A common misconception from friends studying outside a Bsc. is the impression that our universe is expanding out in space, that space is infinite and that simply matter traverses into voids. They seem to have a hard time understand that the expanding universe is space itself expanding and that beyond the outer boundary there is no space for which to measure distance. Any help on other method to explain or conceptualize an image for them to help assist in understanding our world? Also this brings me to something I’ve been pondering regarding multiverse/parallel universe theories. Between the many theoretical universes there is no space for which to measure distance between them, so not even a meter separates them because a meter doesn’t exist beyond space. So could we say the separation between universes is zero because space isn’t defined? As we expand, do they reciprocate in time, I see it as a ripple in water I suppose. So what would be your conceptualization on this matter, when speaking multidimensional, does that regard the fact that we aren’t on the same membrane of space, so no distance is truly between us? I’m aware this is a bit amateurish but I'm here to discuss and listen.