Criticism of the theory of relativity
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Criticism of the theory of relativity of Albert Einstein was mainly expressed in the early years after its publication in the early twentieth century, on scientific,
pseudoscientific Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claim ...
, philosophical, or ideological bases.Hentschel (1990)Goenner (1993ab)Wazeck (2009) Though some of these criticisms had the support of reputable scientists, Einstein's theory of relativity is now accepted by the scientific community. Reasons for criticism of the theory of relativity have included alternative theories, rejection of the abstract-mathematical method, and alleged errors of the theory. According to some authors,
antisemitic Antisemitism (also spelled anti-semitism or anti-Semitism) is hostility to, prejudice towards, or discrimination against Jews. A person who holds such positions is called an antisemite. Antisemitism is considered to be a form of racism. Antis ...
objections to Einstein's Jewish heritage also occasionally played a role in these objections. There are still some critics of relativity today, but their opinions are not shared by the majority in the scientific community.Farrell (2007)Wazeck (2010)


Special relativity


Relativity principle versus electromagnetic worldview

Around the end of the 19th century, the view was widespread that all forces in nature are of electromagnetic origin (the " electromagnetic worldview"), especially in the works of Joseph Larmor (1897) and Wilhelm Wien (1900). This was apparently confirmed by the experiments of Walter Kaufmann (1901–1903), who measured an increase of the mass of a body with velocity which was consistent with the hypothesis that the mass was generated by its electromagnetic field. Max Abraham (1902) subsequently sketched a theoretical explanation of Kaufmann's result in which the electron was considered as rigid and spherical. However, it was found that this model was incompatible with the results of many experiments (including the Michelson–Morley experiment, the
Experiments of Rayleigh and Brace The experiments of Rayleigh and Brace (1902, 1904) were aimed to show whether length contraction leads to birefringence or not. They were some of the first optical experiments measuring the relative motion of Earth and the luminiferous aether which ...
, and the
Trouton–Noble experiment The Trouton–Noble experiment was an attempt to detect motion of the Earth through the luminiferous aether, and was conducted in 1901–1903 by Frederick Thomas Trouton and H. R. Noble. It was based on a suggestion by George FitzGerald that ...
), according to which no motion of an observer with respect to the luminiferous aether ("aether drift") had been observed despite numerous attempts to do so.
Henri Poincaré Jules Henri Poincaré ( S: stress final syllable ; 29 April 1854 – 17 July 1912) was a French mathematician, theoretical physicist, engineer, and philosopher of science. He is often described as a polymath, and in mathematics as "The ...
(1902) conjectured that this failure arose from a general law of nature, which he called "the
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. For example, in the framework of special relativity the Maxwell equations have ...
". Hendrik Antoon Lorentz (1904) created a detailed theory of electrodynamics ( Lorentz ether theory) that was premised on the existence of an immobile aether and employed a set of space and time coordinate transformations that Poincaré called the Lorentz transformations, including the effects of
length contraction Length contraction is the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. It is also known as Lorentz contraction or Lorentz–FitzGerald ...
and local time. However, Lorentz's theory only partially satisfied the relativity principle, because his transformation formulas for velocity and charge density were incorrect. This was corrected by Poincaré (1905) who obtained full Lorentz covariance of the electrodynamic equations.Miller (1981), pp. 47–75Lorentz (1904) Criticizing Lorentz's 1904 theory, Abraham (1904) held that the Lorentz contraction of electrons requires a non-electromagnetic force to ensure the electron's stability. This was unacceptable to him as a proponent of the electromagnetic worldview. He continued that as long as a consistent explanation is missing as to how those forces and potentials act together on the electron, Lorentz's system of hypotheses is incomplete and doesn't satisfy the relativity principle.Miller (1981), pp. 75–85Abraham (1904) Poincaré (1905) removed this objection by showing that the non-electromagnetic potential (" Poincaré stress") holding the electron together can be formulated in a Lorentz covariant way, and showed that in principle it is possible to create a Lorentz covariant model for gravitation which he considered non-electromagnetic in nature as well.Poincaré (1906) Thus the consistency of Lorentz's theory was proven, but the electromagnetic worldview had to be given up.Darrigol (2000), pp. 372–392Janssen (2007), pp. 25–34 Eventually, Albert Einstein published in September 1905 what is now called special relativity, which was based on a radical new application of the relativity principle in connection with the constancy of the speed of light. In special relativity, the space and time coordinates depend on the inertial observer's frame of reference, and the luminiferous aether plays no role in the physics. Although this theory was founded on a very different kinematical model, it was experimentally indistinguishable from the aether theory of Lorentz and Poincaré, since both theories satisfy the relativity principle of Poincaré and Einstein, and both employ the Lorentz transformations. After Minkowski's introduction in 1908 of the geometric spacetime model for Einstein's version of relativity, most physicists eventually decided in favor of the Einstein-Minkowski version of relativity with its radical new views of space and time, in which there was no useful role for the aether.Einstein (1905)


Claimed experimental refutations

Kaufmann–Bucherer–Neumann experiments: To conclusively decide between the theories of Abraham and Lorentz, Kaufmann repeated his experiments in 1905 with improved accuracy. However, in the meantime the theoretical situation had changed.
Alfred Bucherer Alfred Heinrich Bucherer (* 9 July 1863 in Cologne; † 16 April 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 ...
and Paul Langevin (1904) developed another model, in which the electron is contracted in the line of motion, and dilated in the transverse direction, so that the volume remains constant. While Kaufmann was still evaluating his experiments, Einstein published his theory of special relativity. Eventually, Kaufmann published his results in December 1905 and argued that they are in agreement with Abraham's theory and require rejection of the "basic assumption of Lorentz and Einstein" (the relativity principle). Lorentz reacted with the phrase "I am at the end of my Latin", while Einstein did not mention those experiments before 1908. Yet, others started to criticize the experiments. Max Planck (1906) alluded to inconsistencies in the theoretical interpretation of the data, and Adolf Bestelmeyer (1906) introduced new techniques, which (especially in the area of low velocities) gave different results and which cast doubts on Kaufmann's methods. Therefore, Bucherer (1908) conducted new experiments and arrived at the conclusion that they confirm the mass formula of relativity and thus the "relativity principle of Lorentz and Einstein". Yet Bucherer's experiments were criticized by Bestelmeyer leading to a sharp dispute between the two experimentalists. On the other hand, additional experiments of Hupka (1910), Neumann (1914) and others seemed to confirm Bucherer's result. The doubts lasted until 1940, when in similar experiments Abraham's theory was conclusively disproved. (It must be remarked that besides those experiments, the relativistic mass formula had already been confirmed by 1917 in the course of investigations on the theory of spectra. In modern particle accelerators, the relativistic mass formula is routinely confirmed.)Pauli (1921), pp. 636–637Pauli (1981), pp. 334–352Staley (2009), pp. 219–259Planck (1906b)Bucherer (1908)Kaufmann (1906) In 1902–1906,
Dayton Miller Dayton Clarence Miller (March 13, 1866 – February 22, 1941) was an American physicist, astronomer, acoustician, and accomplished amateur flautist. An early experimenter of X-rays, Miller was an advocate of aether theory and absolute space ...
repeated the Michelson–Morley experiment together with
Edward W. Morley Edward Williams Morley (January 29, 1838 – February 24, 1923) was an American scientist known for his precise and accurate measurement of the atomic weight of oxygen, and for the Michelson–Morley experiment. Biography Morley was born in New ...
. They confirmed the null result of the initial experiment. However, in 1921–1926, Miller conducted new experiments which apparently gave positive results.Miller (1933) Those experiments initially attracted some attention in the media and in the scientific communityLalli (2012), pp. 171–186 but have been considered refuted for the following reasons:Swenson (1970), pp. 63–68Lalli (2012), pp. 187–212. Einstein,
Max Born Max Born (; 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a n ...
, and
Robert S. Shankland Robert Sherwood Shankland (January 11, 1908 – March 1, 1982) was an American physicist and historian. Biography Robert S. Shankland was an undergraduate at the Case School for Applied Sciences from 1925–1929 and received his master's degre ...
pointed out that Miller had not appropriately considered the influence of temperature. A modern analysis by Roberts shows that Miller's experiment gives a null result, when the technical shortcomings of the apparatus and the error bars are properly considered.Roberts (2006) Additionally, Miller's result is in disagreement with all other experiments, which were conducted before and after. For example, Georg Joos (1930) used an apparatus of similar dimensions to Miller's, but he obtained null results. In recent experiments of Michelson–Morley type where the coherence length is increased considerably by using lasers and masers the results are still negative. In the 2011 Faster-than-light neutrino anomaly, the OPERA collaboration published results which appeared to show that the speed of neutrinos is slightly faster than the speed of light. However, sources of errors were found and confirmed in 2012 by the OPERA collaboration, which fully explained the initial results. In their final publication, a neutrino speed consistent with the speed of light was stated. Also subsequent experiments found agreement with the speed of light, see measurements of neutrino speed.


