Saxophonist and composer John Zorn may have just won a $500,000 MacArthur fellowship, but he started out as a rebel in the 1970s and transformed New York’s downtown music scene. Since then, he’s led a hardcore band, a jazz quartet and a chamber ensemble, and he founded a record label to promote hundreds of underappreciated musicians. Kurt Andersen talks with WNYC’s John Schaefer about Zorn and why he’s MacArthur-worthy.