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 on which he based his theories, most notably to the work of Henri Poincaré and Hendrik Lorentz for special relativity, and to the work of David Hilbert, Carl F. Gauss, Bernhard Riemann, and Ernst Mach for general relativity. Subsequently, claims have been put forward about both theories, asserting that they were formulated, either wholly or in part, by others before Einstein. At issue is the extent to which Einstein and various other individuals should be credited for the formulation of these theories, based on priority considerations.
Various scholars have questioned aspects of the work of Einstein, Poincaré, and Lorentz leading up to the theories' publication in 1905. Questions raised by these scholars include asking to what degree Einstein was familiar with Poincaré's work, whether Einstein was familiar with Lorentz's 1904 paper or a review of it, and how closely Einstein followed other physicists at the time. It is known that Einstein was familiar with Poincaré's 1902 paper [Poi02], but it is not known to what extent he was familiar with other work of Poincaré in 1905. However, it is known that he knew [Poi00] in 1906, because he quoted it in [Ein06]. Lorentz's 1904 paper [Lor04] contained the transformations bearing his name that appeared in the Annalen der Physik. Some authors claim that Einstein worked in relative isolation and with restricted access to the physics literature in 1905.
Background
In the history of special relativity, the most important names that are mentioned in discussions about the distribution of credit are Albert Einstein, Hendrik Lorentz, Henri Poincaré, and Hermann Minkowski. Consideration is also given to numerous other scientists for either anticipations of some aspects of the theory, or else for contributions to the development or elaboration of the theory. These include Woldemar Voigt, August Föppl, Joseph Larmor, Emil Cohn, Friedrich Hasenöhrl, Max Planck, Max von Laue, Gilbert Newton Lewis and Richard Chase Tolman, and others. In addition, polemics exist about alleged contributions of others such as Olinto De Pretto who according to some mathematical scholars did not create relativity but was the first to use the equation.On Olinto De Pretto alleged contributions by a mathematical historian, see , The Guardian, 10 November 1999. Einstein's first wife Mileva Marić was featured in a PBS biography that claimed she made uncredited contributions, but the network later wrote that the show was "factually flawed and ultimately misleading" and these claims have no foundation according to serious scholars.On Mileva Marić's alleged contributions, see The Einstein Controversy, Physics Central, 17 December 2008.
In his History of the theories of ether and electricity from 1953, E. T. Whittaker claimed that relativity is the creation of Poincaré and Lorentz and attributed to Einstein's papers only little importance.Whittaker (1953), pp. 27–77 However, most historians of science, like Gerald Holton, Arthur I. Miller, Abraham Pais, John Stachel, or Olivier Darrigol have other points of view. They admit that Lorentz and Poincaré developed the mathematics of special relativity, and many scientists originally spoke about the "Lorentz–Einstein theory". But they argue that it was Einstein who eliminated the classical ether and demonstrated the relativity of space and time. They also argue that Poincaré demonstrated the relativity of space and time only in his philosophical writings, but in his physical papers he maintained the ether as a privileged frame of reference that is perfectly undetectable, and continued (like Lorentz) to distinguish between "real" lengths and times measured by observers at rest within the aether, and "apparent" lengths and times measured by observers in motion within the aether. Darrigol summarizes:
Most of the components of Einstein's paper appeared in others' anterior works on the electrodynamics of moving bodies. Poincaré and Alfred Bucherer had the relativity principle. Lorentz and Larmor had most of the Lorentz transformations, Poincaré had them all. Cohn and Bucherer rejected the ether. Poincaré, Cohn, and Abraham had a physical interpretation of Lorentz's local time. Larmor and Cohn alluded to the dilation of time. Lorentz and Poincaré had the relativistic dynamics of the electron. None of these authors, however, dared to reform the concepts of space and time. None of them imagined a new kinematics based on two postulates. None of them derived the Lorentz transformations on this basis. None of them fully understood the physical implications of these transformations. It all was Einstein's unique feat.
