A case could be made for Mickey Hart as the coolest musician in the Grateful Dead. He was the only member committed to authentically experimental side pursuits during the Dead's creatively lean stadium years, making field recordings, albums of droning prayer bowls and babies' heartbeats, and radio operas about talking bugs. But maybe he's also the uncoolest, as he was responsible, somehow, for the drum circles that rippled from the parking lots and the Quaalude tom-tom thunder that defined the Dead at their most sluggish. New Age jam-band aesthetics aside, Hart is 68 and blindingly enthusiastic; seeing him and his new band might be fun. —Jesse Jarnow