A good scientific theory is not just stated in a small number of words, but is unbendingly precise. Once you're inside a branch, the thickness of the branch is completely unobservable to you. The idea of thickness and thinness is only relevant when we're comparing different branches from some kind of god's eye view. But that's exactly what we're doing when we're talking about a branch where the not sees one rollor right imean, we're not in that branch. It doesn't mean it's true, but the theories have ben very successful. Always have that form, so far.