Quantum mechanics can be described by a set of postulates. (Sometimes five, sometimes four. It depends how you write them.)
In the "standard" Interpretation, one of these postulates invokes something called "state collapse".
MWI can be described by the same set of postulates without doing that.
When you have two theories that describe the same data, the simpler one is usually the right one.
This falls under 1) above, and is also covered here below. Was there something new you wanted to convey?
This is for anyone in the LessWrong community who has made at least some effort to read the sequences and follow along, but is still confused on some point, and is perhaps feeling a bit embarrassed. Here, newbies and not-so-newbies are free to ask very basic but still relevant questions with the understanding that the answers are probably somewhere in the sequences. Similarly, LessWrong tends to presume a rather high threshold for understanding science and technology. Relevant questions in those areas are welcome as well. Anyone who chooses to respond should respectfully guide the questioner to a helpful resource, and questioners should be appropriately grateful. Good faith should be presumed on both sides, unless and until it is shown to be absent. If a questioner is not sure whether a question is relevant, ask it, and also ask if it's relevant.