Time Loops and World Creation

ETA: Please be mindful of spoilers in the comments.

Rather O_o sort of speculation that entered my head and demanded to be shared right now . . .

So, on reflection, my favorite thing about the Space & Time episodes for Comic Relief is the way, right at the end, that the Doctor knows his future self is going to come through the door with the information he needs to resolve the loop. This is a step up in sophistication from the time loops we've seen before--like in Time Crash or the loop that gets the Doctor out of the Pandorica--where a character essentially stumbles into a time loop and has to have it explained to them so that they can carry the rest of it out. Mechanically it works out exactly the same: a piece of information that appears seemingly out of nowhere is passed back and forth in a stable loop. But the attitude, somehow, matters immensely. It's almost like the Doctor has willed the information he needs into existence--he's not a pawn going through a loop set out for him, he's creating the loop and causing it to happen.

So the question becomes, how far could you push something like that? ( This is where it gets complicated . . . )