Is that hysterical laughter? And are those accelerated heartbeats the phantasmagoric echoes of Chile, circa 1973? These sounds are not leaking into the Museo Nacional de Bellas Artes but are rather the reverberations of an album released that same year: Pink Floyd’s The Dark Side of the Moon, which plays on a loop in this exhibition of works made by Alfredo Jaar between 1974 and ’81. Jaar was seventeen when General Pinochet’s coup d’état tore his country apart, and the young artist sought refuge in this soundtrack of madness and despair. Pink Floyd’s front-man and lyricist Roger Waters last year released The Dark Side of the Moon Redux, a “reimagining” of the album from which this retrospective takes its title. Where he chose to replace David Gilmour’s guitar solos with homiletic spoken word, curator Pablo Chiuminatto has gone the other way. Rather than over-explain, Chiuminatto’s approach offers little contextualization or research for Jaar’s early works, which mark a turning point in the career of one of Latin America’s most significant artists. The restrained curation lends the show a provisional feel, an analysis of sketches by an obsessive apprentice. These range from Jaar’s initial experiments with dry-transfer lettering methods, such …