Acceleration in special relativity

It was also claimed that special relativity cannot handle acceleration, which would lead to contradictions in some situations. However, this assessment is not correct, since acceleration actually can be described in the framework of special relativity (see Acceleration (special relativity), Proper reference frame (flat spacetime), Hyperbolic motion,
Rindler coordinates In relativistic physics, the coordinates of a ''hyperbolically accelerated reference frame'' constitute an important and useful coordinate chart representing part of flat Minkowski spacetime. In special relativity, a uniformly accelerating particle ...
,
Born coordinates In relativistic physics, the Born coordinate chart is a coordinate chart for (part of) Minkowski spacetime, the flat spacetime of special relativity. It is often used to analyze the physical experience of observers who ride on a ring or disk r ...
). Paradoxes relying on insufficient understanding of these facts were discovered in the early years of relativity. For example,
Max Born Max Born (; 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a n ...
(1909) tried to combine the concept of rigid bodies with special relativity. That this model was insufficient was shown by Paul Ehrenfest (1909), who demonstrated that a rotating rigid body would, according to Born's definition, undergo a contraction of the circumference without contraction of the radius, which is impossible ( Ehrenfest paradox).
Max von Laue Max Theodor Felix von Laue (; 9 October 1879 – 24 April 1960) was a German physicist who received the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals. In addition to his scientific endeavors with cont ...
(1911) showed that rigid bodies cannot exist in special relativity, since the propagation of signals cannot exceed the speed of light, so an accelerating and rotating body will undergo deformations.Pauli (1920), pp. 689–691Born (1909)Laue (1911)Ehrenfest (1909) Paul Langevin and von Laue showed that the twin paradox can be completely resolved by consideration of acceleration in special relativity. If two twins move away from each other, and one of them is accelerating and coming back to the other, then the accelerated twin is younger than the other one, since he was located in at least two inertial frames of reference, and therefore his assessment of which events are simultaneous changed during the acceleration. For the other twin nothing changes since he remained in a single frame.Laue (1921a), pp. 59, 75–76Langevin (1911) Another example is the Sagnac effect. Two signals were sent in opposite directions around a rotating platform. After their arrival a displacement of the interference fringes occurs. Sagnac himself believed that he had proved the existence of the aether. However, special relativity can easily explain this effect. When viewed from an inertial frame of reference, it is a simple consequence of the independence of the speed of light from the speed of the source, since the receiver runs away from one beam, while it approaches the other beam. When viewed from a rotating frame, the assessment of simultaneity changes during the rotation, and consequently the speed of light is not constant in accelerated frames.Laue (1921a), pp. 25–26, 128–130Langevin (1921) As was shown by Einstein, the only form of accelerated motion that cannot be non-locally described is the one due to
gravitation In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stron ...
. Einstein was also unsatisfied with the fact that inertial frames are preferred over accelerated frames. Thus over the course of several years (1908–1915), Einstein developed general relativity. This theory includes the replacement of Euclidean geometry by non-Euclidean geometry, and the resultant curvature of the path of light led Einstein (1912) to the conclusion that (like in extended accelerated frames) the speed of light is not constant in extended gravitational fields. Therefore, Abraham (1912) argued that Einstein had given special relativity a coup de grâce. Einstein responded that within its area of application (in areas where gravitational influences can be neglected) special relativity is still applicable with high precision, so one cannot speak of a coup de grâce at all.Pais (1982), pp. 177–207, 230–232Einstein (1908)Einstein (1912)Einstein (1916)Abraham (1912)


Superluminal speeds

In special relativity, the transfer of signals at superluminal speeds is impossible, since this would violate the Poincaré- Einstein synchronization, and the
causality Causality (also referred to as causation, or cause and effect) is influence by which one event, process, state, or object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the cau ...
principle. Following an old argument by Pierre-Simon Laplace, Poincaré (1904) alluded to the fact that Newton's law of universal gravitation is founded on an infinitely great
speed of gravity In classical theories of gravitation, the changes in a gravitational field propagate. A change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational field which it produces. In ...
. So the clock-synchronization by light signals could in principle be replaced by a clock-synchronization by instantaneous gravitational signals. In 1905, Poincaré himself solved this problem by showing that in a relativistic theory of gravity the speed of gravity is equal to the speed of light. Although much more complicated, this is also the case in Einstein's theory of general relativity.Poincaré (1906)Carlip (1999)Poincaré (1904) Another apparent contradiction lies in the fact that the
group velocity The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the ''modulation'' or ''envelope'' of the wave—propagates through space. For example, if a stone is thrown into the middl ...
in anomalously dispersive media is higher than the speed of light. This was investigated by
Arnold Sommerfeld Arnold Johannes Wilhelm Sommerfeld, (; 5 December 1868 – 26 April 1951) was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and mentored many students for the new era of theoretica ...
(1907, 1914) and Léon Brillouin (1914). They came to the conclusion that in such cases the signal velocity is not equal to the group velocity, but to the
front velocity In physics, front velocity is the speed at which the first rise of a pulse above zero moves forward. In mathematics, it is used to describe the velocity of a propagating front in the solution of hyperbolic partial differential equation. Various ...
which is never faster than the speed of light. Similarly, it is also argued that the apparent superluminal effects discovered by
Günter Nimtz Günter Nimtz (born 22 September 1936) is a German physicist, working at the 2nd Physics Institute at the University of Cologne in Germany. He has investigated narrow-gap semiconductors and liquid crystals. His claims show that particles may tra ...
can be explained by a thorough consideration of the velocities involved.Pauli (1921), 672–673PhysicsFaq: FTLSommerfeld (1907, 1914)Brillouin (1914) Also quantum entanglement (denoted by Einstein as "spooky action at a distance"), according to which the quantum state of one entangled particle cannot be fully described without describing the other particle, does not imply superluminal transmission of information (see quantum teleportation), and it is therefore in conformity with special relativity.


