The Origins of Deutsche Physik (1910s)
“Just as the cubists had an inability to paint decently, so, here lies together the audacity and the inability the theoretical physicists want to impose on others.” - Philipp Lenard
Around the same time as Albert Einstein (1879-1955) and David Hilbert (1862-1943) were engaged in a race to find the correct formulation of Einstein’s field equations for his theory of general relativity (see essay below), there was a crisis unfolding in the physics community.
A movement which began as a response to German soldiers’ acts during the first world war spread to academia and began gaining support among prominent colleagues of Einstein, including Arnold Sommerfeld (1868-1951) and Johannes Stark (1874-1957). At its core, the academic dimension of the debate regarded the increasing use of the English language in scientific writing, including by German authors, editors and translators. Following the burning of the library at Louvain/Leuven (see essay below) a front developed between German and British intellectuals, spearheaded by a handful of prominent physicists.
“Manifestos rained down. Under the heading of Louvain, English universities and institutions of higher learning gave written voice to their disgust” (Derez, 2016)
The German scientists were first to engage, with the publication of ‘Manifest der 93’ in October of 1914, expressing their support the army. Responding a few weeks later, 117 British scientists published a ‘Reply to German Professors’ rejecting this position outright. The January 1915 publication of an “aufforderung” (proclamation) against the “Engländerei” (Englishness) influencing German physics further sharpened the conflict. Notable signatories to the latter included Sommerfeld, Stark, Phillip Lenard (1862-1947), Gustav Mie (1868-1957) and others. Einstein, the most prominent German physicist of the time, remained prominently absent from the debate. Indeed, he and Hilbert both distrusted the motives driving the German manifestos and refused to sign them. In response, Hilbert was faced with an auditorium of students facing away from the blackboard. Einstein, was made the movement’s primary antagonist.
What followed next is a warning story about the potentially corrupting influence of politics in science, and the origins of a unique experiment by Johannes Stark and Phillip Lenard to blend conservative and nationalistic principles with physics.
Context
Often times, the context of Deutsche Physik is introduced via the narration of Eddington’s role in proving Einstein’s general relativity theory (see essay below).
That is, the two men’s shared pacifist views is often introduced as the concurrent neoliberal counterpart to the movement which later became Deutsche Physik. Briefly, Eddington (a Quaker from England) was notable for having defied the anti-German sentiment in English academia in order to raise funding for, and complete, an expedition whose goal it was to prove a theory which would supplant Sir Isaac Newton (1643-1727)’s. Succeeding in 1919, Eddington thus was instrumental in earning Einstein the 1921 Prize in Physics (which technically was awarded for Einstein’s work on the photoelectric effect).
Indeed, Einstein and Eddington did hold pacifist views and indeed did become targets of the proponents of Deutsche Physik. However, the question of why Einstein became the primary antagonist for a large part of the German physics community is much more nuanced. Interestingly, as Philip Ball has argued, the introduction of nationalism in physics likely has its origins back even prior to World War I.
The Disgruntled Experimentalists
Leading the movement that would later be termed Deutsche Physik were, most prominently, two German experimental physicists. Born twelve years apart in the latter half of the 20th century, both investigated electromagnetic phenomena and both were confronted with rapid disruptions in their fields spearheaded by the younger theoretician Einstein and his scientific descendants.
After Philipp Lenard (1862-1947) earned his doctorate in 1886, the Hungarian-born physicist worked in various posts as a lecturer and demonstrator, first in Aachen, Bonn, Breslau, Heidelberg, Kiel and (in 1907) at the University of Heidelberg. A 1905 Nobel laureate in Physics, he was recognized for his research on cathode rays (the “radiation” emitted from hot metals) which he began in 1888, approximately three decades after their discovery by Julius Plücker (1801-1868) and Johann Wilhelm Hittorf (1824-1914). Prior to Lenard, cathode rays were generated in rather primitive glass tubes equipped with electrodes made from metal, across which a voltage was introduced. Frustrated by the impracticalities of this configuration (the rays located inside sealed glass tubes were difficult to access and polluted by the presence of air molecules) Lenard designed an alternative experimental setup using small aluminium sheets (“windows”) at the end of the glass tube. Thick enough to withstand the pressure differences of a vacuum, yet thin enough to allow for the passage of rays detectable up to 8 cm away, the setup allowed Lenard to show that cathode rays could have photographic effects in plates coated in keton (pentadecylparatolylketone). This result was published in a 1894 paper entitled ‘Über die magnetische Ablenkung der Kathodenstrahlen’ (“The magnetic deflection of cathode rays”) in (what would later become) Annalen der Physik.
