What song is sung together by Natalie and Diana in Act 2, Scene 1? What does it reveal?

Electrodes are placed on her head, music begins, and suddenly the real Diana appears, describing her experience in song (an intermittently edgy rock tune, "Wish I Were Here"). As Diana sings, Natalie joins her, both singing of the intensity of an experience for which they're not really there. They speak to each other, talking about how "everything is different now."