Alfred Bucherer
Encyclopedia
Alfred Heinrich Bucherer (* July 9, 1863 in Cologne
; † April 16, 1927 in Bonn
) was a German physicist
, who is known for his experiments on relativistic mass. He also was the first who used the phrase "theory of relativity
" for Einstein's theory of special relativity
.
, the University of Strassburg, the University of Leipzig
, and the University of Bonn
. In Bonn he habilitated
in 1899 and taught there until 1923.
In 1903 Bucherer published the first German-language book to be completely based on vector calculus.
(1895, 1900), Bucherer (1903b) believed in the validity of the Principle of relativity
, i.e. that all descriptions of electrodynamic effects should only contain the relative motion of bodies, not of the aether. However, he went a step further and even assumed the physical non-existence of the aether. Based on those ideas he developed a theory in 1906, which also included the assumption that the geometry of space is riemannian
. But the theory was vaguely formulated and in 1908 Walter Ritz
showed that Bucherer's theory leads to wrong conclusions with respect to electrodynamics. And contrary to Albert Einstein
, he didn't connected his rejection of the aether with the relativity of space and time.
In 1904 he developed a theory of electron
s in which the electrons contract in the line of motion and expand perpendicular to it. Independently of him Paul Langevin
developed a very similar model in 1905. The Bucherer-Langevin model was an alternative to the electron models of:
All three models predicted an increase of the electron mass if their velocities are approaching the speed of light
. The Bucherer-Langevin model was quickly abandoned, so some experimentalists tried to distinguish between Abraham's theory and the Lorentz-Einstein theory by experiment. This was done by Walter Kaufmann
(1901–1905) who believed that his experiments confirmed Abraham's theory, and disproved the Lorentz-Einstein theory. But in 1908 Bucherer conducted some experiments as well, and obtained results which seem to confirm the Lorentz-Einstein theory and the principle of relativity. With exceptions like Adolf Bestelmeyer
with whom Bucherer had a polemical dispute, Bucherer's experiments were regarded as decisive. But it was shown in 1938 that all those experiments of Kaufmann, Bucherer, Neumann etc. showed only a qualitative increase in mass, but were too imprecise to distinguish between the different models. This lasted until 1940, when similar experimental equipments were sufficiently accurate to confirm the Lorentz-Einstein formula.
Bucherer (1906) was the first who used — during some critical remarks on Einstein's theory — the expression "Einsteinian relativity theory / theory of relativity" ("Einsteinsche Relativitätstheorie"). This was based on Max Planck
's term "relative theory" for the Lorentz-Einstein theory. And in 1908 Bucherer himself rejected his own version of the relativity principle, and accepted the "Lorentz-Einstein theory".
Later (1923, 1924), Bucherer criticized general relativity
in some papers. However, this criticism was rejected because Bucherer misinterpreted Einstein's equivalence hypothesis.
Cologne
Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...
; † April 16, 1927 in Bonn
Bonn
Bonn is the 19th largest city in Germany. Located in the Cologne/Bonn Region, about 25 kilometres south of Cologne on the river Rhine in the State of North Rhine-Westphalia, it was the capital of West Germany from 1949 to 1990 and the official seat of government of united Germany from 1990 to 1999....
) 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...
, who is known for his experiments on relativistic mass. He also was the first who used the phrase "theory of relativity
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
" for Einstein's theory of special relativity
Special relativity
Special relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...
.
Education
He studied from 1884 until 1899 at the University of Hannover, the Johns Hopkins UniversityJohns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
, the University of Strassburg, the University of Leipzig
University of Leipzig
The University of Leipzig , located in Leipzig in the Free State of Saxony, Germany, is one of the oldest universities in the world and the second-oldest university in Germany...
, and the University of Bonn
University of Bonn
The University of Bonn is a public research university located in Bonn, Germany. Founded in its present form in 1818, as the linear successor of earlier academic institutions, the University of Bonn is today one of the leading universities in Germany. The University of Bonn offers a large number...
. In Bonn he habilitated
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...
in 1899 and taught there until 1923.
In 1903 Bucherer published the first German-language book to be completely based on vector calculus.
Theory of relativity
Like Henri PoincaréHenri Poincaré
Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...
(1895, 1900), Bucherer (1903b) believed in the validity of the Principle of relativity
Principle of relativity
In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference....