Interestingly, the then-unknown German physicist Wilhelm Röntgen (1845-1923) read Lenard’s paper shortly after its publication. Röntgen had been experimenting with the external effects of passing an electrical discharge through various types of vacuum tubes, including designs by Heinrich Hertz (1857-1894), Hittorf, William Crookes (1832-1919) and one Nikola Tesla (1856-1943). Having read Lenard’s work, Röntgen decided to reproduce the experiment in his laboratory at the University of Würzburg. However, as Lenard had purchased all the available keton (pentadecylparatolylketone) in Germany at the time, Röntgen had to settle for barium platinocyanide as a substitute. While the former material, used by Lenard, is sensitive to UV-light (leaving an image on a cardboard plate coated with it) the latter, as Röntgen would discover, is also sensitive to X-rays. Thus, when Röntgen recreated Lenard’s experiment, in addition to photographic effects (generated by UV-light), he also found shadows which he determined to originate from a bench in the laboratory. Investigating the origins of this “noise” further, in the following weeks (eating and sleeping in his laboratory) he discovered X-rays and saw the first radiographic image, of his own flickering ghostly skeleton holding a piece of lead in front of a barium platinocyanide screen.
Although he missed out on the discovery of X-rays, Lenard was first to observe that the electrons emitted from metals irradiated with ultraviolet light (read: the photoelectric effect) in many ways are similar to cathode rays. Specifically, he discovered that the energy of such electrons do not depend on the intensity of the light, only its wavelength. This result was published in a 1902 paper entitled ‘Ueber die lichtelektrische Wirkung’ (“On the photoelectric effect“) in Annalen der Physik three years prior to one of the “annus mirabilis” papers that would later earn Einstein the Nobel (see essay below).
Among the paper’s handful of citations, Einstein repeatedly cites Lenard. That same year was the year Lenard was awarded the Nobel Prize in Physics for “his work on cathode rays”. Yet still, in private, he grew increasingly resentful. As he glimpsed publicly in his Nobel lecture, no doubt with reference to the 1901 Nobel Prize (awarded to Röntgen),
“I have by no means always been numbered among those who pluck the fruit; I have been repeatedly only one of those who planted or cared for the trees”
As Lenard indeed later claimed, he, not Röntgen was the “mother of the X-rays” because he had designed the apparatus that produces them, likening Röntgen’s role to that of a midwife and neglecting both Röntgen’s introduction of barium platinocyanide as well as the actual discovery and identification of X-rays as a separate phenomenon. As perhaps best summarized in Lenard’s biography on the Nobel Prize website,
“Lenard was an experimentalist of genius, but more doubtful as a theorist. Some of his discoveries were great ones and others were very important, but he claimed for them more than their true value.”
