Glossary
Primary Universe
The universe we ordinarily live in. In Donnie Darko it is the timeline in which the jet engine falls on October 2, 1988 and kills Donnie in his bed.
Sparrow describes the Primary Universe as "fraught with great peril" - the ordinary world of war, plague, famine and death. It is also the only universe that is meant to persist: when a Tangent Universe branches off it, the Living Receiver's task is to restore the Primary Universe by returning the Artifact.
The film shows the Primary Universe only in its first minutes and its last. Everything between the jet engine falling and the storm over Middlesex takes place in the Tangent Universe.
Defined in The Philosophy of Time Travel