'Let the stars shine in peace!' Niels Bohr and stellar energy, 1929-1934.

Faced with various anomalies related to nuclear physics in particular, in 1929 Niels Bohr suggested that energy might not be conserved in the atomic nucleus and the processes involving it. By this radical proposal he hoped not only to get rid of the anomalies but also saw a possibility to explain a puzzle in astrophysics, namely the energy generated by stars. Bohr repeated his suggestion of stellar energy arising ex nihilo on several occasions but without ever going into detail. In fact, it is not very clear what he meant or how seriously he took the stellar energy hypothesis. This paper relates Bohr's comments to the period's attempts to find a mechanism for stellar energy and also to the role played by astrophysics at the Copenhagen institute. Moreover, it looks at how Bohr's hypothesis was received not only by physicists but also by astronomers. In this regard the disciplinary status of astrophysics and its contemporary relation to the new quantum mechanics is of relevance. It turns out that, with very few exceptions, the hypothesis was met with silence by astronomers and astrophysicists concerned with the problem of stellar energy production. And yet, for a brief period of time it did have an impact on how physicists thought about the interior of the stars.

To be or not to be: the early history of H3 and H3+.

Triatomic hydrogen became a major research area only after 1980, but its history goes back to J. J. Thomson's discovery in 1911. In fact, the possible existence of H(3) was suggested as early as 1895. This paper outlines the history of H(3) and H(3)(+) up to the mid-1930s, when chemists and physicists ceased to believe in the existence of the H(3) molecule. In the intervening years, there was a great deal of interest in 'active hydrogen' and also in the configuration of H(3), which was examined by Bohr in 1919. While H(3) was abandoned, H(3)(+) was not. Although the properties of H(3)(+) were largely unknown, the existence of the ion was firmly established, and its structure studied by means of the new methods of quantum chemistry.

Problems and challenges in the historical study of the neurosciences.

The paper focuses on historiographical questions relevant to the historical study of the neurosciences. I attempt to illuminate these questions by looking at them from the perspective of general historiography of science. In the first section, I consider the disciplinary structure of the modern neurosciences and discuss some of the historiographical problems that are involved in the historical description of a highly multidisciplinary field. For example, how far back in time can one trace brain research as part of the construction that we call the neurosciences? The main part of the paper deals with recent trends in contextualist historiography in relation to the neurosciences. I suggest that one important source for the trend, as it emerged in the 1970s, was a renewed interest in the history of phrenology and its reception in Britain. By looking at the historiography of phrenology, some of the rival positions in modern historiography of science can be illuminated. In the last part of the paper, I comment on the advantages and disadvantages of contextualist historiography of science, including its relation to the producers of science, the scientists.