Imogen Rivers

This paper offers a novel argument for superspace substantivalism. _Superspace_ is a modified spacetime represented formally through combining ordinary spatial dimensions with anticommuting dimensions whose coordinates are labelled in Grassmann numbers rather than real numbers. At supersymmetric worlds, physical laws exhibit _supersymmetry_—viz., a symmetry that transforms bosons into fermions and vice versa. _Superspace substantivalism_ is the thesis that, at supersymmetric worlds, among the most fundamental structures is superspace. Initially, the focus will be on a prevalent doctrine in the philosophy of physics literature which I call the _mimetic ideal_. On the mimetic ideal, interpreting physical theories aims primarily at specifying their _ontology_, namely at achieving accurate _reference_ (in natural-language accounts of those theories) or _representation_ (in model-theoretic portrayals of those theories) with respect to aspects of physical reality. However, I show that the mimetic ideal doesn’t seem able to account for important aspects of physics practice (Sect. 2 ). In Sect. 3, therefore, I articulate and defend a new, _diegetic ideal_, according to which the interpretation of physical theories should aim at _perspectival coordination_ between interpreters and practising physicists. Perspectival coordination, in the context of interpreting physical theories, means that interpreters and practising physicists share a perspective or a point of view on some aspect of physical reality described by that theory. In Sect. 4, I apply this analysis to the study of supersymmetric quantum field theories (QFTs): reframing the realist framework which underlies Baker’s (2020) agnosticism, I examine the exciting upshot that superspace substantivalism is true. I conclude with some reflections on what perspectival coordination means for realism (Sect. 5 ).