The whole universe being changed by the act of observation and forced to split into multiple world lines is ridiculous. It seems evident to me that the universe already exists across all those world lines, as a wave, and the only thing that is being divided into multiple world lines is the observer's state of awareness (what we sometimes refer to as its state of consciousness or, simply, consciousness).
But only the state of awareness is split. The observer still encompasses all states of awareness in those world-lines where it still extends (exists). Further, if any two of those states of awareness should ever become identical, then they are once again the SAME state of awareness. This is why the wave behavior reasserts itself as soon as the observer is not focused precisely on where the "particle" is (it's not really a particle at all, if anything the observer "particalized" their state of awareness).
You may get some understanding with a very rough metaphor by looking out at a vast forest of identical trees, then focusing on a specific tree, then looking back at the forest. Chances are when you again focus on a specific, random selected tree, it won't be the same one you had previously focused on. Ooh, quantum uncertainty!
The basis gist of all this is the observer is not changing the universe by the act of observation, the observer is changing the observer's state of awareness of the universe, and in a way relative only to the observer. This seems to explain all of it much more reasonably than anything I have ever read, and my attempts at the math (alas, I studied the wrong subjects in college) appear to support me thus far.