Klaus Hentschel Book order

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 ofits 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: (a) the author’s 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 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.

Few scientific communities have been more thoroughly studied than 20th-century German physicists. Yet their behavior and patterns of thinking immediately after the war remains puzzling. During the first five postwar years they suspended their internecine battles and a strange solidarity emerged. Former enemies were suddenly willing to exonerate each other blindly and even morally upright physicists began to write tirades against the 'denazification mischief' or the 'export of scientists'. Personal idiosyncracies melded into a strangely uniform pattern of rejection or resistance to the Allied occupiers, with attendant repressed feelings and self-pity. Politics was once again perceived as remote, dirty business. It was feared that the least concession of guilt would bring down even more severe sanctions on their discipline. Using tools from the history of mentality, such as analysis of serial publications, these tendenciesare examined. The perspective of emigré physicists, asreflected in their private letters and reports, embellish this portrait.

Astronomy relies heavily on nonverbal representations, as most celestial objects are only visible through the light or radiation they emit. Throughout history, images have been crucial, from prehistoric moon sketches to ancient star charts, and from medieval celestial maps to modern photographs and spectrograms. Both two-dimensional images and three-dimensional models have been integral to the field. Technical charts and graphs, such as the Hertzsprung-Russell diagram and light curves of variable stars, further illustrate this relationship. Recent advancements have led to stunning images from ground-based telescopes, satellite observatories, and deep space probes. However, the connection between science and imagery is complex. Questions arise regarding the accuracy of these visual representations and the challenges in translating observations into graphic forms. The pursuit of improved representational techniques and resolution can impact research practices, and technological advancements play a significant role. Additionally, the collaboration between astronomers and graphic specialists, including illustrators and photographers, is vital for effective communication. This collection of papers, presented at a conference in 1999, addresses these themes and is aimed at those interested in visual representations and the history of astronomy.

Focusing on the "Einstein Tower," an architecturally historic observatory built in Potsdam in 1920, this book investigates German scientific life by blending biography, architectural history, scientific theory and research, and scientific politics.