  Joseph:
Or, I was accurately distinguishing between that which we can know, and that which we can't possible know.
"I'll believe it when I see it" is and has often been a perfectly reasonable guide for acting in the world as it is. Or, another way of restating your point, of what use is an 'idea of infinity' within our universe, where we live and breath?
But, extrapolations of parochial logic have also often failed in the past. The world only looks flat. The Sun only looks like it circles the Earth. There is and always was a truth 'beyond our present horizon', and we have often been totally clueless about what that truth was. The honest answer about what lies beyond our present horizon at any time is 'we don't know,' and on the subject of 'an idea of infinity and beyond', of singular universe vs. manyverses vs. megaverse, that is certainly the case.
Mankind is very good at simultaneously doing two incongruous things: a] moving out our present horizon of understanding and b] being totally wrong about what lies beyond that horizon.
In what context is our finite matter, finite energy universe, the one that some(not all)claim is singularly unique? (That is, some who have never been exposed to any quantum theory...)
The very concept of 'uniqueness' demands gradient, and yet, that demands a context. (The uniqueness of 'A' requires an extreme gradient in the rate of change of 'A' wrt the context A is unique in.) And yet, 'A' can be unique, and still not be singular. If 'A' can exist in that context, then what conservative rule prohibits 'B' from being int he same context? Both 'A' and 'B' can be unique and not be singular. A=A does not negate B=B.
Draw a control volume around 'it.' In what context does that control volume exist, in which A is unique? State the obvious, 'the parochial rules of this universe prohibit observation outside of this universe.' Here is where we live and breath and act and obey our parochial traffic laws, from our definition of our Universe, all the way down to Planck lengthtime. Our horizons  in two directions  extends only so far. Bookend border guards, can venture no further from where we are, here at the center of our little universe...
Now, parochially, in our universe, we immerse ourselves daily in conservative laws; conservation of energy, conservation of mass, or transformation of one to the other; a strict accounting with no possible IPO inside of our own universe.
Now, point to me the conservational law, or any parochial True Believer Law, that authoritatively declares 'Within the context that we claim our universe exists in, there is Only One Thus, So Say We All." Then, two? Then, where the limit? If it is possible for 'one' to exist in the context of ... nothing, then what price two? three? four? ...
And yet, observationally, inside of the sand box so to speak, we observe things like 'oscillons.' Odd coherent events, matter and energy, with additive, attractive, repulsive properties, analagouus to particle interactions, but at much larger scales, vibrating media. (See, I told you this was in a sand box...) This isn't 'mysticism', this is purely observational and repeatable. Hell, my kid repeated this for his Jr High science fair project one year. These 'oscillons' behave like particles, in that sense. They attract, they repel, they combine, they split. They are long lived. They are matter/energy interacting 'events' that exist at a time scale and length scale far in excess of the vibrating media, shaking grains of sand that they are formed in. Picture a box of vibrating sand.
So, there is observational evidence of very small scale events manifesting themselves as larger scale events. A possibly never provable hypothesis is, events below Planck lengthtime can manifest themselves as events greater than Planck lengthtime via a similar phenomena, and if that is hypothetically possible, then it is possible that the very smallest subatomic particles 'in our traffic cop enforced universe' are manifestations of events smaller than Planck lengthtime 'outside of our Universe'.
And, if that is hypothetically possible, then an analogous transitional phenomena may exist without our ability to detect it at the opposite bookend scale of the universe, with our universe, itself, in the role of some other scaled universe sub 'planck lengthtime' event, manifesting in the larger scale universe only as out contribution to the smallest particles in it. Lather, rinse, repeat.
From what? From nothing. But, our parochial traffic laws don't allow that.
And yet, they do. Watch:
0 = 0
A + A = 0
Let B = A:
A + B = 0.
There you go, two (A, B) for the price of none, fully conserved.
Want to see me build four from nothing?
A + A + B + B = 0
Lather, rinse, repeat...
In fact, it can be argued, based on our own conservative rules, that the existence of 'two' is more likely than 'one', else
A = 0
A = 0 is a contradiction, unless A is uniquely 0, and yet, here we are.
A + A = 0 is not, and if two, then four, and if four, then eight, and so on ...
Why? Because in a megaverse ultimately governed by quantum rules, what can happen will happen, eventually...somewhere. Out of an infinite number of possibilities, the odd finite universe exists, because it can.
In the quantum world, the 'path' that a photon takes when a beam of light bounces off a mirror we perceive as a deterministic event, but that is not the quantum reality. The quantum reality is, every possible path  an infinite number of them, is taken simultaneously, and that which manifests itself is the most probable path in our universe.
And, from such 'ideas of infinity' , right on the frontier of that horizon of human understanding, comes the field of quantum physics and quantum mechanics, which so far, has provided the only explanation for many of the purely observational facts we see within our universe.
It only seems like magic gibberish, but so must have Kepler seemed when he was toiling at the horizon.
regards, Fred

