Introduction Ether: The Multiple Lives of a Resilient Concept

OUP UNCORRECTED PROOF – FIRST PROOF, 1 Introduction Ether—The Multiple Lives of a Resilient Concept Massimiliano Badino and Jaume Navarro 1.1 ETHEREAL NARRATIVES When did the ether disappear? Did it actually ever exist? Is it not back among some contemporary physicists? Are you trying to chase a ghost or to resuscitate a zombie? Questions like these were common in the academic events where the papers compiled in this volume were presented. Indeed, the ‘Ethereal Aether’, or ‘the nothing that connects everything’, to quote only two titles of books devoted to the history of the ether,1 has often attracted the attention of historians of science, philosophers and physicists, and its epistemic and ontological status been the subject of much discussion and speculation. While the electron became the favourite probe for theories of scientific realism in times past, the ether was a frequent case study of theories of scientific change. For quite some time, the story of its supposed rejection via the experiments of Michelson and Morley in the late nineteenth century helped Popperians and was used by many physics teachers. Later on, the ether became a major symbol of the incommensurability between classical and modern physics, exemplifying the Kuhnian struggle between a young generation of relativists and quantum physicists and the stubbornness of conservatives and crackpots. More recently, social historians of science have moved away from the categories of belief and unbelief in determining the nuances of the abandonment of the ether in the early twentieth century, bringing in elements such as technical or pedagogical use.2 In any case, there is a major consensus in thinking that the ether was mostly erased from any central role in physics and in culture after World War I. The best and most often quoted work on the history of the ether, the 1981 volume Conceptions of Ether, took for granted this timeline by limiting the study of the History of Ether Theories to the period 1740–1900.3 The recurrent question of ‘what did Einstein really think of the ether’ is only an exception to this rule, and even then the view is that the ether qua theory disappeared in spite of (some of ) Einstein’s opinions.4 Badino, M. and Navarro, J., ‘Introduction: Ether—The multiple lives of a resilient concept’ in Ether and Modernity, edited by J. Navarro. © Oxford University Press 2018 DOI 10.1093/oso/ 9780198797258.003.0001 0003629866.INDD 1 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 2 Introduction Certainly, in the narratives of the death, rejection or demise of the ether, Einstein and the theory of relativity play a central role. But, as the chapters in this book show, far from killing the ether off, special and general relativity (and, to a lesser degree, quantum physics) caused an explosion of ether narratives into different directions, and only a few of them can be traced back to a Manichean dichotomy between classical and modern. These stories cross each other; they share contexts, aims and actors, thus making it difficult to disentangle them into simple narrative strands. Thus, the absence of a chapter specifically devoted to ‘Einstein and the ether’ should not be understood in terms of Edmund Whittaker’s old strategy to diminish Einstein’s role in the development of relativity but as a way of emphasising the complexities of the ether in the early twentieth century.5 Rather, this book is a snapshot of the multiple lives of the ether in the first decades of the last century. From developments in pure mathematics to wireless technologies, from modernist art to spiritualism and from popular to alternative views of physics, the chapters in this book present us with an array of narratives that develop along several lines of fracture, none of which can give us a single coherent picture. Thus, far from consolidating the traditional dichotomies between classical and modern, between British and Continental, between material and spiritual and between ‘true’ and popular physics, this book challenges the explanatory role of these fissures. Indeed, these dichotomies are as many ways to tell the story of the ether: however, they fail to capture the whole story and it is in their failure that one can catch a glimpse at the peculiar features of this concept. Thus, the goal of this introduction is to follow some of these lines of fracture and to unearth the dynamics underlying the place of the ether in the early twentieth century. 1.2 CLASSICAL AND MODERN The most obvious way to tell the story of the ether in the twentieth century is perhaps along the line of fracture that separates classicality and modernity. It is very tempting to make use of the revolutionary watershed, which includes both relativity and quantum theory, in order to safely locate the ether within the realm of ‘classical physics’ as opposed to a newer and advanced ‘modern physics’. The narrative of the ether would thus unfold as the battle of some diehards for hopelessly old-fashioned scientific practices and values and against the unstoppable tide of progress. But, as some historians of science have shown, rather than mere labels, ‘classical’ and ‘modern’ are extremely fluid, largely coconstructed and continuously renegotiated categories which transcend the boundaries of physics and belong to the public sphere at large.6 For this reason, the central argument of this volume concerns the comparison