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Johann Georg von Soldner (16 July 1776 in
Feuchtwangen Feuchtwangen is a city in Ansbach district in the administrative region of Middle Franconia in Bavaria, Germany with around 12,000 citizens and 137km² of landmass making it the biggest city in the Ansbach district by Population and Landmass. In t ...
,
Ansbach Ansbach (; ; East Franconian: ''Anschba'') is a city in the German state of Bavaria. It is the capital of the administrative region of Middle Franconia. Ansbach is southwest of Nuremberg and north of Munich, on the river Fränkische Rezat, a ...
– 13 May 1833 in
Bogenhausen Bogenhausen (Central Bavarian: ''Bognhausn'') is the 13th borough of Munich, Germany. It is the geographically largest borough of Munich and comprises the city's north-eastern quarter, reaching from the Isar on the eastern side of the Englischer ...
,
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
) was a German
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...
,
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...
and
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
, first in
Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...
and later in 1808 in
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
.


Life

He was born in Feuchtwangen in Ansbach as the son of the farmer Johann Andreas Soldner. He received two years' teaching at the Feuchtwanger Latin School. Soon Soldner's mathematical talent was discovered: Soldner managed to measure the fields of his father by self-built instruments. At night, he studied math textbooks and maps. Since he never had been to high school, he pursued private studies of languages and
mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
in Ansbach, in 1796. In 1797, he came to Berlin, where he worked under the astronomer
Johann Elert Bode Johann Elert Bode (; 19 January 1747 – 23 November 1826) was a German astronomer known for his reformulation and popularisation of the Titius–Bode law. Bode determined the orbit of Uranus and suggested the planet's name. Life and career Bo ...
as a geometer, and was involved with astronomical and geodetic studies. From 1804 to 1806, he was the leader of a team which worked on the survey of Ansbach. In 1808, he was invited by Joseph von Utzschneider to Munich to work on
trigonometry Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. T ...
for the newly formed Tax Survey Commission. For his services to the theoretical basis for the Bavarian land survey Soldner was knighted. In 1815 he was appointed as an
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
and he was a member of the Academy of Sciences at Munich. In 1816, Soldner was appointed as the director of the observatory in Bogenhausen in Munich, which was built from 1816 to 1818 due to the co-operation of Utzschneider,
Georg Friedrich von Reichenbach Georg Friedrich von Reichenbach (24 August 1772 – 21 May 1826), German scientific instrument maker, was born at Durlach in Baden on 24 August 1772. Early life Reichenbach's father was a master mechanic, and a master cannon-borer, who moved to M ...
and
Joseph von Fraunhofer Joseph Ritter von Fraunhofer (; ; 6 March 1787 – 7 June 1826) was a German physicist and optical lens manufacturer. He made optical glass, an achromatic telescope, and objective lenses. He also invented the spectroscope and developed diffract ...
. Beginning with 1828, Soldner was unable to completely fulfill his duties because of a
liver disease Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common. Signs and symptoms Some of the sig ...
. As a result, his young assistant
Johann von Lamont Johann von Lamont, FRSE (13 December 1805 – 6 August 1879), born John Lamont, was a Scottish-German astronomer and physicist. Biography Lamont was born at Corriemulzie near Inverey in Aberdeenshire, Scotland. The son of Robert Lamont ( ...
(under his supervision) lead the operations of the observatory. Soldner died in Bogenhausen and was buried in the cemetery on the western side of the St. Georg church.


Work

The Ramanujan-Soldner constant and the Soldner coordinate system are named for him. The latter was used until the middle of the 20th century in Germany. In 1809, Soldner calculated the
Euler–Mascheroni constant Euler's constant (sometimes also called the Euler–Mascheroni constant) is a mathematical constant usually denoted by the lowercase Greek letter gamma (). It is defined as the limiting difference between the harmonic series and the natural l ...
's value to 24 decimal places. He also published on the
logarithmic integral function In mathematics, the logarithmic integral function or integral logarithm li(''x'') is a special function. It is relevant in problems of physics and has number theoretic significance. In particular, according to the prime number theorem, it is a ...
. ;Light bending Soldner is now mostly remembered for having concluded — based on
Newton Newton most commonly refers to: * Isaac Newton (1642–1726/1727), English scientist * Newton (unit), SI unit of force named after Isaac Newton Newton may also refer to: Arts and entertainment * ''Newton'' (film), a 2017 Indian film * Newton ( ...
's
corpuscular theory of light In optics, the corpuscular theory of light states that light is made up of small discrete particles called " corpuscles" (little particles) which travel in a straight line with a finite velocity and possess impetus. This was based on an alternate ...
— that light would be diverted by heavenly bodies. In a paper written in 1801 and published in 1804, he calculated the amount of deflection of a light ray by a star and wrote: ''"If one substitute into tang ω the acceleration of gravity on the surface of the sun, and the radius on that body is set to unity, one finds ω=0,84""''. Soldner already noted that if it were possible to observe fixed stars in close distance to the sun, it might be important to take this effect into consideration. However, because (at that time) such observations were impossible, Soldner concluded that those effects can be neglected. Soldner's work on the effect of gravity on light came to be 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. Other prescient work that became unpopular and largely forgotten for similar reasons include possibly
Henry Cavendish Henry Cavendish ( ; 10 October 1731 – 24 February 1810) was an English natural philosopher and scientist who was an important experimental and theoretical chemist and physicist. He is noted for his discovery of hydrogen, which he termed "infl ...
's light-bending calculations,
John Michell John Michell (; 25 December 1724 – 21 April 1793) was an English people, English natural philosophy, natural philosopher and clergyman who provided pioneering insights into a wide range of scientific fields including astronomy, geology, opti ...
's 1783 study of gravitational horizons and the spectral shifting of light by gravity, and even
Isaac Newton Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the grea ...
's study in '' Principia'' of the gravitational bending of the paths of "corpuscles", and his description of light-bending in ''
Opticks ''Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light'' is a book by English natural philosopher Isaac Newton that was published in English in 1704 (a scholarly Latin translation appeared in 1706). (''Optick ...
''.
Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
calculated and published a 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 Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in ...
sympathies and his enthusiasm for the
Deutsche Physik ''Deutsche Physik'' (, "German Physics") or Aryan Physics (german: Arische Physik) was a nationalist movement in the German physics community in the early 1930s which had the support of many eminent physicists in Germany. The term was taken ...
movement. At the time, Einstein may well have been genuinely unaware of Soldner's work, 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 Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass. The lower the gravitational potential (the closer t ...
. In any case, Einstein's subsequent 1915
general theory of relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the differential geometry, geometric scientific theory, theory of gravitation published by Albert Einstein in 1915 and is the current descr ...
argued that all these calculations had been incomplete, and that the Newtonian arguments, combined with light-bending effects due to gravitational time dilation, gave a combined prediction that was twice as high as the earlier predictions.Will 2006


References

;Soldner's publications * * * ;Secondary sources * * * * * * ;Endnotes {{DEFAULTSORT:Soldner, Johan Georg Von 1776 births 1833 deaths 19th-century German physicists People from Ansbach (district)