Max Planck As Editor of the Annalen Der Physik

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Ann. Phys. (Berlin) 17, No. 5, 273 – 301 (2008) / DOI 10.1002/andp.200810294

Historical Review

“… you can’t say to anyone to their face: your paper is rubbish.” Max Planck as Editor of the Annalen der Physik

Dieter Hoffmann∗ Max Planck Institute for the History of Science, Boltzmannstr. 22, 14195 Berlin, Germany

Received 23 January 2008 Published online 23 April 2008

Key words Max Planck, Wilhelm Wien, Annalen der Physik, edition of scientific journals, modern physics, German Physical Society. PACS 01.65.+g In honour of Max Planck (1858–1947) on the occasion of his 150th birthday Max Planck’s place in the history of the Annalen der Physik, which spans some two hundred years, can be characterized as unique. Planck not only published the majority of his own scientific papers in this periodical but was also connected to it personally in various editorial positions. Thus for over half a century, from 1894 until 1947, he contributed decisively toward its promotion as a leading international professional journal of modern physics. This paper documents Planck’s diverse relationships with the Annalen der Physik and analyzes his editorship against the backdrop of the evolving physics in the first quarter of the 20th century. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

1 Annalen der Physik

In the summer of 1790 Carl Gren, professor of physics, chemistry and pharmacology at the University of Halle, founded the “Journal der Physik”. From 1795 it appeared under the name Neues Journal der Physik and finally, after Gren’s death in 1798, as the Annalen der Physik. It numbered among the first professional journals in science, nevertheless it lacked the international aura and repute enjoyed by such sister periodicals as the Annales de Chimie et Physique (founded 1789) or the Philosophical Magazine (founded 1798) originating at just about the same time. Germany was still a developing nation in the field of the natural and technical sciences, which were being defined and developed by the discoveries and inventions of British and French scientists and engineers. The intellectual metropolises of the world were Paris and London; and the language of physics and the sciences in general at the turn of the 18th to the 19th centuries was French. English dominated in the areas of technology and engineering. The task Gren’s Journal took on, and that its successor editors William Gilbert (1799–1824) and Johann Christian Poggendorff (1824–1877) continued to pursue, was to convey to the German scientific community the latest scientific findings by means of translations of original papers or reviews. Original papers by German authors were also accepted, of course, not least as reprints from series issued by the important academies, which had hitherto – before the founding of the first professional journals at the close of the 18th century – provided and vouched for the transmission of research results. Book reviews and notices rounded off the picture.

∗ E-mail: [email protected]

Fig. 1 Max Planck as student, 1878. © Archive of the MPG Berlin.

A century later the situation had changed fundamentally. Germany was vying with Britain and France not only politically for power in Europe and took the lead in many ﬁelds of science and technology. In physics in particular, considerable progress was made during the ﬁnal third of the 19th century by German or German-speaking scholars including Ludwig Boltzmann, Hermann von Helmholtz, Friedrich Kohlrausch and Wilhelm Conrad Röntgen. The Annalen der Physik (und Chemie), under the editorship of Gustav Wiedemann since the death of Poggendorff in 1878, became the leading professional journal in physics in this time. Original papers now made up the majority of its articles and their topics were increasingly at the forefront of physical research of the day [1,2]. These changes are also mirrored in Max Planck’s life story and his editorship of the Annalen.

2 Max Planck’s biography [3]

Planck was born on April 23, 1858 in Kiel. His father Johann Julius Wilhelm had been working at the local university as professor of law since 1850. In 1867 he was appointed to the Ludwig-Maximilians-Universität in Munich. So the young Planck mainly grew up in the Bavarian metropolis. He also gained most of his early intellectual impressions from there, although his family tradition had a strong Prussian streak. In 1874 he had just turned 16 when he passed his school leaving examinations and took up studies in physics at the University of Munich. In 1877 he left for Berlin for two semesters. Since Bismarck’s uniﬁcation of the

Reich, the city was not just the capital of the German empire but was gaining increasing fame at home and abroad as a centre for science and culture. The University of Berlin advanced to the top institution of instruction and research. With the appointment of Hermann Helmholtz and Gustav Kirchhoff in the field of physics, an epoch began in which “the general history of physics became most intimately linked with the history of Berlin physics.” [4] Although the lectures by these two famous physicists were rather a disappointment for Planck, the high level at which science was being cultivated by them and in Berlin general would have a lasting influence on the course his life was to take. But first he took his doctorate in the spring of 1879 at the University of Munich, defending a thesis on the second law of heat theory. He earned his Habilitation degree already in the following year analyzing the equilibrium states of isotropic bodies at different temperatures [5]. This work became Planck’s future focus of research: thermodynamics, or more specifically, the 2nd law of thermodynamics and the concept of entropy [6]. In the years that followed he systematically examined the consequences of the 2nd law and the significance of the concept of entropy for thermodynamic equilibria in physico-chemical systems. His related publications from the 1880s treated, among other things, the thermodynamic theory of melting, evaporation and sublimation, the determination of the function of entropy for numerous systems in physical chemistry as well as the thermodynamic explanation of thermal phenomena. The most important and discerning findings of this early period concerned the theory of dilute solutions. Planck was able to specify the laws governing a drop in freezing point and a rise in boiling point and determine the chemical equilibrium in such solutions. Throughout his life Planck never entirely left the field of thermodynamics. In 1920 he succeeded in finding the ultimate thermodynamic formulation for Nernst’s heat theorem and in 1934 he gave the Braun-Le Chatelier principle – the principle of least resistance – its final form. Another achievement deserving mention is theFokker-Planck equation found in 1917, a formula of centralimportance in statistical physics. Planck’s early papers on thermodynamics very quickly attracted the attention and applause of the professional world. Thus after a five-year period as unsalaried private lecturer at Munich, he was able to accept an appointment as extraordinary professor of theoretical physics at the university of his home town Kiel, for the summer term of 1885. Merely four years later he became Gustav Kirchhoff’s successor as director of the Institute of Theoretical Physics at the University of Berlin. Thus he invested not just one of the most respected professorships in physics in Germany but one of the few chairs devoted exclusively to theory. Planck’s professional activities – extending beyond his retirement in 1927 – wrought lifelong ties to Berlin. His character and scientific competence contributed decisively toward establishing theoretical physics as an independent subdiscipline of physics. These personal gifts also prepared the way to a blossoming of the field in Berlin and, after Helmholtz’s death in 1894, were brought to bear on the local development of physics overall, particularly on science policy and institutionalization. At Berlin Planck also addressed a new field of research beginning in the middle of the 1890s, the theory of heat radiation. Setting out from the contemporary advances and the general establishment of Maxwell’s electrodynamics, he attempted to connect his thermodynamic studies with the electromagnetic theory of light. His main concern was finding a consistent interpretation of radiation as an electromagnetic process by recourse to thermodynamics. In his inaugural address before the Prussian Academy of Science in the summer of 1894, Planck said in this regard: “It is likewise to be hoped that we may gain closer insight into electrodynamic processes that are directly determined by temperature, such as are expressed in thermal radiation, without first having to take the arduous detour through the mechanistic interpretation of electricity.” [7]

3 Planck and the theory of heat radiation

The theory of heat radiation was one of the newest and most demanding ﬁelds of physics of the time. Little was known, for example, about the laws governing the emission by a hot object of heat or light rays. Moreover, it became evident that the related problems were unusually difﬁcult and complex, both from

www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 276 D. Hoffmann: Max Planck as Editor of the Annalen der Physik the theoretical point of view as well as with regard to the experiments. One of the leading laboratories to examine the problem of heat radiation was the German bureau of standards, the Physikalisch-Technische Reichsanstalt (PTR). Founded in 1887 it was the country’s largest and most important institution of physics and was located in Charlottenburg, at that time still a separate city from Berlin. Pursuant to its founding charter, the PTR conducted research in metrology as well as fundamental physics on problems of particular importance or requiring intensive analysis or costly apparatus [8]. The physics of heat radiation fell under this category. There was a burning need among scientists and engineers for reliable data about the fundamental laws of thermal and luminous radiation, also for commercial applications. At the close of the 19th century the lighting industry and lamp technology had seen stormy development that revealed a serious lack of reliable criteria for the assessment and certification of new light sources. Gas and electric lighting were in hot competition with each other. The goal set by the Reichsanstalt was, based on a generally valid theory of heat radiation, to find a suitable radiation standard for light sources, in other words, an objective unit of luminosity. Its progress report for 1895 accordingly states: “The experiments on the radiation of black bodies offer hope that it will be possible to arrive at better success regarding the idea expressed earlier that radiation from a light source can be explained by that from a constant source of heat.” [9] It is within this scientific and institutional context that Max Planck’s efforts to work on the problem of heat radiation fall. He remained loyal to his own scientific program all the same, drawing the behavior of entropy in processes of thermal radiation into the focus of his considerations. By working toward applying his earlier studies on the concept of entropy to Maxwell’s theory of the electromagnetic field, his purpose was not just to find out an exactly valid law of heat radiation and therefore of the entire electromagnetic spectrum. Along this path he also wanted to expose an as yet unrecognized deeper connection between the two fields of thermodynamics and electrodynamics. Planck’s researches on heat radiation sought nothing less than final unification of the three fields of physics – mechanics, thermodynamics and electrodynamics – as a crowning finishing touch to classical physics. His epistemological interests included, moreover, the search for absolute, generally valid givens: “… the quest for laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life.” [10] One absolute magnitude of this type existed in the theory of heat radiation in the form of the radiation emitted from what was referred to as a black body. This radiation is independent of specific material properties and can be described by a universal, material-independent radiation function f(ν, T ),asGustav Kirchhoff had discovered in 1859 [11]. However, complications of both an experimental and a theoretical nature arose in establishing this function and posed a major challenge for physics in the final third of the 19th century [12]. Stefan’s T 4-law and particularly its theoretical derivation on the basis of Maxwellian electrodynamics by Ludwig Boltzmann (in 1884) [13] was an important advance – Hendrik Antoon Lorentz praised it as a “pearl of theoretical physics”. The next important step was taken by Wilhelm Wien from the already mentioned Physikalisch-Technische Reichsanstalt in Berlin-Charlottenburg. In 1893 he formulated what came to be called Wien’s displacement law