Similar to Lenard, Johannes Stark (1874-1957) was an experimental physicist working mainly on topics related to electricity and electromagnetic radiation when Einstein’s star began to rise. Born in Schickenhof in the Kingdom of Bavaria, Stark studied physics, mathematics and chemistry at the University of Munich, and in 1897 graduated with a doctorate in experimental physics. He taught unpaid at the lauded University of Göttingen (see related essay here) beginning in 1900 before moving on to professorships at Hannover and Aachen. Like Lenard (and Einstein, and most other early-career academics) he struggled to secure a permanent position in a prominent physics department, moving from institution to institution until settling at the University of Greifswald in 1917. Like Leonard, he too was eventually awarded the Nobel Prize in Physics, in 1919, for his experimental work and “discovery of the Doppler effect in canal rays and the splitting of spectral lines in electric fields”, now typically referred to as the Stark effect. Like Lenard, Stark too appears to have been engaged in a variety of disputes with fellow German physicists, including Sommerfeld whom he was engaged in a professional rivalry with over (what he saw as) the over-mathematization of physics which the latter (in a sense) epitomized. The appointment of Sommerfeld’s former student Peter Debye (1884-1966) for a professorship at Göttingen (where Stark had lectured) seems to exacerbated his antagonism towards (what he later called) the “dogmatic spirit in physics” (Stark, 1938). Adding to this, as Walker writes, the outbreak of World War I transformed Stark both “spiritually and ideologically” (Walker, 1995).
As I detailed in the essay ‘The Battle Line at Louvain (1914)’, the reaction of the international community to the war atrocities were indeed quite at odds with the propaganda being fed most Germans, including its scientists. When Stark in 1917 moved to the small university town of Greifswald by the Baltic Sea, he became a front-and-center witness to the revolutions that followed Germany’s surrender. As Walker writes, “When the soldiers returned home—often with their weapons—they found a home front devastated by hunger and a power vacuum. Throughout Germany left-wing soldiers’ and workers’ councils took over political power at the local level. Many Germans believed that the country was going to experience a repeat of the Russian Revolution.”
The Dispute with Einstein
Ironically given his later career choices, it was Stark who, as the editor of the journal Jahrbuch der Radioaktivität und Elektronik in 1907 inquired to the (then generally unknown) Einstein to write a review article on the principle of relativity. Einstein accepted and, in the process of writing the paper, first came to contemplate the thought experiment that would eventually lead to his formulation of the theory of general relativity. Lenard too, indeed seems to have admired Einstein in the 1900s and 10s, calling him a “deep, comprehensive thinker” in 1909. At this point two men’s correspondence suggests that each held the other in high admiration. It even seems that Lenard was considering suggesting Einstein for a professorship of theoretical physics in Heidelberg as late as in 1913, the same year Einstein was offered his first professorship (Walker, 1995).
“Thank you for the kind words. Nothing can make me happier than a thinker of great depth and scope deriving some pleasure from my work. I must also tell you that your kind letter of 16. Nov. 1905 has been on my desk ever since then, first in Kiel and now here, and that I think more and more about the differences in our conceptions of photoelectric velocities and things related to it. For I believe that, in a certain sense, both of us are right”
— Excerpt, Letter from Lenard to Einstein (1909)
The antagonism of Lenard, Stark and other physicists against Einstein (and more generally the advancements in theoretical physics he was spearheading) indeed seems to have remained civil and professional prior to 1920.
Jakob Laub and the Existence of Aether
Lenard’s public opposition to Einstein’s theory of relativity seems to have begun in 1910, but at this point contained no personal attacks against Einstein. Lenard, like many other older physicists (he was 48 at the time) disagreed with the implications of Einstein’s ideas and, for instance, remained a firm proponent for the existence of a space-filling substance typically referred to as an “aether”. Indeed, Lenard engaged his research assistant Jakob Johann Laub (1884-1962) in a variety of (ultimately failed) experiments to prove the existence of aether. Laub, a great admirer of Einstein, happened to have written his dissertation on Einstein’s theory of special relativity and the two began corresponding in 1909. Their letters reveal Laub’s deteriorating relationship with Lenard and Einstein’s views both on Lenard’s work and his demeanour. As Einstein wrote Laub in 1910 (Hillman et al, 2016),
“Lenard must, however, in many things be wound quite askew. His recent lecture on these fanciful ethers appears to me almost infantile. Further, the study he commanded of you […] borders on the absurd. I am sorry that you must spend your time on such stupidity.”
