Do not read this unless you have read "The Philosophy of Time Travel"
The Artifact (in this case a jet engine) Provides the first sign that the Tangent Universe has happened. (fyi, it was made of metal!)
Donnie somehow got ouside of God's path by sleepwalking and escaping death. The cause of his sleepwalking: becoming the Living Reciever. Sleepwalking is one of the side effects of being the Living Reciever. Other side effects are increased strength, telekinesis, mind control, and the ability to conjure fire and water. Donnie knew what he had become, which is why he had the creepy smirk. (Note how Gretchan says "Donnie Darko? What kind of name is that? It sounds like the name of a superhero." Then Donnie says "what makes you think I'm not?)
He became the Living Reciever by escaping God's path. So which came first? This one event had no single cause to it. (Debating it loops continously)
The Philosophy of Time Travel states:
"The primary universe is fraught with great peril. War, plague, famine and natural disaster are common. Death comes to us all.
The Fourth Dimension of Time is a stable construct, though it is not impenetrable.
Incidents when the fabric of the fourth dime(n)sion becomes corrupted are incredibly rare.
If a Tangent Universe occurs, it will be highly unstable, sustaining itself for no longer than several weeks.
Eventually it will collapse upon itself, forming a black hole within the Primary Universe capable of destroying all existence."
So if Donnie were not to return the Artifact in time, both universes would be destroyed all life would end. When Frank said the world would end, he didn't mean the universe would end. He said the world as we know it would end. We only know the world as far as we can conciously experiance. If we are dead, we cannot conciously experiance the world. If you die, the world (for you)ends.
the moment he escaped death, one member of the Manipulated Living (Frank) tells him when the Tangent Universe in which he has just created (by escaping God's path) will end.
In the Tangent Universe, every person associated becomes the Manipulated Living. Metal is the transitional element of time travel. The Manipulated Living caused events which point the Living Reciever to bring the metal (jet engine) back to its original universe, thus creating a new time portal back to the last event of Go'd original path before the Tangent Universe was created.
Every event that happened had a purpose. The Manipulated Dead have the ability to set traps for the Living Reciever, which lead him to bring the Artifact back into the Primary Univers (God's destined present/future)
Frank was a Manipulated Dead, he set a trap for the Living Reciever(Donnie) so he could complete his mission. This was Frank's trap:
He purposly ran over Gretchan, because Gretchan was the only thing he cared about in this world. Frank knew it would make Donnie angry, so that Donnie would kill Frank. Since Donnie killed Frank, he was going to prison, and he knew that.
That way, Donnie would have even more inclination to return the artifact to the Primary Universe, because if he didn't, not only would the world(s) end, but Donnie would die alone in prison. So Donnie had no choice but to use his Fourth Dimensional Power to send the Artifact back into the Primary Universe, and make all things begin at where God's plan left off. That was Frank's trap.
All the Manipulated Living wake up in the end, when they are no longer living in the Tangent Universe, but in the Primary Universe. They are crying because they portrayed everything that actually happened in the Tangent Universe to be a dream. All the irrational, and bizzare behavior they took part in for a purpose, disturbed them in their dreams. This is why they cried. (Jim Cunningham, Gym Teacher, etc.)
So this Tangent Universe was comparable to, say, a rabbit cage. like an inclosed yet false(not in God's plan) environment.
All the people in the environment(Tangent Universe), are comparible to, say, rabbits.
Frank was a rabbit acting like a human.
All the humans were humans acting like "rabbits" metaphorically speaking.
This is why in the movie theatre, Donnie asks Frank, "Why are you wearing that stupid bunnie suit?" Frank then replies, "Why are you wearing that stupid man suit?
Cellar Door: What it stood for was that the most artistic, beutiful thing can be "ugly"(cellar door), but the beauty behind it is that it is art. It had no meaning. The beauty of its exsistence having no meaning at all can be...beautiful. The english teacher(Manipulated Living) writing it on the board was another act to guide donnie into returning the Arifact. It made Donnie open the cellar door to Roberta Sparrow's house, so that he and Gretchen would be in a dark place. This dark place would be a good place for them to get "mugged" by that highschool punk kid. This event led to Gretchen being thrown into the middle of the road, which led to Frank killing her, which was the beginnig of Frank's plot in the first place.
How did Donnie get the axe in the Middlesex High statue made of pure bronze? Controlling metal is one of the powers a Living Reciever has.
Also notice how he used water to flood the school. Just a thought.
The fat guy in the orange suit seemed very random at first glance. Its not. If you watch carfully, the fat guy in the orange suit is also one of the FAA agents from the beginning (at the scene of the jet engine). The FAA are following Donnie Darko around.
Donnie Darko is a movie full of metaphorical meaning, some not contributing to the plot.(humans/bunnies, vice versa)
Did that explain the story better or am I completly wrong here?