of images of the ether in science and in culture with the explicit goal of tracking the different dynamics, timescales, and meanings with which the term ‘ether’ was appropriated by different communities. Only in this way does it become possible to map out the complex conceptual clusters hidden under the deceivingly simple notions of classicality and modernity. What is normally used as a sharp dichotomy reveals so many intersections, entanglements and overlaps that it was not 0003629866.INDD 2 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Classical and Modern 3 inconsistent to regard something like the ether as classical and modern at the same time, although for different reasons in different places and by different actors. Let us begin at the beginning, that is, with physics. In the early years of the past century, Einstein’s relativity theory was viewed by many more as an opportunity to rethink the ether than a reason to reject it. In Chapter 5, Scott Walter argues that the foundations of electron theory rested on a plexus of dynamical and kinematic problems. On the one hand, the description of electromagnetic phenomena in different states of motion called for a redefinition of the terms ‘space’, ‘time’, ‘speed of light’ and ‘reference frame’. On the other, the bare fact that electric charges were involved required a medium of propagation for electromagnetic waves. For all its cumbersomeness, the ether allowed for a unification of kinematics and dynamics: it was the supporting medium and the absolute frame of reference and it was the storage device of energy. The British versions of electron theory, described by Richard Noakes in Chapter 6, made good use of these features. In addition, the ether proved useful even when combined with the most advanced mathematical tools as shown by Poincaré’s combination of group transformations and Langevin’s velocity waves to obtain the Lorentz contractions. By contrast, Einstein only offered ‘a pair of postulates, the logical consistency of which was suspect’ and the hypothesis of the relativity of time, a suggestion that even a flexible mind like Poincaré’s looked upon as uninviting. In this context, it is scarcely surprising that some physicists were reluctant to abandon the ether completely and tried instead to rethink its role under the kinematic constraints of Einstein’s relativity. This quest for a novel way to understand the dynamical foundations of the electrodynamics of moving bodies generated what Walter calls the ‘conceptual drift of the concept of ether’: a series of attempts at filling up with a renewed ether the void that Einstein’s epistemological austerity had left behind. Deprived of kinematic properties, the ether simply became a substratum, the loftiest metaphysical concept a physicist’s conscience could bear and deal with. It is within this framework that one has to look at the reception of Minkowski’s work, which, slowly but steadily, became the veritable vehicle of acceptance of special relativity. Connemara Doran’s novel step-bystep analysis of the road from Poincaré to Minkowski’s geometrisation tools, provided in Chapter 4, helps understand this evolution. Efforts to make relativity and the ether happy together continued during the 1910s and 1920s in Britain. In Chapter 12, Aaron Wright describes this process as a sort of ‘domestication’ of the ether, an approach towards modern physics which marked Dirac’s physical education and eventually fed his understanding of the role of the ether. Einstein’s 1905 famous conclusion that the ether was ‘superfluous’ contained a positive message: after all, relativity had not pronounced the ether non-existent. This alleged compatibility between the ether and relativity was one of the main weapons on the ether front. If the ether could be neither observed experimentally nor undermined theoretically, the only remaining option was to characterise it through its functions. This was the rationale behind many of the ‘relabelling strategies’ so clearly described by Wright in the opening sections of the chapter. 0003629866.INDD 3 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 4 Introduction This functional reinterpretation of the ether is key to understanding its vicissitudes. Fortunately, relativity, particularly general relativity, offered plenty of conceptual space. Its unprecedentedly complicated mathematical architecture was far from being selfexplanatory. On the contrary, several corners in its symbolic maze had to be interpreted and many of them were open to alternative interpretations. Einstein himself admitted this point in 1916, and in 1918 he explicitly stated that, according to general relativity, one had to ascribe physical properties to the empty space via specific components of the gravitational potential. As Richard Staley explains in Chapter 10, for Einstein, this mathematical prescription created the site for a new role of the concept of ether. This is just one instance, albeit possibly the most illustrious, of a line of thought that became popular especially in the British scientific and public discourse: relativity had not declared the ether dead and, in fact, it might even vindicate it eventually. Thus, for example, Ebenezer Cunningham drew a very straightforward conclusion from special relativity: if there are multiple inertial frames, then there should be multiple ethers. On the contrary, as partly seen in Chapter 2, which is by Imogen Clarke, and Chapter 8, which is