What the Einstein-Marić correspondence 1897-1903 tells us
One of the more familiar clams in relation to Einstein's first wife is that there is evidence in letters that demonstrates that Mileva Marić played a substantive role in Einstein's scientific work, or that she collaborated on some of his papers (e.g., Troemel-Ploetz 1990, pp. 425-426). The letters in question are 54 exchanged between Einstein and Marić in the years when they were students at Zurich Polytechnic and just after. These had been in the possession of the Hans Albert Einstein family since Marić's death and were discovered in 1986 thanks to the efforts of the historian Robert Schulmann. (For an account of their discovery, see Highfield and Carter 1993, pp. 278-281.) Of the 54, 11 were written by Marić and 43 by Einstein, the difference indicating that at that time Einstein was not concerned abut saving her letters. (In a letter dated 17 December 1901, in the context of discussing his living quarters, he wrote: "You know what a dreadful state my worldly possessions are in.") The claims about the significance of this correspondence in relation to Marić were most comprehensively articulated by Evan Harris Walker in a letter to Physics Today:
I find statements in 13 of his 43 letters to her [note 6] that refer to her research or to an ongoing collaborative effort – for example , in document 74, "another method which has similarities to yours."
In document 75, Albert writes: "I am also looking forward very much to our new work. You must continue with your investigation." In document 79 he says, he says "we will send it to Widermann's Annalen." In document 96, he refers to "our investigations"; in document 101, to "our theory of molecular forces." In document 107, he tells her: "Prof. Weber is very nice to me… I gave him our paper."
Note 6: Documents 50, 57, 74, 75, 79, 93, 94, 96, 101, 102, 107, 111 and 127.
[Walker 1991, pp. 122, 124, n.6; Einstein Collected Papers, vol. 1, 1987.]
The superficiality of Walker's analysis is exemplified by his citing the above quotations in documents 74 and 75. Contrary to the implication in his comments, these remarks do not relate to Einstein's extracurricular research on physics. The full context of the relevant (and closely related) quotations provided by Walker are as follows:
For the investigation of the Thomson effect I have again resorted to another method, which has some similarities with yours for the determination of the dependence of κ on T & which indeed presupposes such an investigation. If only we could already start tomorrow! With Weber we must try to get on good terms at all costs, because his laboratory is the best and the best equipped. (Doc. 74; Einstein to Marić, 30 August or 6 September 1900.)
I am also looking forward very much to our new studies [Arbeiten = work]. You must now continue with your investigation – how proud I will be when maybe I'll have a little doctor [i.e., Ph.D.] for a sweetheart while I am myself still a totally ordinary man. (Doc. 75; Einstein to Marić, 13? September 1900.)
The relevant background information is that Marić and Einstein both chose topics on heat conduction for their dissertations required for the Zurich Polytechnic final diploma examinations in July 1900 (Collected Papers, vol. 1, doc. 74, n.6, doc. 75, n. 5; Popović 2003, pp. 60, 67). The two letters cited by Walker relate to the respective dissertations undertaken by Marić and Einstein. Following her failing to obtain the teaching diploma in 1900, Marić intended taking the exams the following year and had hopes of developing her dissertation into a Ph.D thesis (supervised by Prof. Heinrich Weber). (She gave up this ambition shortly after failing the diploma examinations for the second time in 1901 [Collected Papers, vol. 1, doc 111; Popović 2003, p. 60].) After Einstein graduated in July 1900 he planned to use Weber's laboratory for research on electrochemistry with Weber as his doctoral dissertation adviser (Collected Papers, vol. 1, doc. 74, doc. 82; Fölsing 1997, p. 74). Marić alluded to their respective dissertation plans when she wrote to her friend Helene Kaufler in October 1900: "For the time being I am studying at home with Albert; next week we begin our laboratory work" (Collected Papers, vol. 1, doc 81; Popović p. 67); and in December 1900 she wrote: "Albert is still here [in Zurich] and will remain here until he finishes his doctoral dissertation, which will probably take until Easter…" (Popović pp. 69-70). In other words, contrary to his claim, these two citations by Walker do not provide evidence of Marić having contributed to Einstein's extra-curricular investigations or to his published work. (It is relevant to what follows that after Einstein gave up on his doctoral thesis with Weber in early summer 1901 he worked on a dissertation with a different topic, molecular forces in gases, with Zurich University professor Alfred Kleiner as his doctoral advisor. [Collected Papers, vol. 1, docs. 63, 74, 82, 85, 100, 125, 129.])
