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.