Arne Schirrmacher, Humboldt University, Germany
Models at an Exhibition. The Planetary Atom on Display in Europe and What this Meant for Science

As far as it is known, Bohr himself only produced more or less schematic drawings of his atomic model, which can be found in his notes, letters and manuscripts or which have been produced for him to be used in his lectures. Others, however, in particular in Germany and Britain built real three-dimensional physical models, which found their way into prominent museums and big exhibitions. My talks reconstructs the trajectories Bohr's ideas took in disciplinary and popular spaces and analyzes the motivations for physicists like Arnold Sommerfeld, Wolfgang Pauli, Lawrence Henry Bragg or Douglas Hartree to step out of modest theory into proposals of atomic iconography. Unlike later objects that were directly manufactured for schools or museums the early physical wood-and-brass interpretations were part of a process of scientific reflection and interpretation of Bohr's atomic model, and a epistemological means to extend his findings in order to explain problems like shape, bonding and stability of atoms and molecules. In this way they represented procedures of approximation, computational strategies as well as descriptive vocabulary in the same way as they provided a popular image of modern physics. This peculiar spell they exerted on many viewers, even physicists could not evade. Lawrence Bragg noted on a visit of Bohr at the London Science Museum in 1946, where models of the early 1920s were still on display, that he “even found Bohr himself gazing at them in a fascinated way ...”