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He also participated in many scientific lectures and colloquia.  There is an anecdote<ref name="waller"/> (sources differ on whether it is apocryphal) about an exchange during a lecture that he gave in 1919 at the Royal Society on the topic of general relativity.  An audience member, Ludvig Silberstein, suggested to him "Professor Eddington, you must be one of three persons in the world who understands general relativity."  Silberstein was presumably thinking of himself, Eddington, and Einstein.  Eddington paused for a moment.  Silberstein then said "Don't be modest, Eddington!"  Eddington replied "I'm trying to think who is the third."

He also participated in many scientific lectures and colloquia.  There is an anecdote<ref name="waller"/> (sources differ on whether it is apocryphal) about an exchange during a lecture that he gave in 1919 at the Royal Society on the topic of general relativity.  An audience member, Ludvig Silberstein, suggested to him "Professor Eddington, you must be one of three persons in the world who understands general relativity."  Silberstein was presumably thinking of himself, Eddington, and Einstein.  Eddington paused for a moment.  Silberstein then said "Don't be modest, Eddington!"  Eddington replied "I'm trying to think who is 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.

 

In the 1930's Eddington got into a dispute with Subrahmanyan Chandrasekhar, who had proposed a model of stellar evolution for large stars&mdash;[[white dwarf|white dwarves]] with a mass greater than 1.44 times the mass of the sun, which is known as the Chandrasekhar limit.  This work presaged the notion of black holes.  Eddington rejected the notion that a purely mathematical analysis could be accepted if it led to such a seemingly absurd physical result.  Chandrasekhar turned out to be right.

 

 

Physical quantities that are dimensionless always fascinate physicists.  One is the "fine structure constant", represented as <math>\alpha\,</math>.  It is named because it is the ratio of certain line spacings in the fine structure lines in spectra.  It is defined as <math>\frac{1}{4 \pi \varepsilon_0} \frac{e^2}{\hbar c}</math>.  It had been measured at the time to be very close to 1/136.  Eddington proposed, apparently on grounds of pure mathematical elegance, that it was exactly 1/136.  Later measurements showed that it was instead very close to 1/137, and Eddington proposed that it was exactly 1/137.  He was wrong both times; the modern value of <math>1/\alpha\,</math> is 137.036.

==References==

==References==

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[[Category:Astronomers|Eddington, Arthur]]

[[Category:Astronomers|Eddington, Arthur]]