Johanna Wolff

Johanna Wolff (University of Hong Kong): "Spin as a Determinable". Listen to the talk here.

Abstract: To understand the ontology of quantum mechanics, it would be helpful to understand better the ontology of the quantities characteristic of quantum mechanics. The literature on quantum mechanics has, with a few exceptions, not dealt extensively with the nature of quantum mechanical quantities. Focus on quantities, instead of the traditional interpretive options, might help us to gain a new perspective on what is problematic about the ontology of quantum mechanics. Of all the quantities described by quantum mechanics, spin is perhaps the most paradigmatic; it has no analogue in classical mechanics, and it displays all the features that make quantum mechanical quantities mysterious: it is discrete and different spin components are incompatible. In my paper I would like to develop a metaphysical model of spin, with the hope that this will allow us a better understanding of the quantities in quantum mechanics in general. I will try to model spin on the distinction between determinates and determinables, which is often invoked to shed light on quantities in other areas of physics. To do so I will first describe some of the notorious features of spin, which any metaphysical model of spin needs to capture. Then I show where exactly the traditional distinction between determinables and determinates fails to be adequate for spin. Finally I explore and assess three possible ways of tweaking the determinate/determinable distinction to make it fit better with the problematic features of spin.

For the full abstract, see here.