Composed in the mid-’70s on GROOVE, a primitive computer-music application, Laurie Spiegel’s The Expanding Universe is a landmark of electronic composition. Sixties minimalism is an obvious influence on the New York composer’s chiming overtones and intricate counterpoints, but so are her experiences playing mandolin and banjo as a child—not for nothing is the album’s sparkling centerpiece titled “Appalachian Grove.” Ambient before there was a name for it, and an early example of real-time electronic performance, it’s a groundbreaking work; unlike some products of the avant-garde, it’s also immediately welcoming—a warm wash of consonant tones and lush textures. “Kepler’s Harmony of the Worlds” was included on the Golden Record onboard the Voyager spacecraft that’s currently hurtling through the cosmos—proof that Earth’s intelligent life also possesses rare emotional depth.