If two models generate the same predictions, they are the same model, and the simpler (in the Kolgomorov complexity sense) is best understood as the truth (in so far as that concept is meaningful at all). A force acting on everything in the universe except one atom, or a (equal and opposite) force acting on that one atom, is the same thing[1], just as a universe where all distances are multiplied by two is indistinguishable from the current universe. Again, there's no way to make an observation from outside the universe; we can only make relative measurements, observe patterns, and use them to make predictions.

[1] ultimately, this comes down to: they generate the same sense-impressions that I subjectively experience - but for simplicity let's assume an objective universe exists, other humans exist, and we can observe the same things - I believe this assumption is justified as the most parsimonious explanation of the patterns I perceive in the sense-impressions I experience