Program

15.00h: Robert van Leeuwen, University of Amsterdam

String theorists and reality (1968-1989)

Between the late 1960s and the late 1980s, the field of theoretical particle physics transformed from an experimentally-oriented enterprise into a highly mathematical practice that was prominently concerned with the construction of a unified theory of all forces via the study of string theory. By considering the history of string theory, I present an account of this transformation. To achieve this, my account balances between formal progress at the level of tools and methods, and shifts in legitimations and interpretational stances. I identify a long-term trend in particle theory, from an empiricist undertaking in the 1960s, via the establishment of the so-called Standard Model of particle physics in the 1970s, to a practice of unification physics that was motivated by realist notions of unification and explanation. With the rise of string theory in the mid-1980s, this trend was consolidated in a new way of doing physics, grounded, I argue, in a broad (implicit) stance of mathematical realism.

16.00h: Giora Hon, Senior Vossius Fellow & University of Haifa

Unpacking “For reasons of symmetry”: Rules of Inference in Symmetry Arguments

Hermann Weyl (1952) succeeded in presenting a consistent over-arching analysis that accounts for symmetry in (1) material artifacts, (2) natural phenomena, and (3) physical theories. Weyl showed that group theory is the underlying mathematical structure for symmetry in all three domains. But in this study Weyl did not include appeals to symmetry arguments which, for example, Einstein expressed on several occasions as “for reasons of symmetry” [wegen der Symmetrie; aus Symmetrie-gründen]. An argument typically takes the form of a set of premises and rules of inference that lead to a conclusion. Symmetry may enter an argument both in the premises and the rules of inference, and the resulting conclusion may also exhibit symmetrical properties. Taking our cue from Pierre Curie (1894), we distinguish two categories of symmetry arguments, axiomatic and heuristic; they will be defined and then illustrated by historical cases.