Intentional or not, Walker's following up the quotation "You must continue with your investigation" (doc. 75) with "we will send it to Widermann's Annalen" (document 79) suggests that the "it" refers to Marić's investigation (her ongoing heat conduction dissertation). The full context of the latter quotation is as follows:
The results on capillarity, which I recently found in Zurich, seem to be totally new despite their simplicity. When we come to Zurich, we shall seek to get empirical material on the subject through Kleiner. If a law of nature emerges from this, we will send it to Wiedemann's Annalen. (Einstein to Marić, 3 October 1900.)
So the context in document 79 is actually Einstein's research on capillarity, as is Walker's quotation from document 96, the full context of which is the following:
Michele [Besso] arrived with wife and child from Trieste the day before yesterday... Yesterday evening I talked shop with him with great interest for almost 4 hours. We talked about the fundamental separation of luminiferous ether and matter, the definition of absolute rest, molecular forces, surface phenomena, dissociation. He is very interested in our investigations, even though he often misses the overall picture because of petty considerations… The day before yesterday he went on my behalf to see his uncle Prof. Jung, one of the most influential professors of Italy & also gave him our paper. (Einstein to Marić, 4 April 1901.)
The paper in question is Einstein 1901 (Collected Papers, vol. 1, ed. J. Stachel et al, 1987, p. 285). As indicated in the previous letter (above), Einstein attributes the current "results on capillarity" solely to himself. And indeed, when she wrote to Helene about his forthcoming paper on the subject, Marić also attributed it solely to Einstein, with no hint of any contribution from herself:
Albert wrote a paper on physics [Einstein 1901] that will probably soon be published in Annalen der Physik. You can imagine how proud I am of my darling. This is not just an everyday kind of paper but is a very important one; it deals with the theory of liquids. (20 December 1900, Popović 2003, pp. 69-70)
Einstein's work on capillarity was part of his wider investigation of molecular forces that led to a second paper (Einstein 1902a), as well as his doctoral dissertation under the supervision of Kleiner (Letter Einstein to Grossman, 14 April 1901; Collected Papers, vol. 1, doc. 100).
The last quotation supplied by Walker is as follows: "Prof. Weber is very nice to me… I gave him our paper." This is from a letter written in early summer 1901 by Einstein from Winterthur, Switzerland, where he was teaching, while Marić was preparing to retake the Zurich Polytechnic final diploma examinations for the second time. Here is the full context:
How is your work going, dear sweetheart? Everything proceeding jolly well? Does oId [Heinrich] Weber behave decently or does he again have 'critical theorems [comments]'? The local Prof. [Gustave] Weber is very nice to me and shows interest in my investigations. I gave him our paper. If only we would soon have the good fortune to continue pursuing this lovely path together. But destiny seems to bear some grudge against the two of us. But this will make things all the more beautiful later on, when all obstacles and worries have been overcome. (Collected Papers, vol. 1, doc. 107.)
Footnote 5 indicates that the paper in question was that on capillarity, Einstein 1901, which we have seen Marić attributed solely to Einstein, expressing pride in his achievement to Helene Kaufler. (On Einstein's writing "our" in this context, and of his wish that they might be able to continue "this lovely path together", see below.)