Paradoxes

Insufficient knowledge of the basics of special relativity, especially the application of the Lorentz transformation in connection with
length contraction Length contraction is the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. It is also known as Lorentz contraction or Lorentz–FitzGerald ...
and time dilation, led and still leads to the construction of various apparent paradoxes. Both the twin paradox and the Ehrenfest paradox and their explanation were already mentioned above. Besides the twin paradox, also the reciprocity of time dilation (''i.e.'' every inertially moving observer considers the clock of the other one as being dilated) was heavily criticized by Herbert Dingle and others. For example, Dingle wrote a series of letters to Nature at the end of the 1950s. However, the self-consistency of the reciprocity of time dilation had already been demonstrated long before in an illustrative way by Lorentz (in his lectures from 1910, published 1931Miller (1981), pp. 257–264) and many others—they alluded to the fact that it is only necessary to carefully consider the relevant measurement rules and the
relativity of simultaneity In physics, the relativity of simultaneity is the concept that ''distant simultaneity'' – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame. This possi ...
. Other known paradoxes are the Ladder paradox and Bell's spaceship paradox, which also can simply be solved by consideration of the relativity of simultaneity.Chang (1993)Mathpages: DingleDingle (1972)


Aether and absolute space

Many physicists (like
Hendrik Lorentz Hendrik Antoon Lorentz (; 18 July 1853 – 4 February 1928) 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. He also derived the Lorentz t ...
, Oliver Lodge, Albert Abraham Michelson,
Edmund Taylor Whittaker Sir Edmund Taylor Whittaker (24 October 1873 – 24 March 1956) was a British mathematician, physicist, and historian of science. Whittaker was a leading mathematical scholar of the early 20th-century who contributed widely to applied mathema ...
,
Harry Bateman Harry Bateman FRS (29 May 1882 – 21 January 1946) was an English mathematician with a specialty in differential equations of mathematical physics. With Ebenezer Cunningham, he expanded the views of spacetime symmetry of Lorentz and Poincare ...
, Ebenezer Cunningham, Charles Émile Picard,
Paul Painlevé Paul Painlevé (; 5 December 1863 – 29 October 1933) was a French mathematician and statesman. He served twice as Prime Minister of the Third Republic: 12 September – 13 November 1917 and 17 April – 22 November 1925. His entry into politic ...
) were uncomfortable with the rejection of the
aether Aether, æther or ether may refer to: Metaphysics and mythology * Aether (classical element), the material supposed to fill the region of the universe above the terrestrial sphere * Aether (mythology), the personification of the "upper sky", sp ...
, and preferred to interpret the Lorentz transformation based on the existence of a preferred frame of reference, as in the aether-based theories of Lorentz, Larmor, and Poincaré. However, the idea of an aether hidden from any observation was not supported by the mainstream scientific community, therefore the aether theory of Lorentz and Poincaré was superseded by Einstein's special relativity which was subsequently formulated in the framework of four-dimensional spacetime by Minkowski.Miller (1983), pp. 216–217Warwick (2003), pp. 410–419, 469–475Paty (1987), pp. 145–147Lodge (1925)Michelson (1927)Prokhovnik (1963) Others such as Herbert E. Ives argued that it might be possible to experimentally determine the motion of such an aether,Ives (1951) but it was never found despite numerous experimental tests of Lorentz invariance (see
tests of special relativity Special relativity is a physical theory that plays a fundamental role in the description of all physical phenomena, as long as gravitation is not significant. Many experiments played (and still play) an important role in its development and justific ...
). Also attempts to introduce some sort of relativistic aether (consistent with relativity) into modern physics such as by Einstein on the basis of general relativity (1920), or by Paul Dirac in relation to quantum mechanics (1951), were not supported by the scientific community (see Luminiferous aether#End of aether?).Kragh (1990), pp. 189–205Dirac (1951) In his
Nobel lecture The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfre ...
,
George F. Smoot George Fitzgerald Smoot III (born February 20, 1945) is an American astrophysics, astrophysicist, cosmology, cosmologist, Nobel laureate, and the 2nd contestant to win the $1 million prize on ''Are You Smarter than a 5th Grader? (U.S. game show ...
(2006) described his own experiments on the Cosmic microwave background radiation anisotropy as "New Aether drift experiments". Smoot explained that "one problem to overcome was the strong prejudice of good scientists who learned the lesson of the Michelson and Morley experiment and Special Relativity that there were no preferred frames of reference." He continued that "there was an education job to convince them that this did not violate Special Relativity but did find a frame in which the expansion of the universe looked particularly simple."Smoot (2006), pp. 123–124


Alternative theories

The theory of complete
aether drag In the 19th century, the theory of the luminiferous aether as the hypothetical medium for the propagation of light waves was widely discussed. The aether hypothesis arose because physicists of that era could not conceive of light waves propagating ...
, as proposed by George Gabriel Stokes (1844), was used by some critics as
Ludwig Silberstein Ludwik Silberstein (1872 – 1948) was a Polish people, Polish-American physicist who helped make special relativity and general relativity staples of university coursework. His textbook ''List of publications in physics#Special theory of relativi ...
(1920) or Philipp Lenard (1920) as a counter-model of relativity. In this theory, the aether was completely dragged within and in the vicinity of matter, and it was believed that various phenomena, such as the absence of aether drift, could be explained in an "illustrative" way by this model. However, such theories are subject to great difficulties. Especially the aberration of light contradicted the theory, and all auxiliary hypotheses, which were invented to rescue it, are self-contradictory, extremely implausible, or in contradiction to other experiments like the
Michelson–Gale–Pearson experiment The Michelson–Gale–Pearson experiment (1925) is a modified version of the Michelson–Morley experiment and the Sagnac-Interferometer. It measured the Sagnac effect due to Earth's rotation, and thus tests the theories of special relativity and ...
. In summary, a sound mathematical and physical model of complete aether drag was never invented, consequently this theory was no serious alternative to relativity.Joos (1959), pp. 448ffMichelson (1925)Lenard (1921a)Silberstein (1921a) Another alternative was the so-called emission theory of light. As in special relativity the aether concept is discarded, yet the main difference from relativity lies in the fact that the velocity of the light source is added to that of light in accordance with the
Galilean transformation In physics, a Galilean transformation is used to transform between the coordinates of two reference frames which differ only by constant relative motion within the constructs of Newtonian physics. These transformations together with spatial rotatio ...
. As the hypothesis of complete aether drag, it can explain the negative outcome of all aether drift experiments. Yet, there are various experiments that contradict this theory. For example, the Sagnac effect is based on the independence of light speed from the source velocity, and the image of
Double star In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a bi ...
s should be scrambled according to this model—which was not observed. Also in modern experiments in particle accelerators no such velocity dependence could be observed.Norton (2004), pp. 14–22De Sitter (1913)Fox (1965)Ritz (1908) These results are further confirmed by the
De Sitter double star experiment The de Sitter effect was described by Willem de Sitter in 1913 (as well as by Daniel Frost Comstock in 1910) and used to support the special theory of relativity against a competing 1908 emission theory by Walther Ritz that postulated a variable ...
(1913), conclusively repeated in the X-ray spectrum by K. Brecher in 1977; and the terrestrial experiment by Alväger, ''et al''. (1963);, which all show that the speed of light is independent of the motion of the source within the limits of experimental accuracy.


