Hertha Sponer, Maven of Quantum Spectroscopy

          @misc{ pirsa_PIRSA:25100069,
            doi = {10.48660/25100069},
            url = {https://pirsa.org/25100069},
            author = {},
            keywords = {Quantum Foundations},
            language = {en},
            title = {Hertha Sponer, Maven of Quantum Spectroscopy},
            publisher = {Perimeter Institute},
            year = {2025},
            month = {oct},
            note = {PIRSA:25100069 see, \url{https://pirsa.org}}
          }
          

Abstract

As is well known to historians, in the early days of quantum theory James Franck frequently reported fresh experimental results to Bohr and others, on the basis of which major theoretical advances were made. These data – and indeed, the design and execution of the ground-breaking experimental work whence they came – were not, contrary to the usual assumptions, due to Franck himself. This work was done by Hertha Sponer; she was the one running the spectroscopy labs in Göttingen in these years, as well as teaching the main physics seminars in these areas. It was her experimental prowess that enabled significant insights into this new theory, and her expert instruction that guided and inspired a new generation of quantum physicists in Göttingen and beyond. Yet Sponer’s name has been nearly completely erased from this history. If she is mentioned at all it is usually as Franck’s “student” or “assistant” (of which she was neither – she was his academic equal) or as Franck’s second wife (as she was, but which entirely disregards her international standing as a scientist in her own right). Extant accounts of Sponer’s life and work are few and exclusively concern her post-WWII years as a professor of physics at Duke. But Sponer was no longer working at the cutting-edge of quantum theory in these decades, and so her role in that field’s development is left largely ignored. This talk reintroduces Sponer to the early history of quantum physics in her (arguably) rightful role, maven of quantum spectroscopy. I shall present two cases where I believe she earns this title: her early understanding and experimental confirmation of electron waves, and together with Franck first using quantum tunneling to interpret hitherto unexplained molecular phenomena.