No, conservation of mass is very important, it's just a
Universal law, not a 3 dimensional law.
Why don't we observe it being broken? It's entirely possible we do observe it being broken, we just don't know what to look for. Who knows.
Oh, and I thought the whole alternate universes thing is *very* fuzzy science.
It is, i could be completely and totally wrong. And we could be the only living creatures in the entire Universe; both hypothesis (and many more besides) are entirely possible.
It does, however, make
logical sense that there are at least 10 dimensions (or 9 and a bit dimensions depending on how you look at it), based on extrapolating upwards from the 3 we work with. That doesn't really mean a whole lot, but it counts for
something.
Also; Quantum Entanglement gleefully breaks causality in half, and while it's not quite as solid a theory as, say Gravity, as theories go Quantum Entanglement is pretty good and it has a rather surprising amount of evidence backing it up, with more accrueing each day. You wouldn't
believe the hoops some people are jumping through to try and prove that Quatum Entanglement doesn't violate causality after all. Retrocausality is my favorite
It's probably also pertinent to point out that what appears to be breaking causality from a 3 dimensional standpoint may not neccessarily be breaking causality from a 9 dimensional one. In this respect, causality is a theory that requires 3 spatial dimensions and 1 temporal dimension, if you have more than 1 linear temporal dimension, causality becomes kind of, well not moot, but complicated.