Johann Georg von Soldner (16 July 1776, Feuchtwangen

Feuchtwangen

Feuchtwangen is a city in Ansbach district in the administrative region of Middle Franconia in Bavaria, Germany.-Geography:Geographically and geologically the land around Feuchtwangen comprises the eastern part of the Swabian-Franconian Escarpment Land , also sometimes called the gypsum-keuper...

, Ansbach

Ansbach

Ansbach, originally Onolzbach, is a town in Bavaria, Germany. It is the capital of the administrative region of Middle Franconia. Ansbach is situated southwest of Nuremberg and north of Munich, on the Fränkische Rezat, a tributary of the Main river. As of 2004, its population was 40,723.Ansbach...

 - 13 May 1833, Bogenhausen

Bogenhausen

Bogenhausen 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 Garten to the city limits, bordering on Unterföhring to the north, Aschheim to the east...

, Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

) was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 physicist

Physicist

A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

, mathematician

Mathematician

A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 and astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

, first in Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 and later in 1808 in Munich

Munich

Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

.

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 maths textbooks and maps. Since he never had been to high school, he pursued private studies of languages and mathematics

Mathematics

Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

 in Ansbach, in 1796.

In 1797 he came to Berlin, where he worked under the astronomer Johann Elert Bode

Johann Elert Bode

Johann Elert Bode was a German astronomer known for his reformulation and popularization of the Titius-Bode law. Bode determined the orbit of Uranus and suggested the planet's name.-Biography:...

 as a geometer, and was involved with astronomical and geodetic studies. From 1804-1806 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

Trigonometry is a branch of mathematics that studies triangles and the relationships between their sides and the angles between these sides. Trigonometry defines the trigonometric functions, which describe those relationships and have applicability to cyclical phenomena, such as waves...

 for the newly formed Tax Survey Commission. For his services to the theoretical basis for the Bavarian land surveying Soldner was knighted. 1815 he was appointed as a astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 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 1816-1818 due to the co-operation of Utzschneider, Georg Friedrich von Reichenbach

Georg Friedrich von Reichenbach

Georg Friedrich von Reichenbach , German scientific instrument maker, was born at Durlach in Baden on August 24 1772.-Early life:...

 and Joseph von Fraunhofer

Joseph von Fraunhofer

Joseph von Fraunhofer was a German optician. He is known for the discovery of the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.-Biography:Fraunhofer was born in Straubing, Bavaria...

.

Beginning with 1828, Soldner was unable to completely fulfill his duties because of a liver disease

Liver disease

Liver disease is a broad term describing any single number of diseases affecting the liver.-Diseases:* Hepatitis, inflammation of the liver, caused mainly by various viruses but also by some poisons , autoimmunity or hereditary conditions...

. As a result, his young assistant Johann von Lamont

Johann von Lamont

Johann von Lamont was a Scottish-German astronomer and physicist.-Biography:Von Lamont was born John Lamont at Corriemulzie near Inverey in Aberdeenshire, Scotland. The son of Robert Lamont and Elizabeth Ewan, his education began at the local school in Inverey, near Braemar...

 (under his supervision) lead the operations of the observatory. Soldner died in Bogenhausen and was buried on the cemetery on the western side of the St. Georg church.

Work

The Ramanujan-Soldner constant

Ramanujan-Soldner constant

In mathematics, the Ramanujan–Soldner constant is a mathematical constant defined as the unique positive zero of the logarithmic integral function...

 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–Mascheroni constant

The Euler–Mascheroni constant is a mathematical constant recurring in analysis and number theory, usually denoted by the lowercase Greek letter ....

's value to 24 decimal places. He also published on Logarithmic integral function

Logarithmic integral function

In mathematics, the logarithmic integral function or integral logarithm li is a special function. It occurs in problems of physics and has number theoretic significance, occurring in the prime number theorem as an estimate of the number of prime numbers less than a given value.-Integral...

.

Light bending
Soldner is now mostly remembered for having concluded — based on Newton

Isaac Newton

Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

's Corpuscular theory of light — 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 possibly Henry Cavendish

Henry Cavendish

Henry Cavendish FRS was a British scientist noted for his discovery of hydrogen or what he called "inflammable air". He described the density of inflammable air, which formed water on combustion, in a 1766 paper "On Factitious Airs". Antoine Lavoisier later reproduced Cavendish's experiment and...

's light-bending calculations, John Michell

John Michell

John Michell was an English natural philosopher and geologist whose work spanned a wide range of subjects from astronomy to geology, optics, and gravitation. He was both a theorist and an experimenter....

's 1783 study of gravitational horizons and the spectral shifting of light by gravity, and even Isaac Newton

Isaac Newton

Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

's study in "Principia

Principia

Principia could refer to:*Philosophiae Naturalis Principia Mathematica, Isaac Newton's three-volume work containing explanations of his laws of motion and his law of universal gravitation*Principia , a stem-group coralline alga...

" of the gravitational bending of the paths of "corpuscles", and his description of light-bending in "Opticks

Opticks

Opticks is a book written by English physicist Isaac Newton that was released to the public in 1704. It is about optics and the refraction of light, and is considered one of the great works of science in history...

".

Albert Einstein

Albert Einstein

Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 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

Plagiarism

Plagiarism is defined in dictionaries as the "wrongful appropriation," "close imitation," or "purloining and publication" of another author's "language, thoughts, ideas, or expressions," and the representation of them as one's own original work, but the notion remains problematic with nebulous...

 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

Deutsche Physik

Deutsche Physik or Aryan Physics was a nationalist movement in the German physics community in the early 1930s against the work of Albert Einstein, labeled "Jewish Physics"...

 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

Gravitational time dilation is the effect of time passing at different rates in regions of different gravitational potential; the lower the gravitational potential, the more slowly time passes...

. 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

Gravitational time dilation

Gravitational time dilation is the effect of time passing at different rates in regions of different gravitational potential; the lower the gravitational potential, the more slowly time passes...

, gave a combined prediction that was twice as high as the earlier predictions.