## Zur einheitlichen Feldtheorie. Offprint from Sitzungsberichte der Preussichen Akademie der Wissenschaften, XXII, 1925. Signed by Einstein and dated 22.1.31. [WITH:] Typed letter signed from Einstein to Reginald B. Haselden, curator of manuscripts at the Huntington Library, dated 1 February 1931.

Berlin: Akademie der Wissenschaften, 1929.

First edition, offprint issue, **signed by Einstein**, of one of his most important papers on unified field theory, with an accompanying **typed letter signed** to Reginald B. Haselden, who was Curator of Manuscripts at the Huntington Library during Einstein’s time at the California Institute of Technology, where he spent the winter terms of 1931, 1932 and 1933 as visiting professor. Einstein’s work on unified field theory was inspired by James Clerk Maxwell’s success in finding a unified theory of electricity and magnetism, one of the greatest achievements of nineteenth-century physics, which showed that light was a form of electromagnetic wave, and made possible modern inventions such as radio, television and the telephone. Einstein continued his attempts to devise a unified theory of gravitation and electromagnetism for the rest of his life; his contributions in this area represent about a quarter of his entire research output and half his scientific production after 1920. Although he was ultimately unsuccessful, a similar vision was realized in the decades after his death in the construction of the ‘standard model’, a unified theory of electromagnetism with the weak and strong nuclear forces (which were unknown in Einstein’s time), and efforts to incorporate gravity into the model continue to this day. “In 1928, [Einstein] embarked on a new approach to a unified field theory … involving what he called ‘distant parallelism’ … By early 1929 he had solved the main problems involved in writing down field equations for his unified theory. On the day of official publication of the third of a formidably technical series of nine articles on the theory … excited headlines appeared in foreign newspapers throughout the world … In this frenzied, unscientific atmosphere, Einstein’s new theory was hailed in the press as an outstanding scientific advance. Yet Einstein had stated in his article that it was still tentative; and soon he found he had to abandon it” (Hoffman, *Einstein*, pp. 225-6). “[Einstein] did propose [in the present paper] a set of field equations, but added that ‘further investigations will have to show whether [these] will give an interpretation of the physical qualities of space’. His attempt to derive his equations from a variational principle had to be withdrawn. Nevertheless, in 1929 he had ‘hardly any doubt’ that he was on the right track … Einstein’s colleagues were not impressed. Eddington and Weyl were critical. Pauli demanded to know what had become of the perihelion of Mercury, the bending of light, and the conservation laws of energy-momentum. Einstein had no good answer to these questions, but that did not seem to overly concern him” (Pais, pp. 346-7). This paper is included on Shields’s list of Einstein’s most significant papers; see *Albert Einstein, Philosopher-Scientist* (1949), p. 758.

*Provenance*: Offprint signed by Einstein on the front wrapper: ‘Albert Einstein, Pasadena 22.1.31’.

“By the early 1920s, Einstein had already started to consider extensions of general relativity, including three variations proposed independently by Hermann Weyl, Theodor Kaluza, and Arthur Stanley Eddington. The goal was to combine electromagnetism and gravitation into a unified field theory that would geometrize both phenomena … Einstein hoped to extend the mathematical methods he applied so successfully to gravitation and develop a single set of equations describing a geometric field theory.

“After pondering the three theories, Einstein became most intrigued by Eddington’s so-called affine theory, which changed the definition of the Christoffel connection (also known as the affine connection), the mathematical entity that represents how parallel lines are transported through spacetime along a curved manifold. That definition gave the connection additional flexibility, hypothetically allowing it to describe electromagnetic potentials.

“Finding Eddington’s model incomplete, Einstein aspired to develop his own version. In March 1923 Einstein submitted a draft of his new theory, which he had developed on a sea voyage to Japan, to the Prussian Academy of Sciences in Berlin. The *New York Times* trumpeted his submission in a 23 March article, “Einstein to announce theory ‘surpassing even relativity.’” The piece falsely suggested that Einstein had found a way of explaining terrestrial magnetism, a complex mechanism that was not fully understood at the time.

“Einstein worked on the affine theory for two more years. By the end of 1925, he realized that he could find no singularity-free solutions (a singularity is a point or region at which physical parameters become infinite) to the field equations he had developed. He decided to scrap his extension of Eddington’s work. For the next several years, he explored different options, including an investigation of Kaluza’s theory.

“Kaluza’s work added a fifth dimension to Einstein’s field equations. An extra mathematical restraint, called the cylindrical condition, forbade direct observation of it. But that undetectable fifth dimension allowed room in the equations to house electromagnetic terms. Those components could be shown under certain circumstances to obey Maxwell’s equations and thus offered tantalizing hints of unification. However, the theory was not invariant under general transformations of coordinates, and having to impose a particular coordinate system for the theory to work seemed artificial. It also didn’t have physically realistic solutions. Nevertheless, motivated in part by Swedish physicist Oskar Klein’s publication of an independent five-dimensional unification attempt, Einstein spent parts of 1926 and 1927 exploring ways to bring Kaluza’s notion to fruition.

