An der Schwelle zum Atomzeitalter. Die Vorgeschichte der Entdeckung der Kernspaltung im Dezember 1938

On the Threshold of the Atomic Age: The History of the Discovery of Nuclear Fission in December 1938: - Fifty years ago in mid-December 1938, Otto Hahn and Fritz Strassmann at the Kaiser Wilhelm Institute of Chemistry discovered nuclear fission by demonstrating, using chemical methods, the presence of barium in the decay products of neutron-irradiated uranium. This essay points out the constellation of conditions and prerequisites (Historischer Erfahrungsraum/“historical field of experience”) which led to the discovery of nuclear fission, and was constituted by specific components (“presentabilia”) both internal and external to science in general and to atomic research in particular. A decisive role was played by the constellation of the three members of the Berlin team and their personal situations under the political conditions of the 1930s. Further “presentabilia” were the institutional, instrumental and disciplinary conditions under which the team worked and the methods available to the individual members of the team. It was very important that some of the “presentabilia” were “not-present” to the members of the team. In particular, after Meitner's departure from Berlin Hahn and Strassmann had no access to methods and tools for proving the presence of alpha rays; nothing was known of the existence of actinides; no cyclotron or other source of neutrons more productive than those already in use in Berlin, Paris and Rome was available; it was very important that Strassmann and Hahn were not convinced of the strong validity of the resonance process induced by thermal neutrons; etc.     

Die Mathematisierung der Naturwissenschaften vor dem Hinter-grund der Bildungsvorstellungen des 19. Jahrhunderts

Both, astronomy in the first half of the 19th century and physics in the second half of the 19th century functioned as models and paradigms for the other sciences. The paradigmatic character of a theoretical, mathematical astronomy was due mainly to its capability to predict future events. According to the influence of the Romantische Naturphilosophie the mathematization of physics in Germany took place belatedly compared to France. A modified Newtonian research program with its mathematical implications was adopted by German physicists only after the establishment of the principle of energy conservation. German physicists of the late 19th century claimed over and above the results of physicists the successes of German technology for physics and interpreted these achievements as “cultural” achievements. They combined this claim with a request for a better representation of physics in the curricula of secondary schools so as to be comparable to that of mathematics. The resistance of the most prestigious secondary schools, the Humanistische Gymnasien, against this request meant that the concept of Bildung as propagated by physicists was not accepted generally in Germany.     

Die Seele auf der Bühne der Justiz. Die Entstehung der Kriminalpsychologie im 19. Jahrhundert und ihre interdisziplinäre Erforschung

The mind on the stage of justice: The formation of criminal psychology in the 19th century and its interdisciplinary research. – Criminal psychology emerges at the end of the 18th century as a new academic discipline in lectures and publications. It has recently been investigated by a considerable number of contributions from researchers of different academic backgrounds. In many respects criminal psychology can be seen as a predecessor of criminology. Its subject is the analysis of the origins of crime and its causes and determinants in the human mind. Criminal psychology embraced at that time philosophical, medical, legal and biological aspects. The latter increase in importance in the second half of the 19th century. The conditions of individual responsibility were generally codified in penal law, but had to be individually investigated in crucial cases through expertise in court. There a conflict emerged between medical experts and judges about their ability and competence to decide. At the end of the 19th century criminal psychology is used to fulfil the needs and interests of a criminal law which understands itself as increasingly utilitarian. Force and new instruments of treatment of offenders were legitimized by scientists who were very optimistic about their own epistemological abilities.     

Theophrast über Pflanzenkrankheiten. Ein Beitrag zur Geschichte der Phytopathologie in der Antike

Already before Theophrastus there was a botanical literature which also dealt with the diseases of plants, but we have only indirectly access to it — mainly by way of Theophrastus. The botanical excursus of the Hippocratic series of writings De genitura, De natura pueri, De morbis IV, which attributes the health of plants to a balance of warmth and cold and a correct quantity of specific humidity, forms an exception. This excursus hints at what is more fully developed in Theophrastus discussion of the diseases of plants: The diseases of plants are understood in close analogy to those of animals or human beings. In both cases, a basic distinction is made between inner, dietetic diseases and outer, traumatic ones. According to Theophrastus, especially humidity and an innate warmth are life-sustaining factors. A disturbance of the natural humidity/warmth-household must be counteracted by respective measures. As far as the terminology of plant diseases is concerned, Theophrastus relies on already existing concepts. Classical literature after Theophrastus has made no substantial contributions to phytopathology.     

Das Werden des Kosmos Von der Erfahrung der zeitlichen Dimension astronomischer Objekte im 18. Jahrhundert

The Permanent ‘Becoming’ of the Cosmos: On Experiencing the Time Dimension of Astronomical Entities in the 18th Century. - This paper deals with two of the initial stages through which the dimension of time, in the sense of an irreversible development, found its way into astronomical-cosmological thinking. The one resulted from the first consequental application of Newtonian principles and laws to cosmic entities outside of our solar system found in the General Natural History or Theory of the Heavens of Immanuel Kant (1755): Endeavoring to explain through natural causes first the peculiarities of the solar system, no longer naturally explainable through the celestial mechanics of Isaac Newton (such as the common orbital plane and rotational direction of all the members of the solar system and the distribution of the masses) - which, however, had been deducible in Johannes Keplers Weltharmonik -, and endeavoring secondly to explain above all the beginning of the inertial movement of all discrete heavenly bodies - which, however, could have been derived from René Descartes's vortex theory - without using arbitrary acts of God as Newton had done, Kant had to introduce an initial state in which matter in the form of atoms was equally and almost homogeneously distributed over the whole space (similar to the permanent state in Descartes's theory). Thereupon, according to Kant, the initial movements of the slowly growing masses resulted from the effect of gravitational forces. The parameters within the solar system which had to be explained, could then be easily deduced from the process of mass concentration at different points and from the resulting vortex movements. - The other initial stage is found in the classification of ‘nebulae’ by William Herschel who introduced the historical time factor, in the above-mentioned sense, as a principle of order in addition to the outward shape, which had become common for all the different elements in natural history during the second half of the 18th century. Thereupon the different shapes of the nebulae could be interpreted as stages of development from the primordial nebular state to multiple or single stars. (Herschel had not yet considered them to be accumulations of stars for lack of a suitable telescope.) Both initial stages, which arose out of the thinking of the second half of the 18th century, were still premature for astronomy and cosmology; they have only been taken up again since the end of the 19th century as a result of the emergence of astrophysics, which provided the empirical data for the earlier speculations and conclusions from analogy.