Observing Symmetries in Physics

Abstract

There is a debate about whether so-called local symmetries in physics have direct empirical consequences. In this paper I defend the orthodoxy according to which they don’t against a recent argument by Hilary Greaves and David Wallace. In the course of doing so I will first explain what physical symmetries are, emphasising the distinction between transformations of representations and transformations of physical systems, and then the differences between various kinds of symmetry. I will then explicate the nature of so-called ‘Galileo’s Ship Scenarios’, and go on to argue that that so far it has not been shown that there are any that are only explicable by local symmetries.