Prof. Dr. Klaus Hentschel

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 paper reconstructs what may have led the American professorof chemistry andnatural philosophy John William Draper to introduce a new kind ofradiation, whichhe dubbed `Tithonic rays''. After presenting his and earlierempirical findings onthe chemical action of light in Section 3, I analyze his pertinentpapers in Section 4with the aim of identifying the various types of argumentshe raised infavor of this new actinic entity (or more precisely, this newnatural kind of raybesides optical, thermal and perhaps also phosphorogenic rays).From a modernperspective, all of these obviously belong within theelectromagnetic spectrum,but not so for many thinkers of the 19th century. I close withremarks about whyDraper''s interpretation was abandoned in the second half of the19th century (hehimself recanting only in 1872), and why I think such a naturalhistory ofargumentation (as one might call my approach in Section 4) may beuseful for acomparison-oriented history of science.

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.

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

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

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.

ZusammenfassungEs wird die wechselseitige Beeinflussung Einsteins und Schlicks anhand ihrer ab 1915 erhaltenen Korrespondenz in vier Schwerpunkten untersucht. Schlicks Selbstverständnis als Philosoph wie auch einzelne Themata seines Denkens (wie etwa das der Einfachheit) bildeten sich mit seiner Auseinandersetzung um die Relativitätstheorie Einsteins heraus, deren systematische Explikation durch Schlick auf Einsteins Beifall stieß. Als die Ursache für das Auseinanderdriften beider Denker nach 1925 werden fundamentale Differenzen im Wirklichkeitsverständnis und in der Interpretation des Kausalitätsprinzips aufgewiesen, die beide auch zu komplementären Formen der Wissenschaftsgeschichtsbetrachtung führten.

The main features of a new online database of scientific illustrators are portrayed. We list illustrators of scientific publications of all genres (especially atlases, articles, textbooks) who were active between 1450 and 1950, thus excluding illuminators of medieval manuscripts as well as illustrators still active. Currently (Sept. 26, 2012), we already have more than 3,461 entries, with particular emphasis on anatomy, dermatology, botany, zoology, mineralogy, astronomy, and general natural history. Access to the database with its 20 search fields is free and open to all interested users at www.uni-stu ttgart.de/hi/gnt/dsi/

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

An effort of proponents of relativity theory to find evidence for the so-called gravitational red-shift of spectral lines as one of the experimental consequences of Einstein's generalized theory of relativity is reconsidered with reference to hitherto unpublished documents. It is shown how much interest Albert Einstein in fact took, around 1920, in the data analysis of Leonhard Grebe and Albert Bachem, who tried to explain why most earlier efforts to find the gravitational red-shift had failed. They carefully measured the line profiles of the spectral lines both in the sun's Fraunhofer lines and in pressure-independent laboratory comparison spectra. Then they rejected all lines with strong neighbouring lines which could cause apparent shifts of the line centres; the remaining seven well-isolated lines showed the gravitational red-shift with acceptable accuracy. Nevertheless, their claim to have successfully isolated the relativistic effect never convinced the astrophysicists of their day—the reasons for the scientific community's scepticism, contrasted against the enthusiastic group of Einstein sympathizers, are also discussed

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.

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.