These things may represent the beginning of our understanding of the physical; none of them seems to be exhaustively understood as yet. Also, the entire idea of a "physical object" probably needs to be rethought; for all such objects are such as they are because of their participation in universal fields (e.g., particle, gage, Higgs fields). That which is perceived to be "solid" may not actually be so; rather "solidity" may be but the surface presentation of a phenomenon that has a nature and causes that run deeper than we can see from our perch in 3+1D spacetime.
As to physical objects, all things are composed of matter. Matter's other "face" is energy. Here's a question for you: Is energy "physical?" By this I mean energy in contradistinction to force, which seems to be a physical property of objects.
BTW, I don't know the answer to this question. I'm just wondering out loud here. I'd be interested in your view.
In any case, I don't see the basis for your remark that A-G and I are reductionists, because I think it's fair to say neither she nor I knows for a fact what things could possibly "reduce" to when there is still so much that we don't know. I think it's fair to say that we both tend to be open-minded and curious. FWIW.
I also think it's fair to say we both love scientific inquiry and the world of episteme more generally. And neither of us buys into the idea of the so-called "Cartesian split."
[Dear A-G, forgive me for speaking for you! If I've misrepresented your views, please do correct me!!!]
Actually, things are only solid because of the Pauli Exclusion principle. In fact, were it not for Pauli's Principle, you would fall directly to the Center of the Earth (without passing GO or collecting $200).
It appears to me that the quantum world is addressed in different ways by three different disciplines. Quantum mechanics is non-relativistic and speaks to bosons, leptons, quarks, etc. I tend to think of particles as the messenger constructs or placemarkers in quantum field theory. To think of them as substantive would be misleading - after all, even ordinary matter under the standard model is not yet observed in laboratory conditions (Higgs field/boson).
When betty boop speaks to quantum physics, she usually approaches it from quantum field theory. The four fundamental fields are strong and weak atomic force, electromagnetism and gravity. There is much speculation about the existence of other fields which may help to explain phenomenon such as information content of the universe and biological systems, etc. She and I are both keenly interested in those subjects.
But the bottom line is that a field exists in all points of space/time, and the mechanism is wave function. IOW, “quantum field theory” is relativistic. Quantum chromodynamics is the quantum field theory for the strong atomic force. Electroweak theory is the quantum field theory for the unified forces of electromagnetism and the weak atomic force. Efforts continue to develop a quantum field theory for gravity – the tiniest of the fundamental forces (relatively speaking).
Which brings me to the third discipline, geometry, which is my personal favorite and which answers your question. All particles and all fields have the characteristic of dimensionality – space/time in our 4D block. That is why they are physical.
Fom my point of view, geometry is the most fundamental approach to physics even at the quantum level. Matter of all kinds can arise from a higher dimensional vacuum, and a higher dimensional shockwave (brane theory, ekprotic cosmology, etc.) can provoke a big bang. In sum, it is the geometry - the expansion of space/time which gives rise to the fields which then give rise to the messenger constructs/placemarkers (or particles).
You are engaging in circular definitions here.
What property of the spritual allows it to interact with the physical, while simultaneously distinguishing it from being physical?