by Jaume Navarro, Arthur Eddington was happy to assume only one collection of point events, and he saw in this symbolic representation of the physical world the same connecting function formerly accomplished by the ether. Another interesting instance is Poincaré’s ‘structural’ reinterpretation, discussed by Doran in Chapter 4. According to Poincaré, the existence of the ether could be reduced to ‘a natural kinship between all the optical phenomena’. From this point of view, which could safely be defined as ontic structural realism avant la lettre, the ether hypothesis was no longer true or false—it was simply more or less convenient. These examples illustrate two deeply entwined points. First, the development of modern physics, relativity as well as the quantum, did not happen as a gestalt jump out of the classical world. Quite the contrary—new theories, concepts and perspectives were conceived in constant dialogue with tradition, which never really died out. It is by exploring the consistency of new ideas with regards to classical wisdom that the full extent of their revolutionary potential can be appreciated.7 Second, and related, modern physics is not a complete overcoming of the classical one, as the narrative mentioned at the beginning of this section would have it. The conceptual space for the ether lies at the very heart of the dialectic between classic and modern: in what modern science does not tell us—in what it does not bother to specify, determine and interpret. Dirac, as discussed in Chapter 12, represents another illuminating example of this entanglement between the classic and the modern. For him, a reasonable relativistic or quantum theory of a system should be based, via analogy, on a corresponding classical theory of the same system, a point critically reiterated in his 1951 theory of electron.8 Precisely this intuition led him from a new classical theory of the electron to formulating an ether for quantum electrodynamics as a field of velocities that a charge sitting in a certain point would pick up. Once again, there is a specific mathematical object, the electromagnetic potential, signalling the presence of the ether, but, as Wright perceptively observes, Dirac did not confine himself to carving out a space for 0003629866.INDD 4 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Classical and Modern 5 the ether: he showed how a classical concept could still contribute to solve the riddles of modern science. For many experts, relativity and the ether could coexist peacefully and even fruitfully but, for others, they were mutually exclusive. In Chapters 7 and 10, Arne Schirrmacher and Richard Staley, respectively, explore in different ways the politically tinged support for this claim in Germany and we shall return to this issue later in this introduction, in Sections 1.3 and 1.4. For the moment, however, we would like to focus on the interesting case of Dayton C. Miller, thoroughly discussed by Roberto Lalli in Chapter 9. The conceptual flexibility of the ‘modern ether of relativity’, so to speak, contrasted with stricter experimental demands, namely a very precise value—a round zero—for the ether-drift experiments. As Miller promptly noted, no such exact result had ever been ever attained, thus leaving some space for the ether. Moreover, the very possibility of performing Michelson–Morley-like experiments presupposed the existence of the ether. These two points made a powerful effect on the American physical community, which had built its fortune especially on physical astronomy and recognised the ether as an indispensable tool to make sense of their daily practices. This explains why the ether-drift experiments, promptly if not fully satisfactorily accommodated in classical physics, were paradoxically resuscitated by relativity. This experimental branch of the story turned the survival of the ether into an all-ornothing affair. But even in this case of head-on confrontation, the actors were not rejecting modernity as a whole. Instead, they were denouncing relativity as a wrong track, both scientifically and culturally. This suggests that the dialectic of modernity should not be viewed as a clash between blocks but rather as the result of crafty political and rhetorical tactics aiming at formulating the most effective alignment of concepts, values and emotions. One can find excellent examples of this tactic in the public discourse on the ether. The first key factor for understanding the dynamics underlying the debate on the ether in the public sphere is the particular conjuncture of European society and culture in the early decades on the twentieth century. New social actors and new political ideas shook the very foundations of the international order patiently put together during the nineteenth century. The appalling carnage of World War I and the tumultuous upheaval happening in Russia took the entire continent aback. Behind the lights and the dances of the belle époque, fear and uncertainty were the dominating feelings among Europeans. In this period of emotional instability, Oliver Lodge’s plea for the ether could find more than one interested ear. As Imogen Clarke and Michael Whitworth duly stress in Chapters 2 and 3, respectively, Lodge’s communication prowess was almost unmatched. In his capacity as scientific expert and public figure, he managed to make his points heeded both at physics meetings and in the social arena. More importantly, he knew how to get at the