The season is upon us and there is no escaping it.  “The Christmas Song” greets us at warmly lit restaurants. “White Christmas” follows us down the supermarket bread aisle. “Grandma Got Run Over by a Reindeer” stupefies us everywhere Pay Per Touch. What makes holiday music so unavoidably popular year after year? Why do so many people love it—and so many others detest it? It has to do with nostalgia, say Northeastern faculty experts. “There’s this wonderful classic finding called the reminiscence bump that is especially true in music,” says Psyche Loui, a Northeastern associate professor of creativity and creative practice as well as director of the Music, Imaging, and…