λ · T = constant , and three years later also Wien’s radiation law, ρ(ν, T )=αν3e−βν/T where ρ(ν, T ) is the energy density for a given frequency and temperature and α, β are universal constants. In the years that followed, precision measurements were able to verify Wien’s radiation law and in early 1899 Max Planck eventually succeeded in deriving the law on the basis of thermodynamic considerations. Wien’s radiation law thus seemed to be the best, not only as far as empirical conﬁrmation was concerned, but also as to its theoretical underpinning [14]. Planck presented the results of his research on this topic in May 1899 at a meeting of the Prussian Academy. He also expressed his conviction that his choice of “radiation entropy and hence also Wien’s energy distribution law, is a necessary consequence of applying the principle of the increase of entropy to electromagnetic radiation theory and that therefore the limits of

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 277 validity of this law, if such do exist at all, coincide with those of the second law of heat theory.” That meant, Wien’s radiation law should have “general validity.” [15] In this connection Planck had already introduced the natural constant that was later described as the elementary quantum of action h. He pointed out that h, in combination with the velocity of light and the gravitational constant, opened the possibility “of positing units for length, mass, time and temperature, which … necessarily retain their signiﬁcance for all times and for all – even extraterrestrial and extrahuman – cultures, and which therefore can be denoted as ‘natural constants’.” [16]

4 The quantum hypothesis

The PTR continued its series of precision measurements of heat radiation in conjunction with the related development of appropriate measurement methods and instruments, even after Wien’s radiation law had been confirmed. It was not only the Reichsanstalt’s primary research agenda to test the radiation laws experimentally. These precision measurements were supposed to provide the basis for defining a suitable standard for sources of light. Discrepancies had been found between the theory and the measurement curves for the blackbody energy even before then. In the summer of 1900 Heinrich Rubens and Ferdinand Kurlbaum, fellows of the Technical College in Berlin-Charlottenburg and guest researchers at the PTR, employing the residual ray method in the extreme ultraviolet region detected such blatant deviations from Wien’s radiation law that they could no longer be dismissed. Rubens told his colleague Planck about the new findings before these results were reported at the upcoming colloquium of the Physical Society (Physikalische Gesellschaft). Friendship between these two men explains this confidence only in part. Planck was considered by the physics community as the authority on heat radiation because of his intense work on the problem during the last years. Gerhard Hettner, at that time a doctoral student of Rubens, recalled: “When on Sunday, October 7th 1900, Rubens came with his wife to visit Planck, the conversation also turned to the measurements that Rubens was working on. He explained that for his longest waves the law postulated recently by Lord Rayleigh … held. A generally valid radiation formula would in any case have to come out in that form for large λT .” [17] This comment prompted Planck to rethink his work on the theory of heat radiation, particularly his derivation of Wien’s radiation law. That same evening he found a “happily guessed interpolation formula” for his colleagues’ experimental data and informed Rubens about it by postcard as well. They met again a few days later, at which time Rubens was able to declare that “the new formula agreed excellently with his observations.” [17] At the Physical Society’s meeting on October 19th, Ferdinand Kurlbaum then reported about the experiments he had conducted with Rubens on long wavelength emissions by the black body at various temperatures and Planck added a prepared statement during the following “thorough”discussion [18]. This was his first formal presentation of his radiation formula in public. He had arrived at it by trial and error, that is, formally modifying his earlier expression for the entropy for Planck oscillators. Instead of the entropy expression prescribed by Wien’s radiation law: d2S = const dE2 E he set: d2S = const dE2 E(E + const) whereupon, by integration and a number of intermediary steps, he obtained the new (Planckian) radiation formula: Aν3 ρ(ν, T )= eBν/T − 1

Fig. 2 On 14 December 1900 Max Planck presented the derivation of his radiation law to the German Physical Society. Shown is the corresponding page of the meeting protocol. © Archive of the DPG Berlin. with A and B again being universal constants still to be determined and conformed to experiment. The formula agreed perfectly with the known measurement data [19]. Eight weeks later, on December 14, 1900, at another meeting of the Physical Society, Planck then delivered a first physical justification for his ad hoc introduced radiation law, his “happily guessed interpolation formula.” The elementary quantum of action h played only one part in it. A new (statistical) treatment of the radiation oscillators was its main basis [20]. This day is now generally considered – following Max von Laue [21] – “the birthday of quantum physics”, even though Planck at that time did not have any concrete notions about a “quantum hypothesis” and its significance would only be recognized in the decade to come. Planck’s difficulty at the time lay in abandoning his skepticism toward Boltzmann’s statistical physics and its atomistic foundation. In order to derive the new radiation formula, he was compelled to use what he had hitherto vehemently rejected, Boltzmann’s combinatorial definition of entropy with its probabilistic and atomistic character to determine the entropy function for the oscillating radiators [22]. This, the using of the “Boltzmann method”, he later described as an “act of desperation.” [23] Referring back to Boltzmann’s statistical conception of thermodynamics, according to Planck, the entropy (S) of an observed system of resonators in a given state was supposed to be set proportional to the natural logarithm of the probability (W ) in such a way that the resonators have a total energy E. Thus holds: S = k ln W.

Venturing beyond Boltzmann, who already knew about this relation between S and W but had never written down the formula, Planck introduced the proportionality factor k, which is now known as the Boltzmann constant k. He immediately realized its universal and absolute validity for statistical physics as a whole [24]. In order to be able to work statistically with this new approach as Boltzmann would have, he used another trick that is likewise attributable to Boltzmann who had used it in 1877 for the statistics of a molecular gas. Planck subdivided the possible (continuous) energy states of his (identical) oscillators into cells of constant, but not arbitrarily small quantities, rather “energy elements” ε: 0 to 1ε; 1ε to 2ε; 2ε to 3ε;etc.Fromthe number of possible partitions it was then possible to find out the probability of the given state and from that to determine the sought entropy of the oscillators as well as the radiation field’s energy density. Because Wien’s displacement law requires that the energy (E) be proportional to the frequency (ν), E was set = hν. Planck’s radiation law was the final result: 8πν2 hν ρ(ν, T )= . c3 ehν/kT − 1

Besides the variable magnitudes for temperature (T ) and frequency (ν), it just contains three other fundamental natural constants: Boltzmann’s constant (k), the velocity of light (c) and (Planck’s) quantum of action (h). This must have specially gratified Planck. As mentioned at the outset, absolutes were the object of his epistemological quest. In addition, the new radiation law permitted exact determination of these natural constants at a precision that eclipsed former methods and results [25]. In the following weeks Planck summarized the findings that had been presented before the Physical Society and they were published as a separate paper in the Annalen der Physik [26]. Planck initially gave no concrete particulars about the physical significance of the “energy cells” introduced in his original papers. The procedure he had chosen thus had hardly anything in common with what we currently understand as quantization. The American historian of science Thomas S. Kuhn was the first to give a consistent account of this in 1978 [27]. Kuhn’s assessment was not left unchallenged [28]; however most historians of physics today do basically go along with Kuhn’s argumentation that Planck’s approach did not constitute a quantization of the resonators in the modern sense [29]. Nevertheless, Planck’s derivation of the radiation law marked the first step in introducing the quantum concept into physics. Planck himself only explicitly mentioned discrete energy states of his resonators around 1908. Just two years previously, in his lectures on the theory of thermal radiation that surveyed the research on blackbody radiation, he was still cautioning against unfounded speculations about the physical significance of the “element of action” (Wirkungselement). All in all, as he declared in 1910, it was prudent to “proceed as conservatively as possible in introducing the quantum of action h into the theory; i. e., only those modifications should be made to the existing theory as have proven to be absolutely necessary.” [30] We can generally conclude that initially neither Planck nor his contemporaries were aware of the significance of the new radiation law and the fundamental importance of the natural constant h. One had “merely found a formula that apparently described the radiation conditions correctly. But whether there was something fundamentally new about the new quanta or not was not known,” Peter Debye noted in retrospect [31]. The first sign of our modern understanding of the quantum-like character of atomic events and the central role of h in its description came with Albert Einstein’s light-quantum hypothesis from 1905 as well as his and Paul Ehrenfest’s critical analysis of Planck’s radiation law (1905/06). Einstein’s analysis first showed that Planck’s radiation law was irreconcilably and fundamentally at odds with classical physics [32]. But even then, it took about another decade for the revolutionary consequences of Planck’s quantum hypothesis to be established and for problems in quantum physics finally to become the focus of physical research [33]. Personally, Planck certainly did not exclude this possibility but he did not play a decisive role in the further development of his quantum idea. Its evolution was rather the work of a younger generation of physicists. After the first Solvay conference (in 1911), they began increasingly to review the problem of quanta and eventually forged quantum mechanics in its modern form. Planck took part in the discussions about the physical and epistemological problems underlying it and actively promoted this new line of research publicly

www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 280 D. Hoffmann: Max Planck as Editor of the Annalen der Physik in science policy as well as personally, extending a helping hand to its young representatives. But as to the development of the ﬁeld itself, his only inﬂuence was that of a sympathetic critic [34].