layman’s heart. In an age in which the cleavage between the common man and official science was rapidly increasing, Lodge was able to create a sense of proximity between people and the ether. The ether was still with us—relativity had never really expunged it and it could still be 0003629866.INDD 5 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 6 Introduction seen at work as he was broadcasting his speeches on the BBC. The ether embodied all those cognitive values of intelligibility, visualisability and intuitiveness that the mathematical abstruseness of modern physics wanted to obliterate. It rested on a perfectly logical analogy: in the same way that water waves need water, so electromagnetic waves need an electromagnetic medium to propagate. Furthermore, the ether was indispensable for the good face of modernity: as Chapter 8 shows, the association of the ether with wireless technologies gave the former a clear seal of modernity and the latter a reassuring sense of stability and continuity. While relativity and quantum physics were useless for understanding technology, let alone improving it, the ether, by contrast, played a central role. The magic of the wireless, which allowed people from the opposite ends of the earth to speak as if together in the same room, made perfect sense once the electromagnetic waves were pictured as perturbation of an all-pervasive medium. As the output of a type of physics now in jeopardy, the wireless technology literally embodied scientific as well as cultural values, both modern and traditional. It is unsurprising, therefore, that the wireless community became instrumental in sustaining the concept of the ether well beyond its survival in official science. In Lodge’s capable hands and with the cooperation of the wireless practitioners, the ether became a highly symbolic notion. It obviously related to electromagnetic theory, a chapter of science in which Britons had been unquestioned masters, from Faraday to Maxwell, to William Thomson, to Joseph J. Thomson and, why not, Lodge himself. And it also related to the wireless technology and Britain’s imperial supremacy in electrifying and communicating the world. The ether, in sum, symbolised the cherished values of the classical British civilisation: stability, intelligibility and common sense. And, while it opposed all the uncomfortable novelties of the new century—moral uncertainties, social changes, Bolshevik revolutions, Freudian abysses and cerebral mathematical theories—it was modern in a good way: it expressed sensible progress and dynamism; it had a future in science as well as in society. The public image of the ether was neither classical nor modern but a cunning combination of both. 1.3 KNOWLEDGE, ETHOS AND AUTHORITY One of the most serious flaws of the standard narrative on the ether is that it sets the entire issue in terms of a choice between scientific theories. By making the question depend on the intrinsic cognitive qualities of the two options, relativity theory and the ether hypothesis, it regroups all the nuances of the debate into two broad categories: the former were necessarily right, and the latter, wrong. By contrast, this book shifts the focus from the theories to the actors of this debate, to retrieve their distinctive voices, backgrounds and agendas. In this way, we can now appreciate elements previously neglected by historians. One major example is the theme of authority, which permeates several articles. In order to be an influential contributor to a debate, one needs to gain sufficient authority; but—and this is the particularly intriguing aspect—in the ether debate, authority 0003629866.INDD 6 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Knowledge, Ethos and Authority 7 is a peculiar mixture of knowledge and ethos. Dirac, a Nobel laureate, was wittingly provoking the scientific community in 1951 by connecting his well-respected work with the anachronistic notion of the ‘æther’, in his battle for a new formulation of quantum electrodynamics. Although the attempt did not meet with great acceptance, Dirac not only used his authority and knowledge to bring back some form of ether but also used the authority of the ether, so to speak, to create a debate on the foundations of quantum electrodynamics. Oliver Lodge and Arthur Eddington are two major examples of this entanglement between ethos, knowledge and authority. In Chapter 3, Whitworth describes with commendable precision Lodge’s techniques to approach his public in order to foster not only a sense of expertise but also moral trust. By showing wisdom rather than just knowledge and by helping the reader (or the listener) to co-create the space for the ether, Lodge becomes the personification of those ideals of stability, reasonableness and Christian patience which were associated with the Victorian culture and of which the ether was an expression. And as Clarke argues in Chapter 2, Lodge and Eddington were very effective in convincing the general public that there was a genuine scientific discussion on the ether and that his was an active voice in this discussion. Although different on most points, Lodge’s and Eddington’s argumentative strategy included using their scientific authority to promote a critical attitude towards the infallibility of science. By claiming that, on the ether problem, the jury was still out, they achieved multiple results: they presented themselves as humble men with no pretension to know