Endlessly quoted in television shows, advertisements and sci-fi movies, the imposing and enigmatic 2001: A Space Odyssey casts a long shadow on popular culture even as it retains an unknowability true to its subject. A space opera told in multiple movements, Kubrick’s cosmic riddle of a film polarized contemporary critics with its daring reliance on near-wordless narration, associative logic and trance-inducing visual experimentation, and these cryptic qualities have only grown in suggestive power over the half-century since its release. The film’s millennia-spanning narrative, dreamt up with Arthur C. Clarke, chronicles the events that transpire around the mysterious appearances of a black monolith that anticipates evolutionary leaps in human history and consciousness. Drawing conflict less from human squabbles than from confrontations with the unknown, Kubrick saves the film’s most indelible “character” for the potentially malicious HAL 9000 supercomputer, a harbinger of all-knowing artificial intelligence whose “visage” evocatively resembles the aperture of a camera lens.