Principle of the constancy of the speed of light

Some consider the ''principle of the constancy of the velocity of light'' insufficiently substantiated. However, as already shown by
Robert Daniel Carmichael Robert Daniel Carmichael (March 1, 1879 – May 2, 1967) was an American mathematician. Biography Carmichael was born in Goodwater, Alabama. He attended Lineville College, briefly, and he earned his bachelor's degree in 1898, while he was st ...
(1910) and others, the constancy of the speed of light can be interpreted as a natural consequence of ''two'' experimentally demonstrated facts:Hentschel (1990), pp. 343–348.Carmichael (1910) # The velocity of light is independent of the ''velocity of the source'', as demonstrated by
De Sitter double star experiment The de Sitter effect was described by Willem de Sitter in 1913 (as well as by Daniel Frost Comstock in 1910) and used to support the special theory of relativity against a competing 1908 emission theory by Walther Ritz that postulated a variable ...
, Sagnac effect, and many others (see emission theory). # The velocity of light is independent of the direction of ''velocity of the observer'', as demonstrated by Michelson–Morley experiment,
Kennedy–Thorndike experiment The Kennedy–Thorndike experiment, first conducted in 1932 by Roy J. Kennedy and Edward M. Thorndike, is a modified form of the Michelson–Morley experimental procedure, testing special relativity. The modification is to make one arm of the class ...
, and many others (see luminiferous aether). Note that measurements regarding the speed of light are actually measurements of the two-way speed of light, since the one-way speed of light depends on which convention is chosen to synchronize the clocks.


General relativity


General covariance

Einstein emphasized the importance of
general covariance In theoretical physics, general covariance, also known as diffeomorphism covariance or general invariance, consists of the invariance of the ''form'' of physical laws under arbitrary differentiable coordinate transformations. The essential idea is ...
for the development of general relativity, and took the position that the general covariance of his 1915 theory of gravity ensured implementation of a generalized relativity principle. This view was challenged by
Erich Kretschmann Erich Justus Kretschmann (14 July 1887 – 1973) was a German physicist. (Gebhardt gives a list of Kretschmann's publications.) Life Kretschmann was born in Berlin. He obtained his PhD at Berlin University in 1914 with his dissertation entitled ...
(1917), who argued that every theory of space and time (even including Newtonian dynamics) can be formulated in a covariant way, if additional parameters are included, and thus general covariance of a theory would in itself be insufficient to implement a generalized relativity principle. Although Einstein (1918) agreed with that argument, he also countered that Newtonian mechanics in general covariant form would be too complicated for practical uses. Although it is now understood that Einstein's response to Kretschmann was mistaken (subsequent papers showed that such a theory would still be usable), another argument can be made in favor of general covariance: it is a natural way to express the
equivalence principle In the theory of general relativity, the equivalence principle is the equivalence of gravitational and inertial mass, and Albert Einstein's observation that the gravitational "force" as experienced locally while standing on a massive body (suc ...
, ''i.e.'', the equivalence in the description of a free-falling observer and an observer at rest, and thus it is more convenient to use general covariance together with general relativity, rather than with Newtonian mechanics. Connected with this, also the question of absolute motion was dealt with. Einstein argued that the general covariance of his theory of gravity supports Mach's principle, which would eliminate any "absolute motion" within general relativity. However, as pointed out by Willem de Sitter in 1916, Mach's principle is not completely fulfilled in general relativity because there exist matter-free solutions of the field equations. This means that the "inertio-gravitational field", which describes both gravity and inertia, can exist in the absence of gravitating matter. However, as pointed out by Einstein, there is one fundamental difference between this concept and absolute space of Newton: the inertio-gravitational field of general relativity is determined by matter, thus it is not absolute.Janssen (2008), pp. 3–4, 17–18, 28–38Norton (1993)De Sitter (1916ab)Kretschmann (1917)Einstein (1920, 1924)


Bad Nauheim Debate

In the "Bad Nauheim Debate" (1920) between Einstein and (among others) Philipp Lenard, the latter stated the following objections: He criticized the lack of "illustrativeness" of Einstein's version of relativity, a condition that he suggested could only be met by an aether theory. Einstein responded that for physicists the content of "illustrativeness" or " common sense" had changed in time, so it could no longer be used as a criterion for the validity of a physical theory. Lenard also argued that with his relativistic theory of gravity Einstein had tacitly reintroduced the aether under the name "space". While this charge was rejected (among others) by
Hermann Weyl Hermann Klaus Hugo Weyl, (; 9 November 1885 – 8 December 1955) was a German mathematician, theoretical physicist and philosopher. Although much of his working life was spent in Zürich, Switzerland, and then Princeton, New Jersey, he is assoc ...
, in an inaugural address given at the University of Leiden in 1920, shortly after the Bad Nauheim debates, Einstein himself acknowledged that according to his general theory of relativity, so-called "empty space" possesses physical properties that influence matter and ''vice versa''. Lenard also argued that Einstein's general theory of relativity admits the existence of superluminal velocities, in contradiction to the principles of special relativity; for example, in a rotating coordinate system in which the Earth is at rest, the distant points of the whole universe are rotating around Earth with superluminal velocities. However, as Weyl pointed out, it is incorrect to handle a rotating extended system as a rigid body (neither in special nor in general relativity)—so the signal velocity of an object never exceeds the speed of light. Another criticism that was raised by both Lenard and Gustav Mie concerned the existence of "fictitious" gravitational fields in accelerating frames, which according to Einstein's Equivalence Principle are no less physically real than those produced by material sources. Lenard and Mie argued that physical forces can only be produced by real material sources, while the gravitational field that Einstein supposed to exist in an accelerating frame of reference has no concrete physical meaning. Einstein responded that, based on Mach's principle, one can think of these gravitational fields as induced by the distant masses. In this respect the criticism of Lenard and Mie has been vindicated, since according to the modern consensus, in agreement with Einstein's own mature views, Mach's principle as originally conceived by Einstein is not actually supported by general relativity, as already mentioned above.Goenner (1993a), pp. 124–128Lenard, Einstein, Gehrcke, Weyl (1920)


Silberstein–Einstein controversy

Ludwik Silberstein, who initially was a supporter of the special theory, objected at different occasions against general relativity. In 1920 he argued that the deflection of light by the sun, as observed by
Arthur Eddington Sir Arthur Stanley Eddington (28 December 1882 – 22 November 1944) was an English astronomer, physicist, and mathematician. He was also a philosopher of science and a populariser of science. The Eddington limit, the natural limit to the lumin ...
et al. (1919), is not necessarily a confirmation of general relativity, but may also be explained by the Stokes-Planck theory of complete aether drag. However, such models are in contradiction with the aberration of light and other experiments (see "Alternative theories"). In 1935, Silberstein claimed to have found a contradiction in the
Two-body problem in general relativity The two-body problem in general relativity is the determination of the motion and gravitational field of two bodies as described by the field equations of general relativity. Solving the Kepler problem is essential to calculate the bending of lig ...
. The claim was refuted by Einstein and Rosen (1935).Havas (1993), pp. 97–120Einstein/Rosen (1936)Silberstein (1936)