The remaining quotation cited by Walker, "our theory of molecular forces" (doc. 101), occurs in the following context in a letter dated Milan, 15 April 1901:
As for science, I've got an extremely lucky idea, which will make it possible to apply our theory of molecular forces to gases as well. You certainly remember that the force function appears explicitly in the integrals that have to be evaluated for the calculation of diffusion, thermal conduction & viscosity. Hence, with gas molecules, only our constants cα are necessary for the calculation of these coefficients for ideal gases, and one does not have to venture into the theoretically so uncertain area of deviations from the ideal gas state. I can hardly await the outcome of this investigation. If it leads to something, we will know almost as much about the molecular forces as about the gravitational forces, and only the law of the radius will still remain unknown. Unfortunately, I must also admit that this idea for the investigation of salt solutions rested on such a weak basis that I think that one should first restrict oneself to the investigation of infinitely dilute solutions, in which an interaction between the molecules of the dissolved substance does not yet occur. One can so determine a great number of cα 's, which could be used for an approximate verification of the hypothesis of the kinship with gravitation. It is possible that information about the law of action itself will more likely be provided by the quantities (γ – T dγ/dT) / volume energy  and the integrals from the theory of gases. Could you send me Kirchhoff's Heat.
The notion expressed here of extending his theory of molecular forces beyond liquids to gases was mentioned in a letter Einstein wrote to Marcel Grossman at this time:
As for science, I have a few splendid ideas, which now only need proper incubation. I am now convinced that my theory of atomic attractive forces can also be extended to gases, and that it will be possible to obtain the characteristic constants of almost all elements without great difficulty. That will then also bring the problem of the inner kinship between molecular forces and Newtonian action-at-a-distance forces much nearer to its solution. It is possible that experiments already done by others for other purposes will suffice for the testing of the theory. In that case I shall utilize all the already existing results in my doctoral dissertation. It is a glorious feeling to perceive the unity of a complex of phenomena which appear as separate entities to direct sensory observation. (Einstein to Grossman, 14 April 1901; Collected Papers, vol. 1, doc. 100)
So ideas that Einstein expressed in his letter to Marić of 15 April were to be incorporated in his doctoral thesis under the supervision of Prof Kleiner. He wrote out the thesis some time during October to November 1901 while teaching temporarily at Schaffhausen, Switzerland (Collected Papers, vol. 1, doc. 129). Here is what Marić had to say about the thesis in a letter to Helene Kaufler Savic in December 1901:
Albert has written a magnificent study, which he has submitted as his dissertation. He will probably get his doctorate within a few months. I have read this work with great joy and real admiration for my little darling, who has such a clever head. I will send you a copy when it gets printed. It deals with research into the molecular forces in gases using various phenomena. (Popović 2003, pp. 79-80)
So again Marić attributes the paper entirely to Einstein, and in glowing terms that preclude the notion that she played any appreciable role in its production.
In another of the letters cited by Walker (doc. 127), Einstein again refers to "our theory of molecular forces". The context is as follows:
I got again a very self-evident but important scientific idea about molecular forces. You know that no noticeable evolution of heat takes place when two neutral liquids are mixed together. From this it follows, according to our theory of molecular forces, that there must exist an approximate proportionality between our constants Σcα  and the molecular volumes of the liquids. If this were true, then this would be the end of the molecular-kinetic theory of liquids. I'll see whether I can get hold of Ostwald or Landolt during the vacation period. (Einstein to Marić, 12 December 1901; doc. 127. [Note 14 refers the reader to Einstein 1901.])
Although Einstein uses the inclusive "our", all the ideas to which he alludes are his own. The work in question relates to that in Einstein's 1901 paper and in his Ph.D. dissertation (Collected Papers, vol. 1, ed. J. Stachel et al, pp. 264-266; p. 324, n. 14, 15, 16). As we have seen, Marić attributed both these papers to her husband in effusive terms that negate the notion she contributed substantively to them.
The remaining documents cited by Walker do not support his contention of Marić's having collaborated in Einstein's research in this period. In document 50 Einstein mentions he is studying Helmholtz's writings on atmospheric movements, and a little later expresses regret that he is not she is not with him while he is doing so, and adds that he finds the collaboration (Zusammenarbeiten = working together) wholesome and less dry than reading the books alone. This shows only that under Einstein's instigation they read books on extra-curricular subjects together, not that she contributed to the theoretical ideas he was working on arising from his reading. In his next two letters he alludes to material in Helmholtz's writings, and then in document 57 (cited by Walker) he writes when they are together again in Zurich "we will start immediately with Helmholtz's electromagnetic theory of light". In other words he is again alluding to material they will read together.
