Klaus Hentschel Book order

This book examines the gradual development of the concept of ‘light quanta’ or ‘photons,’ a term used since 1926. The various synonyms employed by physicists reflect diverse mental models of what light quanta represent: Are they finite, quantized energy packets or bullets of light? Atoms or molecules of light? Light corpuscles or quantized waves? Singularities or spatially extended structures capable of interference? The notion of ‘light quantum’ first appeared in Einstein’s 1905 paper addressing the photoelectric effect, but its conceptual history predates and extends beyond that year. Some semantic layers trace back to Newton and Kepler, while others emerged or faded over time. The book explores six distinct mental models of light quanta and presents two historiographic approaches to concept formation: the author’s model of conceptual development as semantic accretions and Mark Turner’s model of conceptual blending. Both models are shown to be valuable for understanding this complex topic. This work represents a historiographically sophisticated exploration of the fully developed concept and its twelve semantic layers, integrating the history of science, terminology, and a philosophically informed history of ideas, alongside 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.