In 1921, the experimental physicist Rudolf Ladenburg put forward the first quantum interpretation of optical dispersion. Theoretical physicists had tried to explain dispersion from the point of view of quantum theory ever since 1913, when Niels Bohr proposed his quantum model of atom. Yet, their theories proved unsuccessful. It was Ladenburg who gave a breakthrough step toward our quantum understanding of dispersion. In order to understand Ladenburg’s step, I analyze Ladenburg’s experimental work on dispersion prior to 1913, the reasons why the first theories of dispersion after 1913 were not satisfactory, and Ladenburg’s 1921 proposal. I argue that Ladenburg’s early experimental work on dispersion is indispensable to understand his 1921 paper. The specific kind of experiments he performed before 1913, the related interpretative problems, and the way he tried to solve them, led him reapproach the dispersion problem in 1921 in a way that was completely different from the way theoretical physicists had done it before.

One model, the resonance model, shaped scientific understanding of optical dispersion from the early 1870s to the 1920s, persisting across dramatic changes in physical conceptions of light and matter. I explore the ways in which the model was transmitted across these conceptual divides by analyzing the use of the model both in the development of theories of optical dispersion and in the interpretation of experimental data. Crucial to this analysis is the integration of the model into quantum theory because of the conceptual incompatibility between the model and quantum theory. What is more, a quantum understanding of optical dispersion set the grounds for the emergence of the first theories of quantum mechanics in 1925. A long-term history of the model’s transmission from the 1870s to the 1920s illuminates the ways in which the continuity of knowledge is possible across these discontinuities.

It is commonplace to recount the history of quantum physics on the basis of phenomena that have found no satisfactory explanation in the context of so-called classical physics. This is the case of, for example, blackbody radiation, the photoelectric effect, specific heats, and series of spectral lines. This story goes in another direction: new knowledge about quantum physics not only emerged from the need to explain new phenomena that conflicted with old theoretical structures, but also from the attempts to provide a quantum explanation of phenomena, like optical dispersion, which for a long time had found a very convincing explanation in old physical models, such as the resonance model. The boundary between classical and quantum domains of knowledge was not fixed a priori, but historically negotiated in the context of specific problems, including the problem of optical dispersion.

Se presenta una actividad docente en un entorno universitario mediante el análisis de conceptos de la Geografía Económica a través del visionado de videoclips musicales integrados en la plataforma YouTube. El alumnado (N=33) trabaja de manera grupal y colaborativamente, en sesiones presenciales y sesiones tutorizadas, seleccionando un grupo musical y una canción y analizando en profundidad la letra y las imágenes presentes en el vídeo, con el objeto de observar e intentar resolver problemáticas cotidianas. Son los propios estudiantes quienes califican la práctica. A través de un breve cuestionario los alumnos destacan la realización de un trabajo participativo, ameno, divertido y novedoso. Se observa una alta motivación de los estudiantes y la capacidad de reflexión y de debate sobre cuestiones geográficas y económicas actuales. Se sugiere un mayor seguimiento por parte del profesorado y, por tanto, una mayor dedicación de horas si se desea implementar en cursos venideros. This article shows a teaching exercise implemented at the university level through the analysis of different concepts related to Economic Geography, by the viewing of music video clips through the YouTube platform. The students (N=33) work collaboratively in teams, choosing a music band and a song and analyzing in depth its lyrics and pictures, in order to observe and try to solve everyday problems. The students themselves qualify the exercise. The evaluation is done through a brief questionnaire which highlights a participatory approach and an entertaining, dynamic and original work. A high motivation and students’ capacity for critical reflection on current geographical and economic issues are observed. It is suggested a higher follow-up of the activity and, therefore, a greater dedication of hours to be implemented in future classes.