[geordief (OP)]

I sometimes wonder what the "nothing" is that separates all the physical objects.

I notice that in Quantum Theory one only defines  the presence of an object by the likelihood of it actually being  physically detected.

Can we say the same for space?
That its likelihood of being deduced is the  mathematical inverse of an object being detected?

So "space" and physical objects "bleed into" one  another and there is no defined boundary between them.

Is "space" a property of matter and perhaps vice versa?

[alancalverd]

I notice that in Quantum Theory one only defines  the presence of an object by the likelihood of it actually being  physically detected.

Not entirely true. Many particles have been postulated or even identified by an anomalous absence of energy, recoil, or some other phenomenon predicted by classical mechanics. 

It is true that without matter, space would be both meaningless and ubiquitous, but that statement has no consequence.

[geordief (OP)]

I notice that in Quantum Theory one only defines  the presence of an object by the likelihood of it actually being  physically detected.

Not entirely true. Many particles have been postulated or even identified by an anomalous absence of energy, recoil, or some other phenomenon predicted by classical mechanics. 

It is true that without matter, space would be both meaningless and ubiquitous, but that statement has no consequence.

I didn't write correctly  what I had in my head.I was trying to convey that an (quantum) object's position could be seen as extending  non locally(not ,as I actually wrote  that it's presence was detectable)

Not sure if that affects the way you now understand my post.

My feeling was that since "empty space" was equally "non-local" as are the objects "in it" then we could see the apparently two different concepts as "blending in to one another"(and that mathematically the detectable position of one was the inverse of the other)

Space is never empty and objects are never "full".

As you say though ,no consequences may flow from this (trivial?)  observation but I do enjoy eliminating false  conceptions (if indeed I have)

If it simply had the effect of  reducing the number of questions(often posed by me) on science forums as to what "space" is  it might  have  that consequence.

[alancalverd]

Quantum theory must degenerate to classical mechanics when an object or assembly is large enough. So if I look at a brick, I know that most of the protons, neutrons and electrons are withing the observed volume and constitute the observed mass, but there is a finite (though infinitesimal) probability that any of "its" particles could be anywhere else at any moment.

However the statement that a particle is (or could be) somewhere only has meaning if "particle" and "somewhere" are two different concepts.

[geordief (OP)]

Quantum theory must degenerate to classical mechanics when an object or assembly is large enough. So if I look at a brick, I know that most of the protons, neutrons and electrons are withing the observed volume and constitute the observed mass, but there is a finite (though infinitesimal) probability that any of "its" particles could be anywhere else at any moment.

However the statement that a particle is (or could be) somewhere only has meaning if "particle" and "somewhere" are two different concepts.

Thanks.I don't think I can take this idea any further.

Can I change the subject a bit and ask whether  the particles in your brick assembly are better viewed as a system of interactions rather  than a static collection of physical objects ?(albeit moving with each other)

If there were no interactions  in the assembly would the assembly cease to exist for all intents and purposes so that the only practical assembly(brick) is a  system of interactions?

I have in mind   (giving me the idea) that a photon is only said to exist (By some,anyway) at the book ending moments of emission and absorption
(maybe nobody says that.I can't quite recall if they do)

If that is the case with the photon might it apply to the physical objects within the brick?(they only exist insofar as they are interacting with their neighbours)

[set fair]

My current view is that matter and space are closely related. I think space is caused by uncertainty and mass reduces uncertainty which we observe as curved space.