“In 1928 Einstein was diagnosed with heart disease and his physician urged him to rest. As he recovered, he worked on an idea for unification called distant parallelism, which proposed an independent web of connections between each point in spacetime that supplemented the standard relationships of general relativity. In early January 1929, Einstein submitted a paper to the Prussian Academy and issued an announcement. Though the paper was extremely preliminary, lacking any inkling of experimental evidence, the *New York Times* published a front-page story about it on 12 January, proclaiming that ‘Einstein himself considers it by far his most important contribution to mankind—scientifically more important than his original theory.’

“Einstein’s article ‘Zur einheitlichen Feldtheorie’ (‘On unified field theory’) was published in *Sitzungsberichten der Preussischen Akademie der Wissenschaften* (*Proceedings of the Prussian Academy of Sciences*) on 30 January. Within three days, the first printing of the journal offprint—a thousand copies—sold out, and another thousand copies were soon printed. Soon thereafter, *Nature*’s News and Views section published a more accessible account of the work, including a quote by Einstein: ‘Now, but only now, we know that the force which moves electrons in their ellipses about the nuclei of atoms is the same force which moves our earth in its annual course about the sun, and is the same force which brings to us the rays of light and heat which make life possible upon this planet.’

“With Einstein’s 50th birthday approaching, his new idea rapidly caught fire, at least in the popular press. The *New York Times* published almost a dozen articles that year about distant parallelism, rivaling its coverage of the 1919 eclipse results. Although by then the bulk of the physics community was focused on quantum mechanics and related fields and had no interest in Einstein’s attempts at unification, reporters managed to gauge the reaction of at least a few physicists …

“One of the few knowledgeable physicists who kept up with Einstein’s unified models was Wolfgang Pauli. Einstein saw Pauli as an important sounding board—honest, thorough, critical, but often right. To Einstein’s dismay, Pauli found many flaws in distant parallelism, including its inability to match key predictions of general relativity, such as gravitational light bending. It also did not match the expected features of electromagnetism as mapped out by Maxwell’s equations. Finally, it did not take into account key electron properties gleaned from the Dirac equation.

“In December, Pauli wrote to Einstein, ‘I would take any bet with you that you will have given up the whole distant parallelism at the latest within a year from now, just as you had given up previously the affine theory. And I do not want to rouse you to contradiction by continuing this letter, so as not to delay the approach of the natural decease of the distant parallelism theory.’

“Privately, Pauli told Pascual Jordan, ‘Einstein is said to have poured out, at the Berlin colloquium, horrible nonsense about new parallelism at a distance. The mere fact that his equations are not in the least similar to Maxwell’s theory is employed by him as an argument that they are somehow related to quantum theory. With such rubbish he may impress only American journalists, not even American physicists, not to speak of European physicists.’

“Pauli’s perceptions that American journalists would be the ones most interested in Einstein’s work were right on the mark. More than in European journalism, there was a tradition in US journalism of using hype to sell papers. Newspapers in the US did not even seem to notice the failure of Einstein’s earlier attempts at unification, their lack of viable solutions and experimental evidence, or the other problems with his theories. Journalists placed them in virtually the same category of general relativity, which had actually passed several key tests. Although Pauli maintained a continued interest in unifying the natural forces, he remained cynical about the way such ideas were represented by the press—later mocking, for example, the overblown press treatment of a similarly undeveloped and unsupported unification model Werner Heisenberg advanced in the late 1950s.

“Einstein thought at first that Pauli was too harsh about distant parallelism and that he failed to see its elegance. However, after about another year of exploring the concept, he had to concede that Pauli was right” (Halpern).

The accompanying letter to Haselden reads:

‘Ich danke ihnen sehr für die entzückende Aufmerksamkeit. Das Männchen ist ein strahlendes Vorbild für geruhsame Lebensweise, dem ich gerne folgen möchte.’

‘Thank you very much for your delightful attention.The male is a shining example of a peaceful way of life, which I would like to follow.’

It is not clear to whom, or what, Einstein is referring (the term ‘Männchen’ often refers to a small male animal, rather than a person).

Norman 700; Weil 165*; cf. *PMM* 416. Halpern, ‘Albert Einstein, celebrity physicist,’ *Physics Today*, 1 April 2019, pp. 38-45.

Offprint: Large 8vo (265 x 187mm), pp. 8. Original printed wrappers (creased and wrinkled). Without the printed statement ‘Uberreicht vom Verfasser’, indicating that this is a commercially available reprint rather than an author’s presentation offprint. Letter: 1 page, on letterhead of the California Institute of Technology (279 x 215mm). Together two items. Very good.

Item #5292

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Price:
$15,000.00
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