Dr Katherine (Katie) Mack is a theoretical cosmologist. Her work focuses on finding new ways to learn about the early universe and fundamental physics using astronomical observations, probing the building blocks of nature by examining the cosmos on the largest scales. Throughout her career as a researcher at Caltech, Princeton, Cambridge, and now University of Melbourne, she has studied dark matter, black holes, cosmic strings, and the formation of the first galaxies in the Universe. Dr Mack is also an active online science communicator and is passionate about science outreach. As a science writer, she has been published by Slate, Cosmos, Sky & Telescope, Time.com, The Economist tech blog “Babbage”, and other popular publications. She is active on Twitter as @AstroKatie and her website is www.astrokatie.com.