The long-running series in which readers answer other readers’ questions on subjects ranging from trivial flights of fancy to profound scientific and philosophical concepts If an alien landed and asked you: “What is this thing you call music?” what would you play for them? And why? Heather, Kent Post your answers (and new questions) below or send them to nq@theguardian.com . A selection will be published next Sunday. Due to a production error, a new Notes & Queries question was not published on