everything, they challenged some mainstream interpretations of relativity and they sympathetically nodded to their privileged audiences—the wireless community in the case of Lodge, mathematical idealists in the case of Eddington, and a broad array of liberal Christians in both. This interplay of ethos and knowledge is key to understanding the complex dynamics of scientific and popular culture in the early decades of the twentieth century, but it also helps clarify the tectonic shifts within the scientific culture itself, particularly along both the geographical and the disciplinary fracture lines. During the nineteenth century, these differences were increasingly painted in critical terms and, often, related to specific mentalities, spirits, cultures and ethos. The criticism levelled by William Thomson and Peter Guthrie Tait against the Continental abuse of mathematics, for instance, and Pierre Duhem’s famous distinction between the French and the British ‘minds’ are examples of this train of thought. The debate on the ether was not immune from these geographical undertones. As Noakes argues in Chapter 6, Lodge blamed Germany’s materialist, decadent and ultimately dangerous morals on a philosophy that neglected, among other things, the ether. After all, the infection of modern science had started in Germany, the fatherland of both relativity and quantum theory. Given the peculiarities of the German thought and ethos, this genesis was not surprising, and the result had to be properly domesticated before any British attempt of appropriation. But, on the other side of the Channel, they thought it differently. Notoriously, Philip Lenard exposed relativity as contrary to the German—to wit, Aryan—spirit, using his authority as a Nobel laureate to challenge Einstein’s views and even to accuse him of 0003629866.INDD 7 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 8 Introduction plagiarism; he also fought a bitter struggle against J. J. Thomson and George Simpson, whom he regarded as careless and unfair experimenters. On several occasions, as Schirrmacher describes in Chapter 7, Lenard contrasted his rigorous and systematic approach to experimental physics with the sloppy attitude of the Britons. Much to his dismay, the latter were also more successful in terms of publication policy and accessibility, a feature that only made Lenard more furious. The case of Lenard shows how national differences often intersect disciplinary boundaries. But the issue was more complex. Relativity and its mathematical maze were not born within the experimental domain. With the new strange player in the scientific community, the theoretical physicist, doubts could be legitimately raised that the theoretician’s mathematical dreams could simply lead too far. Unlike those of the experimenter, the theoretician’s constraints were vague and shaky: for the latter, common sense was a burden, a relic of a past scientific ethos. And the ether played on both sides of the divide: for some, it was a theoretical figment of the imagination, but for others it was the most experimentally grounded object in the fight against the excesses of modern theoretical physics. Miller rebelled against this drift of modernity, but his story reveals an ironic twist. His painstaking efforts to obtain precise checks of the predictions of relativity, brilliantly described by Lalli in Chapter 9, eventually came to a close via the experiments of Georg Joos, who was not only a German but also a representative of a new—and modern—experimental physics. Eventually, the ultimate application of the experimenter’s ethos made the experimenter himself a dispensable player in the scientific game. 1.4 MATTER AND SPIRIT In nineteenth-century science, the ether served two main functions: it was the supporting medium for electromagnetic radiation and it was the storage for the energy no longer available for human usage. Each function required the ether to be a material entity of a very peculiar nature. It had to be rigid enough to allow the extremely fast propagation of transversal waves, thin enough not to slow down the planets moving through it and capable somehow of keeping the dispersed energy until, at some point in time, it could be released. None of these formidable properties was ever made consistent with the others: they were all justified by conceptual requirements internal to the electromagnetic theory. But, for many, the unresolved tension between the several properties of the ether was more of an opportunity than a hindrance. An entity of undefinable, amphibious features, the ether could not simply be an ordinary part of the physical domain: rather, it could be the bridge between our world and the ultramundane. The ether became an obvious resource to the resurgent spiritualism of the second half of the nineteenth century. A late convert to this trend, Oliver Lodge, became a powerful advocate of this culture, placing himself in the British tradition of natural theology. Lodge could easily inscribe his own agenda in this unfinished project as the rhetorical strategies unfolded by Clarke, Whitworth and Noakes show. Lodge’s favourite argument that science does not have all 0003629866.INDD 8 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Matter and Spirit 9 answers was meant in the broadest way possible. The verdict against the ether was not carved into stone, not only because science always reassesses its results but also because there were superior goals