My research interests focus on cosmic magnetism, time-domain astrophysics and interstellar gas. My main goal is to understand why the Universe is magnetic: in particular, I am using the unique capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) to conduct the Polarisation Sky Survey of the Universe's Magnetism (POSSUM). POSSUM is based around an effect called "Faraday rotation", in which light from a background object is subtly changed when it passes through a cloud of magnetized gas. By measuring the Faraday rotation in the emission from a million distant galaxies over 50% of the sky, POSSUM aims to transform our understanding of magnetic fields in galaxies, clusters and in diffuse intergalactic gas, and to thus address key unanswered questions on Milky Way ecology, galaxy evolution and cosmology. The data from POSSUM will provide a substantial legacy to the astronomical community, while the new instrumentation required for this project is prototyping the technology needed for the Square Kilometre Array.