Descripción

Pablo Ruiz de Olano (Notre Dame)

Abstract

During the 1950s and 1960s, particle physicists took decisive steps towards developing what is now known as the Standard Model of Particle Physicsts. As it is commonly agreed, symmetries and conservation laws played a crucial role in this achievement. In spite of this, however, there is still a relative scarcity of works explaning how exactly symmetries and conservation laws were used during these two decades, and why they were so useful in producing successful theories of elementary particle physics. In this paper, I attempt to accomplish two different things. First, I provide a case-study documenting the various ways in which symmetries and conservation laws were as a matter of historical fact used during the 50s and 60s, in order to develop a theory for the strong nuclear interaction. The case-study covers the years between 1955 and 1964, and focuses on two different approaches championed by Murray Gell-Mann and Julian Schwinger on the one hand, and Tsung Dao Lee and Chen Ning Yang on the other hand. Secondly, I make a philosophical claim about the manner in which the particle physics community evaluated these two research programs. My claim is, in particular, that decisions about the relative merits of the two approaches were made by appealing to a small number of epistemic values, which include the epistemic values of empirical adequacy, fruitfulness, and consistency with other accepted theories. I conclude with some remarks about what this second claim entails for the question of why is it that symmetries and conservation laws proved so useful in guiding research during the early history of particle physics.