The Stardroppers is a science fiction novel by John Brunner, originally published in 1963 as Listen, the Stars , then in revised and expanded form in 1972. It is about an undercover United Nations agent investigating a new fad, "stardropping", whereby physics-violating equipment is used to listen to sounds believed to be alien or paranormal signals. Superficially a harmless but expensive hobby, stardropping reins in a fanaticism resembling addiction, where some users assemble in semi-social communes and spend all of their money on increasingly improved equipment. The fad gains an additional aspect of risk when users begin disappearing into thin air, in cases of increasing profile and witnessing.