5 Max Planck, the Physical Society and the Annalen

It may have taken more than a decade for Planck’s quantum hypothesis to establish itself and its originator to be acknowledged as the “father of quantum theory” but around the turn of the century Max Planck was already being held in high regard as a physicist and numbered among the leading scholars of his day. This acclaim had come particularly from his trenchant analyses on the concept of entropy and on processes of thermodynamic equilibria in physico-chemical systems [35]. The concept of entropy also formed the basis of his papers on the theory of radiation and the quantum hypothesis. The fact that he was an influential initiator and participant of the first Solvay conference in Brussels in 1911 [36], a summit of the leading contemporary physicists, documents his pioneering role in the early history of quantum theory as well as in physics in general. It manifests his competency about the issues concerning the interaction between radiation and matter being debated on that occasion, as well as his status in physics of that time. It was due to this fact also that around 1910 Planck increasingly took on the role of representative for the scientific community of Berlin and later of Germany as a whole. In doing so he assumed the place occupied by his mentor Hermann von Helmholtz during the last quarter of the nineteenth century. This was brought about not only by Planck’s extraordinary scientific rank and excellence as well as his rising national and international prestige but also by the fact that he was always ready to take on administrative and political functions for the sake of his field. Such activities agreed not only with his professional ethos and his Prussian sense of duty but also with his conviction that modern science functions optimally only when the researchers themselves do not shy away from such responsibilities. Therefore Planck was not an otherworldly or reclusive scientist – yet he was very wary about making any public political statements and only a few such expressions of opinion can be found in his popular papers and lectures from the second half of his life. Planck’s caution about making political statements contrasts remarkably with the broad range of official functions he was willing to assume as a science policy-maker. For instance, he served as dean repeatedly and in 1914/15 even as Rector magnificus of the University of Berlin, headed the Society of German Scientists and Physicians (Gesellschaft Deutscher Naturforscher und Ärzte) during its jubilee year 1922, and for more than a quarter of a century – between 1912 and 1938 – held the position of permanent secretary of the Prussian Academy of Sciences. From 1930 through 1937 he also served as president of the Kaiser Wilhelm Society for the Advancement of the Sciences. Thus he vested in some of the most powerful offices that a scientist could attain without enlisting himself completely into the service of the state. Planck’s engagement on behalf of science and its professional autonomy started with his activities in the Physical Society. He joined the society when it still bore the name “Physical Society of Berlin.” The minutes of the meeting of March 22, 1889 note: “Prof. Max Planck was nominated by A. König for membership” and his official admission into the society was approved at the next meeting [37]. The new member delivered his first talk some months later at the meeting on December, 12th 1889 and he spoke about the excitement of electricity and heat in electrolytic solutions. Other talks followed in subsequent years, numbering more than two dozen talks, mostly during the period before World War I. Moreover – as he proudly reminisced in 1938 on the occasion of his 80th birthday – he was able “to rival any other member … as far as the total number of sessions that I attended is concerned. Particularly around the turn of the century, there was hardly a meeting at which I was not present and hardly an after-session gathering that I missed.” [38] From the mid-1890s Planck became increasingly involved in the society’s administrative affairs, and along the way gathered influence on its activities and profile: first as treasurer, later as member of the board and finally also as the chairman of the society for the terms 1905/06, 1908/09 and 1915/16. During the society’s transition from the Physikalische Gesellschaft in Berlin to the Deutsche Physikalische Gesellschaft (DPG) Planck was one of the driving forces behind opening its doors to all German physicists and was

Fig. 3 Number of Planck’s publications in Annalen der Physik and other journals, as indicated, versus publication year. involved in the revisions to its statutes. So it was certainly not a matter of chance that the DPG named him honorary member in 1927 and two years later founded the “Max Planck Medal” for the golden jubilee of his doctoral degree [39]. This distinction remains the society’s most prestigious to this day. The first medallists of this award were its namesake and Albert Einstein. Other important anniversary dates also did not go by unnoticed. In honour of Planck’s 60th birthday in 1918 and notably his 80th in April 1938 the DPG organized special sessions. On the latter occasion the society seized the opportunity to celebrate itself as well, as a kind of self-promotion. All in all, the total of Planck’s activities for the Physical Society is impressive and unmatched in the 150 years of the society’s history. Equally unique and unmatched among his fellow physicists are Max Planck’s relations with the Annalen der Physik. This was his preferred choice for publishing his scientific papers – starting with his first article on saturation from 1881 [40] up to his last physical analyses on a synthesis between wave and corpuscular mechanics from 1940/41 [41]. Taking the three-volume compilation of Max Planck’s articles and talks as a basis [42], from the 121 articles in total, 41 appeared in the Annalen, i. e., 34%. Second came the Transactions of the Prussian Academy, the Sitzungsberichte der Preußischen Akademie with 33 articles (27%), and as distant followers came the Physical Society’s proceedings, Verhandlungen der Physikalischen Gesellschaft, the Zeitschrift für Physikalische Chemie,andthePhysikalische Zeitschrift, each representing a little bit more or less of 10% of the total count (see Figs. 3 and 4). Besides that, Max Planck bore direct responsibility for this journal for over 50 years. With Gustav Wiedemann’s arrival as editor of the Annalen in 1877 came an important organizationalchange. Thenceforth the Physical Society shared the official responsibility for its publication. This was expressed on its title page by the additional phrase: “In collaboration with the Physical Society in Berlin and in particular with Mr. H. Helmholtz.” Unfortunately no archival sources exist that indicate what this collaboration concretely meant or what the nature of the related responsibilities for the Physical Society were – whether they pertained to the content or were purely pecuniary. As far as Hermann Helmholtz was personally concerned, we may assume that his collaboration was not limited to that of a “factotum.” He surely exerted his own influence in consultations with the main editor on the choice of papers for publication, of course particularly those

Fig. 4 (online colour at: www.ann-phys.org) Distribution of Planck’s publications. (“Son- stige” = other journals.) concerning theoretical and general topics [43]. When Hermann von Helmholtz died in September 1894, the Physical Society entrusted Max Planck with this duty or supervisory function for volume 54 (1895). Thus we ﬁnd on the frontispieces of the volumes appearing between 1895 and 1920 the note: “In collaboration with the Physical Society in Berlin [– as of 1899: the German Physical Society –] and in particular with Max Planck.” When Paul Drude in Gießen was commissioned with the editorship in 1900, a fundamental reform was instituted for the issuance of the Annalen that took physical shape in the appointment of a board for the journal. The members of this panel of 5 physicists were Friedrich Kohlrausch, Georg Quincke, Wilhelm Conrad Röntgen, Emil Warburg as well as Max Planck. At 42 years of age Planck was by far the youngest on this advisory board; thus he represented a new generation of physicists. Moreover, he was the only real theoretician among them. Planck undoubtedly regarded this appointment as a great honour. It was a clear sign that he now ranked among Germany’s ﬁrst physicists.

6 Max Planck and Wilhelm Wien as editors of the Annalen [2,44]

Paul Drude’s term of ofﬁce as responsible main editor hardly lasted 5 years. In the summer of 1906 Drude took his own life, having not even reached the age of 43 [45]. Consequently the editorship of the Annalen was again available and Wilhelm Wien and Max Planck agreed to take on this responsibility as of volume 21 (1906). Wilhelm Wien was the responsible “main editor or redactor” but that did not diminish Planck’s role, as he continued to be a member of the advisory board and remained the go-between for the German Physical Society. No documents have survived about the negotiations behind this appointment or who took the crucial decisions. The existing correspondence between Max Planck and Wilhelm Wien1 –albeit

1 This exchange from the period 1900 to 1928 and comprising 200 letters is preserved at the manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, as well as among the Wilhelm Wien papers at the archive of the Deutsches Museum in Munich.

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 283 involving only the later decision processes – does reveal, however, that it was the Physical Society that had the final say, more precisely, its science committee, besides the publisher. In 1890 Arthur Meiner had taken over the publishing house of Johann Ambrosius Barth and thereafter assumed the responsibility for the Annalen. According to one of Planck’s letters [46], “pursuant to the statutes,” the DPG’s science committee represented “the society’s interests at the Annalen,” undertook to settle issues involving the staffing of the editorial and advisory positions as well as those involving otherwise unresolvable disputes between the editors and the board and other problems arising out of the editing of the Annalen and the other journals carried by the society. The minutes or other documents about the meetings and decisions reached by this panel have unfortunately not been preserved, so we must rely on secondary information from letters or recollections by those who had been present. Planck and Wien must have first discussed and possibly even reached some agreement about Drude’s successor in July already, that is, just a few days after Drude’s death. Planck wrote in a letter from July 28th:

“Our letters have crossed paths; but since you would, in any event, soon like to receive word about your inquiry regarding the Annalen, I reply promptly to yours … I imagine my future employment as an editor as similar to now, just with the difference that I appear outwardly to be bearing greater responsibility. This would ﬁnd expression in that, just as Ostwald and van’t Hoff appear side by side on the title page of the Zeitschrift für physikalische Chemie,thetwo editors would likewise be set next to each other. Only one of them can see to the managerial administration, of course: on the other hand, in doubtful cases, when a rejection and return for revision (shortening) is concerned, I would be consulted, as previously. This makes a difference from earlier insofar as I used to be able to deny any responsibility toward the outside (and have done so, e. g., in the recent Denizot case), because I saw myself not as “coeditor” but merely as an occasional editorial collaborator. In the future that would change.”

Wilhelm Wien, born in 1864 and since 1900 professor at Würzburg, was one of Germany’smost prominent younger physicists. But this fact alone was surely not the only reason why he was taken into consideration as Drude’s successor in editing the Annalen. His investigations into the physics of heat radiation and canal rays were pioneering achievements that later (1911) earned him the Nobel prize. He was one of Hermann Helmholtz’s pupils and had worked for many years at the Physikalisch-Technische Reichsanstalt in Berlin- Charlottenburg. Thus he was, shall we say, part of the “Berlin biotope.” [47] As Planck was able to report, Paul Drude supposedly once described Wien as “his most worthy successor.” [48] Last but not least, Planck, who apparently played a central role in the matter, knew Wien very well and had been corresponding with him and meeting him personally for many years. Berlin physicists had already picked Wien out to succeed Drude as director of the physics institute at the University of Berlin. Wien declined that appointment in September because he had been unable to obtain the assurance of a new building for the institute, however, the Annalen question seemed to have reached a positive result. This can be gathered from one of Planck’s letters in September 1906: “Still, the inquiries by the board and by the science committee of the Phys. Soc. will take up some time yet; for, Meiner wants to invite all the proper authorities to express their official opinions, and that is surely very useful too, because your introduction into the editorial office will then proceed under the best of auspices.” [49] A few weeks later everything was finally settled. In October 1906 the Annalen’s readership could also be officially informed about the change in the editorship in a notice by the publisher [50]. Meanwhile the editorial work had already begun. Planck and Wien were discussing concrete details like how best to handle rejection of a submitted paper without getting the Annalen drawn into wearisome and fruitless polemics with the author [51]. In general, such troublesome cases formed the majority of these discussions between the co-editors because as main editor Wien was in charge of deciding about whether to accept a manuscript and largely did so on his own, only consulting with his co-editor about doubtful issues or submissions that he deemed exceeded his own expertise in physics [52]. Planck estimated that between

Fig. 5 Wilhelm Wien (1864–1928). © Archive of the DPG Berlin.

