Katie Mack is a theoretical astrophysicist and one of the most popular scientists on Twitter, with more than 350,000 followers. Throughout her career as a researcher at Caltech, Princeton, Cambridge, Melbourne and now North Carolina State University, she has studied dark matter, black holes, cosmic strings and the formation of the first galaxies. As a science writer, she has been published by Slate, Time, and Scientific American, as well as having a regular column in Cosmos magazine. Less