Symbol Δτ

The passage around this formula

The resulting clock phase is $\Delta\phi_{\rm clock}=2\pi\,\Delta\nu\,\Delta\tau\approx0.294\ \text{rad}$. This, again, is an exact evaluation of a stated formula under stated idealized assumptions — a single-photon clock transition, no recoil, no laser phase, a static height difference held exactly one second — offered as illustrative, not as a report of anything measured. No such experiment has been performed at this scale; it is precisely the regime the cited proposals argue is at the edge of feasibility with current optical-clock coherence and large-scale atom-fountain technology, not a regime already demonstrated.

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