Document 93, written from his parents' place in Milan, contains a long paragraph in which Einstein recounts "an interesting idea" he has had on latent kinetic energy of heat in solids and liquids that conceives these as the energy of electrical resonators. At the end of the paragraph he muses on the specific heat of glass and finishes with the suggestion that Marić (now back in Zurich) find some literature on this.
In document 102 (again from Milan) Einstein reports that he is again studying Boltzmann's theory of gases, noting that he thinks "however, O. E. Myer has enough empirical material for our investigation". He adds that if Marić goes to the library she can check this, but that it can wait until he is back in Zurich. As noted by the editors of volume 1 of the Collected Papers, these references are to ideas he is developing for his doctoral dissertation, which we have seen Marić attributed without qualification to Einstein. (Collected Papers, vol. 1, ed. J. Stachel et al, pp. 265-266.)
Document 111 opens with Einstein's enthusing about Lenard's 1900 paper on the photoelectric effect, followed by reassurances of his continuing love, and questioning how her pregnancy is going. He then adds: "Imagine how lovely it will be when we are again be able to work together totally undisturbed , and nobody will any longer be able to interfere! You will be amply compensated for your present worries by a lot of joy, and the days will pass peacefully by, undisturbed and unhurriedly." In other words, Einstein is alluding to the time when, as students at Zurich, they studied and read books together and trying to raise Marić's spirits by envisaging a similar situation in the future. At that time (May 1901) she had yet to fail her teaching diploma examinations for the second time, was still working on her dissertation she hoped to develop into a Ph.D. thesis, so Einstein's fond hopes of a future life together devoted to science had yet to be extinguished.
Finally we turn to document 94 (letter 27 March 1901), in which we find the oft-quoted sentence: "How happy and proud I will be when the two of us together will have brought our work on relative motion to a victorious conclusion!" However, against this one unspecific allusion to "our" work in relation to the electrodynamics of moving bodies there are half‑dozen other letters in the period from August 1899 through December 1901 in which Einstein writes of his ideas on the subject, providing specific details of what he is working on. For example:
"I also wrote to Professor Wien in Aachen about my paper on the relative motion of the luminiferous ether against ponderable matter…" (28 September 1899)
"I'm busily at work on an electrodynamics of moving bodies, which promises to be quite a capital piece of work." (17 December 1901)
"I spent all afternoon at [Professor] Kleiner's telling him my ideas about the electrodynamics of moving bodies…" (19 December 1901)
"I want to get down to business now and read what Lorentz and Drude have written about the electrodynamics of moving bodies." (28 December 1901)
And to Marcel Grossman:
"A considerably simpler method of investigating the relative motion of matter relative to luminiferous ether that is based on ordinary interference experiments has just sprung to my mind…" (6? September 1901: Collected Papers, vol. 1, doc. 122)
As Stachel writes:
In summary, the letters to Marić show Einstein referring to his studies, his ideas, his work on the electrodynamics of moving bodies over a dozen times (and we may add a couple more if we include his letter to Grossmann), as compared to one reference to our work on the problem of relative motion. In the one case where we have a letter of Marić in direct response to one of Einstein's, where it would have been most natural for her to respond to his ideas on the electrodynamics of moving bodies, we find the same response to ideas in physics that we find in all her letters: silence. (Stachel 2002, p. 36)
It is important to appreciate both the background and the context in which the relevant sentence from document 94 occurs. The couple were now separated with little prospect of their being together in the immediate future. Roger Highfield and Paul Carter quote the whole paragraph, in which Einstein is seeking to reassure Marić of his continuing love, observing: "By italicizing the key sentence, one shows how it sat marooned, not in one of Einstein's many passages of close scientific argument, but amid an outpouring of reassurance that his love for Mileva remained absolute despite their separation" (1993, p. 72). And equally important, the sentence should be seen in the light of Einstein's frequent attempts to interest Marić in his extracurricular work, his expressed long‑term hope being that they would have a joint future devoted to science. In any case, this letter was written some four years before Einstein alighted on the key idea that led to his writing the 1905 special relativity theory. Moreover, there is not a single piece of evidence of Marić's having expressed any ideas on the subject.