Philosophical criticism

The consequences of relativity, such as the change of ordinary concepts of space and time, as well as the introduction of non-Euclidean geometry in general relativity, were criticized by some philosophers of different
philosophical schools {{Horizontal TOC, nonum=on A * Absurdism * Academic skepticism * Achintya Bheda Abheda * Advaita Vedanta * Agnosticism * Ajātivāda * Ājīvika * Ajñana * Alexandrian school * Analytic philosophy * Analytical Thomism * Anarchist schools of t ...
. Many philosophical critics had insufficient knowledge of the mathematical and formal basis of relativity,Hentschel (1990), Chapter 6.2, pp. 555–557 which led to the criticisms often missing the heart of the matter. For example, relativity was misinterpreted as some form of relativism. However, this is misleading as it was emphasized by Einstein or Planck. On one hand it's true that space and time became relative, and the inertial frames of reference are handled on equal footing. On the other hand, the theory makes natural laws invariant—examples are the constancy of the speed of light, or the covariance of Maxwell's equations. Consequently, Felix Klein (1910) called it the "invariant theory of the Lorentz group" instead of relativity theory, and Einstein (who reportedly used expressions like "absolute theory") sympathized with this expression as well.Hentschel (1990), pp. 92–105, 401–419Klein (1910)Petzoldt (1921)Planck (1925) Critical responses to relativity were also expressed by proponents of neo-Kantianism (
Paul Natorp Paul Gerhard Natorp (24 January 1854 – 17 August 1924) was a German philosopher and educationalist, considered one of the co-founders of the Marburg school of neo-Kantianism. He was known as an authority on Plato. Biography Paul Natorp was b ...
, Bruno Bauch etc.), and
phenomenology Phenomenology may refer to: Art * Phenomenology (architecture), based on the experience of building materials and their sensory properties Philosophy * Phenomenology (philosophy), a branch of philosophy which studies subjective experiences and a ...
( Oskar Becker, Moritz Geiger etc.). While some of them only rejected the philosophical consequences, others rejected also the physical consequences of the theory. Einstein was criticized for violating Immanuel Kant's categoric scheme, ''i.e.'', it was claimed that space-time curvature caused by matter and energy is impossible, since matter and energy already require the concepts of space and time. Also the three-dimensionality of space, Euclidean geometry, and the existence of absolute simultaneity were claimed to be necessary for the understanding of the world; none of them can possibly be altered by empirical findings. By moving all those concepts into a metaphysical area, any form of criticism of Kantianism would be prevented. Other pseudo-Kantians like Ernst Cassirer or
Hans Reichenbach Hans Reichenbach (September 26, 1891 – April 9, 1953) was a leading philosopher of science, educator, and proponent of logical empiricism. He was influential in the areas of science, education, and of logical empiricism. He founded the ''Gesel ...
(1920), tried to modify Kant's philosophy. Subsequently, Reichenbach rejected Kantianism at all and became a proponent of
logical positivism Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
.Hentschel (1990), pp. 199–239, 254–268, 507–526Reichenbach (1920)Cassirer (1921)Natorp (1910)Linke (1921)Friedlaender (1932) Based on
Henri Poincaré Jules Henri Poincaré ( S: stress final syllable ; 29 April 1854 – 17 July 1912) was a French mathematician, theoretical physicist, engineer, and philosopher of science. He is often described as a polymath, and in mathematics as "The ...
's conventionalism, philosophers such as Pierre Duhem (1914) and
Hugo Dingler Hugo Albert Emil Hermann Dingler (July 7, 1881, Munich – June 29, 1954, Munich) was a German scientist and philosopher. Life Hugo Dingler studied mathematics, philosophy, and physics with Felix Klein, Hermann Minkowski, David Hilbert, Edmund Hu ...
(1920) argued that the classical concepts of space, time, and geometry were, and will always be, the most convenient expressions in natural science, therefore the concepts of relativity cannot be correct. This was criticized by proponents of
logical positivism Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
such as Moritz Schlick,
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. He ...
, and Reichenbach. They argued that Poincaré's conventionalism could be modified to bring it into accord with relativity. Although it is true that the basic assumptions of Newtonian mechanics are simpler, it can only be brought into accord with modern experiments by inventing auxiliary hypotheses. On the other hand, relativity doesn't need such hypotheses, thus from a conceptual viewpoint, relativity is in fact simpler than Newtonian mechanics.Hentschel (1990), pp. 293–336Schlick (1921)Reichenbach (1924)Dingler (1922) Some proponents of Philosophy of Life,
Vitalism Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...
, Critical realism (in German speaking countries) argued that there is a fundamental difference between physical, biological and psychological phenomena. For example,
Henri Bergson Henri-Louis Bergson (; 18 October 1859 – 4 January 1941) was a French philosopherHenri Bergson. 2014. Encyclopædia Britannica Online. Retrieved 13 August 2014, from https://www.britannica.com/EBchecked/topic/61856/Henri-Bergson
(1921), who otherwise was a proponent of special relativity, argued that time dilation cannot be applied to biological organisms, therefore he denied the relativistic solution of the twin paradox. However, those claims were rejected by Paul Langevin,
André Metz André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew, and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries. It is a variation ...
and others. Biological organisms consist of physical processes, so there is no reason to assume that they are not subject to relativistic effects like time dilation.Hentschel (1990), pp. 240–243, 441–455Metz (1923)Bergson (1921) Based on the philosophy of Fictionalism, the philosopher
Oskar Kraus Oskar Kraus (24 July 1872 – 26 September 1942) was a Czech philosopher and jurist. Life Oskar Kraus, who converted from the Jewish to the Protestant faith, was born in Prague, the son of Hermann Kraus and Clara Reitler-Eidlitz. In 1899 he mar ...
(1921) and others claimed that the foundations of relativity were only fictitious and even self-contradictory. Examples were the constancy of the speed of light, time dilation, length contraction. These effects appear to be mathematically consistent as a whole, but in reality they allegedly are not true. Yet, this view was immediately rejected. The foundations of relativity (such as the equivalence principle or the relativity principle) are not fictitious, but based on experimental results. Also, effects like constancy of the speed of light and relativity of simultaneity are not contradictory, but complementary to one another.Hentschel (1990), pp. 276–292Kraus (1921) In the Soviet Union (mostly in the 1920s), philosophical criticism was expressed on the basis of
dialectic materialism Dialectical materialism is a philosophy of science, history, and nature developed in Europe and based on the writings of Karl Marx and Friedrich Engels. Marxist dialectics, as a materialist philosophy, emphasizes the importance of real-world con ...
. The theory of relativity was rejected as anti-materialistic and speculative, and a mechanistic worldview based on " common sense" was required as an alternative. Similar criticisms also occurred in the People's Republic of China during the Cultural Revolution. (On the other hand, other philosophers considered relativity as being compatible with Marxism.)Vizgin/Gorelik (1987), pp. 265–326Hu (2007), 549–555


Relativity hype and popular criticism

Although Planck already in 1909 compared the changes brought about by relativity with the Copernican Revolution, and although special relativity was accepted by most of the theoretical physicists and mathematicians by 1911, it was not before publication of the experimental results of the eclipse expeditions (1919) by a group around Arthur Stanley Eddington that relativity was noticed by the public. Following Eddington's publication of the eclipse results, Einstein was glowingly praised in the mass media, and was compared to Nikolaus Copernicus,
Johannes Kepler Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws ...
and Isaac Newton, which caused a popular "relativity hype" ("Relativitätsrummel", as it was called by Sommerfeld, Einstein, and others). This triggered a counter-reaction of some scientists and scientific laymen who could not accept the concepts of modern physics, including relativity theory and quantum mechanics. The ensuing public controversy regarding the scientific status of Einstein's theory of gravity, which was unprecedented, was partly carried out in the press. Some of the criticism was not only directed to relativity, but personally at Einstein as well, who some of his critics accused of being behind the promotional campaign in the German press. Goenner (1993a)