in intellectual inquiry, goals which science could not avoid. Thus, the reminder that the universe was still for the better part mysterious and ‘unseen’ was not only the expression of a healthy epistemological modesty but also the evocation of the spiritual subtext accompanying the scientific discourse. It is precisely within this framework that Lodge could parallel electron theory and psychic research: both had been mysterious at one time but were now ‘concrete and tractable’. On this emotional front, World War I also played an important role. As Lodge, Lenard and many others had lost their beloved ones in the trenches, the need to believe that the cruel carnage was not the ultimate end grew stronger. This powerful thought, which Lodge condensed in his book Raymond, could not find a more sympathetic audience: the storage power of the ether worked for electricity and the still-mysterious soul equally well. In Britain, the connection with the project of natural theology gave to the discourse on the ether a characteristic psychical and almost religious tinge. By contrast, in other areas of Europe, the tension between matter and spirit presented itself in cultural, political and artistic varieties. Lenard’s political usage of the ether as a brand of Deutsche Physik was part of a powerful neo-Romantic movement whose declared aim was to recover German Naturphilosophie and a more authentic relation with the spiritual side of nature. Aggressively opposed to the ruthless industrialisation and the blind scientificity of the modern world, the upholders of this movement sang the praise of a mystical connection between natural environment, people and spiritual tradition. This was the notorious concept of the Volk, a profound combination of blood, soil and an omnipresent ‘ether’ connecting individuals in a spiritual unity.9 The connection between occultism and radical political ideas is old. In his book, Mesmerism and the End of the Enlightenment in France, Robert Darton superbly described how mesmerism—a practice later supported by the Society for Psychical Research—got mixed with Rousseau’s ideas of a primeval human energy and eventually became a vector of radical politics during the Enlightenment.10 In the 1920s, many German intellectuals moved along a similar track. Inspired and supported by the indefatigable Eugen Diederichs, the publisher of a massive edition of Meister Eckart’s works, the self-proclaimed Free German Youth organised mountain walks and gatherings at which Madame Blavatsky’s theosophy was discussed in a lively manner. What the Free German Youth had in common with other spiritualistic movements with which it was in contact was its struggle against the damaging aspects of modernity, together with a firm belief in an all-pervading medium. One Herbert Reichstein even claimed in the 1920s that the first Aryan was created by a shock from an electro-spiritual ether. However, the Free German Youth was unique in that it stressed the connection between science and art. In its pretension to the ability to explain everything, modern science progressively neglected the inward eye and turned man into a cosmopolitan producer of material goods. The path to counter this decline was forcefully outlined by Julius Langbehn—one of the most influential minds in the Free German Youth—in his Rembrandt als Erzieher (also published by Diederichs): 0003629866.INDD 9 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 10 Introduction Germans must be turned into artists, and science must be turned into art. Only through an artistic relation with the world would it become possible to recover the ‘spirit’ and ‘possession of such a spirit meant recalling that which was truly genuine, the Germanic past, as opposed to modern and evil rationalism’.11 Science, spiritualism and art were thus intertwined in a project of cultural renewal. However, the relations with modernity could be wavery. For the intellectuals of the Free German Youth, art had primarily an antimodernist meaning. Fidus (the pseudonym of Hugo Höppener), arguably its most representative artist, declared overtly that his work originated from a connection with the ultramundane world; but, in terms of content, he was committed to retrieving the legacy of traditional Germany. By contrast, in Chapter 11, Linda Henderson shows very clearly that Umberto Boccioni was attempting a very daring synthesis between spiritualism and modernity via a reconfiguration of the notion of matter. For Boccioni—not by chance an enthusiastic reader of theosophical writings himself—the storage function of the ether, on which Lodge’s occultist arguments rested, became the vehicle to cross the borders between ether and matter. Unlike cubism, in this case the mixture of past, present and future was not in the memory but in the bodies themselves: matter was ether condensed, and ether was matter vaporised. Hence, matter embodied the elan of the spirit, to use an expression of Bergson (whose works were published in German, once again, by the energetic Diederichs). Although the appropriation of modernity changed importantly from one current to another, a common pattern seems recurrent, to wit, the rejection of purely rational thought and the search for alternative ways of accessing reality, possibly a deeper reality. In this regard, some chapters in this book demonstrate that sensory perception (at times opportunely extended) and aesthetic intuition maintained a central role. The aesthetic approach to science, as much as the aesthetic approach to life, aspired to attain a superior form of knowledge, one that could not be easily conceptualised, but could serve as an effective guide for daily tasks, scientific or otherwise. Doran, Staley and Wright insist, with different nuances, on this theme. It is less relevant that, for Poincaré, Mach and Dirac, the path to the unity and beauty of this world view passed through the symmetries of mathematics or those of sensorial experience; what is relevant is that this form of knowledge was immediate, intuitive, irreflexive and, in some sense, spiritual. 