— Excerpt, Letter from Einstein to Laub (1910)
Einstein eventually offered to help Laub find new work. As Einstein wrote by the end of November 1910, “This is a twisted fellow, Lenard. So entirely composed of gall and intrigue. However, you are considerably better off than him. You can go away from him, however, he must do business with the monster until he bites the dust.”
The Pragmatic and the Dogmatic Spirit in Physics
Although Einstein was quite confident to reject the various aether theories as obsolete after his introduction of special relativity (showing that Maxwell’s equations do not require the aether for the transmission of electromagnetic and gravitational forces), many experimental physicists were not yet quite so convinced. As Johannes Stark in 1938 outlined in a paper in Nature entitled ‘The Pragmatic and The Dogmatic Spirit in Physics’, some were indeed quite happy to reject theories outright if they arose not due to empirical observations, but rather as the result of mathematical deduction (what he called the “dogmatic school”). As Stark writes condescendingly,
“The physicist of the dogmatic school operates in quite a different manner […] He starts out from ideas that have arisen primarily in his own brain, or from arbitrary definitions of relationships between symbols to which a general and so also a physical significance can be ascribed. By logical and mathematical operations he combines them and so derives results in the form of mathematical formulae. He then seeks to give these a physical meaning by applying them to the results of experience.”
Indeed, both the abstract nature of Einstein’s theories and their wide-ranging implications likely played a role in the widening dispute between experimentalists of the older guard and younger, more mathematically-inclined theoreticians such as Einstein. As Lenard once stated,
“Just as the cubists had an inability to paint decently, so, here lies together the audacity and the inability [the theoretical physicists] want to impose on others.”
The introduction of differential geometry to physics via general relativity, for instance, was likely difficult for the older generation to accept and adapt to. As briefly mentioned in the introduction, Einstein himself struggled to formulate his theory of general relativity in this new language (see essay here), which required the incorporation of Ricci “tensor” calculus in Riemannian geometry, quite afield from the “classical” experiments of Galileo, Michael Faraday (1791-1867) and Lenard Stark.
Treason via Scientific Dissemination
The notion that as people age, they become more conservative and less receptive to change is a commonly observation. That the older Lenard struggled to accept the changing of the paradigm (to which he had made his biggest contributions), should therefor perhaps not come as a surprise. Ironically, fast forward to middle of the 1920s and Einstein found himself in the same situation with regards to statistical and probabilistic nature of quantum mechanics (see essay below).
However, Lenard and Stark struggled not only to accept the claims of Einstein’s theories, they also objected to the way the theories were being propagated. According to Stark, Einstein and his supporters had “improperly” (Walker, 1995) publicized relativity theory through newspaper articles and foreign lectures. Using phrases such as ‘scientific revolution’, Stark claimed, Einstein’s supporters were exploiting the fertile ground of the postwar period for political and social revolutions, betraying Germany and German science by playing on internationalism.
Transition to Overt Anti-Semitism (1920s)
Two events in 1920 further accelerated the dispute between Einstein and his conservative, conspiratorial opponents into what would anyone would now recognize as overt anti-semitism.
Mass Meeting at the Berliner Philharmonie
Following Eddington’s successful 1919 expedition, Einstein acquired worldwide fame and was again nominated for the Nobel Prize. In reaction, an “anti-Einstein rally” was staged at the Berlin Philharmonic on August 24th 1920, promoted by an inflammatory article in the daily Berlin newspaper Tägliche Rundschau, which claimed that “Her Albertus Magnus has been resurrected; he has stolen the work of others and has mathematized physics to such an extent that fellow physicists have been left clueless” (van Dongen, 2007). The author was a fanatical, obscure and overtly anti-semitic right-wing publicist named Paul Weyland (1888-1972)1. The article summarized the accusations of both Lenard and Ernst Gehrcke (1878-1960), in addition to various contentions, false claims and thinly-vailed anti-semitic tropes (van Dongen, 2007). The piece promised that through the lectures in Berlin Philharmonic, the “true Einstein” would be revealed. Einstein’s colleague Max von Laue (1879-1960) responded to these claims in the same newspaper five days later wholeheartedly in Einstein’s defence.
