Paul Gerber
Encyclopedia
Paul Gerber was a German 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...

. He studied 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...

 from 1872-1875. In 1877 he became a teacher at the Realgymnasium (high school) in Stargard
Stargard Szczecinski
Stargard Szczeciński is a city in northwestern Poland, with a population of 71,017 . Situated on the Ina River it is the capital of Stargard County and since 1999 has been in the West Pomeranian Voivodeship; prior to that it was in the Szczecin Voivodeship...

 in Pommern. Gerber is known for his controversial work on the speed of gravity
Speed of gravity
In the context of classical theories of gravitation, the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational...

 and the Perihelion shift of Mercury's orbit.

Basic concept

Based on the electrodynamic laws of Wilhelm Eduard Weber
Wilhelm Eduard Weber
Wilhelm Eduard Weber was a German physicist and, together with Carl Friedrich Gauss, inventor of the first electromagnetic telegraph.-Early years:...

, Carl Friedrich Gauß, Bernhard Riemann
Bernhard Riemann
Georg Friedrich Bernhard Riemann was an influential German mathematician who made lasting contributions to analysis and differential geometry, some of them enabling the later development of general relativity....

, between 1870-1900 many scientists tried to combine gravitation with a finite propagation speed and tried to derive the correct value for the Perihelion shift of Mercury's orbit.Zenneck 1901, 46ffOppenheim 1920, 153ff In 1890 Maurice Lévy
Maurice Lévy
Maurice Lévy was a French engineer and member of the Institut de France.Lévy was born in Ribeauvillé in Alsace. Educated at the École Polytechnique, where he was a student of Adhémar Jean Claude Barré de Saint-Venant, and the École des Ponts et Chaussées, he became an engineer in 1863...

 succeeded in doing so by combining the laws of Weber and Riemann, whereby the speed of gravity
Speed of gravity
In the context of classical theories of gravitation, the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational...

 is equal to the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

 in his theory.Levy 1890 However, because the basic laws of Weber and others were wrong (for example, Weber's law was superseded by Maxwell's equations), those hypothesis were rejected.

A variation of those superseded theories (albeit not directly based on Weber's theory) was the one of Gerber, which was developed by him in 1898 and 1902.Gerber 1898, 1902 By assuming a finite speed of gravity, he developed the following expression for the gravitational potential:
Using the Binomial theorem to second order it follows:
According to Gerber, the relation of the speed of gravity (c) and the Perihelion shift (Ψ) is:
where, ε = Eccentricity
Eccentricity (mathematics)
In mathematics, the eccentricity, denoted e or \varepsilon, is a parameter associated with every conic section. It can be thought of as a measure of how much the conic section deviates from being circular.In particular,...

, a = Semi-major axis
Semi-major axis
The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape...

, τ = Orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...

.
So Gerber was able to calculate a speed of gravity of ca. 305 000 km/s, nearly the speed of light.Zenneck 1901, 49ffOppenheim 1920, 156f

Controversy

Gerber's formula gives for the Perihelion shift:
It was noted by the Einstein- and relativity critic Ernst Gehrcke
Ernst Gehrcke
Ernst J. L. Gehrcke was a German experimental physicist. He was director of the optical department at the Reich Physical and Technical Institute. Concurrently, he was a professor at the University of Berlin...

 in 1916,Gehrcke (1916) that this formula is mathematically identical to 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...

's formula (1915) for general relativity.Einstein (1915 and (1916), 822, where e = Eccentricity, a = Semi-major axis, T = Orbital period.
So Gehrcke initiated a reprint of Gerber's 1902-paper in the Annalen der Physik
Annalen der Physik
Annalen der Physik is one of the oldest physics journals worldwide. The journal publishes original, peer-reviewed papers in the areas of experimental, theoretical, applied and mathematical physics and related areas...

 in 1917, where he questioned the priority of Einstein and tried to prove a possible Plagiarism
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...

 by him.Gerber 1917 However, according to Albrecht Fölsing
Albrecht Fölsing
Albrecht Fölsing is a trained physicist turned into a scientific journalist. Having studied physics in Berlin, Philadelphia, and Hamburg, he worked as an academic research assistant for the German electron synchrotron named Desy. In the years 1973-2001, Fölsing was head of the Nature and Science...

Fölsing 1993, Chap. 5 and Roseveare,Roseveare 1982, Chap. 6 those claims were rejected, because soon after Gerber's paper was reprinted, scientists like Hugo von Seeliger
Hugo von Seeliger
Hugo von Seeliger , also known as Hugo Hans Ritter von Seeliger, was a German astronomer, often considered the most important astronomer of his day....

,Seeliger (1917) Max von Laue
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...

Laue (1917, 1920) published some papers, where it was claimed that Gerber's theory is inconsistent and his formula is not the consequence of his premises. And Einstein wrote in 1920:Einstein 1920
In the recent past, Roseveare argued that Gerber's derivation is unclear, however, he claimed to have found the way by which Gerber possibly found his result (although Roseveare's derivation was criticized as wellMathPages: Gerber's Gravity, Gerber’s Light Deflection). More importantly, Roseveare showed that Gerber's theory is in conflict with experience: the value for the deflection of light in the gravitational field of the sun is too high in Gerber's theory, and if the relativistic mass is considered, also Gerber's prediction for the perihelion advance is wrong.

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