5 and 10% of incoming papers fell within this category [52]. The proportion that the historian of physics Lewis Pyenson figures for the Annalen is between 15 and 20% [53]. The majority of the rejections concerned articles of questionable or insignificant content and those containing serious errors. Planck’s criticism of such contributions was withering and his characterizations of their authors blunt. This starkly contrasts the style he used in his publications and other statements directed to the public. Then his tone was ever tactfully obliging and diplomatic. Practically no personal judgments are to be found in his articles, but in his letters to Wilhelm Wien there was no such restraint. Papers are characterized as “awkwardly weak,” [54] “mediocre,” [55] “scientifically completely worthless,” [56] “sheer nonsense,” [57] “nonsense,”(dummes Zeug) [58] “senseless bungling,”(sinnlose Stümpereien) [59] or even “the work of a dilettante” [60] or “conceited bunk” (eitel Blendwerk) [61]; and “one couldn’t possibly print such rot.” [62] Some hapless author was certified as having an “amateurish way of thinking,” [63] and a certain Herr Kohl “did full credit to his name.” [64] But the majority of the controversially debated papers were processed without any kind of polemics ensuing. Reason for a rejection existed primarily if the subject of the paper was of no current import in physics, was incorrect in substance or not clearly or confusingly presented. The length of an article could also play an important role and overly “corpulent” manuscripts were returned with an allusion to insufficient space or the Annalen’s guidelines or with the advice to cut it down. Dissertations were likewise rejected if – as, for instance, in Hans Geiger’s case – they were “only secondarily reckoned for the Annalen.” [65] As a

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 285 rule, in rejecting a paper – as we learn from a letter to Wien [66] – the approach was “that one proceeds as parsimoniously as possible with indications about the reasons to the authors, just so as not to commit oneself officially to any specific rule. The deeper reason for this is, of course, that one can’t say to someone’s face: your paper’s rubbish [taugt nichts].” Such a procedure naturally also assured that the author had little to go on in opposing the rejection of a given manuscript. Besides Planck’s uncontested authority as a scientist, this was another reason why throughout his many years as editor there were relatively few disputes fought out in extenso, as for instance the later in detail discussed case of A. Bucherer. For Planck, the pivotal point determining acceptance or rejection of a submission was “whether in an article … any kind of connections are made to physically verifiable issues” [67] and in this way to secure that the Annalen would publish the most interesting and cutting-edge results of contemporary physical research. On these points Max Planck’s and Wilhelm Wien’s interpretations seem to have coincided. Not a single example exists in the extant correspondence that would reflect some clash of opinion that the two could not settle between themselves. Wilhelm Wien was thus not resorting to euphemism or superficial amiability when in the summer of 1920 he confided to Planck that throughout their joint editorship of the Annalen “not even the slightest dissonance ever resulted between us.” [68] Problems could develop not just between authors and the two editors or even between the two editors themselves, but likewise with the Annalen’s advisory board. As already mentioned at the beginning, this panel was appointed by the Physical Society, that is, its science committee, to which the journal was directly accountable and which otherwise had the final say in any cases of conflict. It had been established during a reorganization of the Annalen in 1900 and was composed of maximally six members, all famous and very recognized physicists who through their exceptional expertise had gained the general respect of the physics community in Germany:

The Members of the Advisory Board of the Annalen der Physik 1900–1945 Max Planck (1858–1947) 1900– 1945 F. Kohlrausch (1840–1910) 1900–1910 W. Voigt (1850–1919) 1910–1919 W.C. Röntgen (1845–1923) 1900– 1923 G. Quincke (1834–1924) 1900– 1924 E. Warburg (1846–1931) 1900– 1930 W. Gerlach (1889–1979) 1930–1945 F. Paschen (1865–1947) 1929– 1945 R. Pohl (1884–1976) 1929– 1945 Following the death of a board member, the editors apparently had a right to submit suggestions to the Physical Society and the publisher. This is documented by the case of Friedrich Kohlrausch [69] and we read in a letter Planck wrote to Wien after Kohlrausch’s death:

“About the reappointment of the position on the board of the Annalen vacated by Kohlrausch’s death, I also asked the other members of the board, Quincke and Röntgen, besides Warburg, and received from them all the unanimous reply that they fully agree to Voigt’s joining the board. Now, I think it suits the purpose best if you write directly to Meiner in the name of the editors that the editors and the board wish to ﬁll the vacant position with Voigt and then, provided Meiner approves, which is surely to be expected, indicate this to Voigt (or have Meiner do this (would probably be better)), by which the business is then perfected.” [70]

Not merely as a coeditor or a member of the editorial staff but, indeed, as a member of the advisory board and an in-house power of the Physical Society [71], Max Planck should be regarded as the Annalen’s “strong man,” if not its “grey eminence.” The way the work was distributed between him and Wilhelm Wien

www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 286 D. Hoffmann: Max Planck as Editor of the Annalen der Physik and their separate roles in the editing of the journal reflect this. Strategic matters – such as in the above quote – were mostly broached by Planck. Letters from the summer of 1920 also show this. At that time, the ‘journal problem’, new restrictions imposed on publishing necessitated by the economic shortages of the post-war period, was being hotly debated in the Physical Society and among physicists generally [72]. Planck likewise led the discussions about the general role played by the advisory board. He always spoke in favor of a high degree of independence for the editors, emphasizing that in the reviewing an editor “take full liberty in every case … not officially subordinate himself to any specific rule.” [73] Concretely put, the two editors alone “are to decide on the acceptance or shortening of papers,” without the board, for example [74]. Thus the board’s role remained solely limited to the supervision and ultimate settlement of problem cases. Two are documented in the correspondence between Max Planck and Wilhelm Wien. One involved an interminable quibble, as it were, with Alfred Bucherer [2]. In the fall of 1906 he had submitted a manuscript to the Annalen in which, embarking from Einstein’s papers, he had postulated a new principle of relativity that Planck deemed “entirely worthless” and therefore advocated be rejected. In view of “the auth[or’s] standing as private lecturer in Bonn,” however, he wanted to avoid a too curtly worded refusal, especially considering Bucherer’s reputation as an incorrigible squabbler in such situations [75]. That turned out to be the case here, too, so the board had to step in to clear up the matter, ending up “settling” it (in the editors’ favour) as well [76]. Later on Planck and Wien had to contend with other purported developments of Einstein’s theory of relativity by Bucherer that Planck thought would “not be a feather in the Annalen’s cap” (würde den Annalen nicht zur Zierde gereichen) [77]. Nevertheless Planck advised a diplomatic approach and considered it “questionable to decline the paper directly, as Mr.Bucherer is, after all, a “full honorary professor”.” [78] A more delicate case concerned Georg Quincke, a nestor of experimental physics in Germany and himself a member of the board. In the spring of 1920 he had submitted a paper to the Annalen editors that sought to explain the results of experiments by the assumption of longitudinal electric oscillations. This claim contradicts Maxwellian electrodynamics and Quincke’s argumentation was not convincing either, so Planck suggested that he consult with Emil Warburg “about this very fatal business for the Annalen editorial effort … strictly confidentially and on his own authority.” Likewise on the board, Emil Warburg was a long-time colleague of Quincke familiar enough with his working approach for him to have “sufficient objectivity to be able to judge the circumstances clearly.” [79] Although Warburg very quickly came to share Planck’s and Wien’s opinion that the paper did not belong in the Annalen [80], it was agreed that the matter be resolved without personal offence for Quincke by his “being talked into voluntarily withdrawing the manuscript for the time being.” [81] Almost two years passed without any progress being made. After Warburg likewise recommended “simply to tell the ‘truth’ – naturally with as much sugar coating around the bitter pill as possible,” [81] Wilhelm Wien as managing editor finally took action. In a letter to the “doyen of the experimental art” he set forth that “the interpretation of the experiments as an effect of electric longitudinal oscillations is in direct contradiction to the general laws of electrodynamics that until now have been upheld by the most disparate findings. As interesting and important as your experiments undoubtedly are, the editors do not regard the results as such as could yield conclusions of so far-reaching and revolutionary a significance as would be the existence of electric longitudinal waves. It would therefore rather be advisable to strengthen the proof of the existence of electric longitudinal oscillations in such a way as to place beyond all doubt these revolutionary findings for the entire foundation of modern physics.” [82] Whether the outcome of this exchange with Wien or other efforts eventually led to a retraction of Quincke’s manuscript by the turn of the year 1922 to 1923 cannot in retrospect be verified beyond doubt. In any event Planck was able to add to his new year’s greetings to his colleague congratulations “that the difficult Quincke affair seems to have been settled without adverse consequences.” [83] Not every controversial case required such a hard struggle by the two editors for a peaceful resolution. Their correspondence indicates that in dubious cases Planck frequently took pains to give due acknowledgment to the author’s personal standing, academic rank or merits. For example Johannes Stark’s experimental mastery was recognized without reserve. Yet “his often untenable, almost always arbitrary theoretical conceptions” [84] were hard to swallow. “… if he does not better himself, we shall have to shut the door on him one day. But I would be

