Prof. Dr. Klaus Hentschel

ZusammenfassungBei der Durchsicht des Nachlasses von Rudolf Tomaschek fand ich ein 30 Seiten umfassendes Typoskript seines damaligen Assistenten Hugo Watzlawek aus dem Jahr 1944 mit dem Titel „Interatomare Energie“. Heute würde man eher von „inneratomarer Energie“, oder von „Kernenergie“ sprechen, da der Inhalt des Typoskripts „technische Kernphysik“ einschließlich ihrer potentiellen militärischen Anwendungen betrifft. Der Text bietet einen ungefilterten, erstaunlich kenntnisreichen, aber in vielem auch erschreckenden Einblick in die technokratische Gedankenwelt sowie den Wissensstand und Anwendungshorizont eines „technischen Kernphysikers“ im „Dritten Reich“, der unter Verweis auf konkurrierende amerikanische Forschungen 1944 nachdrücklich um weitere Mittel für kernphysikalische und -technische Forschung sowie für die Entwicklung von Kernwaffen bittet. Der vorliegende Aufsatz kommentiert und kontextualisiert das Typoskript; meine ebenfalls online gestellte annotierte Transkription des Typoskriptes bietet ungekürzten Zugang zum Originaltext samt knapper, für dessen Verständnis notwendiger historischer und technischer Erläuterungen.Among the papers of Rudolf Tomaschek I discovered a 30-page typescript from 1944 by his then assistant Hugo Watzlawek entitled “Interatomare Energie”. Nowadays one would rather say ‘inneratomic energy’ or ‘nuclear energy’ since the typescript treats issues of nuclear engineering including its potential military uses. It presents an unfiltered, surprisingly informed view into the technocratic mindset, state of knowledge and application horizon of a “technical nuclear physicist” in the Third Reich. Watzlawek in 1944 urgently petitions for more funding for research in nuclear physics and technology, citing analogous research underway in America. The present paper places the typescript within its historical and technical context. My succinctly annotated transcription of the original text—also made freely available online—provides full accessibility to this document.

Comparisons as a Bridge between History and Philosophy of Science. Both in history and philosophy of science, comparisons are looked upon with considerable skepticism. A widespread syndrome of casuitis, i.e., the tendency of historians of science to produce extremely narrow and local studies that do not present a case for any broader thesis of interest to philosophers, has widened the gulf between history and philosophy of science.This may be somewhat surprising to sociologists, philosophers, or general,legal and cultural historians, who have been using comparisons successfully for a long time–albeit not always without controversy. In the first part of this paper, I assess the status of comparisons in science studies, in order to explain why their systematic use is not nearly as natural as might elsewhere be expected. This critical section is followed by a very brief outline of the prerequisites for fruitful comparison as formulated by general and sociological historians in their detailed methodological discussions. To these are added some necessary conditions from the perspective of modern history of science. In the third part I present four examples of such systematic comparisons taken from my own research.

ZusammenfassungBei der Durchsicht des Nachlasses von Rudolf Tomaschek (1895–1966) fand ich ein 30 Seiten umfassendes Typoskript seines damaligen Assistenten Hugo Watzlawek (1912–1995) aus dem Jahr 1944 mit dem Titel „Interatomare Energie“. Heute würde man eher von „inneratomarer Energie“, oder von „Kernenergie“ sprechen, da der Inhalt des Typoskripts „technische Kernphysik“ einschließlich ihrer potentiellen militärischen Anwendungen betrifft. Der Text bietet einen ungefilterten, erstaunlich kenntnisreichen, aber in vielem auch erschreckenden Einblick in die technokratische Gedankenwelt sowie den Wissensstand und Anwendungshorizont eines „technischen Kernphysikers“ im „Dritten Reich“, der unter Verweis auf konkurrierende amerikanische Forschungen 1944 nachdrücklich um weitere Mittel für kernphysikalische und -technische Forschung sowie für die Entwicklung von Kernwaffen bittet. Der vorliegende Aufsatz kommentiert und kontextualisiert das Typoskript; meine ebenfalls online gestellte annotierte Transkription des Typoskriptes bietet ungekürzten Zugang zum Originaltext samt knapper, für dessen Verständnis notwendiger historischer und technischer Erläuterungen.