Yet still, notices of the rally were published in the other Berlin newspapers to attract a large audience to the 1,600 seat theatre. The event was marketed as sponsored by a non-existent front organization supposedly entitled the ‘Working Society of German Scientists for the Preservation of Pure Science’. Weyland spoke first,
“Meine Damen und Herren! Hardly ever in science has a scientific system been set up with such a display of propaganda as the general principle of relativity, which on closer inspection turns out to be in the greatest need of proof.”
Lenard was one of the twenty other lectures scheduled for the event. However, despite having been impressed by Weyland’s enthusiasm, he eventually decided against it, and was not present. Einstein however, was. As noted in an article entitled ‘Der Kampf gegen Einstein’ in Vossische Zeitung the following day, he appeared unshaken by the attacks, which he identified as politically motivated (given his well-known left-wing, pacifist views and involvement with the newly founded League of Nations). As van Dongen writes, although promoted as a scientific lecture series,
“According to one account, anti-Semitic pamphlets were handed out, and according to another, swastika lapel pins were being sold. Lenard’s antirelativistic booklet was also being sold.”
‘Antwort’ and Public Debate with Lenard
Einstein responded to Weyland and his speakers’ claims in an August 27th article entitled ‘Meine Antwort‘ (“My response”) in Berliner Tageblatt. His response was aimed at both Weyland, Gehrcke and, crucially, Lenard (despite the fact that the latter eventually decided not to speak at the event). He challenged them to a debate at the upcoming 86th meeting of the German Society of Scientists and Physicians, which was to be held on September 20th in Bad Nauheim2. The public nature of Einstein’s invitation spurred some 5-600 people to the auditorium to hear the “Einsteindebatte”.
No official account of the debate exists. By stitching together various partial accounts, the main objection raised by Lenard against Einstein’s theory seems to have been that it relied on fictional gravitational fields to ensure the validity of the principle of equivalence (van Dongen, 2007):
“Lenard exemplified this issue with the case of a “braking train”: If, according to the principle of equivalence, the inertial forces felt by passengers in a train that is slowing down can be understood as forces due to some gravitational field, then what masses should have generated that field? Einstein replied that such a gravitational field would be a perfectly valid solution of the field equations for a certain configuration of distant masses; that is, for an appropriate set of boundary conditions. Lenard responded that this just explained away a valid concern by a purely formal argument.”
Some reports claim that the argument proceeded in a perfectly, “exemplary” and “calm” manner. Historians of Einstein however, seem to be in agreement that he was seriously considering leaving Germany after the rally and debate. Elsa, his wife, suffered a nervous breakdown following to the latter.
Revealing Their True Motives
As Walker (1995) wrote, “although Lenard had not taken part in the Berlin lectures and hitherto had only expressed his opinion in a professional fashion in scientific journals, Einstein’s personal attack in the daily press deeply offended Lenard, who was seventeen years his senior”. Lenard also left the conference in Bad Nauheim deeply distressed. He renounced his membership in the German Society of Physicists (Deutsche Physikalische Gesellschaft) and began denying admittance to his office to any of its members. Starting in 1921, he claimed that Einstein had a close connection with Moscow and was trying to intimidate opponents of relativity with threatening letters.
Following the assassination of Walther Rathenau (a Jewish German foreign minister and personal friend of Einstein) in 1922, Lenard refused to lower his Heidelberg institute’s flag at half mast. Public demonstrations by students lead to Lenard having to be taken into protective custody, furthering his turn towards more blatant extreme right-wing ideologies.
On November 8th 1923, a group of about two thousand “brown shirts” lead by an unknown Austrian former corporal named Adolf Hitler marched on a beer hall in Munich in a failed coup d’état that lead to the death of 15 Nazis, four policemen and one innocent bystander.
