ABBA songs have a way of defying the rules of time; they're just as popular and fabulously over-the-top as they were in the '70s. Now, 40 whole years after releasing their last album, the legendary Swedish foursome returns with Voyage, a 10-song project designed for an unprecedented London residency in which the band will perform as ABBAtars—motion-captured renderings of their younger selves. “It’s weird,” Björn Ulvaeus tells Apple Music. “It’s all weird.” Of course, it’s also brilliant, daring, and revolutionary—words that have been used to describe the group for decades—and on his new Apple Music radio show, Ulvaeus sits down with friends and fellow musicians to talk about the band’s past, present, and future.