Abstract
AN OFT-RECURRING RELATIVITY BLUNDER.—Many people have been temporarily misled by a fallacy in considering the Einstein bending of rays of light. They imagine that it ought to produce a sensible shift in the position of the further component of a double star, owing to its light passingclose to the nearer component, or similarly that the satellites of Jupiter ought to undergo the shift at the time of occultation. Another form of the fallacy is put forward by M. de Saussure in Astr. Nachr. No. 5235, in an article entitled “Influence de la deviation des rayons lumineux sur la valeur du diamdtre du soleil.” He notes that the light from each limb of the sun would be subject to the Einstein bending, but that sinceit has only traversed half the gravitational field as compared with a star behind the sun, the bending at each limb is 1.75″/2. So far he is correct. His error comes in when he asserts that the true diameter of the sun is 1.75″less than that measured, equivalent to 1300 km. In fact we only see the full Einstein shift when the distance from the eye to the place of bending is small compared with the distance from the eye to the object viewed. This is obviously the case for a star near the sun, but not for the components of a double star, for Jupiter's satellites or for the sun's limb.
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Our Astronomical Column. Nature 112, 216 (1923). https://doi.org/10.1038/112216a0
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DOI: https://doi.org/10.1038/112216a0