What does this equation mean?

No experiment has run the differential two-height, two-internal-state protocol at the meter-and-second scale used illustratively above; it remains a proposal, not a result [ 10 , 11 ] . What existing data already constrain is the space this construction is allowed to occupy. Dual-species atom-interferometric tests of the weak equivalence principle have matched the free-fall trajectories of different atomic species to extraordinary precision by actively canceling the very laser/recoil terms this paper identifies as confounds, which is direct evidence that no large anomalous mass-dependence is hiding in the dominant phase term this construction must avoid [ 12 ] . Separately, ordinary macroscopic clock comparisons across height differences already confirm the leading coefficient of gravitational redshift to high precision through completely classical (non-interferometric) means, constraining $\Delta$$\tau$$\approx$ g\,$\Delta$ z\,T/$c^2$ itself rather than the interferometric phase built from it.