All universes exist in the same space.
If the term is "universe", meaning all in one, then there must be a means by which to differentiate this "verse" from another,
if there are alternatives to this one. That is pure logic in physics, because no two objects can occupy the same "space" at the same time, no one "verse/sphere" can be in the same juxtuposition as another at the same moment...which leads me to the loop hole.
Time.
Or more precisely, "phased time". Since time can be micro as well as macro in scope, and since there isn't enough band width to consider the whole of time here, let's focus on
one second in time (which is very coarse in precision even for linear thinking), and it's potential for infinite "verses/spheres" of existence:
Here is me, now, in this existence and continuim. I occupy this "space" while typing this post, and time continues as I do so (linear time). If another of "ME" attempted to occupy the exact same position I am now in as I type this, trying to do the exact same thing I am doing were to appear...there would be hell to pay according to the laws of physics.
I would be annhialiated (as well as a sizable chunk of the earth supporting me phyisically. BUT...if another "ME" were to be one half second out of phase with me and my time (linear), then there would be no problem, and no awareness by the two "MEs" of eachother, and we obliviously continue to happily occupy the same exact "universe" or "space".
Unfortunately, the converse is not true (or maybe fortunate after all and an insight into the design of physical space and time). This would satisfy the conclusion that "space" is limited, yet allow for the "Multi" in "verses/spheres" ad infinitum, because "time" is not limited. Just modify the phase of time with the same space, and one has a whole new playground to grow up in...
Now, the potential for "slipping" from one "multiverse" to another is possible, but only under stringent conditions. Plus, once done, there is an upset in the overall balance of time/space, that eventually must be reconciled. And I still could not meet (touch), the other version of myself, even if we did end up in the same room (in his world or mine). And one more thing. If I were designed for this particular "time" and space, and suddenly found myself in a phased version of my space (my time being off), I think that would cause me physically, a great deal of discomfort (rhythmically), if not my eventual life..."out of my element" appears to take on a whole new aggradenza, or warning...
We are not talking about time travel here (though that does come into play and would have been affected by leaving one's here and now), but rather time at this moment, phased or off slightly from what we are set up for.
In a nut shell, If I am here and exist at 2.4 ghz frequency, and another version of me is here and exists at 2.3 ghz frequency, all is well.
If for some reason I drop to 2.3 ghz frequency (slip out of my time stream), I best not be sitting in the seat I currently occupy, nor in the vicinity of the "me" that is sitting in a similar seat in the "universe".
My opinion is that whoever is watching "time" is very very good at it.
v/r
Q/Q/Q/Q...(lol)