A Simultaneous Discovery: The Case of Johannes Stark and Antonino Lo Surdo

In 1913 the German physicist Johannes Stark (1874–1957) and the Italian physicist Antonino Lo Surdo (1880–1949)discovered virtually simultaneously and independently that hydrogen spectral lines are split into components by an external electric field. Both of their discoveries ensued from studies on the same phenomenon, the Doppler effect in canal rays, but they arose in different theoretical contexts. Stark had been working within the context of the emerging quantum theory, following a research program aimed at studying the effect of an electric field on spectral lines. Lo Surdo had been working within the context of the classical theory, and his was an accidental discovery. Both discoveries, however, played important roles in the history of physics: Starks discovery contributed to the establishment of both the old and the new quantum theories; Lo Surdos discovery led Antonio Garbasso (1871–1933)to introduce research on the quantum theory into Italian physics. Ironically, soon after their discoveries, both Stark and Lo Surdo rejected developments in modern physics and allied themselves with the political and racial programs of Hitler and Mussolini.Matteo Leone is a doctoral student in the history of science at the University of Bari, Italy;his main fields of research are the history of spectroscopy and atomic physics. Alessandro Paoletti is Curator of the Museum of the Department of Physics at the University of Genoa, Italy. Nadia Robotti is Professor of the History of Physics at the University of Genoa; her main fields of research are the history of atomic physics, the old quantum theory, and spectroscopy.