Undisputed facts
The following facts are well established and referable:
In 1889 ([Poi89]), Henri Poincaré argued that the ether might be unobservable, in which case the existence of the ether is a metaphysical question, and he suggested that some day the ether concept would be thrown aside as useless. However, in the same book (Ch. 10) he considered the ether a "convenient hypothesis" and continued to use the concept also in later books in 1908 ([Poi08], Book 3) and 1912 ([Poi13], Ch. 6). In 1895, Poincaré argued that results like those obtained by Michelson and Morley (Michelson–Morley experiment) show that it seems to be impossible to detect the absolute motion of matter or the relative motion of matter in relation to the ether. In 1900 [Poi00] he called this the Principle of Relative Motion, i.e., that the laws of movement should be the same in all inertial frames. Alternative terms used by Poincaré were "relativity of space" and "principle of relativity".[Poi02] In 1904 he expanded that principle by saying: "The principle of relativity, according to which the laws of physical phenomena must be the same for a stationary observer as for one carried along in a uniform motion of translation, so that we have no means, and can have none, of determining whether or not we are being carried along in such a motion." However, he also stated that we do not know if this principle will turn out to be true, but that it is interesting to determine what the principle implies. In 1900 ([Poi00]), Poincaré published a paper in which he said that radiation could be considered as a fictitious fluid with an equivalent mass of . He derived this interpretation from Lorentz's 'theory of electrons' which incorporated Maxwell's radiation pressure. Poincaré had described a synchronization procedure for clocks at rest relative to each other in [Poi00] and again in [Poi04]. So two events, which are simultaneous in one frame of reference, are not simultaneous in another frame. It is very similar to the one later proposed by Einstein.[Sta89], p. 893, footnote 10 However, Poincaré distinguished between "local" or "apparent" time of moving clocks, and the "true" time of resting clocks in the ether. In [Poi02] he argued that "some day, no doubt, the ether will be thrown aside as useless". Lorentz' paper [Lor04] containing the transformations bearing his name appeared in 1904. Albert Einstein in [Ein05c] derived the Lorentz equations by using the principle of constancy of velocity of light and the relativity principle. He was the first to argue that those principles (along with certain other basic assumptions about the homogeneity and isotropy of space, usually taken for granted by theorists) are sufficient to derive the theory—see Postulates of special relativity. He said: "The introduction of a luminiferous ether will prove to be superfluous inasmuch as the view here to be developed will not require an absolutely stationary space provided with special properties, nor assign a velocity vector to a point of the empty space in which electromagnetic processes take place." * Einstein's Elektrodynamik paper [Ein05c] contains no formal references to other literature. It does mention, in §9, part II, that the results of the paper are in agreement with Lorentz's electrodynamics. Poincaré is not mentioned in this paper, although he is cited formally in a paper on special relativity written by Einstein the following year. In 1905 Einstein was the first to suggest that when a material body lost energy (either radiation or heat) of amount , its mass decreased by the amount .[Ein05d], last section Hermann Minkowski showed in 1907 that the theory of special relativity could be elegantly described using a four-dimensional spacetime, which combines the dimension of time with the three dimensions of space. Einstein in 1920 returned to a concept of aether having no state of motion.Einstein, Albert: "Ether and the Theory of Relativity" (1920), republished in Sidelights on Relativity (Methuen, London, 1922) Extract of page 318
Comments by Lorentz, Poincaré, and Einstein
Lorentz In a paper that was written in 1914 and published in 1921,[Lor14] Lorentz expressed appreciation for Poincaré's Palermo paper (1906)[Poi06] on relativity. Lorentz stated:
However, a 1916 reprint of his main work "The theory of electrons" contains notes (written in 1909 and 1915) in which Lorentz sketched the differences between his results and that of Einstein as follows:
Regarding the fact, that in this book Lorentz only mentioned Einstein and not Poincaré in connection with a) the synchronisation by light signals, b) the reciprocity of the Lorentz transformation, and c) the relativistic transformation law for charge density, Janssen comments:
And at a conference on the Michelson–Morley experiment in 1927 at which Lorentz and Michelson were present, Michelson suggested that Lorentz was the initiator of the theory of relativity. Lorentz then replied:
Poincaré Poincaré attributed the development of the new mechanics almost entirely to Lorentz. He only mentioned Einstein in connection with the photoelectric effect,[Poi13] but not in connection with special relativity. For example, in 1912 Poincaré raises the question whether "the mechanics of Lorentz" will still exist after the development of the quantum theory. He wrote:
Einstein It is now known that Einstein was well aware of the scientific research of his time. The well known historian of science, Jürgen Renn, Director of the Max Planck Institute for the History of Science, wrote on Einstein's contributions to the Annalen der Physik:Renn, J.,: Albert Einstein in den Annalen der Physik, 2005
Einstein wrote in 1907 that one needed only to realize that an auxiliary quantity that was introduced by Lorentz and that he called "local time" can simply be defined as "time". In 1909. See also English translation and 1912. English translation: Einstein explained:
But Einstein and his supporters took the position that this "light postulate" together with the principle of relativity renders the ether superfluous and leads directly to Einstein's version of relativity. Einstein refers to Poincaré in connection with the inertia of energy in 1906 and the non-Euclidean geometry in 1921,. but not in connection with the Lorentz transformation, the relativity principle or the synchronization procedure by light signals. However, in the last years before his death Einstein acknowledged some of Poincaré's contributions (according to Darrigol, maybe because his biographer Pais in 1950 sent Einstein a copy of Poincarè's Palermo paper, which he said that he had not read before). Einstein wrote in 1953:
Timeline This section cites notable publications where people have expressed a view on the issues outlined above.
Sir Edmund Whittaker (1954)