Okay, here is what I gather: he uses the storm to go through a portal/wormhole, back in time to his bed. And I've heard it theorized that Donnie, as a "manipulated living" (manipulated by Frank), has the power of telekinesis, which he uses to rip the engine from the plane and kill himself.
What I don't get is, where does this plane come from, if we're now in the past? Does he summon it from the tangent universe? (Meaning, as our present reality marches on, so do alternate realities, like the one in which Donnie doesn't die and his mom and sister are on the plane.)
In Roberta Sparrow's book, it says there is no choice but to return the artifact back to the primary universe. If so, doesn't that change Donnie's reception as a savior? He had no choice but to send the engine back to the primary universe...right? But did he still have the choice of whether or not to leave his bedroom? He had a little time; when he was laughing, he could have left, and saved himself. So maybe he still is a hero? But then, there wouldn't have been anyone to save if he could have left his room, because he wouldn't have had any Frank interactions, right?
Man, this movie makes my head spin! Can anyone help?
Quite agree. The engine landing on the house appears to be part of a sort of "loop" in time. And it can be easily seen as a paradox. That said....what Donnie changed was his participation in events, not events he had nothing to do with. He had the power of choice over that, but over nothing more.