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 287 unhappy to do that to the discoverer of the Doppler effect on canal rays, and then, only in an emergency.”[85] A similar route was taken in the case of Franz Kiebitz, fellow at the research department of the Imperial Institute of Telegraphy in Berlin. The technical content of his paper on differential equations describing a coupled pair of oscillating circuits [86], in Wien’s opinion, should rather be published in the Jahrbuch für drahtlose Telegrafie than in the Annalen. Planck emphasized Kiebitz’s scientific merits, pointing out that the paper had been “written accurately.” For that reason it appeared subsequently in the Annalen, especially since – Planck likewise explained – apparently “a principle risk … [seemed] not to be attached to it, because it is clearly of a finalizing character and the treated topic completely finished off, so nothing more, at least of a principle nature, can be linked to it.” [87] Also in the case of the Prague physicist Frantisek Kolacek, Planck had qualms about simply rejecting the submitted paper. In Planck’s opinion “the author has already provided so many contributions to the Annalen, some of them quite valuable, that we shall have to tolerate one of lesser quality for once. What a pity that the author as a person is always so inseparably linked to each of his elaborations.” [88] A linkage of quite another sort existed in the case of Gunnar Nordström. He was born in 1881, had studied physics in Göttingen and had just started a scientific career as lecturer at Helsinki’s technical college. Although Planck assessed the paper he submitted as “somewhat unclear,” [89] he nonetheless proposed it be accepted because “especially for the first contributed mailing one should demonstrate as much goodwill as possible so that the person concerned gets to have a say at all. Later on, one may be more cautious, all right.” [90] Consequently, Planck as an editor did not simply follow abstract or indeed “sacred” principles. The Annalen’s relationship with its authors also mattered to him, in particular to establish solid linkages with prominent or talented physicists. However, he encouraged nurturing such ties not just with individual authors but also with institutions like the Berlin Imperial Institute of Physics (PTR). Founded in 1887 by H. von Helmholtz and W. von Siemens, the PTR became the largest and most important physical institution in Germany by the turn of the century. In addition to its routine metrological measurements and research it also pursued high-level basic research in physics. It was there that the precision measurements on blackbody radiation were conducted that inspired Max Planck to advance the quantum hypothesis. The Annalen was one of the publication organs preferred by the PTR’s physicists. Conflicts did nevertheless occasionally arise. When in the summer of 1907 Ernst Gehrcke and Otto Reichenheim submitted an article that was based on a talk presented before the Physical Society and hence had already been published in its proceedings [91], this challenged an issue of principle in editorial policy. As a rule, only original publications were accepted. Thus ensued a debate about the pros and cons, which Emil Warburg was also brought into. At that time Warburg was the president of the PTR as well as member of the Annalen’s board and a very well accepted member of the physical community in Germany and abroad. Planck cautioned to keep things in perspective and step lightly because “the collaboration of the Reichsanstalt on the Annalen [is] one of its most valuable assets that under no condition may be sacrificed for the sake of a formal principle. Proof of this is the abundance of the most valuable Annalen articles that come from the R.A. [Reichsanstalt]. Their loss in future could eventually spell the Annalen’s doom. That is why also for that reason I am decidedly in favour of accepting the paper by G. and R. and would regret it if within the R. A. the thought arose that the Annalen’s editors did not place much importance on the R. A.’s collaboration.” [92] This reasoning was followed and the paper by Gehrcke and Reichenheim appeared in its submitted form in the Annalen’s 23th volume [93]. This problem case touched on the Annalen’s relationship with other periodicals and publications in physics. The Annalen’s editors viewed themselves and their professional journal as an outlet for original papers that treated a problem in physics definitively. This contrasted against the Verhandlungen der Physikalischen Gesellschaft, which generally documented contributions presented during the meetings of the Physical Society and was thus “more for preliminary papers destined for rapid publication.” [94] The contribution by Gehrcke and Reichenheim shows, however, that there was a willingness to make exceptions to the rule. Exceptions were similarly granted for reprinting of the session reports by the German academies and other scholarly societies. As Wien argued in a letter to Planck [95], such texts “are received directly by only a limited number of professors, initially to their generally not large membership, then to the libraries and the small number of people who procure their own,” whereas the Annalen “addresses an

www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 288 D. Hoffmann: Max Planck as Editor of the Annalen der Physik audience that is mostly more numerous.” The other periodicals published alongside the Annalen were an entirely different problem. They were very much perceived as rivals. At first the only competition was the Physikalische Zeitschrift, founded and principally supported by the Göttingen physicists in 1899. However, its profile resembled that of the DPG’s proceedings, tuned rather toward prompt, up-to-date reporting. One of its specialties was survey articles on particular physical problems. Thus the Physikalische Zeitschrift and the Annalen der Physik each served very specific needs of the physical community and were able to coexist very nicely. Thanks to its heritage and nimbus, the Annalen managed to secure its dominance at least until World War I. This “even outwardly perceptible advantage ” – as Planck put it to Wien in 1907 [96] – over its “junior partner” is mirrored in the correspondence between the editors. There is the occasional discussion about “shuffling off [specific papers] onto the Physikalische Zeitschrift. Then more space remains for us for real physical analyses.” [97] Incidentally, new activities in this field were observed with suspicion. When in 1916 Stefan Meyer from the Vienna Radium Institute and Rudolf Seeliger, a fellow of the Reichsanstalt, planned a new journal for atomic and radiation physics, Wien recommended that “for the time being they should definitely wait and see” and commented this idea drastically and with nationalistic overtones: “To me this seems to be a special Austrian endeavour to accommodate the copious numbers of not very valuable scientific papers from Vienna’s Radiological Institute. Seen from the position of the Annalen, this is just fine with us. We have not received so much valuable material from Austria that we should be unduly disturbed by the decrease. I just don’t understand that a publisher nowadays can enter into such a dubious endeavor and that a physicist from the Reichsanstalt feels himself compelled to participate in such an Austrian endeavour.” [98] Planck in his reply also appealed “to wait for the time being … besides the fact that I also have no idea what measures one could resort to in this matter.” [99] The opinion of both was more moderate when in 1910 Waldemar von Ignatowsky and Eugen Jahncke had the idea to set up a new journal for theoretical physics. Planck communicated this to Wien with the words: “What do you think of this? On the one hand it could perhaps be very good for the Annalen to be somewhat relieved of the influx of theoretical papers, on the other hand a stricter division of theoretical and experimental research is not at all agreeable. I have been asked to support this affair, but for the time being have strong reservations.” [100] Incidentally, none of these plans could have been realized for not only did the scientific community have its reservations, but also the economic shortages and political chaos worked against them. As the years went by, the Annalen’s leadership among German physics journals and its role of moulding public opinion seeped away. The reforms instituted in the periodicals business after the war leveled the playing field for physics journals. Yet it was not the Physikalische Zeitschrift that challenged the Annalen’s ranking as the leading physics journal in the German language. A relative newcomer, the Zeitschrift für Physik founded in 1920, took over this position.With its great openness toward developments in modern physics, it emerged as the most important publishing organ for the young fields of quantum theory and quantum mechanics. This and the fact that – as Planck noted in a letter to Wien [101] – “the Annalen often presents things that had already been briefly announced elsewhere” caused the journal to become increasingly “boring,” particularly for younger and more innovative physicists. They, along with others in their field, began to lose interest in the Annalen. The result was the loss of what Planck lamented as the majority of his regular contributors during the 1920s [102]. Among them were also the physicists from the Reichsanstalt, although they were not exactly pioneers of modern physical research. This shows that now the “outwardly perceptible advantage that we possess over other journals” [103] had finally expired and the Annalen no longer deserved the part of primus inter pares among German-speaking physics journals.

7TheAnnalen and modern physics

A profound revolution in the foundations of physics coincided with Max Planck’s and Wilhelm Wien’s co- editorship of the Annalen. Quantum theory and relativity established themselves as the two bearing pillars of modern physics. Max Planck’s own quantum hypothesis and the theory of blackbody radiation underlying it were important stepping-stones in this development. Not just quantum theory but also the theory of

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 289 relativity gained an important boost from his attention. He was one of the physicists to very quickly realize the revolutionary significance of Einstein’s Annalen paper on the electrodynamics of moving bodies and was instrumental in furthering lasting appreciation of Einstein’s theory of relativity [104]. The fact that the majority of the theses Planck supervised before World War I examined related problems reveals the depth of his interest and active promotion of relativity theory [105]. So it was by no means a coincidence that Planck’s graduates were among the Annalen’s contributing authors. Kurd von Mosengeil is a particularly tragic case in this connection. Shortly after submitting his dissertation he had a fatal accident in the Alps. Planck went out of his way to prepare this manuscript on relativistic radiation theory for publication himself, also making some substantial additions to it [106]. Another of his doctoral candidates, Wilhelm Heil, wrote an equally noteworthy dissertation, entitled “On the Theory of Kaufmann’s Experiments on the Electromagnetic Deflection of β-Rays,” in 1909. It weighed the pros and cons of the contemporaneous theories of the electron by Abraham and by Lorentz and Einstein, reaching the conclusion that the available experimental data did not offer any basis for deciding between the two theories. Erich Hupka, on the other hand, arrived at much more positive conclusions. He was another graduate student, but working under Heinrich Rubens’s guidance at the university’s institute of physics in Berlin. His cathode-ray measurements to test the velocity-dependence of the mass of an electron claimed support for the theory of relativity [107]. Heil criticized Hupka’s results in an outspokenly polemical style [108] and it fell to Planck, as both editor and doctoral advisor, to assume the “role of honest broker” [109] in this controversy. After meeting with the opponents personally and some lengthy correspondence, he managed to reach a compromise acceptable to all without bruising the sensitivities of either party. In the end, the papers and criticisms of both were able to appear in the Annalen’s volumes 31 (1910) and 33 (1911) [110]. Other disputes did not cost Planck as much time and effort, as the co-editors quite quickly became unanimous about rejecting papers that were blatantly faulty in substance as well as about “shuffling off” analyses about the principle of relativity “which rather regard formulation, conceptualization, definitions (rigid bodies!)” onto other periodicals [111]. Planck and Wien shared the view that in the long run theoretical physics would become bland if it moved too far away from experimental findings. The editing of submissions on the theory of relativity was ultimately conducted along these lines [2]. For example, the paper by a Mr. Wisniewski was rejected even though “there is possibly a useful core” to his theory of gravitation. “Yet it is at present very hard to decide … there are simply too few firm indicators for a complete theory of gravitation. (About the Einsteinian one, which does not quite agree with me, observations at the next solar eclipse will hopefully yield a decision.)” [112] In another case, a paper by Hermann Weyl on gravitation theory [113], about which there could be “no question of an experimental verification of his theory” either, there was a greater willingness to act more generously and approve its appearance in print. That “the auth[or] stands at the pinnacle of the research of his time” [114] spoke in its favor. Because considerations on non-Euclidean geometry played an important part in Weyl’s paper, Planck was set before the general question of “to what extent such analyses, which without a doubt are bound to multiply heavily, belong in the Annalen der Physik … For the time being, especially as long as they appear in close connection with gravitation theory, one will probably have to concede them guest rights.” [114] Such guest rights were later also granted to Cornelius Lanczos with his paper on the planar distribution of matter in Einstein’s theory of gravitation [115], even though here too Planck asked “whether the value of such analyses is suitably proportionate to their physical breadth.” [116] Although Planck welcomed the fact, that “more and more mathematicians begin to take an interest in physical problems”, he found it “always bad, when a mathematician makes physical hypotheses.” [117] By the way, even David Hilbert was included in this verdict. Planck found his “deductions about the radiation equilibrium formally interesting and general”, but for physics absolutely uninteresting [118]. In this sense he was concerned to define an editorial policy that would exclude all too mathematical papers. However he was willing to make exceptions, for instance regarding a very mathematical paper on the mechanical foundations of thermodynamics by the Heidelberg physicist (and also later philosopher) Paul Hertz. But this investigation was dealing with such an important and difficult aspect for understanding statistical mechanics, that in this case “the comprehensiveness is a necessity for clarity” [119] and the author was even allowed to