1.5 EPISTEMOLOGY AND EMOTIONS: A PLEA TO PLURALISM Unsurprisingly, we have circled back to knowledge. The philosophical stories we began with insisted that the ether was the idle wheel of electromagnetic theory.12 From the point of view of an epistemology that focuses exclusively on what leads to successful predictions, this claim is hardly questionable: the ether as such certainly did not directly contribute to Maxwell’s equations. This epistemology, in turn, whispered in the historians’ 0003629866.INDD 10 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Epistemology and Emotions: A Plea to Pluralism 11 ear the leitmotiv we see at work in many standard narratives: once Einstein awoke the scientific world from its ethereal slumber, the ether remained an option only for the nostalgic, the passé, the left behind. However, the chapters in this book show that the methodological dichotomies these narratives traditionally hinged on—classic versus modern, progress versus. conservatorism, continuity versus discontinuity—should not be taken to be as clear-cut as they used to be, because the discourse on the ether crosses these distinctions transversally. It is not by chance that Einstein is more evoked than dealt with in this book, for the really interesting question is not ‘Why were people so stubborn to stick to an outdated and blatantly false idea?’, but rather ‘What made the ether such a resilient concept?’. This novel question forces us to jettison the hegemonic positivistic picture of knowledge and assume a pluralistic point of view. The answer is to be found in the complex epistemological landscape and in the structure of feeling, as Raymond Williams used to call it,13 that allowed the ether to survive in the wake of relativity. If we explore this landscape more carefully, we are immediately struck by the richness and variety of the discourses on scientific knowledge in which the ether can be found. For example, as Whitworth shows in Chapter 3, Lodge’s literary ingenuity helped him create a sense that the ether was physically present—and made good use of it in wireless telegraphy—and no abstruse mathematics could convince us to the contrary. The idea that we might have a sense for the ether, present among some British writers, might be traced back to William Thomson’s presidential address at the Birmingham Midland Institute (3 October 1883), ‘The Six Gates of Knowledge’.14 Famously, Thomson argued that knowledge always entered through the senses which, supplemented with the ‘sense of force’, accounted for the six gates of the title, and he did not discard the possibility that other senses—perhaps even a sense of the ether—might at some point be discovered. If we expand our gaze beyond the Channel, we find that both in Der Analyse der Empfindungen (1886) and in Erkenntnis und Irrtum (1905), Ernst Mach repeatedly used his own body as a probe to explore the external world, although he added an important twist to the common-sense empiricism of the British tradition. For Mach, experience was constituted by ‘elements’, a notion importantly larger than just sensorial data: Perceptions, presentations, volitions, and emotions, in short the whole inner and outer world, are put together, in combinations of varying evanescence and permanence, out of a small number of homogeneous elements. Usually, these elements are called sensations. But as vestiges of a one-sided theory inhere in that term, we prefer to speak simply of elements.15 Mach was opening up a world in which the transcendental subject of the Enlightenment progressively lost its role of legislator of nature.16 The boundaries between subject and object became as blurry as those between matter and spirit and the ways to access knowledge expanded to positively encompass emotions, desires and volitions. From this perspective, mere experimental undetectability mattered very little. As Staley and Schirrmacher show, the permanence of the ether in the Germanic culture was related to its capability to serve epistemological functions much higher than that served by the lab. 0003629866.INDD 11 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, 12 Introduction Ultimately, it is the adaptability of the ether to multiple cultural contexts, and the epistemological pluralism that underlies this capability, that the rich diversity of the essays in this volume capture so effectively. Thus the obvious question is: what is it in the epistemological fabric of the concept of ether that allowed it to live so many lives well beyond its early proclaimed redundancy? A preliminary answer, which is more a collection of thoughts for further research than a fully fledged response, is that the ether may be a sort of interstitial concept. Let us close this introduction by elaborating this thought. The reorganisation of knowledge, leading to a deep scientific