presented to the Prussian Academy of Science by Professor Freundlich, the Director of the Einstein Institute in Potsdam, giving the results of the test of the Einstein theory made in Sumatra by a German scientific expedition during the eclipse of 1929.

Professor Freundlich confirms the Einstein theory, but he reveals that the expedition found that Einstein’s calculation that the rays of light are bent out of their course by 1.75 seconds is an underestimate, its own figure being more than two seconds.

The report of the expedition conclusively destroys the arguments against the Einstein theory by its opponents, but at the same time its supporters are also in something of a quandary because of the error detected by the expedition. They are confident, however, that Professor Einstein will in his present experiments on his new field theory succeed in correcting the error and place his relativity theory in an unchallengable position.

Efforts directed in particular to securing verification of Einstein’s theory by measuring the amount by which rays of light are bent out of their course when passing near the sun were made by a number of expeditions which arrived at Alor Star, in the Malay States, from various parts of the world to observe the total eclipse of the sun, which occurred on May 9th., 1929. There were among them two British parties led by Dr. Jackson, of the Royal Observatory, Greenwich, and Dr. Carroll, of the Cambridge Solar Physics Observatory.

The purpose of the expeditions was described by Professor H. H. Turner, Savilian Professor of Astronomy at Oxford University, and a former President of the Royal Astronomical Society, in the “Times” of May 8th.

During the war, he wrote, news reached us rather tardily of Einstein’s wonderful new theory of time, space and gravitation, which he had deduced by purely mathematical reasoning from the simplest hypotheses consistent with experiment. The theory led to the important conclusion among many others that light is not merely an equivalent of matter, but is subject to attraction by matter. A material character for light had been suggested by Newton two centuries ago, but Einstein’s new theory assigned an attraction effect just double that which Newton’s simpler theory indicated. The total eclipse of 1919 would give a good opportunity for testing the theory, but in 1918 we were involved in a war which seemed quite unlikely to be finished in time. Nevertheless, preparations for two English expeditions were started as a forlorn hope. The hope was realised. The war collapsed just in time. The two expeditions were successful and after an exhaustive discussion of the photographs obtained were able to announce that Einstein’s theory represented the facts better than any other.

But if the English astronomers were thus convinced of the value of Einstein’s theory, Professor Turner continued, others were not. Another total eclipse was due in 1922, and a well equipped American Expedition went to Australia in the hope of proving Einstein wrong. The facts proved too strong for them. The Director of the Lick Observatory, who afterwards frankly acknowledged his hope as above, was also frank enough to announce in 1923 that a prolonged study of his photographs declared clearly in favour of Einstein.

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