, i.e. that all descriptions of electrodynamic effects should only contain the relative motion of bodies, not of the aether. However, he went a step further and even assumed the physical non-existence of the aether. Based on those ideas he developed a theory in 1906, which also included the assumption that the geometry of space is riemannian
Riemannian geometry
Riemannian geometry is the branch of differential geometry that studies Riemannian manifolds, smooth manifolds with a Riemannian metric, i.e. with an inner product on the tangent space at each point which varies smoothly from point to point. This gives, in particular, local notions of angle, length...
. But the theory was vaguely formulated and in 1908 Walter Ritz
Walter Ritz
Walther Ritz was a Swiss theoretical physicist.His father, Raphael Ritz, a native of Valais, was a well-known landscape and interior scenes artist. His mother was the daughter of the engineer Noerdlinger of Tübingen. Ritz studied in Zurich and Göttingen...
showed that Bucherer's theory leads to wrong conclusions with respect to electrodynamics. And contrary 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...
, he didn't connected his rejection of the aether with the relativity of space and time.
In 1904 he developed a theory of electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s in which the electrons contract in the line of motion and expand perpendicular to it. Independently of him Paul Langevin
Paul Langevin
Paul Langevin was a prominent French physicist who developed Langevin dynamics and the Langevin equation. He was one of the founders of the Comité de vigilance des intellectuels antifascistes, an antifascist organization created in the wake of the 6 February 1934 far right riots...
developed a very similar model in 1905. The Bucherer-Langevin model was an alternative to the electron models of:
- Hendrik LorentzHendrik LorentzHendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect...
(1899), Henri PoincaréHenri PoincaréJules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and a philosopher of science...
(1905, 1906) and Albert EinsteinAlbert EinsteinAlbert 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...
(1905). in which the electrons are subjected to length contractionLength contractionIn physics, length contraction – according to Hendrik Lorentz – is the physical phenomenon of a decrease in length detected by an observer of objects that travel at any non-zero velocity relative to that observer...
without expansion in the other direction - and the model of Max AbrahamMax AbrahamMax Abraham was a German physicist.Abraham was born in Danzig, Imperial Germany to a family of Jewish merchants. His father was Moritz Abraham and his mother was Selma Moritzsohn. Attending the University of Berlin, he studied under Max Planck. He graduated in 1897...
, in which the electron is rigid.
All three models predicted an increase of the electron mass if their velocities are approaching 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...
. The Bucherer-Langevin model was quickly abandoned, so some experimentalists tried to distinguish between Abraham's theory and the Lorentz-Einstein theory by experiment. This was done by Walter Kaufmann
Walter Kaufmann (physicist)
Walter Kaufmann was a German physicist. He is most well known for his first experimental proof of the velocity dependence of mass, which was an important contribution to the development of modern physics, including special relativity.-Life:In 1890/91 he studied mechanical engineering at the...
(1901–1905) who believed that his experiments confirmed Abraham's theory, and disproved the Lorentz-Einstein theory. But in 1908 Bucherer conducted some experiments as well, and obtained results which seem to confirm the Lorentz-Einstein theory and the principle of relativity. With exceptions like Adolf Bestelmeyer
Adolf Bestelmeyer
Adolf Bestelmeyer was a German experimental physicist.-Life and work:...
with whom Bucherer had a polemical dispute, Bucherer's experiments were regarded as decisive. But it was shown in 1938 that all those experiments of Kaufmann, Bucherer, Neumann etc. showed only a qualitative increase in mass, but were too imprecise to distinguish between the different models. This lasted until 1940, when similar experimental equipments were sufficiently accurate to confirm the Lorentz-Einstein formula.
Bucherer (1906) was the first who used — during some critical remarks on Einstein's theory — the expression "Einsteinian relativity theory / theory of relativity" ("Einsteinsche Relativitätstheorie"). This was based on Max Planck
Max Planck
Max Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came...
's term "relative theory" for the Lorentz-Einstein theory. And in 1908 Bucherer himself rejected his own version of the relativity principle, and accepted the "Lorentz-Einstein theory".
Later (1923, 1924), Bucherer criticized general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
in some papers. However, this criticism was rejected because Bucherer misinterpreted Einstein's equivalence hypothesis.