www.ann-phys.org © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 290 D. Hoffmann: Max Planck as Editor of the Annalen der Physik publish his work in two parts [120]; of course the problem discussed was also very close to Planck’s own thermodynamical work. We also know, that Planck was always very interested in general questions and took the view, that “epistemology is basically no less important as mathematics”, but nevertheless he sought to exclude this “supporting science” (Hilfswissenschaft) of physical research. Therefore the Annalen should not accept in principle “purely epistemological investigations as it also does not publish pure mathematical or technical papers. For that we have other journals.” [121] When in the early 1920s relativity theory became the topic of public controversy and even political debate [122], it also had repercussions on the editing of the Annalen. The principles discussed above regarding overly mathematical and philosophically oriented papers became relevant. A letter by Planck suggests that Wien had recommended having the Physical Society’s newly founded editorial committee impose a general rule in order to be able to regulate the acceptance of papers on relativity theory or even prohibit them across the board. Planck had reservations about acquiescing to what was effectively a ban but conceded that such articles did have to be handled with great caution and restraint. Nevertheless the decision should always be made on a “case-by-case” basis, because

“I could imagine the case of a relativistic paper of truly current physical merit arriving sometime, without it happening to contain new correlations to observable quantities. It could, e. g., show known relations in a new, general connection; and then I would ﬁnd it a shame if we wanted to bar ourselves from the possibility of accepting such a paper by a general regulation. Therefore, I think we should maintain our present practice at the Annalen for the moment.” [123]

During the twenties it became the usual practice for only the occasional paper on relativity theory to gain entrance into the Annalen because – as one author was informed – “pursuant to the [editors’] opinion, from the physical aspect the theory is closed.” [124] Such restrictions also concerned articles criticizing relativity theory. E. Gehrcke complained in a letter to W. Wien when the Annalen editors had rejected a paper by S. Mohorovic from Zagreb, “a very pro-German foreigner” and staunch critic of Einstein’s theory of relativity [125]. This had not only deeply depressed the author but prompted Gehrcke to comment that “it does not appear to me good that papers touching on relativity theory be rebuffed so very severely and abruptly, especially when it regards papers suited to clarifying the essence of the relativistic method while casting the matter in a critical light.” [126] Despite this appeal, the decision was not reexamined and Mohorovic was not able to publish his paper in the Annalen. There certainly was a willingness to bend this principle from time to time nonetheless, as the following case clearly demonstrates. When Erwin Schrödinger submitted to the Annalen a paper on the accomplishment of the relativity condition in classical mechanics in the spring of 1925 [127], nothing stood in the way of its going into press. Planck’s comment about it was: “It really is good that we did not commit ourselves to rejecting all relativistic speculations. Cases simply do vary and the editors must have a certain amount of freedom.” [128] Whereas essays on relativity theory could count on a sympathetic and positive welcome by the Annalen’s editors at least until World War I, after which enthusiasm leveled off, the reception that papers on quantum theory experienced was almost the reverse. For many years Max Planck could not conceal his scepticism about the developments in radiation and quantum theory. It is not surprising that it would also ﬁnd its expression in his correspondence with Wilhelm Wien and his editorial work for the Annalen. One of Planck’s letters from 27 February 1909 reads:

“Soon I too am going to say a word about radiation theory again, especially since Einstein is now going to publish all sorts of reservations as well (in the Physikalische Zeitschrift). He arrives at the assumption that the elementary quanta h have meaning also for processes in a pure vacuum. I don’t believe that as yet, and surely neither do you, Lorentz quite certainly neither. Why should one complicate the theory unnecessarily? There are enough difﬁculties as it is, and one can be quite satisﬁed if everything can be clumped together in a single place, the processes inside the molecule.” [129]

In the fall of the same year he reported to Wien:

“As to the radiation, a new way out occurred to me that appears to me to be tractable even though it leads me even further away from Einstein and Stark. The energy of the resonators does not need to be an integral multiple of hv at all, nor, indeed, the energy of the free radiation.” [130]

In a letter dated February 21, 1910 Planck even speaks of “J. Stark’s phantasms,” probably a reference to Stark’s papers in the Physikalische Zeitschrift, in which various arguments in support of the light quantum hypothesis were discussed [131]. An embarrassing error in physics had escaped Stark’s notice that A. Sommerfeld, among others, had pointed out to him, triggering a bitter controversy between the two physicists [132]. Planck was not sparing either with his critique of Stark’s bold physical interpretations. For instance, he regarded “Stark’s application of the quantum hypothesis to the Doppler effect as very attackable.” [133] Even so, such critical evaluations did not hinder him from regarding the young Stark as a “very talented and accomplished man” [134] and a “mind rich in ideas,” [135] also assessing his research at very least as “stimulating.” The discovery of the Stark effect in 1913 ultimately confirmed this assessment and he considered it “a sign that this man does have some mettle. Though he does have more luck in trials than in studies, the main thing is that he does deliver.” [136] These reservations about the first attempts at quantum theory led at least in one case to a pioneering paper from the early history of quantum theory not being published in the Annalen. Arthur Erich Haas had submitted his analysis of the physical significance of the elementary action quantum h to the Annalen’s editorial office at the end of 1909. It was the first paper to relate the nature of h with atomic structure [137]; nevertheless it was not approved for publication [138]. When the paper subsequently appeared in the spring of 1910 in the Sitzungsberichte of the Viennese Academy, Planck congratulated himself on “the adeptness with which we avoided being duped by him. Misunderstandings, completely arbitrary assumptions, unacceptable results follow each other in quick succession …” [138] Notwithstanding this faux pas, Planck cannot generally be charged with ignorance in the face of new ideas and developments. Five years later when he refereed a paper by Thomas Wereide, lecturer of physics at Oslo University, on the exchange of energy between the ether and matter, he supported publication despite numerous misplaced speculations [139]. He merely recommended a careful recalculation of the derivations, noting that “in this virgin field a certain latitude [must] reign, otherwise science does not come across new ideas.” [140] All in all, as Planck himself confessed about his editing, he apparently rather shied away from “the charge of suppressing alien opinions than of too much lenience in their evaluation.” [141] Planck and Wien were quite sceptical about the developments in the early history of quantum theory, and even more so about the emerging quantum mechanics. For both of them it was too radical a break with existing principles in classical physics. In a letter to Planck at the turn of the years 1924/25, Wien noted in this regard, with a tinge of resignation: “Theoretical physics really is in a peculiar state.” [142] In the following year when New Year’s greetings were again being exchanged, something new had come up in this regard, perhaps even giving a spark of hope. Erwin Schrödinger had submitted his famous papers on wave mechanics to the Annalen for publication and Wien deemed them so unquestionably suitable that he merely let Planck know that “a paper by Schrödinger [will] soon appear in the Annalen [143], in which the quantum problem is interpreted as a problem of characteristic oscillations such that the lines of the Balmer series appear as suspensions between two very high-frequency oscillations. I am curious what you will say about it.” [144] In reply Planck wrote his colleague: “I am in suspense about Schrödinger’s paper on spectral lines. I trust his acumen and his imagination enough for him to be able to make a bolder leap.” [145] After reading Schrödinger’s papers, Planck felt his verdict vindicated. He found “the business extraordinarily interesting,” [146] indeed, as he enthusiastically exclaimed: “The things by Schrödinger are wonderful. I am now studying Schlesinger’s (probably: Schrödinger – DH) differential equations with great fervour.” [147]

8WiththeAnnalen after Wien

Soon after this moment of glory in the history of the Annalen der Physik the collaboration between the joint editors Max Planck and Wilhelm Wien came to an end. Having just reached the age of 64, Wilhelm Wien passed away in Munich on August 30, 1928. The Physical Society appointed the physicist from Marburg, Eduard Grüneisen, to succeed him as main editor. Whether this choice had something to do with the fact that Grüneisen was not only a colleague of Planck’s but also a family acquaintance can no longer be reconstructed today, as no documents about this procedure have come down to us. In any event, there must at least have been a similarly collegial friendship between Planck and Grüneisen as had existed with his predecessor. Perhaps it was even a teacher-pupil partnership, as Grüneisen, born in 1877, had attended Planck’s lectures on theoretical physics and Planck had been one of the evaluators of his dissertation. They had not lost sight of each other even after he had claimed his degree, because since 1904 Grüneisen had been on the staff of the Imperial Institute of Physics in Berlin (PTR) – ultimately becoming director of the department for electricity and magnetism – until his appointment as professor at Marburg in 1927. As neither correspondence between Planck and Grüneisen nor the papers of either physicist have been preserved, we know very little about their editorial collaboration. Only the speech of Eduard Grüneisen on the occasion of Planck’s 80th birthday in 1938 is extant, where he mentioned, that “for decades Planck has participated with words and deeds in the service of Annalen. The extent of his participation, however, is known only to the editors and the publishing house.” [148] But neither were they able to stem the tide against the Annalen. Its standing as the leading journal for basic research in physics in the German language was eventually lost to the Zeitschrift der Physik; internationally it lost to the Physical Review. The period of the Third Reich also falls within the Planck-Grüneisen co-editorship. On the face of it, the journal’s character seemed to change little. As a result of the arbitrary measures and racist laws imposed by the National Socialists an unprecented exodus of high- ranking scientists took place during this period [149]. A disproportionate share of physicists were among them, which only gradually became apparent in the Annalen at first. Until the second half of the thirties Jewish physicists and emigrés still numbered among its contributing authors. The journal was thus able to maintain its scientific character. Nor did it compromise itself in any way as far as the elaborations of the Aryan physics movement (Deutsche Physik)were concerned [150]. That remained the almost exclusive prerogative of the newly founded Zeitschrift für die gesamte Naturwissenschaft.TheAnnalen kept alive a sense of its own scientific tradition – also manifest in a certain conservatism respecting the innovative developments of modern physics. During the twenties it led to a poor reflection of the development of quantum mechanics in the Annalen’s pages; likewise during the thirties only very few articles can be found covering topics in nuclear physics. Nevertheless, the currents of the time did not leave the Annalen untouched. The special issue celebrating Arnold Sommerfeld’s 70th birthday is one illustration. When the initial preparations were being made for it in the spring of 1938, the publisher approached the editors with the wish that only “Aryans” be solicited for contributions to it. The editors accepted this preference with practically no resistance, even though it constituted a case of discrimination and exclusion of fellow physicists that had hitherto seen no precedence in physics publishing within Germany. The Sommerfeld jubilee issue of the Annalen thus appeared at the end of 1938 containing contributions only by “unencumbered” (unbelasteter) authors [151]. Some of Sommerfeld’s pupils, like Wolfgang Pauli, were not content to lodge an internal protest [152]. They organized a more suitable birthday issue in The Physical Review [153]. At the beginning of 1938 the Annalen had, in addition, honoured Max Planck’s 80th birthday with a double issue as well [154]. In it, 22 physicists – ranging from Planck’s closest friend and student Max von Laue to Robert A. Millikan at Caltech in California – acknowledged the scientific merits of this Nestor of German theoretical physics. However, there too one searches in vain for Jewish colleagues among the list of authors. Planck’s doctoral students Fritz Reiche and Hartmut Kallmann, for example, or his erstwhile assistant Lise Meitner are missing, along with many other fellow physicists who were closely associated, scientifically as well as personally, with Planck. Whether this was again the regulatory or discriminatory effect of the publisher’s or the Nazi science authorities’ wishes is not overtly documented but the dedication by the advisory board

