Mike Nelson’s installations are ephemeral yet loaded with memories. He erects familiar environments—drive-in cinemas, photo labs, a minicab booth—only to tear them down when the exhibition is over. Though his work is conspicuously devoid of human presence, it is often filled with objects that Nelson finds at flea markets and auctions; these impart a sense of human presence. At the Hayward Gallery, the two-time Turner prize nominee presents sculpture and installations that reflect on science fiction, politics, and our increasingly homogenized world. —E.C.