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Walter Kaufmann (physicist)
Encyclopedia
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
.
at the technical universities of Berlin
and Munich
, since 1892 he studied physics
at the Universities of Berlin
and Munich and in 1894 he attained a doctorate
. Starting from 1896 he worked as an assistant at the physical institutes of the Universities of Berlin and Göttingen. Kaufmann habilitated in 1899 and became a professor extraordinarius
of physics in at the University of Bonn
. After a renewed activity at the Berliner Physikalisches Institut he followed a call as professor ordinarius for experimental physics
and leader of the physical institute at the Albertina in Königsberg
, where he taught up to his retirement in 1935. Subsequently, he worked as a guest lecturer at the University of Freiburg
.
of the electron (later called relativistic mass
). However, those measurements were not precise enough to differentiate between the Lorentz ether theory
of Hendrik Antoon Lorentz and the theory of Max Abraham
.
At the end of 1905 he performed experiments that were still more exact. Here Kaufmann was the first to discuss Albert Einstein
's theory of special relativity
and argued, that although Einstein's theory is based on completely different conditions and is also logically more satisfying, the theory is observationally equivalent to Lorentz's theory. Therefore he spoke of the theory of "Lorentz-Einstein". It is notable that Kaufmann himself interpreted the results of his experiments as a confirmation of Abraham's theory, and a refutation of the Lorentz-Einstein principle of relativity
, which for some years weighed heavily against the theories of Lorentz and Einstein. However, Kaufmann's results were criticized by Max Planck
and Adolf Bestelmeyer
in 1906. So physicists like Alfred Bucherer
(1908), Neumann (1914) and others, repeated those experiments and arrived at results which apparently confirmed the "Lorentz Einstein" theory and disproved Abraham's theory. However, it was later pointed out that the Kaufmann-Bucherer-Neumann experiments after 1904 were also not precise enough to distinguish among the theories.
However, this problem occurred only for this kind of experiments. The investigations of the fine structure
of the hydrogen lines
already in 1917 provided a clear confirmation of the Lorentz-Einstein formula, and the refutation of Abraham's theory..
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
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
. 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
Modern physics
The term modern physics refers to the post-Newtonian conception of physics. The term implies that classical descriptions of phenomena are lacking, and that an accurate, "modern", description of reality requires theories to incorporate elements of quantum mechanics or Einsteinian relativity, or both...
, including 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...
.
Life
In 1890/91 he studied mechanical engineeringMechanical engineering
Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...
at the technical universities of Berlin
Technical University of Berlin
The Technische Universität Berlin is a research university located in Berlin, Germany. Translating the name into English is discouraged by the university, however paraphrasing as Berlin Institute of Technology is recommended by the university if necessary .The TU Berlin was founded...
and Munich
Technical University of Munich
The Technische Universität München is a research university with campuses in Munich, Garching, and Weihenstephan...
, since 1892 he studied physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
at the Universities of Berlin
Humboldt University of Berlin
The Humboldt University of Berlin is Berlin's oldest university, founded in 1810 as the University of Berlin by the liberal Prussian educational reformer and linguist Wilhelm von Humboldt, whose university model has strongly influenced other European and Western universities...
and Munich and in 1894 he attained a doctorate
Doctorate
A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder to teach in a specific field, A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder...
. Starting from 1896 he worked as an assistant at the physical institutes of the Universities of Berlin and Göttingen. Kaufmann habilitated in 1899 and became a professor extraordinarius
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
of physics in at 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...
. After a renewed activity at the Berliner Physikalisches Institut he followed a call as professor ordinarius for experimental physics
Experimental physics
Within the field of physics, experimental physics is the category of disciplines and sub-disciplines concerned with the observation of physical phenomena in order to gather data about the universe...
and leader of the physical institute at the Albertina in Königsberg
University of Königsberg
The University of Königsberg was the university of Königsberg in East Prussia. It was founded in 1544 as second Protestant academy by Duke Albert of Prussia, and was commonly known as the Albertina....
, where he taught up to his retirement in 1935. Subsequently, he worked as a guest lecturer at the University of Freiburg
University of Freiburg
The University of Freiburg , sometimes referred to in English as the Albert Ludwig University of Freiburg, is a public research university located in Freiburg im Breisgau, Baden-Württemberg, Germany.The university was founded in 1457 by the Habsburg dynasty as the...
.
Measurements of velocity dependence of mass
His early work (1901-1903) confirmed for the first time the velocity dependence of the electromagnetic massElectromagnetic mass
Electromagnetic mass was initially a concept of classical mechanics, denoting as to how much the electromagnetic field, or the self-energy, is contributing to the mass of charged particles. It was first derived by J. J. Thomson in 1881 and was for some time also considered as a dynamical...
of the electron (later called relativistic mass
Mass in special relativity
Mass in special relativity incorporates the general understandings from the concept of mass-energy equivalence. Added to this concept is an additional complication resulting from the fact that "mass" is defined in two different ways in special relativity: one way defines mass as an invariant...
). However, those measurements were not precise enough to differentiate between the Lorentz ether theory
Lorentz ether theory
What is now often called Lorentz Ether theory has its roots in Hendrik Lorentz's "Theory of electrons", which was the final point in the development of the classical aether theories at the end of the 19th and at the beginning of the 20th century....
of Hendrik Antoon Lorentz and the theory of Max Abraham
Max Abraham
Max 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...
.
At the end of 1905 he performed experiments that were still more exact. Here Kaufmann was the first to discuss 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 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...
and argued, that although Einstein's theory is based on completely different conditions and is also logically more satisfying, the theory is observationally equivalent to Lorentz's theory. Therefore he spoke of the theory of "Lorentz-Einstein". It is notable that Kaufmann himself interpreted the results of his experiments as a confirmation of Abraham's theory, and a refutation of the Lorentz-Einstein 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....
, which for some years weighed heavily against the theories of Lorentz and Einstein. However, Kaufmann's results were criticized by 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...
and Adolf Bestelmeyer
Adolf Bestelmeyer
Adolf Bestelmeyer was a German experimental physicist.-Life and work:...
in 1906. So physicists like Alfred Bucherer
Alfred Bucherer
Alfred Heinrich Bucherer was a German physicist, who is known for his experiments on relativistic mass...
(1908), Neumann (1914) and others, repeated those experiments and arrived at results which apparently confirmed the "Lorentz Einstein" theory and disproved Abraham's theory. However, it was later pointed out that the Kaufmann-Bucherer-Neumann experiments after 1904 were also not precise enough to distinguish among the theories.
However, this problem occurred only for this kind of experiments. The investigations of the fine structure
Fine structure
In atomic physics, the fine structure describes the splitting of the spectral lines of atoms due to first order relativistic corrections.The gross structure of line spectra is the line spectra predicted by non-relativistic electrons with no spin. For a hydrogenic atom, the gross structure energy...
of the hydrogen lines
Balmer series
The Balmer series or Balmer lines in atomic physics, is the designation of one of a set of six different named series describing the spectral line emissions of the hydrogen atom....
already in 1917 provided a clear confirmation of the Lorentz-Einstein formula, and the refutation of Abraham's theory..
External links
- The Kaufmann Experiments (Power point presentation)
- http://www-atm.jst.go.jp:8080/16030302_1.html (Japanese)
- Viaje medios de comunicación compras at itfisica.net at itfisica.net (Italian)
- Zeittafel (timetable about physics)