User blog comment:HandBanana345/Elizabeth Page/@comment-1396356-20140327005121/@comment-114.108.212.64-20140327134136

You must know when the author is being serious or not. Your example is within the realm of possibility, but highly unlikely. Either way, his say goes. If he gives Columbia additional background information, that info's canon. If he gives Comstock more backstory, that info's canon. If he gives a timeline of events, that info's canon. If the man leaves plot holes, we ask what's what. And if he doesn't respond, that's when it's left to interpretation

As for quantum physics, you have to look at it from a meta point of view. It's true that every action someone does splits the universe into different universes. There's a universe where Elizabeth meets Booker, and there's a universe where she doesn't meet Booker. The canon universe is the first one because it is 'prime' Elizabeth, 'our' Elizabeth. It is the universe which the viewwer/reader/player is given by the work. Whichever universe is brought to the viewer/reader/player becomes the 'prime universe'.