I seem to recall a documentary that I watched a few years ago describing the multiverse, with M-theory, as being similar to slices of bread, all next to each other. (Obviously just an analogy for the lay person). And when these two universes next to each other collided, it would create a new universe. I'm pretty sure that it was said that this had an infinite regress, but now when I search online for any reference to a multiverse with an infinite regress, I can't find one. Are there any multiverse models with an infinite regress?