It's not a perfect vacuum because it's not a vacuum at all and never will be.
Again, by definition it is.
You ignoring that fact does not change that fact.
It is significantly below atmospheric pressure and thus a vacuum.
What does m mostly empty space mean?
Describe it.
The picture below describes it quite well.
But it can be described in two simple ways (maybe more).
1 - space which is mostly empty. It has a small number of particles in it with large distances between these particles (i.e. must larger than the particle size).
2 - Space which can have a lot more put into it without removing anything, or alternatively, which can be compressed to a much smaller volume without removing anything.
The second one removes any ambiguity due to your magic air piece nonsense.
You cannot compress liquids or solids to any appreciable extent. You would need to provide enough pressure to start nuclear fusion to make it denser.
However, you can easily compress gasses.
In fact, gasses follow the relation PV=C, i.e. the pressure times the volume is a constant, assuming you keep the temperature constant and don't have issues with vapour pressure.
Liquids and solids more closely approximate V=C, i.e. regardless of the pressure the volume is constant.
This forms a simple discontinuity where by continually pressurising something selling it in converting to a liquid indicates that it is full.
This is another problem with your denspressure nonsense.
Your magic air pieces should continue compressing even as a liquid, but they don't.
This is more evidence in favour of mainstream science, where molecules have a real physical size and gasses are molecules flying around.
It's full of something other than marbles, can you guess what?
No it isn't.
The fact that the marbles are there taking up space shows it can't be full of any one thing.
Regardless, a large potion is empty space.
If the void was full of air, it would have liquid or solid air in it.
I have no clue how in the hell you came to this thought.
That was explained before. If you were paying attention you would easily understand.
If I take a container, that is "full" of air, it isn't full, because it can easily have more in there.
Here I'll explain some more.
Instead of it being full I can compress the air either by putting more air in or reducing the volume.
While it is a gas, I can continue to do this.
If I do it enough, the gas liquefies, i.e. becomes a liquid. At this point, I can no longer compress it any more.
Because that's how much atmosphere is crushed up from the porosity of the mercury.
But you can start with different volumes of mercury which would thus have a different amount of air.
Meanwhile, (again doing something you hate) if you compare it to another substance, like water, which would have a much larger amount of trapped air, the void is smaller.
So that clearly isn't the case.
If you wish to disagree, provide an explanation that is consistent with these facts.
Stacked atmosphere tells me all I need to know. Evacuation chambers are a clear example of how I know what we are under.
I've explained it all so look it up.
You "explained" it based upon how they would allegedly work under your model. That doesn't show your model is correct.