Prof. Dr. Klaus Hentschel

The manipulation of materials, and to some extent also their systematic classification, form an integral part of the skills and culture of all societies. Yet it took long for proper sciences to develop out of many processing procedures, tapping the accumulated knowledge about specific material characteristics. In the late 20th century an overarching science of workable materials emerged: materials science. This concept and term originated from major boosts in materials research during WWII and the Cold War, first financed by the U.S. Department of Defense and the Advanced Research Project Agency. The COSMAT-Report from 1974, written by the American Presidential Science Advisory Committee’s „Committee on the Survey of Materials Science and Engineering" four years after its inception, and subsequent reports heralded in the second institutionalization phase of materials science in the USA and with some delay also elsewhere. As the field continued to expand, the demand grew from within in the late 1990s for disciplinary status. This article sorts these claims from the various camps and sets them in the context of unfolding institutional change. The developments within the German-speaking realm, thus far unduly neglected in these debates, are added. I close with a systematic discussion of eight indicator arguments for or against a convergence of this complex field of research into a single coherent discipline. Against Bensaude-Vincent’s thesis that materials science still is an “aggregation of fragments of knowledge", I argue that by 2010 materials science did indeed achieve disciplinary status in a historically rare and enduring process of discipline formation through “emergence by integration" rather than by differentiation.

A translator and her science consultant, who have worked together on many books, consider the problems of translating primary and secondary texts in science. Various problems encountered in translating an ongoing documentary edition in the history of science are discussed using the collected works of Albert Einstein as a test case. For instance, each language has its own preferred sentence structure; moreover, not every historical term finds a perfect equivalent in modern usage, and historical accuracy is contextually bounded.

The ArgumentGravitational redshift of spectral lines as one of the three early-known experimental implications of Einstein's general theory of relativity and gravitation was intensively searched for by researchers all over the world, but around 1920 most of the contemporary evidence in the sun's Fraunhofer-spectrum conflicted with the predictions of relativity theory.In 1923 the American astrophysicist Charles Edward St. John announced that his own solar spectroscopic data would force him to retreat from his former skepticism concerning the existence of gravitational redshift. This statement was at the time widely interpreted by scientists and journalists alike as the open confession of a rapid conversion of one of the few remaining serious scientific opponents of Einstein's theory.This paper demonstrates that this illusion of a sudden “Gestalt switch” in St. John's evaluation of data can be dissolved by a careful step-by-step account of St. John's research practice between 1917 and 1923. After a fine-grained diachronic report of the development of St. John's interpretation of his and others' data, the second part of the paper consists in a systematic analysis of the heuristics and arguments used by St. John pro and contra gravitational redshift.

This paper describes a now widely forgotten tradition in the nineteenth century which - to borrow a simile used or implied by the actors themselves - may be described as 'spectroscopic portraiture'. Quite unlike the later obsession with numerical precision in wavelength measurement, and also in stark contrast to the contemporary vogue of photographic mapping which presumptuously claimed 'mechanical objectivity', that is avoidance of any human intervention in the recorded data, there was among some spectroscopists a much greater preoccupation with qualitative rather than quantitative aspects. The atlases of the solar spectrum by Cornu, Thollon, and Piazzi Smyth were supposed to convey the subjectively perceived Gestalt of the Fraunhofer lines, at the expense of precision. I shall argue that this was a systematic research programme addressed to a welldefined but small audience of specialists in the new subdiscipline of spectroscopy which was distinct from other practices such as spectrum analysis, which was directed mainly at chemists. Apart from this, the new tradition can also be identified by the dense net of cross-references in the publications of the various members, and by their critique of earlier work. This tradition of spectrum portraiture started with Kirchhoff's 1861-2 high-resolution chromolithographic plates of the solar spectrum, which were printed off a half-dozen different stones in order to render most faithfully the various line intensities. Focusing especially on the tension between representational goals and technical possibilities in the rapidly developing printing industry, I then trace the emerging tradition through its apogee to the close of the nineteenth century

