James Owen Weatherall (Irvine): “On Stuff: The Field Concept in Classical Physics”

Discussions of physical ontology often come down to two basic options. Either the basic physical entities are particles, or else they are fields. I will argue that, in fact, it is not at all clear what it would mean to say that the world consists of fields. Speaking classically (i.e., non-quantum-ly), there are many different sorts of thing that go by the name “field”, each with different representational roles. Even among those that have some claim to being “fundamental” in the appropriate sense, it does not seem that a single interpretational strategy could apply in all cases. I will end by suggesting that standard strategies for constructing quantum theories of fields are not sensitive to the different roles that “fields” can play in classical physics, which adds a further difficulty to interpreting quantum field theory. Along the way, I will say something about an old debate in the foundations of relativity theory, concerning whether the spacetime metric is a “geometrical” or “physical” field. The view I will defend is that the metric is much like the electromagnetic field: geometrical!