The Grateful Dead spent decades trying to unlock the many mysteries of "Dark Star," the band's best-known jam.

The lore around the famously elastic song—"Dark Star" could run anywhere from a few minutes to more than a half-hour—made it an anthem and enshrined its mystique. Decades after it was first played, Canadian composer John Oswald was inspired to make a composite of live performances of "Dark Star" that reflected the song's evolution over nearly 40 years.

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