Academic and non-academic criticism

Some academic scientists, especially experimental physicists such as the Nobel laureates Philipp Lenard and Johannes Stark, as well as
Ernst Gehrcke Ernst J. L. Gehrcke (1 July 1878 in Berlin – 25 January 1960 in Hohen-Neuendorf) 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 ...
, Stjepan Mohorovičić,
Rudolf Tomaschek Rudolf Karl Anton Tomaschek (23 December 1895 in Budweis, Bohemia – 8 February 1966, Breitbrunn am Chiemsee) was a German experimental physicist. His scientific efforts included work on phosphorescence, fluorescence, and (tidal) gravitation. ...
and others criticized the increasing abstraction and mathematization of modern physics, especially in the form of relativity theory, and later quantum mechanics. It was seen as a tendency to abstract theory building, connected with the loss of intuitive "common sense". In fact, relativity was the first theory, in which the inadequacy of the "illustrative" classical physics was thought to have been demonstrated. Some of Einstein's critics ignored these developments and tried to revitalize older theories, such as aether drag models or emission theories (see "Alternative Theories"). However, those qualitative models were never sufficiently advanced to compete with the success of the precise experimental predictions and explanatory powers of the modern theories. Additionally, there was also a great rivalry between experimental and theoretical physicists, as regards the professorial activities and the occupation of chairs at German universities. The opinions clashed at the " Bad Nauheim debates" in 1920 between Einstein and (among others) Lenard, which attracted much public attention.Hentschel (1990), pp. 74–91Gehrcke (1924a)Mohorovičić (1923) In addition, there were many critics (with or without physical training) whose ideas were far outside the scientific mainstream. These critics were mostly people who had developed their ideas long before the publication of Einstein's version of relativity, and they tried to resolve in a straightforward manner some or all of the enigmas of the world. Therefore, Wazeck (who studied some German examples) gave to these "free researchers" the name "world riddle solver" ("Welträtsellöser", such as
Arvid Reuterdahl Arvid Reuterdahl (February 15, 1876 – January 13, 1933) was a Swedish-American engineer, scientist and educator. Biography Reuterdahl was born at Karlstad on February 15, 1876.
, Hermann Fricke or Johann Heinrich Ziegler). Their views had quite different roots in monism, Lebensreform, or
occultism The occult, in the broadest sense, is a category of esoteric supernatural beliefs and practices which generally fall outside the scope of religion and science, encompassing phenomena involving otherworldly agency, such as magic and mysticism an ...
. Their views were typically characterized by the fact that they practically rejected the entire terminology and the (primarily mathematical) methods of modern science. Their works were published by private publishers, or in popular and non-specialist journals. It was significant for many "free researchers" (especially the monists) to explain all phenomena by intuitive and illustrative mechanical (or electrical) models, which also found its expression in their defense of the aether. For this reason they objected to the abstractness and inscrutability of the relativity theory, which was considered a pure calculation method that cannot reveal the true reasons underlying the phenomena. The "free researchers" often used Mechanical explanations of gravitation, in which gravity is caused by some sort of "aether pressure" or "mass pressure from a distance". Such models were regarded as an illustrative alternative to the abstract mathematical theories of gravitation of both Newton and Einstein. The enormous self-confidence of the "free researchers" is noteworthy, since they not only believed themselves to have solved the great riddles of the world, but many also seemed to expect that they would rapidly convince the scientific community.Wazeck (2009), pp. 27–84Fricke (1919)Ziegler (1920)Reuterdahl (1921) Since Einstein rarely defended himself against these attacks, this task was undertaken by other relativity theoreticians, who (according to Hentschel) formed some sort of "defensive belt" around Einstein. Some representatives were
Max von Laue Max Theodor Felix von Laue (; 9 October 1879 – 24 April 1960) was a German physicist who received the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals. In addition to his scientific endeavors with cont ...
, Max Born, etc. and on popular-scientific and philosophical level
Hans Reichenbach Hans Reichenbach (September 26, 1891 – April 9, 1953) was a leading philosopher of science, educator, and proponent of logical empiricism. He was influential in the areas of science, education, and of logical empiricism. He founded the ''Gesel ...
,
André Metz André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew, and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries. It is a variation ...
etc., who led many discussions with critics in semi-popular journals and newspapers. However, most of these discussions failed from the start. Physicists like Gehrcke, some philosophers, and the "free researchers" were so obsessed with their own ideas and prejudices that they were unable to grasp the basics of relativity; consequently, the participants of the discussions were talking past each other. In fact, the theory that was criticized by them was not relativity at all, but rather a caricature of it. The "free researchers" were mostly ignored by the scientific community, but also, in time, respected physicists such as Lenard and Gehrcke found themselves in a position outside the scientific community. However, the critics didn't believe that this was due to their incorrect theories, but rather due to a conspiracy of the relativistic physicists (and in the 1920s and 1930s of the Jews as well), which allegedly tried to put down the critics, and to preserve and improve their own positions within the academic world. For example, Gehrcke (1920/24) held that the propagation of relativity is a product of some sort of mass
suggestion Suggestion is the psychological process by which a person guides their own or another person's desired thoughts, feelings, and behaviors by presenting stimuli that may elicit them as reflexes instead of relying on conscious effort. Nineteenth-ce ...
. Therefore, he instructed a media monitoring service to collect over 5000 newspaper clippings which were related to relativity, and published his findings in a book. However, Gehrcke's claims were rejected, because the simple existence of the "relativity hype" says nothing about the validity of the theory, and thus it cannot be used for or against relativity.Hentschel (1990), pp. 163–195Wazeck (2009), pp. 113–193, 217–292Gehrcke (1924b) Afterward, some critics tried to improve their positions by the formation of alliances. One of them was the "Academy of Nations", which was founded in 1921 in the US by Robert T. Browne and
Arvid Reuterdahl Arvid Reuterdahl (February 15, 1876 – January 13, 1933) was a Swedish-American engineer, scientist and educator. Biography Reuterdahl was born at Karlstad on February 15, 1876.
. Other members were Thomas Jefferson Jackson See and as well as Gehrcke and Mohorovičić in Germany. It is unknown whether other American critics such as
Charles Lane Poor Charles Lane Poor (January 18, 1866 – September 27, 1951) was an American astronomy professor, noted for his opposition to Einstein's theory of relativity. Biography He was born on January 18, 1866, in Hackensack, New Jersey, to Edward Erie ...
,
Charles Francis Brush Charles Francis Brush (March 17, 1849 – June 15, 1929) was an American engineer, inventor, entrepreneur, and philanthropist. Biography Brush was born in Euclid Township, Ohio to Isaac Elbert Brush and Delia Williams Phillips. Isaac Brush ...
,
Dayton Miller Dayton Clarence Miller (March 13, 1866 – February 22, 1941) was an American physicist, astronomer, acoustician, and accomplished amateur flautist. An early experimenter of X-rays, Miller was an advocate of aether theory and absolute space ...
were also members. The alliance disappeared as early as the mid-1920s in Germany and by 1930 in the USA.Wazeck (2009), pp. 293–378


