## Einheitliche Feldtheorie von Gravitation und Elektrizität.

Berlin: Akademie der Wissenschaften, 1925.

First edition, extremely rare author’s presentation offprint (not to be confused with the much more common trade offprint – see below), and the copy of Einstein’s son Hans Albert, of Einstein’s first original paper on unified field theory, and the first to use the term “Unified Field Theory” in its title. In the opening paragraph of this paper, Einstein wrote: “After incessant search during the last two years, I now believe I have found the true solution” (Pais, *Subtle is the Lord*, p. 343). The half-dozen papers Einstein had already written on unified field theory were reactions to the ideas of others, such as Eddington, Kaluza and Weyl; it was in this paper that Einstein put forward the first original approach of his own. 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 inventios 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. No other copies of this author’s presentation offprint in auction records (it was not in Einstein’s own reference collection of offprints in the Richard Green Library). OCLC lists nine copies of the ‘offprint’ in US, but it is unclear how many, if any, of these are the author’s presentation offprint (none of the library records state ‘Überreicht vom Verfasser’).

*Provenance*: Hans Albert Einstein (1904-1973), Swiss-American engineer and educator, and the second child and first son of Albert Einstein and Mileva Mari (ownership stamp on front wrapper). He moved to the US in 1938, and spent most of his career at the University of California, Berkeley, where he was a professor of hydraulic engineering.

“Einstein’s early work on the unification program after the completion of the theory of general relativity was, by and large, a reaction to approaches advanced by others. This is the case for the first geometrization of the electromagnetic field, proposed in 1918 by Hermann Weyl; for the first exploration of a five-dimensional theory suggested by Theodor Kaluza in 1919; and for the first attempt to base a unified field theory on the concept of the affine connection, rather than on the metric field, as advanced by Arthur Eddington in 1921” (*Cambridge Companion to Einstein*, pp. 289-90).

Weyl (1885-1955) had introduced a new geometrical object into the theory that he called a “length connection,” and he used it to establish a link between the geometrical structure, given by the length connection, and the electromagnetic field. Einstein was initially enthusiastic about Weyl’s idea, calling it “a first-class stroke of genius,” but quickly found a serious objection to it, showing that it implied that the wavelength of light emitted by a radiating atom would depend on the prehistory of that atom, contrary to observation. Nevertheless, in March 1921, Einstein elaborated on Weyl’s theory in his paper ‘Uber eine naheliegende Ergänzung des Fundamentes der allgemeinen Relativitätstheorie.’

Another idea to which Einstein responded was put forward as early as 1919 by Theodor Kaluza (1885-1954), at the time Privatdozent in mathematics at the University of Königsberg; he introduced the concept of a fifth dimension to the underlying space-time manifold of general relativity and attempted to represent the electromagnetic field in terms of the additional components of the metric tensor. Einstein showed that for the equation of motion of an electron, Kaluza’s theory predicted that the influence of the gravitational field was larger by many orders of magnitude than any reasonable physical interpretation would allow for. Nevertheless, Einstein later encouraged Kaluza to publish his idea and Einstein and Jakob Grommer (1879-1933) published a response to it in 1923 (‘Beweis der Nichtexistenz eines überall regulären zentrisch symmetrischen Feldes nach der Feld-Theorie von Kaluza’).

A third approach toward a unified field theory was advanced most notably by Eddington (1882-1944) in the early twenties, and was also taken up by Einstein. The idea was to base the theory on the concept of an affine connection as the fundamental mathematical quantity, rather than on the metric tensor. The associated (Ricci) curvature of spacetime is not then, in general, a symmetric tensor, and Eddington suggested that the anti-symmetric part of the curvature could be identified with the electromagnetic field, the symmetric part being the usual metric. Eddington did not, however, provide the field equations that would determine the affine connection, a problem Einstein addressed in a series of three brief notes published in 1923 (‘Zur allgemeinen Relativitätstheorie;’ ‘Bemerkung zu meiner Arbeit ‘Zur allgemeinen Relativitätstheorie’;’ ‘Zur affinen Feldtheorie’). Einstein proposed to obtain the field equations from a variational principle, but this turned out to be almost equivalent to the variational formulation of general relativity with a Maxwellian field provided by Hilbert in 1915 (‘Die Grundlagen der Physik, Erste [& Zweite] Mitteilung’, published in the *Göttingen Nachrichten*). This equivalence was highlighted by Hilbert in lectures held in Hamburg and Zürich in the summer and fall of 1923, and prompted his republication of a merged version of his two communications on the ‘Foundations of Physics’ in the *Mathematische Annalen *in 1924.

