The definition of a physical "void" is only meaningful in relation to the Universe we exist it. You can not ask how our Universe can exist within another "void" when the thing you are asking about is outside of our Universe (terms become undefined).
Well, first let me make one distinction: you most certainly can ask. You can always ask.
In any case, that's precisely why I was asking. I wanted to clarify and make sure there were no prevailing theories about what might exist beyond our universe. I'm not implying that anything does; in fact, I'm personally inclined to believe the opposite. As you said, terms become undefined.
There probably can't be an "absolute" void in our Universe because at any given moment a photon may be passing through the area, and there is always some curvature even if it is minute.
Good news for my hypotheses.
I have no idea. Nor does anyone else, despite claims to the contrary.
I was only looking for ideas, I'm not disappointed to hear that it's currently unknown.
It is localized and entirely self-sufficient, but is not contained within itself.
When I say contained within itself, I mean to say that all of its mass and energy have been conserved since "time" began, and that its influence is contained within the local space it created.
If that's not the case, then I'm curious to hear what is.
There is no "out there". The very idea is simply a consequence of our brains trying to apply localized perceptions and dimensionality to a system it is not equipped to deal with.
Maybe. Maybe not. Either way, I agree with you.
And I'm hesitant to say this, but my current understanding of "out there" is somewhat like a video game engine. With additive geometry, you add something to a negative space. To function properly, it generally must be a closed system (or anomalies occur). Bringing this concept into a real-life context, I view the universe as a relative "positive" volume in "negative" space with the distinction that the "negative" space isn't actually there.
When the "positive" volume (the universe) was "added" into the negative space, it created its own field of influence and essentially defined its own boundaries, beyond which lie only a curvature the wraps around itself. The "negative" space is as you succinctly stated, a consequence of localized concepts of dimentionality.
And honestly... to take it a step further, my hypotheses include the premise that the universe is "contained" within an electromagnetic field -- the aforementioned curvature. This field was created at the beginning of "time" at the "origin", when high-energy photon interaction produced a surplus of quark-antiquark and lepton-antilepton pairs. These pairs, all massive, are the constituents of matter and were created from light (the photon) itself as the universe expanded in all directions at -- you guessed it -- its own speed.
This means that all matter and energy are "contained" -- beyond the point which photon waves permeate, "negative" space begins. To survive, the universe will have had to produce an electromagnetic field to a) provide a "barrier" from "negative" space, and b) act as an oscillating field for charged particles to maneuver in or, I imagine, it would have "died" -- collapsed or simply "fizzle" out.
With the presence of photons (and gluons) and massive particles clocking in at less than one trillionth of a second after the "Big Bang", the conditions for this field to exist are mostly satisfied.