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==The Eclipse of 1919==

==The Eclipse of 1919==

The next year, Eddington presented his observations to the Royal Society as a proof of the theory of relativity. Recent analysis of Eddington’s work revealed that he was biased in selecting his data, and that overall his data was inconclusive about the theory of relativity.<ref>[http://arxiv.org/abs/astro-ph/0102462 Peter Coles (University of Nottingham, UK): ''"Einstein, Eddington and the 1919 Eclipse"'']

The [[theory of relativity|theory of general relativity]] of [[Albert Einstein]] predicts that light from stars grazing the sun will be deflected by 1.75 arc-seconds.  [[Isaac Newton|Newton]]'s "corpuscular" theory predicts a deflection of 0.875 arc seconds.<ref>Johann von Soldner calculated this deflection, and showed that would be independent of the (presumably very fast) speed of the "corpuscles", in 1801.</ref>  Scientists had mostly discarded Newton's theory in terms of the "wave" theory, which didn't address the issue at all.  The predicted deflections were near the limits of the technology of the time.  Furthermore, an eclipse was required to darken the sun so that the starlight may be seen in proximity to the sun.

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Eddington mounted two expeditions, with the best equipment available, to observe the solar eclipse of May 29, 1919.  One team went to Sobral, Brazil, and the other went to the island of Principe, off the African coast.  Upon his return, Eddington presented his observations, that he had successfully measured a deflection in the amount of Einstein's 1.75 arc-seconds, to the Royal Society, as a validation of the theory of relativity.

 

Recent analysis of Eddington’s work revealed that he was biased in selecting his data, and that overall his data were inconclusive about the theory of relativity.<ref>http://arxiv.org/abs/astro-ph/0102462</ref>  Modern techniques for analyzing data from experiments involves extremely careful statistical analysis of the data, and generally demands a "5 sigma" level of statistical certainty, which means that there is only a one-in-three-million chance that the measurements came out that way by chance rather than by the phenomenon being measured.

 

Eddington's observation protocol was somewhat muddled by an incorrect initial calculation, by several people including Einstein himself, of what the effect would be, and some "cherry picking" of the data to be used <ref name="waller">''Einstein's Luck'', John Waller, Oxford University Press, ISBN 0-19-860719-9</ref><ref>[http://arxiv.org/abs/astro-ph/0102462 Peter Coles (University of Nottingham, UK): ''"Einstein, Eddington and the 1919 Eclipse"'']</ref>.  The data selection could be considered "manipulation" or "fudging", by Eddington, who had a personal stake in the outcome.  His analysis techniques would not pass muster today.  Nevertheless, the deflection has been verified with ever-increasing precision in subsequent eclipses, and, with exquisite precision, in the observations of quasar 3C273.

Eddington next promoted the theory of relativity to the English-speaking world in his ''Mathematical Theory of Relativity'' (1923).  As the title suggests, this theory was more a mathematical vision of how the universe should be, rather than what it actually was.  When a reporter asked Eddington whether only three people even understood the theory, Eddington supposedly arrogantly retorted, "Who's the third?"   

Eddington next promoted the theory of relativity to the English-speaking world in his ''Mathematical Theory of Relativity'' (1923).  As the title suggests, this theory was more a mathematical vision of how the universe should be, rather than what it actually was.  When a reporter asked Eddington whether only three people even understood the theory, Eddington supposedly arrogantly retorted, "Who's the third?"   

But Eddington did not fare well after that.  He strongly opposed a theory about massive [[star]]s known as [[white dwarf|white dwarves]] put forth by Indian physicist Subrahmanyan Chandrasekhar, but Eddington was proven wrong and Chandrasekhar later won a Nobel Prize for his work.  Eddington finally lost all credibility when he first insisted that a physical constant (the fine structure constant) measured to be close to 1/136 must precisely equal 1/136 to make the math easier, but when later measurements suggested a value closer to 1/137 Eddington insisted that it must precisely equal to 1/137 instead.  He was wrong both times.

But Eddington did not fare well after that.  He strongly opposed a theory about massive [[star]]s known as [[white dwarf|white dwarves]] put forth by Indian physicist Subrahmanyan Chandrasekhar, but Eddington was proven wrong and Chandrasekhar later won a Nobel Prize for his work.  Eddington finally lost all credibility when he first insisted that a physical constant (the fine structure constant) measured to be close to 1/136 must precisely equal 1/136 to make the math easier, but when later measurements suggested a value closer to 1/137 Eddington insisted that it must precisely equal to 1/137 instead.  He was wrong both times.

==References==

==References==

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[[Category:Astronomers|Eddington, Arthur]]

[[Category:Astronomers|Eddington, Arthur]]