Lawrence
"A theory may be falsified, never it is proven"
Leaving aside the semantics that a theory is proven, and it is hypothesis that has yet to be so judged. This statement depends on the reference 'to all possibilities', when it is a statement of the obvious. However, that is irrelevant, because physical existence does not encompass all possibilities, it is all that is potentially knowable to us, which is determined by a physical process. So there is a closed system, ie one possibility. The relationship between this and what 'really' occurs is unknowable. And science investigates the knowable, not beliefs. It may be extremely complex and vast, ie possibly impossible to ever know all of it accurately and comprehensively, but that is now revealed as a practical, not metaphysical, issue, which is important.
So this statement then takes on a new, and useable, meaning. That is, something can be proven, because there is a valid limit. The point is that the attainment of that will only be known by default. We are compiling knowledge. As at any time, assuming valid presumptions and due process, then a proven theory is really 'the best approximation given knowledge available at this time'. For somewhat obvious reasons we do not bother to explicitly state this caveat. However, given the limit, after sufficient time and investigation, if nothing arises to the contrary, then we can deem that theory to be the 'equivalent of physical existence'. We can never somehow 'directly access' physical existence, we can only have knowledge thereof, and a limited form at that.
Leaving aside definitions as to what constitutes 'observation', and the validity of the argument in the particular case, the big point in this essay is that it is 'properties of' which are manifest, and therefore detectable, which implies substance (eg particle) of some form(s). That is, when considering physical existence, it is the physically existent state of whatever that is being investigated directly. Detection can involve direct sensing, purely conceptualisation (virtual sensing), or a combination. It makes no difference if (big if) the start point is valid and the proper rules are adhered to. My point was that there is no way in which what ultimately constitutes a discrete state of these 'properties' can be differentiated experimentally, the vanishingly small duration and degree of alteration involved precludes this. But I would take issue with Marcoen's assertion about observation in the general sense, because assuming we do not take the word literally, then inference from validated direct observation, ie virtual observation, is valid. The real issue then is what was the start point and the model of physical existence into which any given result was plugged.
Paul