George Gershwin’s Rhapsody in Blue premiered in 1924, and many ensembles are planning anniversary performances in the coming year. One of them is the New York-based ensemble The Knights, which has commissioned a number of composers to write their own rhapsodies in tribute for a series of concerts, including their residency at Carnegie Hall. A Tempo host Rachel Katz this week chats with co-founders and artistic directors Eric and Colin Jacobsen about the initiative and the variety of composers and artists participating.