Fig. 6 Annalen der Physik 32 (1938), page 1. and the publishing house seems to indicate as much: “To the teacher of generations of physicists, for whom the beauty of theoretical physics became an adventure through his lucid, simple presentation, who look up to him in love and admiration and would gladly have lauded their master in this honorary issue in greater numbers than circumstances allow” [155]; somewhat more frankly the editor in chief of the Annalen, Eduard Grüneisen, stated in the anniversary speech mentioned earlier, that Planck “should recognize this jubilee issue as an expression of gratitude, not just from the few, who actually contributed to this issue, but also from the many undisclosed authors, who would have contributed had circumstances permitted.” [156] When in 1943 a single-page dedication in honour of Max Planck’s 85th birthday was drafted by the editors, the board and the publisher [157], it was supposed to be one of the Annalen’s very last issues. Growing shortages and the declaration of total war necessitated that most of Germany’s periodicals stop their presses, among them the Annalen der Physik. Thus also ended Planck’s practical involvement as its ofﬁcial and acting editor – an end that, after almost ﬁfty years of active participation Planck surely had imagined otherwise. When in the summer of 1946 the publishing house of Johann Ambrosius Barth in Leipzig was granted a license by the Soviet Military Administration in Germany to revive the Annalen by releasing its 6th series, Max Planck was again member of the journal’s advisory board and editorial committee. However, in this capacity he certainly did not become practically engaged anymore – the main editorial duties were assigned to Friedrich Möglich in Berlin, who together with Eduard Grüneisen formed

Fig. 7 Max Planck around 1938. © Archive of the MPG Berlin. the actual editorial committee. Yet in its first issue, a † is set after Planck’s name: dated January 3, 1947, it was nevertheless only able to appear that fall. Like the Kaiser-Wilhelm-Gesellschaft, of which he had again invested the presidency on an interim basis in the summer of 1945 and shortly later renamed as Max- Planck-Gesellschaft, the publisher and the Annalen’s editorial office also wanted to secure for the future of its journal the symbolic capital of scientific reputation and international acclaim associated with Max Planck’s name. His death on October 3, 1947 in Göttingen was then taken as an opportunity to publish a commemorative volume in honour of this “very great in physics” and long-time editor of the journal. It appeared on the 90th anniversary of Planck’s birth in the summer of 1948. Even though – as the editorial puts it – “unfortunately, that sombre cloud which today darkens the relations between Germany and the world, still casts its shadow on this enterprise as well,” the community of physicists or Planck adherents was largely reunited again and among the contributing authors one finds numerous colleagues and friends who had been forced to emigrate after 1933 or had suffered discrimination – ranging from Lise Meitner in Stockholm, to James Franck and Max Born in Chicago and Edinburgh, respectively, and Planck’s last PhD student Hartmut Kallmann, who under the wing of a so-called “privileged mixed marriage” had been able to outlast the Third Reich.

9Conclusion

Max Planck’s death ended more than a uniquely long term of responsibility and editorship for the Annalen. It also ended an epoch for the periodical itself, an epoch that coincides almost identically with Max Planck’s

© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ann-phys.org Ann. Phys. (Berlin) 17, No. 5 (2008) 295 life and during which the journal was able to establish itself finally as a leading journal of physics in the German language. For many decades it even became the definitive publication of progress in physics per se – alongside the Philosophical Magazine or the Comptes Rendus. In this Max Planck, by his authority and competency in science, specifically made a contribution that cannot be overstated. This period of Planck’s activity also includes a calling into question of the Annalen’s unique position. The evolution in modern physics and the shaping of modern periodical publishing after World War I made this role as primus inter pares among physics journals slip away, as competitors like the Zeitschrift für Physik or The Physical Review entered the scene, challenged and ultimately eliminated its monopoly position. This development was also furthered by the political developments in Germany after 1933, the expulsion by Nazi Germany of many reputable physicists, the catastrophic conditions in everyday life and research in post-war Germany, as well as, not least, the German schism and Cold War. The German language receded as the accepted idiom of physics and German journals generally lost their central place internationally. The half-century in which Max Planck bore the responsibility for the Annalen marks a high point in another relation, too. For it was still possible for Max Planck and Wilhelm Wien to fulfill the editorial tasks largely on their own. From today’s viewpoint this means that judgments were often quite subjective and the admission or the rejection a paper was sometimes in an authoritharian manner (“nach Gutsherrenart”). But this was quite typical of the period, not just for the editorial work of the Annalen. The same approach can be found with respect of the allocation of funds by the Notgemeinschaft or the Deutsche Forschungsgemeinschaft (German Research Foundation) [158]. That this approach to editorial work, at least in Germany, was customary and broadly accepted in those days is highlighted by the astonishment of Albert Einstein, when confronted with a critical review of a paper he had submitted in 1935 to the Physical Review. In consequence, Einstein withdrew his paper [159]. By the time of Planck’s death at the latest, this monopoly and style was also lost in Germany and the activities of the editors increasingly demanded the involvement of scientific committees and advisory boards and were incorporated in it – ultimately acquiring the modern peer review system as it was introduced already in the 1930s in the USA. The final decade of Max Planck’s life and especially the irritations surrounding the publication of the Sommerfeld special issue (and surely also of the Planck issue) in 1938 demonstrated that even professional publishing was no longer possible but, like other supposedly unbiased institutions in science, conformed to political currents.

Acknowledgements I thank Ann M. Hentschel (Stuttgart) for translating the German version of my paper as well as Ruth Sime (Sacramento) and Mark Walker (Schenectady) for comments, Felix Ameseder (Berlin) for his assistance to complete the references and to create the ﬁgures of this paper, and Stefan L. Wolff (München) for helpful discussions about Wilhelm Wien.

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[37] Protokollbuch der Physikalischen Gesellschaft zu Berlin, Archiv der Deutschen Physikalischen Gesellschaft. [38] Feier des 80. Geburtstages des Ehrenmitgliedes der Deutschen Physikalischen Gesellschaft Herrn Geheimrat Professor Dr. Max Planck, Verh. Dtsch. Phys. Ges. (West Germany) 19 (1938) 2, 61f. [39] R. Beyler, M. Eckert, and D. Hoffmann, Die Planck-Medaille, in: Physiker zwischen Autonomie und Anpassung. Die Deutsche Physikalische Gesellschaft im Dritten Reich, edited by D. Hoffmann and M. Walker (Wiley-VCH, Weinheim, 2008), pp. 217–236. [40] M. Planck, Die Theorie des Sättigungsgesetzes, Annalen der Physik 13, 535–543 (1881) (PAV, vol. 1, pp. 125– 133). [41] M. Planck, Versuch einer Synthese zwischen Wellenmechanik und Korpuskularmechanik, Annalen der Physik 40, 481–492 (1941) (PAV, vol. 2, pp. 704–715 ). [42] M. Planck, Physikalische Abhandlungen und Vorträge. 3 vol. (Friedr. Vieweg & Sohn, Braunschweig, 1958). [43] Exhibition leaﬂet: Annalen der Physik 1790–1990 (Deutsche Staatsbibliothek Berlin, April, 1990). [44] See also: Chr. Jungnickel and R. McCormmach, Intellectual Mastery of Nature, vol. 2 (University of Chicago Press, Chicago, London, 1986), pp. 309–323; and recently St. L. Wolff, Kontrovers, aber kooperativ. Max Planck und Wilhelm Wien – eine Zusammenarbeit über Gegensätze hinweg, Phys. J. 7, 3, 51–55 (2008). [45] For biographical information on Drude, see D. Hoffmann, Annalen der Physik 15, 449–460 (2006); P. Drude, Zur Elektronentheorie der Metalle, in: Ostwalds Klassiker der exakten Wissenschaften 298, edited by H. Grahn and D. Hoffmann (Verlag Harri Deutsch, Frankfurt am Main, 2006). [46] M. Planck to Wilhelm Wien, Grunewald 21 Feb. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [47] On W. Wien’s biography see H. Kangro, Wien, Wilhelm, in: Dictionary of Scientiﬁc Biography, vol. 13, edited by Ch. Gillespie (Charles Scribner’s Sons, New York, 1981), pp. 337–342; D. Hoffmann, Wilhelm Wien und die Physikalisch-Technische Reichsanstalt, Wiss. Fortschr. 39, 2, 29–30 (1989); St. L. Wolff, Physicists in the “Krieg der Geister”: Wilhelm Wien’s “proclamation”, Historical Studies Phys. Biol. Sci. 33, 337–368 (2003). [48] M. Planck to W. Wien. Grunewald 15 Oct. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [49] M. Planck to W. Wien, Munich 21 Sep. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [50] M. Planck to W. Wien. Grunewald 15 Oct. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [51] M. Planck to W. Wien, Grunewald 12 Oct. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [52] M. Planck to W. Wien, Grunewald 28 Jul. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [53] L. Pyenson, The Young Einstein (Adam Hilger, Bristol, 1985), p. 198. [54] M. Planck to W. Wien, Grunewald 17 Apr. 1908, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [55] M. Planck to W. Wien, Grunewald 27 Feb. 1909, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [56] M. Planck to W. Wien, Grunewald 29 May 1917; 29 Jun. 1928, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [57] M. Planck to W. Wien, Berlin-Grunewald 25 Mar. 1928, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [58] M. Planck to W. Wien, Berlin-Grunewald, 13 Jul. 1923, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [59] M. Planck to W. Wien, Grunewald, 2 Mar. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [60] M. Planck to W. Wien, Grunewald 17 Apr. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [61] M. Planck to W. Wien, Axalp 25 Aug. 1908, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [62] M. Planck to W. Wien, Berlin-Grunewald 24 Mar. 1924, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien.