“With Einstein’s response to Weyl, Kaluza, and Eddington in the early twenties we find him reacting to approaches that had been advanced by others … The first original approach put forward by Einstein himself was published in a paper of 1925 [the offered paper] in which also the term ‘unified field theory’ appeared for the first time in a title. In that paper, he explored a metric-affine approach, i.e. he took both a metric tensor field and a linear affine connection at the same time as fundamental variables. Both connection and metric were assumed to be asymmetric. Parallel transport then again defines a Ricci tensor and a Riemann curvature scalar, and Einstein defined tentative field equations in terms of a variational principle, taking the Riemann scalar as a Lagrangian just as in standard general relativity. As regards the interpretation of the mathematical objects, he tried to associate the gravitational and electromagnetic fields with the symmetric and anti-symmetric parts of the metric field. In his attempt to recover the known cases, he could show that the metric was symmetric for the purely gravitational case and the usual compatibility condition for the Levi-Civita connection can be recovered. Maxwell’s equations could be recovered, in the limit of weak gravitational fields, but only in a slightly different form that is not entirely equivalent to the original equations.

“The basic problem of this approach seems to have been that Einstein did not know how to go on from here. Dealing with both an asymmetric metric tensor and an asymmetric connection opened up a vast field of possibilities inherent in the mathematical framework, and many familiar results of the theory of Riemannian geometry no longer held. In particular, verifying the existence of non-singular, spherically symmetric charge distributions posed a formidable challenge. It was also unclear how to explicitly investigate the non-vacuum case beyond the first order approximation of weak gravitational fields. Einstein did not pursue this approach any longer in print but he did take it up once more, twenty years later, as his final approach toward a unified field theory, working on it until his death” (*Cambridge Companion to Einstein*, pp. 293-5).

This author’s presentation offprint is of extreme rarity, and must be distinguished from other so-called ‘offprints’ of papers from the Berlin *Sitzungsberichte*, many of which are commonly available on the market. The celebrated bookseller Ernst Weil (1919-1981), in the introduction to his Einstein bibliography, wrote: “I have often been asked about the number of those offprints. It seems to be certain that there were few before 1914. They were given only to the author, and mostly ‘Überreicht vom Verfasser’ (Presented by the Author) is printed on the wrapper. Later on, I have no doubt, many more offprints were made, and also sold as such, especially by the Berlin Academy.” If the term ‘offprint’ means, as we believe it should, a separate printing of a journal article given (only) to the author for distribution to colleagues, then ‘offprints’ were not commercially available. Although there is certainly some truth in Weil’s remark, in our view it requires clarification and explanation.

Until about 1916, most of Einstein’s papers were published in *Annalen der Physik*; from 1916 until he left Germany for the United States in 1933, most were published in the Berlin *Sitzungsberichte*. The *Sitzungsberichte* differed from other journals in which Einstein published in that it made separate printings of its papers commercially available. These separate printings have ‘Sonderabdruck’ printed on the front wrapper, the usual German term for offprint, but they are not offprints according to our definition. They were available to anyone; indeed a price list of these ‘trade offprints’ is printed on the rear wrapper. True author’s presentation offprints can be distinguished from these trade offprints by the presence of ‘Überreicht vom Verfasser’ on the front wrapper.

In the period 1916 to 1919 or 1920, the *Sitzungsberichte *trade offprints are themselves rare: for example, ABPC/RBH list only three ‘offprints’ of Einstein’s famous 1917 *Sitzungsberichte *paper ‘Kosmologische Betrachtungen zur allgemeinen Relativitätstheorie’ (the auction records do not distinguish between trade and author’s presentation offprints). After 1919 or 1920, however, the trade offprints become much more common, although the author’s presentation offprints are still very rare. The reason for this change is that it was only in 1919 that Einstein became famous among the general public.

It might seem obvious that Einstein’s fame dates from 1905, his ‘annus mirabilis’, in which he published his epoch-making papers on special relativity and the light quantum. However, these works did not make him immediately well known even in the physics community – many physicists did not understand or accept his work, and it was two or three years before his genius was fully accepted even by his colleagues. Among the general public, Einstein became well known only in late 1919, following the success of Eddington’s expedition to observe the bending of light by the Sun, which confirmed Einstein’s general theory of relativity. This was front-page news, and made Einstein universally famous. (See Chapter 16, ‘The suddenly famous Doctor Einstein’, in Pais, *Subtle is the Lord*, for an account of these events). Before 1919 the trade offprints of Einstein’s papers would probably only have been purchased by professional physicists; after 1919 everyone wanted a memento of the famous Dr. Einstein, whether or not they understood anything of theoretical physics, and the trade offprints of his papers were printed and sold in far greater numbers than before to meet the demand. It is telling that when these post-1919 trade offprints appear on the market, they are often in mint condition – they were never read simply because their owners were unable to understand them.

In our view, Einstein’s author’s presentation offprints are rare, from any journal and any period, though of course some are rarer than others. Before 1919 or 1920, the *Sitzungsberichte* trade offprints are also rare, although not are rare as the author’s presentation offprints; after 1919 or 1920, the trade offprints are much more common.

Boni 155; Weil 147.

Author’s presentation offprint (“Uberreicht vom Verfasser”) from Sitzungsberichte der Preussichen Akademie der Wissenschaften, XXII, 1925. Large 8vo (256 x 180 mm), pp. 414-419, original printed wrappers with ownership stamp of Hans Albert Einstein on front wrapper. Very fine con.

Item #4035

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Price:
$14,500.00
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