Ernst Mach, a man to who influenced Albert Einstein significantly in his approach to relativity, did not quite seem to believe in space as a self-existing entity. I'm pretty sure it would be correct to say he thought it was created by matter.
So let's take that idea for a moment and run with it. Wouldn't the idea that matter creates space unavoidably create testable predictions about the nature of how forces work, especially over astronomical distances?
I say this because from my admittedly information-centric perspective, the only way matter can create something approximating what we call space is by creating relationships between particles. Space would then become nothing more than a particular set of rules for how those relationships interact and change over time, capturing for example the idea that they have locality and interact based on rules such as the $\frac{1}{n^2}$ fall off of some forces with distance. With large enough sets of particles, the resulting interactions would become sufficiently smooth and fine-grained to create the abstraction we call space. But Euclidean space as we know it would necessarily be an illusion. (Incidentally, I have no idea if this line of thinking might be related to holographic universe ideas.)
Now, the interesting thing about that argument is this: If one assumes as an experimental hypothesis that matter creates space, I don't easily see no way around the implication that the idea should be testable, at least in principle. That's because a simulation of smooth space created by the particle interactions will necessarily be incomplete and dependent on the distribution of those particles.
So for example, if you only had a universe of two particles, only one space-like relationship would exist. The resulting simulation of space could not possibly be as smooth or rich as the space we know while sitting at the Euclidean limit of a nearly number of particles and particle relationships. It would for example likely have some sort of predominantly one-dimensional field equations, e.g. a the universe with only one electron and one positron might maintain constant attraction between them regardless of their separation distance. (It's also interesting to note that constant 1D-like attraction is approximately how quarks behave when pushed far away from short-range asymptotic freedom envelopes.)
Detecting deviations from the Euclidean limit would be hugely more difficult in our particle-rich universe, but I cannot easily see how it would be flatly impossible. Asymmetries of matter at the scale of the entire universe would for example have to affect the nature of space by creating asymmetries in the number and richness of the underlying particle relationships. If a precise model could be made for how such relationship asymmetries affected our local space abstraction, testable predictions would be possible. The first approximation in any such model would simply be to map out the density and orientation of the relationships based on our best guesses at particle distributions, then see if those relationship sets correlate strongly to any known effects.
The unexpected and quirky distribution in dark matter could certainly be a candidate for such an effect. Again, as an information type I take high correlations pretty seriously, and some of curve fits between certain galactic phenomena and predictions made by the oddly simple MOND rule remain poorly explained at best. If such correlations somehow stemmed from asymmetries in space itself due to large-scale asymmetries in the galaxy-scale distribution of particles, a very different approach might be possible to explaining why the MOND rule sometimes produces such unexpectedly strong curve correlations.
So again, the question is just this: Has the possibility of testing the Machian hypothesis every been explored theoretically? And if not, why not? What am I missing?
(This question is a direct outgrowth of my earlier amusingly unproductive question about whether space exists independently of matter. For that one I received exactly one "yes" answer, exactly one "no" answer, and no up or down votes on either one. Flip a coin indeed!)