Johann Georg von Soldner

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Johann Georg von Soldner (16 July 1776 - 13 May 1833) was a German physicist, mathematician and astronomer first in Berlin and later in 1808 in Munich.

The Soldner constant is named for him. He is now mostly remembered for having concluded due to the Newton's corpuscle theory of the light that light would be diverted by heavenly bodies.

[edit] The Lenard-Einstein controversy

Albert Einstein calculated and published a numerically-similar value for the amount of gravitational light-bending in light skimming the Sun in 1911, leading Phillipp Lenard to accuse Einstein of plagiarising Soldner's result.

Lenard's accusation against Einstein is usually considered to have been at least partly motivated by Lenard's Nazi sympathies and his enthusiasm for the Deutsche Physik movement. At the time, Soldner's result may have been somewhat obscure, and Einstein may well have been genuinely unaware of it, or he may have considered his own calculations to be independent and free-standing, requiring no references to earlier research (Einstein's 1911 calculation was based on the idea of gravitational time dilation): in any case, Einstein's subsequent 1915 general theory of relativity quickly argued that all these calculations had been incomplete, and that the "classic" Newtonian arguments, combined with light-bending effects due to gravitational time dilation, gave a combined prediction that was twice as strong as the earlier predictions.

[edit] Obscurity

Soldner's work on the effect of gravity on light became considered less relevant during the Nineteenth Century, as "corpuscular" theories and calculations based on them were increasingly considered to have been discredited in favour of wave theories of light — it was not immediately obvious that the more "fashionable" wave theories should predict similar effects. Other prescient work that became unpopular and largely forgotten for similar reasons included Henry Cavendish's light-bending calculations, John Michell's 1783 study of gravitational horizons and the spectral shifting of light by gravity, and even Isaac Newton's study in "Principia" of the gravitational bending of the paths of "corpuscles", and his description of lightbending in "Opticks".

[edit] references

• "Henry Cavendish, Johann von Soldner, and the deflection of light", American Journal of Physics 56 413-415 (1988) [1]

• "Johann Georg von Soldner and the gravitational bending of light, with an English translation of his essay on it published in 1801", Foundations of Physics 8 927-950 (1978) [2]