If it's got anything in it, is it really a vacuum? Maybe Vacuum doesn't exist. As soon as you introduce something it is no longer a vacuum. A vacuum is the absence of matter , matter is defined as something of mass, a proton has mass according to the Interweb.
Even space is not true vacuum by this definition, it's got planets and stars in it and the odd molecule, atom in the spaces in between. Photons can have mass in some of the sums.
Did vacuum ever exist, if the start of the universe was a big bang, perhaps after the last cycle of everything got eaten by the black hole, there was still something that went bang and I assume it had an infinite mass.
Similarly, when we create a vacuum in a container for these experiments, at the quantum scale where is the "edge" of the container, is it indeterminate. If particles can pass through it, is it an edge at all?
I am a peasant staring wide eyed at the physic priests trying to understand their stained glass windows. I wonder how we can tell apart what's actually going on separate from the apparatus of the experiment, our methods of measurement and our own brains that have evolved to navigate a very different world with a vocabulary of words like edges, time, matter.
I guess my question is how do we know what we are observing is what is happening and is not being skewed by another variable even a neurological/psychological/philosophical feature? We’re human and we like things to have edges and be predictable, to be contained. I get an odd feeling when I deeply consider the infinite, somewhere between wonder and anxiety, perhaps it’s my brain wrestling to comprehend something it has not evolved to yet.
I guess the answer is the scientific process, theorise, experiment, refute, repeat.