Echoing what Cleretic said here. It's also worth noting that, unless you are going to spend significant time exploring this in active storytelling, it may not be worth getting caught up in the weeds around it. Tripped and fell through a rift is as valid and useful as a twelve page treatise on how a Ronkan Mystic opened a portal through the void to slingshot you past the 13th into the Source if it's just going to be a bullet point in your character's background.