[63] M. Planck to W. Wien, Grunewald 25 Feb. 1922, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [64] M. Planck to W. Wien, Grunewald 30 Sep. 1909, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [65] M. Planck to W. Wien. Grunewald 15 Oct. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [66] M. Planck to W. Wien, Grunewald 1 Jul. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [67] M. Planck to W. Wien, Berlin-Grunewald 25 Jan. 1925, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [68] M. Planck to W. Wien, Berlin-Grunewald 22 Jul. 1920, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [69] M. Planck to W. Wien, Berlin-Grunewald 21 Feb. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [70] M. Planck to W. Wien, Berlin-Grunewald 1 Jun. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [71] D. Hoffmann, Max Planck und die Physikalische Gesellschaft, Phys. J. 6(4) (2008) (in press). [72] M. Planck to W. Wien, Berlin-Grunewald 20 Jul. 1920, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [73] M. Planck to W. Wien, Berlin-Grunewald 1 Jul. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [74] M. Planck to W. Wien, Grunewald 5 Jan. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [75] M. Planck to W. Wien, Grunewald 29 Nov. 1906, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [76] M. Planck to W. Wien, Grunewald 5 Jan. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [77] M. Planck to W. Wien, Berlin-Grunewald 30 Mar. 1925, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [78] M. Planck to W. Wien, Berlin-Grunewald 1 Feb. 1922, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [79] M. Planck to W. Wien, Berlin-Grunewald 19 May 1920, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [80] M. Planck to W. Wien, Berlin-Grunewald 25 Jun. 1920, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [81] M. Planck to W. Wien, Berlin-Grunewald 12 Dec. 1922, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [82] W. Wien to G. Quincke, undated draft, probably end of 1922, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [83] M. Planck to W. Wien, Berlin-Grunewald 12 Jan. 1923, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [84] M. Planck to W. Wien, Berlin-Grunewald 21 Oct. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [85] M. Planck to W. Wien, Berlin-Grunewald 9 Feb. 1921, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [86] F. Kiebitz, Die vollständige Lösung der Differentialgleichungen zweier magnetisch gekoppelter, konstant gedämpfter elektrischer Schwingungskreise, Annalen der Physik 40, 138–156 (1913). [87] M. Planck to W. Wien, Berlin-Grunewald 9 Nov. 1922, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [88] M. Planck to W. Wien, Grunewald 19 Jun. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [89] G. Nordström, Träge und schwere Masse in der Relativitätsmechanik, Annalen der Physik 40, 856–878 (1913). [90] M. Planck to W. Wien, Grunewald 28 Jan. 1913, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien.

[91] E. Gehrcke and O. Reichenheim, Interferenzen planparalleler Platten im kontinuierlichen Spektrum. Verh. Dtsch. Phys. Ges. (West Germany) 8, 209–221 (1906). [92] M. Planck to W. Wien. Grunewald 1 Jul. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [93] E. Gehrcke and O. Reichenheim, Interferenzen planparalleler Platten im kontinuierlichen Spektrum, Annalen der Physik 23, 745–757 (1907). [94] M. Planck to W. Wien. Grunewald 1 Jul. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [95] W. Wien to M. Planck, Würzburg 21 Jun. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [96] M. Planck to W. Wien, Grunewald 23 Jun. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [97] M. Planck to W. Wien, Grunewald 9 Feb. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [98] W. Wien to M. Planck, Würzburg 16 Mar. 1916, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [99] M. Planck to W. Wien, Grunewald 11 Apr. 1916, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [100] M. Planck to W. Wien, Grunewald 13 Jun. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [101] M. Planck to W. Wien, Grunewald 25 Jun. 1920, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [102] W. Wien to M. Planck, Munich 15 Jan. 1928, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [103] M. Planck to W. Wien, Grunewald 23 Jun. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [104] S. Goldberg, Max Planck’s Philosophy of Nature and His Elaboration of the Special Theory of Relativity. Historical Studies Phys. Sci. 7, 125–160 (1976). [105] D. Hoffmann, Max Planck als akademischer Lehrer, in: Die Entwicklung der Physik in Berlin, itw-Kolloquien 35 (AdW der DDR, Berlin, 1984), pp. 55–72. [106] K. von Mosengeil, Theorie der stationären Strahlung in einem gleichförmig bewegten Hohlraum, Annalen der Physik 22, 867–904 (1907) (reprinted in PAV,vol. 2, pp. 138–175); cf. also the related exchange of letters between Planck and Wien dated 26 Jan., 1 and 4 Feb. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [107] E. Hupka, Die träge Masse bewegter Elektronen, Dissertation, Friedrich-Wilhelms-Universität Berlin, 1909. [108] M. Planck to W. Wien, Grunewald 8 and 30 Nov. 1907, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [109] M. Planck to W. Wien, Grunewald 25 Apr. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [110] E. Hupka, Beitrag zur Kenntnis der trägen Masse bewegter Elektronen, Annalen der Physik 31, 169–204 (1910); Zur Frage der trägen Masse bewegter Elektronen, Annalen der Physik 33, 400–402 (1911); W. Heil, Diskussion der Versuche über die träge Masse bewegter Elektronen, Annalen der Physik 31, 519–546 (1910); Zur Diskussion der Hupkaschen Versuche über die träge Masse bewegter Elektronen, Annalen der Physik 33, 403–404 (1911). [111] M. Planck to W. Wien, Grunewald 9 Feb. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [112] M. Planck to W. Wien, Grunewald 29 Jun. 1913, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [113] H. Weyl, Zur Gravitationstheorie, Annalen der Physik 54, 117–145 (1917). [114] M. Planck to W. Wien, Grunewald 16 Sep. 1917, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [115] C. Lanczos, Flächenhafte Verteilung der Materie in der Einsteinschen Gravitationstheorie, Annalen der Physik 74, 518–540 (1924). [116] M. Planck to W. Wien, Grunewald 24 Mar. 1924, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien.

[117] M. Planck to W. Wien, Berlin-Grunewald 13 Oct. 1924, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [118] M. Planck to W. Wien, Grunewald 4 Oct. 1912, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [119] M. Planck to W. Wien, Grunewald 1 Jun. 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [120] P. Hertz, Über die mechanischen Grundlagen der Thermodynamik, Annalen der Physik 33, 225–274 (1910); 537–552. [121] M. Planck to W. Wien, Berlin-Grunewald 12 Jan. 1923, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [122] K. Hentschel, Interpretationen und Fehlinterpretationen (Birkhäuser Verlag, Basel, 1990); S. Grundmann, The Einstein Dossiers (Springer Verlag, Heidelberg, 2005). [123] M. Planck to W. Wien, Grunewald 25 May 1925, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [124] W. Wien to M. Planck, Munich 16 Jan. 1928, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [125] On the roles of E. Gehrcke and S. Mohorovic in the quarrels about relativity theory during the twenties, cf. M. Wazek, Einsteins Gegner, Dissertation, Philosophical faculty of the Humboldt-Universität zu Berlin, 2008. [126] E. Gehrcke to W. Wien. Berlin 4 May 1925. Archive of the Deutsches Museum, Munich, W. Wien’s papers, no. 5130. [127] E. Schrödinger, Die Erfüllbarkeit der Relativitätsforderung in der klassischen Mechanik, Annalen der Physik 77, 325–336 (1925). [128] M. Planck to W. Wien, Grunewald 21 Jun. 1925, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [129] M. Planck to W. Wien, Grunewald 27 Feb. 1909, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [130] M. Planck to W. Wien, Grunewald 25 Oct. 1909, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [131] A. Hermann, Frühgeschichte der Quantentheorie (Physik Verlag, Mosbach, 1969), pp. 96ff. [132] A. Sommerfeld, Wissenschaftlicher Briefwechsel, vol. 1, edited by M. Eckert and K. Märker (GNT-Verlag, Berlin, Diepholz, 2000), pp. 367ff. [133] M. Planck to W. Wien, Grunewald 27 Feb. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [134] M. Planck to W. Wien, Grunewald 14 Jan. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [135] M. Planck to W. Wien, Grunewald 9 Feb. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [136] M. Planck to W. Wien, Grunewald 14 Dec. 1913, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [137] A. E. Haas, Der erste Quantenansatz für das Atom, Dokumente der Naturwissenschaft, vol. 10, edited by A. Hermann (Ernst Battenberg Verlag, Stuttgart, 1965). [138] M. Planck to W. Wien, Grunewald 8 May 1910, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [139] T. Wereide, Der Energieaustausch zwischen Materie und Äther, Annalen der Physik 49, 976–1000 (1916). [140] M. Planck to W. Wien, Grunewald 1 Mar. 1916, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [141] M. Planck to W. Wien, Grunewald 14 Jan. 1911, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [142] W. Wien to M. Planck, Mittenwald 3 Jan. 1925, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien. [143] E. Schrödinger, Quantisierung als Eigenwertproblem, Annalen der Physik 79, 361–376, 489–527 (1926); An- nalen der Physik 80, 437–490 (1926); Annalen der Physik 81, 109–129 (1926). [144] W. Wien to M. Planck, Munich 12 Feb. 1926, Manuscripts department of the Staatsbibliothek zu Berlin der Stiftung Preußischer Kulturbesitz, Nachlaß Wilhelm Wien.

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