Paul J. Steinhardt, a 2018 Simons fellow in theoretical physics, is the Albert Einstein Professor in Science at Princeton University, where he is on the faculty of both the departments of physics and of astrophysical sciences. He is also co-founder and director of the Princeton Center for Theoretical Science. He is a fellow in the American Physical Society and the National Academy of Sciences and has received many prestigious awards, including the 2010 Oliver E. Buckley prize of the American Physical Society. Besides his work in cosmology, Steinhardt also devised the theoretical concept of quasicrystals before they were synthesized in a laboratory, and he helped guide the team that discovered three natural quasicrystals. His latest book, “The Second Kind of Impossible: The Extraordinary Quest for a New Form of Matter,” was published in January 2019.