Potential paradox with the Big Rip and the Multiverse?
I don't know whether this is a real paradox. Infinities are tricky :) For example, we don't have just one infinity. Also, our knowledge about the universe is too narrow too understand the system of our universe (or multiverse) and we can only imagine the universes as some balls which are expanding into some other space = multiverse. If multiverse exists, it is probably not some space with some balls in it. There are a lot of dimensions that are present in here.
So, this isn't a paradox: we shouldn't think about the universes as some physical objects expanding. But we also don't know what to imagine. We just haven't figured it out. But it is probably a lot different from our current physics, math and imagination.