Clock is now set at six minutes to midnight , Chicago-based group says . Comment: Doomsday Clock had been adjusted only 18 times before Thursday . Farthest was 17 minutes after the signing of the Strategic Arms Reduction Treaty .
Clock is now set at six minutes to midnight , Chicago-based group says . Midnight represents a nuclear apocalypse . Doomsday Clock had been adjusted only 18 times before Thursday . Farthest was 17 minutes after the signing of the Strategic Arms Reduction Treaty .