## Research

###### Summary

In modern physics, almost everything about the nature and behaviour of matter can be inferred from claims about the symmetries of the world. For example, recent breakthroughs in the discovery of new elementary particle kinds are almost entirely due to claims about symmetries. This raises an intriguing metaphysical vision according to which the symmetries of the world are fundamental, whereas the material constituents of the world are ontologically derivative of them.

My current research develops a general framework for a metaphysics of modern physics that underwrites this vision: an account according to which symmetries are fundamental ontological items and which details how every non-fundamental claim about the material constituents of the world can be accounted for in terms of claims about those items. This account provides a template for an ontology for a wide range of current and future physics and explains the enormous success of symmetry techniques in the recent history of physics.

###### Publications

The Metaphysics of Invariance

Forthcoming in Studies in the History and Philosophy of Modern Physics.

Decoherent Histories of Spin Networks

Foundations of Physics (2013), Volume 43, Issue 3, pp 310-328.

[Preprint | Published Version]

###### Work in Progress

(Drafts available upon request.)

Symmetry Fundamentalism: A Case Study from Classical Physics

In which I develop an ontology for classical particle mechanics that vindicates symmetry fundamentalism, the thesis that symmetries are fundamental aspects of reality.

Symmetry Fundamentalism in Quantum Mechanics

In which I articulate a symmetry-fundamentalist ontology for non-relativistic quantum mechanics.

The Ontology of Symmetry Groups

In which I develop a metaphysics according to which the mathematical structure of a symmetry group can be captured in terms of a single four-place relation among the possible instantaneous states of the world.

Why Wavefunction Realists Should be Hilbert-Space Fundamentalists

In which I use the symmetry-based characterization of spin degrees of freedom to argue that wavefunction realists should endorse Hilbert-space fundamentalism, the thesis that there is a fundamental space whose points correspond to abstract 'kets' in a linear Hilbert space.

On the Ontological Significance of Eigenstates and Eigenvalues

In which I argue that, on every major approach to the metaphysics of non-relativistic quantum mechanics, Hermitian operators (as well as their eigenstates and eigenvalues) have ontological significance as mathematical surrogates for fundamental physical properties: the fundamental degrees of freedom of the quantum state.