Stark came out in immediate public support of Hitler and the National Socialists following the failed “beer hall” putsch. Writing Hitler at Landsberg (where he was serving his lenient sentence), Stark and his wife invited him to recuperate with them after his release, which Hitler thanked him for wholeheartedly. In May of the following year, Lenard and Stark together published an open letter entitled “The Hitler Spirit and Science” in support of the former corporal, wherein they wrote that (Hentschel, 1996):
“.. .the struggle of the spirits of darkness against the bearers of light […] Hitler and his comrades in struggle […] appear to us as God’s gifts from times of old when races were purer, people were greater, and minds were less deluded... He is here. He has revealed himself as the Führer of the sincere. We shall follow him.”
Hitler and Hess visited Lenard at Heidelberg in 1926. During the 20s, the long-standing personal and professional relationship with Lenard and Stark became a political collaboration. By 1934, Stark in the pages of Nature was expounding his view that
“It can be adduced from the history of physics that the founders of research in physics, and the great discoverers from Galileo and Newton to the physical pioneers of our own time, were almost exclusively Aryans, predominantly of the Nordic race. From this we may conclude that the predisposition towards pragmatic thinking occurs most frequently in men of the Nordic race.
If we examine the originators, representatives and propagandists of modern dogmatic theories, we find amongst them a preponderance of men of Jewish descent. If we remember, in addition, that Jews played a decisive part in the foundation of theological dogmatism, and that the authors and propagandists of Marxian and communistic dogmas are for the most part Jews, we must establish and recognize the fact that the natural inclination to dogmatic thought appears with especial frequency in people of Jewish Origin.”
- Excerpt, The Pragmatic and the Dogmatic Spirit in Physics (Stark, 1938)
In 1934, Lenard published a four-volume physics textbook entitled “Deutsche Physik” where, in the introduction, he proclaims that “like everything that man creates, science is determined by race”.
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References
Hillman, B.J., Ertl-Wagner, B. & Wagner, B.C. 2016. The Man Who Stalked Einstein: How Nazi Scientist Philipp Lenard Changed the Course of History*. Lyons Press.
Stark, J. 1938. The Pragmatic and the Dogmatic Spirit in Physics. Nature 141, pp. 770-772.
van Dongen, J. 2007. Reactionaries and Einstein’s Fame: “German Scientists for the Preservatin of Pure Science,” Relativity, and the Bad Nauheim Meeting. Phys. perspect. 9. pp. 212-230.
Walker, M. 1995. The Rise and Fall of an “Aryan” Physicist. In: Nazi Science*. Springer, Boston, MA.
Stefan Zweig characterized Weyland in the introduction to his Sternstunden der Msnscheit as follows: “Sometimes, very rarely, a completely unworthy person steps onto the world stage, only to sink as quickly back into nothingness.”
Einstein had suggested that he lead a general discussion on the topic of relativity at the meeting even prior to Weyland’s rally.
"The Pragmatic and the Dogmatic Spirit in Physics" expanded on the anonymous article "Weisse Juden' in der Wissenschaft" ("White Jews" in Science) published in 1937 in Das Schwarze Korps, the SS newspaper. As quoted in Nature, "To purge science from this Jewish spirit is our most urgent task. For science represents the key position from which intellectual Judaism can always regain a significant influence on all spheres of national life." (https://www.nature.com/articles/141778a0). It was an attack by Stark on Heisenberg (a "white jew"), possibly preventing Heisenberg from succeeding Sommerfeld in Munich. Sir Richard Gregory, the editor-in-chief of Nature, invited Stark to explain his views, which led to the "The Pragmatic and the Dogmatic" article. By the end of 1937, Nature was banned in Nazi Germany by the minister of education. Sommerfeld's position (Professor of Theoretical Physics at the University of Munich) went to Wilhelm Müller, who was not a theoretical physicist. In 1945, Müller was dismissed and barred from academia due to denazification. Subsequently, Sommerfeld wrote to Hans Bethe, inviting him to return to Munich and take his chair. Bethe politely declined, expressing his love for America.