Chauvinism and antisemitism

Shortly before and during World War I, there appeared some nationalistically motivated criticisms of relativity and modern physics. For example, Pierre Duhem regarded relativity as the product of the "too formal and abstract" German spirit, which was in conflict with the "common sense". Similarly, popular criticism in the Soviet Union and China, which partly was politically organized, rejected the theory not because of factual objections, but as ideologically motivated as the product of western decadence.Hentschel (1990), pp. 123–131 So in those countries, the Germans or the Western civilization were the enemies. However, in Germany the Jewish ancestry of some leading relativity proponents such as Einstein and Minkowski made them targets of racially minded critics, although many of Einstein's German critics did not show evidence of such motives. The engineer
Paul Weyland Paul Wilhelm Gustav Weyland (20 January 1888, Berlin – 6 December 1972, Bad Pyrmont) was the antisemitic leader of the Anti Einstein League. In 1919 Weyland published the novel ''Hie Kreuz - hie Triglaff'' (The Cross against the Triglav), which g ...
, a known nationalistic agitator, arranged the first public meeting against relativity in Berlin in 1919. While Lenard and Stark were also known for their nationalistic opinions, they declined to participate in Weyland's rallies, and Weyland's campaign eventually fizzled out due to a lack of prominent speakers. Lenard and others instead responded to Einstein's challenge to his professional critics to debate his theories at the scientific conference held annually at Bad Nauheim. While Einstein's critics, assuming without any real justification that Einstein was behind the activities of the German press in promoting the triumph of relativity, generally avoided antisemitic attacks in their earlier publications, it later became clear to many observers that antisemitism did play a significant role in some of the attacks.Wazeck (2009), pp. 232–236 Reacting to this underlying mood, Einstein himself openly speculated in a newspaper article that in addition to insufficient knowledge of theoretical physics, antisemitism at least partly motivated their criticisms. Some critics, including Weyland, reacted angrily and claimed that such accusations of antisemitism were only made to force the critics into silence. However, subsequently Weyland, Lenard, Stark and others clearly showed their antisemitic biases by beginning to combine their criticisms with racism. For example, Theodor Fritsch emphasized the alleged negative consequences of the "Jewish spirit" within relativity physics, and the
far right Far-right politics, also referred to as the extreme right or right-wing extremism, are political beliefs and actions further to the right of the left–right political spectrum than the standard political right, particularly in terms of being ...
-press continued this propaganda unhindered. After the murder of Walther Rathenau (1922) and murder threats against Einstein, he left Berlin for some time. Gehrcke's book on "The mass suggestion of relativity theory" (1924) was not antisemitic itself, but it was praised by the far-right press as describing an alleged typical Jewish behavior, which was also imputed to Einstein personally. Philipp Lenard in 1922 spoke about the "foreign spirit" as the foundation of relativity, and afterward he joined the Nazi party in 1924; Johannes Stark did the same in 1930. Both were proponents of the so-called
German Physics ''Deutsche Physik'' (, "German Physics") or Aryan Physics (german: Arische Physik) was a nationalist movement in the Germany, German physics community in the early 1930s which had the support of many eminent physicists in Germany. The term w ...
, which only accepted scientific knowledge based on experiments, and only if accessible to the senses. According to Lenard (1936), this is the "
Aryan Aryan or Arya (, Indo-Iranian *''arya'') is a term originally used as an ethnocultural self-designation by Indo-Iranians in ancient times, in contrast to the nearby outsiders known as 'non-Aryan' (*''an-arya''). In Ancient India, the term ' ...
physics or physics by man of Nordic kind" as opposed to the alleged formal-dogmatic "Jewish physics". Additional antisemitic critics can be found in the writings of Wilhelm Müller,
Bruno Thüring Bruno Jakob Thüring (7 September 1905, in Warmensteinach – 6 May 1989, in Karlsruhe) was a German physicist and astronomer. Thüring studied mathematics, physics, and astronomy at the University of Munich and received his doctorate in 1928, und ...
and others. For example, Müller erroneously claimed that relativity was a purely "Jewish affair" and it would correspond to the "Jewish essence" etc., while Thüring made comparisons between the Talmud and relativity.Kleinert (1979)Beyerchen (1982)Hentschel (1990), pp. 131–150Posch (2006)Wazeck (2009), pp. 271–392Einstein (1920a)Lenard (1936)Stark/Müller (1941)Thüring (1941)


Accusations of plagiarism and priority discussions

Some of Einstein's critics, like Lenard, Gehrcke and Reuterdahl, accused him of plagiarism, and questioned his priority claims to the authorship of relativity theory. The thrust of such allegations was to promote more traditional alternatives to Einstein's abstract hypothetico-deductive approach to physics, while Einstein himself was to be personally discredited. It was argued by Einstein's supporters that such personal accusations were unwarranted, since the physical content and the applicability of former theories were quite different from Einstein's theory of relativity. However, others argued that between them Poincaré and Lorentz had earlier published several of the core elements of Einstein's 1905 relativity paper, including a generalized relativity principle that was intended by Poincaré to apply to all physics. Some examples:Hentschel (1990), pp. 150–162Wazeck (2009), pp. 194–216Laue (1917)Laue (1921b)Gehrcke (1916)Lenard (1921b) *
Johann Georg von Soldner Johann Georg von Soldner (16 July 1776 in Feuchtwangen, Ansbach – 13 May 1833 in Bogenhausen, Munich) was a German physicist, mathematician and astronomer, first in Berlin and later in 1808 in Munich. Life He was born in Feuchtwangen in Ans ...
(1801) was credited for his calculation of the deflection of light in the vicinity of celestial bodies, long before Einstein's prediction which was based on general relativity. However, Soldner's derivation has nothing to do with Einstein's, since it was fully based on Newton's theory, and only gave half of the value as predicted by general relativity. *
Paul Gerber Paul Gerber (1854 Berlin, Germany – 13 August 1909 Freiburg im Breisgau, Germany) was a German physics teacher. He studied in Berlin from 1872-1875. In 1877 he became a teacher at the Realgymnasium (high school) in Stargard in Pommern. Gerber ...
(1898) published a formula for the perihelion advance of Mercury, which was formally identical to an approximate solution given by Einstein. However, since Einstein's formula was only an approximation, the solutions are not identical. In addition, Gerber's derivation has no connection with General relativity and was even regarded as meaningless. * Woldemar Voigt (1887) derived a
transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...
, which is very similar to the Lorentz transformation. As Voigt himself acknowledged, his theory was not based on electromagnetic theory, but on an elastic aether model. His transformation also violates the relativity principle. * Friedrich Hasenöhrl (1904) applied the concept of electromagnetic mass and momentum (which were known long before) to cavity radiation and thermal radiation. Yet, the applicability of Einstein's
Mass–energy equivalence In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame, where the two quantities differ only by a multiplicative constant and the units of measurement. The principle is described by the physicis ...
goes much further, since it is derived from the relativity principle and applies to all forms of energy. *
Menyhért Palágyi Menyhért Palágyi, in German Melchior or Meinhert Palagyi (16 or 26 December 1859 in Paks, Hungary – 14 July 1924 in Darmstadt, Germany) was a Hungarian philosopher, mathematician, and physicist of Jewish descent (his original name was Silbers ...
(1901) developed a philosophical "space-time" model in which time plays the role of an imaginary fourth dimension. Palágyi's model was only a reformulation of Newtonian physics, and had no connection to electromagnetic theory, the relativity principle, or to the constancy of the speed of light. Some contemporary historians of science have revived the question as to whether Einstein was possibly influenced by the ideas of Poincaré, who first stated the relativity principle and applied it to electrodynamics, developing interpretations and modifications of Lorentz's electron theory that appear to have anticipated what is now called special relativity. Darrigol (2004) Another discussion concerns a possible mutual influence between Einstein and
David Hilbert David Hilbert (; ; 23 January 1862 – 14 February 1943) was a German mathematician, one of the most influential mathematicians of the 19th and early 20th centuries. Hilbert discovered and developed a broad range of fundamental ideas in many a ...
as regards completing the field equations of general relativity (see
Relativity priority dispute Albert Einstein presented the theories of special relativity and general relativity in publications that either contained no formal references to previous literature, or referred only to a small number of his predecessors for fundamental results ...
).


