Bridges between theories: Paul Ehrenfest and his struggle to clarify the quantum hypothesis and its consequences

Abstract

In the origins of quantum physics, in the early 20th century, assimilation and maturity of the new theories required the establishment of linkages with their predecessors, before getting rid of them and being able to form a new all-embracing structure of understanding in the discipline. In this paper we analyze the role played by Paul Ehrenfest in a part of that process. In the first part we highlight the parallelism of his work with that of Niels Bohr showing how the combined work of both allows us to argue in support of the conceptual continuity in the development of scientific theories. However, we also show that such continuity has its limits. In our case of study we use the analysis that Albert Einstein and Paul Ehrenfest made of the Stern-Gerlach experiment to show that, in a revolution of knowledge, in the end new paradigms appear with which the new theories finally emerge from the earlier.