In regard to the letters cited by Walker, it is important to note that all but two were written in the period from late summer 1900 to December 1901. During this period the couple were mostly apart (hence the letters). Following her diploma exam failure in 1900, Marić stayed with her parents in Serbia, and then returned to Zurich in early October 1900. She intended retaking the exam the following year and was working on her dissertation during the following months. For his part, Einstein stayed at his parents place in Milan after his exam success in July 1900 and then vacationed with his mother and sister in Switzerland (with a brief interlude in Zurich in August) before returning to Zurich in mid-September 1900 where he started laboratory work in preparation for his first attempt at a doctoral dissertation on thermo-electricity under the supervision of Professor Heinrich Weber.
Einstein went to Milan in March 1901 for a short period before moving in early May to Winterthur, Switzerland, where he had obtained a temporary teaching position. He spent time with his mother and sister during July, and returned to Winterthur before taking up another post, at Schaffhausen in Switzerland, in mid-September. He remained at Schaffhausen until the beginning of January 1902, after which he moved to Bern where he anticipated obtaining a post at the Patent Office.
In the meantime, Marić had failed her diploma exam for the second time in the summer of 1901. She was some three months pregnant at the time, and went to stay with her parents immediately afterwards. By October she had relinquished her ambition of producing a Ph.D. thesis on the basis of her heat conduction dissertation. Her baby girl, Lieserl, was born in January 1902. So the couple were only together for a period from October 1900 to March 1901, during which time Marić had enrolled at Zurich Polytechnic again to prepare for the final diploma examinations in July 1901, and was working on her dissertation. The notion that she was collaborating during this period with Einstein on the material he used in his first papers published in 1901 and 1902 is without any documentation and does not withstand serious consideration. Likewise, the notion that the single sentence on relative motion (not special relativity itself) in March 1901 demonstrates that Marić was a collaborator on Einstein's epoch-making paper written four years later in 1905 is untenable.
In the context of claims relating to the scientific contents of the letters during the years 1897-1902, what is notable is the absence of any discussion of physics in those written by Marić, other than a brief rather jocular account of a lecture by Lenard on elementary kinetic theory of gases that she attended during the 1897-98 winter semester she spent as an auditor at Heidelberg University. Unlike Einstein's, which frequently contain a report of his latest ideas on extra-curricular physics, Marić's are almost completely confined to personal matters, with occasional references to her studies relating to work for Zurich Polytechnic examinations. In two instances there are surviving letters from Marić responding to letters from Einstein in which he discusses in some detail ideas on physics topics on which he is working. In neither of her replies does she even allude to these ideas (Renn and Schulmann 1992, letters 8, 9; 29, 31). Nor is it feasible that letters of Marić's not kept by Einstein might have contained substantive responses to his ideas on extra-curricular physics: had such been the case it is almost inconceivable that there would not be indications of this in Einstein's letters, given his enthusiasm to discuss the ideas expressed in his letters.
Collected Papers of Albert Einstein, Vol. 1. Ed. J. Stachel et al. Princeton University Press, 1987.
Collected Papers of Albert Einstein, Vol. 1. English Translation, Princeton University Press, 1987.
Collected Papers of Albert Einstein, Vol. 2. Ed. J. Stachel et al, Princeton University Press, 1989.
Fölsing, A. (1997). Albert Einstein. New York: Viking Penguin.
Highfield, R. and Carter, P. (1993).The Private Lives of Albert Einstein. London: Faber and Faber.
Popović, M. In Albert's Shadow: The Life and Letters of Mileva Marić, Einstein's First Wife. Baltimore and London: The Johns Hopkins University Press.
Renn, J. and Schulmann, R. (1992). Albert Einstein: The Love Letters. Princeton University Press.
Stachel, J. (2002). Einstein From 'B' to 'Z'. Boston/Basel/Berlin: Birkhäuser.
Troemel-Ploetz, S. (1990). Mileva Einsten-Marić: The Woman Who Did Einstein's Mathematics. Women's Studies International Forum, Vol. 13, no.5, pp. 415-432.
Walker, E. H. (1991). Letter: Physics Today, February 1991, pp. 122- 124.