This paper discusses a series of case studies on observations, experiments, and the theoretical interpretation between 1890 and 1960 of a shift of dark Fraunhofer lines in the solar spectrum. I argue for the use of flow charts to analyze interconnections and to identify sequences of research strategies. Also I advocate using a newly-developed tool called "block diagram" representation of experimental systems as an appropriate method to identify recurrent patterns in the interplay of instrumentation, experiment, and theory in research episodes

This book focuses on the gradual formation of the concept of ‘light quanta’ or ‘photons’, as they have usually been called in English since 1926. The great number of synonyms that have been used by physicists to denote this concept indicates that there are many different mental models of what ‘light quanta’ are: simply finite, ‘quantized packages of energy’ or ‘bullets of light’? ‘Atoms of light’ or ‘molecules of light’? ‘Light corpuscles’ or ‘quantized waves’? Singularities of the field or spatially extended structures able to interfere? ‘Photons’ in G.N. Lewis’s sense, or as defined by QED, i.e. virtual exchange particles transmitting the electromagnetic force? The term ‘light quantum’ made its first appearance in Albert Einstein’s 1905 paper on a “heuristic point of view” to cope with the photoelectric effect and other forms of interaction of light and matter, but the mental model associated with it has a rich history both before and after 1905. Some of its semantic layers go as far back as Newton and Kepler, some are only fully expressed several decades later, while others initially increased in importance then diminished and finally vanished. In conjunction with these various terms, several mental models of light quanta were developed—six of them are explored more closely in this book. It discusses two historiographic approaches to the problem of concept formation: the author’s own model of conceptual development as a series of semantic accretions and Mark Turner’s model of ‘conceptual blending’. Both of these models are shown to be useful and should be explored further. This is the first historiographically sophisticated history of the fully fledged concept and all of its twelve semantic layers. It systematically combines the history of science with the history of terms and a philosophically inspired history of ideas in conjunction with insights from cognitive science.

The paper (given in the section on "Recent work in the History of Philosophy of Science) discusses the method and some of the results of the doctoral dissertation on philosophical interpretations of Einstein's special and general theories of relativity, submitted to the Dept. for History of Science, Univ. of Hamburg, in 1989, also published by Birkhauser, Basel, in 1990. It is claimed that many of the gross oversimplifications, misunderstandings and misinterpretations occurring in more than 2500 texts about the theories of relativity written by scientists, philosophers, and laymen contemporary to Einstein can in fact serve as a clue to a better understanding of the general process by which philosophical interpretations are formed. Another very important source for answering the question of how misinterpretations are formed are hitherto unpublished documents in the estates of physicists and philosophers of that time, including apart from Einstein himself: Bergson, Bridgman, Carnap, Cassirer, Metz, Meyerson, Petzoldt, Reichenbach, Schlick and Vaihinger.

To compile a comprehensive edition of the correspondence of the world-famous physicist, physiologist, philosopher, and pioneer historian of science, Ernst Mach is an urgent desideratum. An estimated 5000 letters to and from Mach are kept in public and private archives worldwide. The largest part of this correspondence was formerly kept in the Ernst Mach Institut für Kurzzeitdynamik der Fraunhofergesellschaft in Freiburg/Breisgau and is now archived at the Deutsches Museum in Munich. A smaller partial estate, based on collections by Ernst Mach’s son Ludwig has been transferred to the Staats- und Universitätsbibliothek Göttingen. Other major collections are kept in Konstanz, Vienna, Prague etc. Mach’s own letters are spread throughout Europe and North America in hundreds of archives hosting private papers or estates of his contacts.

The paper presents and discusses measurements of gravitational redshift made between 1959 and 1971 by Pound and Rebka, Schiffer and Marshall, Brault, Blamont and Roddier, and finally by Snider. It emphasizes the importance of new measurement techniques such as wavelength modulation, electronic amplification, and scattering of atomic beams to the emergence of new tests of Einstein's GRS prediction, which were perceived by the scientific community as the first ‘clean’ verifications of GRS. In particular, the race to be the first to apply the Mössbauer effect to the GRS problem is described. As soon as the Mössbauer effect was stabilized, it was transformed into a measurement technology that in turn triggered new types of experimental tests of GRS