Despite a renewed interest in the philosophical prehistory of logical empiricism, several texts by prominent figures such as, e.g., Moritz Schlick and Hans Reichenbach, published in non-standard journals, have escaped the notice of scholars. Here, a hitherto virtually unknown but significant review of Moritz Schlick's influential book Allgemeine Erkenntnislehre [1st ed. 1918] written by Hans Reichenbach in 1919/20 is reprinted together with comments about its background and the later development, relying on and citing from the unpublished correspondence between Schlick and Reichenbach in 1920. Since they later became the leading figures in the so called Vienna and Berlin circles respectively, this episode marks an important stage in the gradual emancipation of scientific philosophy from its Kantian roots

Die Korrespondenz der beiden Physiker und Wissenschaftshistoriker Ernst Mach und Pierre Duhem ist weitgehend, vielleicht mit Ausnahme nur eines Briefes, erhalten. Neben der Dokumentation dieser historischen Zeugnisse setzt sich der Autor in diesem Aufsatz zum Ziel, die jeweiligen Motive, die Mach resp. Duhem zur Beschäftigung mit Wissenschaftsgeschichte führten und die damit verbundenen Modelle der Wissenschaftsgeschichtsentwicklung beider gegeneinander abzugrenzen. Dazu wurden insb. die in der bisher vorliegenden Sekundärliteratur zu Mach und Duhem überhaupt nicht berücksichtigte Buchbesprechung der Machschen Mechanik durch Duhem sowie die ergänzenden Bemerkungen zu Duhem in späteren Auflagen der Werke und in der Korrespondenz Machs herangezogen, die eine recht detaillierte wechselseitige Kritik ihrer Methodik beinhalten. Den Abschluß meiner Betrachtungen bildet der Versuch einer Sondierung dessen, was in Duhems resp. Machs historischen Betrachtungsweisen über die nicht in Frage stehende Bedeutung als Meilensteine der Wissenschaftsgeschichtsschreibung hinaus noch heute von Relevanz ist.The preserved part of the hitherto unpublished Duhem-Mach correspondence, kept in the Archives de l'Académie des Sciences, Paris, and in the Ernst Mach Institut of the Fraunhofer Society, Freiburg im Breisgau, is documented and commented upon. Biographical, methodological, and philosophical analogies and differences between the points of view of Pierre Duhem and Ernst Mach are discussed, and a critical evaluation is given of their impact as historians of science

The Gradual Formation of the Concept of ‘Light Quanta’. The complex concept of ‘light quanta’ which 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, has a rich history both before and after 1905. Some of its semantic layers lead as far back as Newton and Kepler, others are only fully espoused several decades later, yet others initially increased, then diminished in importance and finally vanished. Two historiographic approaches are discussed and exemplified: a) my own model of conceptual development as a series of semantic accretions, and b) Mark Turner’s model of ‘conceptual blending’. Both of these models are shown to be useful and will be further explored in my own efforts to come to grips with the complex process of concept formation.

In late 1912, Fritz Goos at the Hamburg Physikalisches Staatslaboratorium discovered a systematic dependency of arc-spectra wavelengths on the length of the electric arc used and on its electric parameters, such as, for instance, the current employed. In early 1913, at Heinrich Kayser's better-equipped physical laboratory in Bonn, Goos was able to confirm these effects using a large concave Rowland grating. He was able to establish that variations of between 3 mm and 10 mm in the length of the arc produced wavelength differences of up to 0.02 Å violet shift and -0.007 Å redshift respectively. Further inquiry also revealed a dependency of the wavelength on the region of the arc selected for spectrometric observation. All these surprising effects were soon collectively named ‘pole effect’.As is shown in this paper, the pole effect threatened the validity of the results of the entire research tradition of high-precision spectroscopy which, around 1910, had excelled in establishing several internally coherent systems of wavelength assignments. These wavelength catalogues had been established by spectroscopists such as Heinrich Kayser, Paul Eversheim and their co-workers in Bonn, by August Herman Pfund in Baltimore, and by Charles Fabry and Henri Buisson in Marseille under the aegis of the ‘International Union for Co-Operation in Solar Research’. They had all produced locally consistent, “homogeneous” systems of wavelengths with estimated errors sometimes smaller than 0.001 Å. However, long before 1913, strange non-local inconsistencies had emerged between these systems that were of much greater magnitude than the estimated error. The discovery of the pole effect opened up the possibility that variations in the arc parameters used in the measurements, which the different teams had hitherto not specified, were responsible for the systematic differences, in their respective sets of measurements, coming to up to 0.025 Å.This paper explores the interrelations between local knowledge production, the strategies for the establishment of local coherence, and the ways in which the community of physicists and spectroscopists handled a possible threat to this coherence after 1913. Around 1930, a general agreement was reached about the physical cause of the pole effect, namely Stark effects, caused in turn by intermolecular electric fields of ions in the arc. Much before 1930, however, the community had already succeeded in standardizing the instrumentation used in high-precision spectrometry and had conformed its research practice to such an extent that from 1917 on the pole effect could be routinely circumvented in high-precision spectrometry and interferometry. Thus, experimentation along with its instrumentation, indeed had ‘a life of its own’, independent of the many unsuccessful efforts to explain the pole effect theoretically.