I'm still confused about the part where Elizabeth pull Booker to the future, showed him what she became and gave young Liz advice on how not to become her. From my understanding, the story of Bioshock Infinite has been in a time loop for a very long time. Each time there are factors that always remain constant, e.g., the flipping of the coin. And there are variables with all those player choice and other one off things.

My question, Is old Liz giving advice to young Liz a constant or a variable within the loop? Without her advice, Booker and Liz wouldn't be able to destroy Cyphen(sp) and the SongBird would have stopped them from accomplishing their goal.

Another confusion, Comstock knew Booker will kill him and deliberately pissed him to off to make sure it happens. What does that accomplish? From the little research I did, it seem to be a common factor that everyone agrees on. Booker killing Comstock is leading him to become Comstock. But the ending of the game specifically mentions that Booker becomes Comstock when he accepted his baptism to erase his sin from the indian/chinese wars.

Edit: one more question. What is suppose to happen if everything went according to Comstock plan after he's dead?

Sorry for the bad writing, English is not my 1st language and all these dimension tearing is making me fussy.

There are no loops. There only only branching paths. Old Liz wanted young Liz to take a different path.

Edit: Comstock's plan was for Elizabeth to take over Columbia and bring judgement on the world below just like you see in the 1984 scene with old Elizabeth. What Comstock didn't understand was that the visions of the future he witnessed due to Lutece's inventions were not set in stone, the Comstock you kill on the airship died believing what he had seen would still come to pass. In a recording Lutece mentions that Comstock had confused probability with prophecy.

It's also not a time loop. It's infinite universes. She can travel across space and time through the tears so it's not always at the same time in each universe.

@doe3879: Comstock didn't want to be killed by Booker so Booker would become him. Comstock saw that he would die, and that his death would be a catalyst that caused Elizabeth to become his successor. He saw this by looking into alternate universes through tears. He didn't mind dying because he was already riddled with cancer, and felt comfort knowing his legacy would continue on. He thought once Elizabeth discovered who Booker was, she would turn away from him and see man for the terrible thing it is.

Old Elizabeth giving that Songbird info was a variable, and it was the one that allowed them to take a different path, because it allowed them to destroy the sipher and give Booker the opportunity to attone, leading to his sacrifice.

Actually, it was a loop. Despite minute changes in choices you make, the beginning of the game was the beginning of a new loop (Liz throwing Booker B into the tear). They show you this at the end. Also ouranou, you could consider the Old Liz path to be a "bad end" as from Booker's perspective, he goes back soon after to the same universe where he lost Liz. Consider that dialogue from old Liz to be an necessary component to the loop. It will happen every time, so that young Liz eventually throws another Booker that didn't get baptized into a tear where he'll lose his memory. Yes, it was in another universe where Liz blows up NYC, but that's not part of the loop. The choices that Booker makes throughout the game hardly affect anything in terms of the ending, so I think that old Liz is a constant, but the burned NYC still happened in another universe, or another possibility.