Recombining DImensions

Say that in the beginning there may have been eight Universes compacted together at a particular point after their useful life spans were completed and matter was distributed to a low energy state of maximum entropy. In the gravitational compaction process eight Universes with their numerous dimensions were reduced to four irreducible dimensions compacted with mass and then energy into a singularity. If extra universes exist and they draw together with gravity sometimes, one wonders how their dimensions integrate; interesting to consider.