revolution, always leaves epistemic interstices. One obvious example is the famous phenomenon of the ‘Kuhn losses’.17 Thomas Kuhn argued that, when a new paradigm takes over, it might happen that problems previously well understood in the old paradigm suddenly become intractable. In other words, paradigms always leave epistemic gaps that must be filled with resources external to them. By the same token, relativity made the ether kinematically superfluous, but it left behind the problem of making sense of electromagnetic events occurring in the vacuum, as Dirac would point out. It is hardly surprising, then, that many authoritative physicists tried to fill this interstice by reconfiguring the concept of ether. Analogous interstices can crack open at the interface between science and culture. The chapters in this book provide numerous stories of appropriation of the ether by different communities. The wireless practitioners, the occultists, the Italian futurists, the German experimental physicists, and so on, had questions about which modern science only had useless, irrelevant or even unpleasant answers, if at all. By contrast, the ether could comfortably live in all these spaces made available by the imperfect interconnection between science and culture. As an interstitial concept, the ether was plastic and pliable enough to be adapted to diverse contexts, because it was no longer a specific object but rather a multidimensional concept able to serve a number of epistemic, symbolical, social, political, emotional, moral and even scientific functions, some of which, in contrast, were perfectly in tune with modernity. But such an extreme flexibility had, of course, a downside. Sitting at the interstices between multiple discourses, the ether was not integral to any of them and was not autonomous. Hence, it had to be sustained by the continuous effort of authoritative figures energetically acting in the public sphere. This, in turn, generated a complex dynamics of alliances, negotiations and strategies reaching out a considerable variety of debates. It is precisely its interstitial nature that makes the ether such an effective entry point in that thorny juncture of modernity that was the beginning of the twentieth century. NOTES 1. Lloyd S. Swenson, Jr, The Ethereal Aether. A History of the Michelson–Morley–Miller Aether-Drift Experiments, 1880–1930 (Austin: University of Texas Press, 1972); Joe Milutis, Ether. The Nothing that Connects Everything (London: University of Minnesota Press, 2006). 2. Andrew Warwick, Masters of Theory. Cambridge and the Rise of Mathematical Physics (Chicago: Chicago University Press). See also Graeme Gooday and Daniel J. Mitchell, ‘Rethinking “Classical 0003629866.INDD 12 Dictionary: NOSD 5/18/2018 6:49:08 AM OUP UNCORRECTED PROOF – FIRST PROOF, Epistemology and Emotions: A Plea to Pluralism 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 0003629866.INDD 13 13 Physics”’, in Jed Z. Buchwald and Robert Fox, eds., The Oxford Handbook of the History of Physics (Oxford: Oxford University Press, 2013), 721–764. Geoffrey N. Cantor and Michael J. S. Hodge, Conceptions of Ether. Studies in the History of Ether Theories, 1740–1900 (Cambridge: Cambridge University Press, 1981). Ludwik Kostro, Einstein and the Ether (Montreal: Apeiron, 2000). Edmund Whittaker, A History of the Theories of Aether and Electricity, vol. 2 (London: Longmans, 1953). On this point, see Richard Staley, ‘On the Co-Creation of Classical and Modern Physics’, Isis, 96 (2005): 530–58. On this process of exploration of the relation between classical and modern ideas in physics, see Jochen Büttner, Jürgen Renn and Matthias Schemmel, ‘Exploring the Limits of Classical Physics: Planck, Einstein, and the Structure of a Scientific Revolution’, Studies in History and Philosophy of Modern Physics, 34 (2003): 37–59. For a pedagogical take on the same issue, see Massimiliano Badino and Jaume Navarro, ‘Pedagogy and Research: Notes for a Historical Epistemology of Science Education’, in Massimiliano Badino and Jaume Navarro, Research and Pedagogy: A History of Quantum Physics through its Textbooks (Berlin: Edition Open Access, 2013), 7–30. On the role of analogy in the emergence of quantum physics see Olivier Darrigol, From c-Numbers to q-Numbers: The Classical Analogy in the History of Quantum Physics (Berkeley: University of California Press, 1992). See e.g. George L. Mosse, ‘The Mystical Origins of National Socialism’, Journal of the History of Ideas, 22 (1961): 81–96, and George L. Mosse, Nazi Culture: Intellectual, Cultural, and Social Life in the Third Reich (Madison: University of Wisconsin Press, 1966). Robert Darton, Mesmerism and the End of the Enlightenment in France (Cambridge, MA: Harvard University Press, 1968). Mosse, ‘The Mystical Origins of National Socialism’, p. 88. See e.g. Philip Kitcher, The Advancement of Science (Oxford: Oxford University Press, 1993), pp. 143–9. Raymond Williams, Marxism and Literature (Oxford: Oxford University Press, 1977). William Thomson, ‘The Six Gates of Knowledge’, in Popular Lectures and Addresses, vol. 1 (London: Macmillan, 1891), 260–306. Ernst Mach, The Analysis of Sensation (New York: Dover, 1959), p. 22. On this point, see Jürgen Habermas, Knowledge and Human Interests (Boston: Beacon Press, 1971), pp. 81–90. Thomas S. Kuhn, The Structure of Scientific Revolutions (Chicago: University of Chicago Press, 3rd edn, 1996), pp. 103–10. Dictionary: NOSD 5/18/2018 6:49:08 AM