>>282340160 (OP)
Okay, now I have time. So I personally think the "quantum Rei" is actually Rei's soul in between her swapping bodies after her deaths. This is because the quantum mechanic writings are in her room, and in the same scene we're told that her soul instinctively returns there, with the bodies being just spare parts with Rei's soul just "possessing" them after being left in that room. That's why I think she's shown as a sort of mirage that only appears there for a moment, it was just her soul. Hell, perhaps it wasn't really a vision, and it was meant to be evocative of Shinji feeling "I felt like there was someone there, and I'll eventually match that presence to Ayanami". I don't think Rei actually time travels. That's not even getting into the deterministic idea that if she exists in many places at once, including a point we see as the future and another in its past, it means that future has to exist at the same time as the past which means the past can't be changed, because it already occurred that way in the future, and this logic could be used for any point in the timeline to prove we can't change the past.
On a metanarrative sense, Rei is clearly based on someone with heavy dissociation, with depersonalization/derealization, dissociative amnesia, etc. The feeling of being an observer with an impassable wall between you and your surroundings, including your body, is pretty huge in it, and I always got that feeling from scenes like that one in the first episode. She's always shown with a great deal of disconnection, I think it really works.
Before you call me an armchair psychologist Eva has a ton of psychology stuff in it, especially psychoanalysis. Also I go to a really good psychologist and he's an Eva fan and told me its obvious Rei is based on someone like me, because I used her monologue to explain how I felt..
Thanks for the cute Reifag thread shame it didn't get much attention.