Exploring the "dark ages" of particle physics: isospin, strangeness and the construction of physical-mathematical concepts in the pre-Standard-Model era (ca. 1950-1965)

• Applicant: Privatdozentin Dr. Arianna Borrelli
• Subject Area: History of Science
• Term: from 2013 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244764109

The project proposes a systematic investigation of knowledge production in particle physics of the 1950s and '60s, when unexpected experimental results came to be conceptualized in terms of "new" particles endowed with "new" properties, among them "isospin" and "strangeness". These and other physical-mathematical concepts later came to be embedded into the Standard Model, when it emerged in the 1970s as the first - and to date most successful - theory of particle phenomena. Since then, the pre-Standard-Model era has been regarded as a sort of "dark ages" of particle physics: a long phase of theoretical uncertainty and confusing experimental variety which ended only with the rise of the Standard Model. Aimed at a critical reassessment of this view, the project constitutes the first thorough historical analysis studying the conceptual developments of the 1950s and '60s in their own right, and not simply as a "prelude" to the Standard Model. With an innovative historical-philosophical focus on the formation of concepts rather than on the construction of theories, the project explores the dynamics of formation and development of isospin and strangeness, which has so far been dealt with only in an off-hand way. Those two new quantum numbers indeed "constituted new and empirically useful analytic tools with which to make sense of the properties of the many new particles discovered in the 1950s" (Pickering). However, the conceptualization of experimental results in terms of isospin and strangeness was no purely empirically motivated theoretical invention, but rather a complex dynamical process both driven by experimental results and stimulating new experimental research, both bearing on diverse theoretical and conceptual traditions and forming new ones at the same time. It should be carefully contextualised and explored in its relations to the practices employed both by theorists and experimentalists. Regarding the formation of concepts of isospin and strangeness as the locus of multilayered interplay of theoretical and experimental practices, the proposed project will go beyond the limits of a disciplinary history and contribute to the wider historical-philosophical discussion on the dynamics of concept formation and on the relationship of theory and experiment in modern science.

• DFG Programme: Research Grants