''A Hundred Authors Against Einstein''

A collection of various criticisms can be found in the book ''Hundert Autoren gegen Einstein'' (''A Hundred Authors Against Einstein''), published in 1931. It contains very short texts from 28 authors, and excerpts from the publications of another 19 authors. The rest consists of a list that also includes people who only for some time were opposed to relativity. From among Einstein's concepts the most targeted one is
space-time In physics, spacetime is a mathematical model that combines the three-dimensional space, three dimensions of space and one dimension of time into a single four-dimensional manifold. Minkowski diagram, Spacetime diagrams can be used to visualize S ...
followed by the speed of light as a constant and the
relativity of simultaneity In physics, the relativity of simultaneity is the concept that ''distant simultaneity'' – whether two spatially separated events occur at the same time – is not absolute, but depends on the observer's reference frame. This possi ...
, with other concepts following. Besides philosophic objections (mostly based on Kantianism), also some alleged elementary failures of the theory were included; however, as some commented, those failures were due to the authors' misunderstanding of relativity. For example, Hans Reichenbach wrote a report in the entertainment section of a newspaper, describing the book as “a magnificent collection of naive mistakes” and as “unintended droll literature.”Goenner (1993b), p. 251. Albert von Brunn interpreted the book as a pamphlet "of such deplorable impotence as occurring elsewhere only in politics" and "a fallback into the 16th and 17th centuries" and concluded “it can only be hoped that German science will not again be embarrassed by such sad scribblings”, and Einstein said, in response to the book, that if he were wrong, then one author would have been enough. According to Goenner, the contributions to the book are a mixture of mathematical–physical incompetence,
hubris Hubris (; ), or less frequently hybris (), describes a personality quality of extreme or excessive pride or dangerous overconfidence, often in combination with (or synonymous with) arrogance. The term ''arrogance'' comes from the Latin ', mean ...
, and the feelings of the critics of being suppressed by contemporary physicists advocating the new theory. The compilation of the authors show, Goenner continues, that this was not a reaction within the physics community—only one physicist ( Karl Strehl) and three mathematicians ( Jean-Marie Le Roux, Emanuel Lasker and
Hjalmar Mellin Robert Hjalmar Mellin (19 June 1854 – 5 April 1933) was a Finnish mathematician and function theorist. Biography Mellin studied at the University of Helsinki and later in Berlin under Karl Weierstrass. He is chiefly remembered as the develope ...
) were present—but a reaction of an inadequately educated academic citizenship, which did not know what to do with relativity. As regards the average age of the authors: 57% were substantially older than Einstein, one third was around the same age, and only two persons were substantially younger. Two authors (Reuterdahl, von Mitis) were antisemitic and four others were possibly connected to the Nazi movement. On the other hand, no antisemitic expression can be found in the book, and it also included contributions of some authors of Jewish ancestry (Salomo Friedländer, Ludwig Goldschmidt, Hans Israel, Emanuel Lasker,
Oskar Kraus Oskar Kraus (24 July 1872 – 26 September 1942) was a Czech philosopher and jurist. Life Oskar Kraus, who converted from the Jewish to the Protestant faith, was born in Prague, the son of Hermann Kraus and Clara Reitler-Eidlitz. In 1899 he mar ...
,
Menyhért Palágyi Menyhért Palágyi, in German Melchior or Meinhert Palagyi (16 or 26 December 1859 in Paks, Hungary – 14 July 1924 in Darmstadt, Germany) was a Hungarian philosopher, mathematician, and physicist of Jewish descent (his original name was Silbers ...
).Goenner (1993b)Wazeck (2009), pp. 356–361Israel et al. (1931)


Status of criticism

The theory of relativity is considered to be self-consistent, is consistent with many experimental results, and serves as the basis of many successful theories like quantum electrodynamics. Therefore, fundamental criticism (like that of Herbert Dingle,
Louis Essen Louis Essen FRS O.B.E. (6 September 1908 – 24 August 1997) was an English physicist whose most notable achievements were in the precise measurement of time and the determination of the speed of light. He was a critic of Albert Einstein' ...
,
Petr Beckmann Petr Beckmann (November 13, 1924 – August 3, 1993) was a professor of electrical engineering who became a well-known advocate of libertarianism and nuclear power. Later in his life he disputed Albert Einstein's theory of relativity and oth ...
, Maurice Allais and
Tom van Flandern Thomas C. Van Flandern (June 26, 1940 – January 9, 2009) was an American astronomer and author specializing in celestial mechanics. Van Flandern had a career as a professional scientist, but was noted as an outspoken proponent of certain fring ...
) has not been taken seriously by the scientific community, and due to the lack of quality of many critical publications (found in the process of peer review) they were rarely accepted for publication in reputable scientific journals. Just as in the 1920s, most critical works are published in small publication houses, alternative journals (like "Apeiron" or "Galilean Electrodynamics"), or private websites. Consequently, where criticism of relativity has been dealt with by the scientific community, it has mostly been in historical studies. However, this does not mean that there is no further development in modern physics. The progress of technology over time has led to extremely precise ways of testing the predictions of relativity, and so far it has successfully passed all tests (such as in particle accelerators to test special relativity, and by astronomical observations to test general relativity). In addition, in the theoretical field there is continuing research intended to unite general relativity and quantum theory, between which a fundamental incompatibility still remains.Extract of page 148
/ref> The most promising models are
string theory In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interac ...
and
loop quantum gravity Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attem ...
. Some variations of those models also predict violations of Lorentz invariance on a very small scale.Mattingly (2005)Will (2006)Liberati (2009)


See also

* Alternatives to general relativity * Fringe science * History of special relativity


References


Historical analyses

* * * * * * * * * * * * . * * * * * Mathpages
Herbert Dingle and the Twins
* * * * * * :In English: * * * * * * :* English translation: * * *


Relativity papers

* * * * * * * * * . * . * . See also
English translation
* * * * * * . * * * * * * * * * * . * * * * * * . * * * * * * * Roberts, Thomas J.: ''An Explanation of Dayton Miller's Anomalous "Ether Drift" Result'', 2006, * * Smoot, G. F.; (2006), Nobel lecture

* * * Usenet Physics FAQ

*


Critical works

* * * * * * * * * * * * * * * * * * * * * * * * * * . (This paper is only partly to be considered as critical, since the question after the validity of the relativity principle remained undecided. It was Poincaré himself, who solved many problems in 1905.) * * * Siehe auc

* * * * * {{refend


External links

* The Newspaper clippings and works collected by Gehrcke and Reuterdahl form an important basis for historic research on the criticism of relativity; *
The Ernst Gehrcke Papers
Over 2700 newspaper articles collected by Gehrcke, digitized at the MPIWG. *
Arvid Reuterdahl Papers
digizied by the University of St. Thomas Libraries, which ar
online accessible
Theory of relativity Relativity Philosophy of physics Fringe physics Criticism of science