There are thousands of books on the subject, but what do we actually know about creativity? In this new series, we talk to the researchers who study it as well as artists, inventors, and pathbreakers who live it every day: Ai Weiwei, James Dyson, Elvis Costello, Jennifer Egan, Rosanne Cash, Wynton Marsalis, Maira Kalman, and more. (Ep. 1 of the “How to Be Creative” series.)