Theory 11/Relativistic geodesy/Optical lattice clocks
Height Is Measurable as a Frequency
The claim
The gravitational potential difference between two points is set by the ratio of their clock rates, so elevation can be measured by comparing clocks rather than by levelling.
01Mechanism
Time runs slower deeper in a potential; the fractional frequency difference is proportional to the height difference.
02Prediction
Clock comparison should recover known height differences.
03Refutation
Clock rates independent of elevation at the achieved precision would remove the method.
04What makes it checkable
Optical lattice clocks now reach fractional stabilities where a centimetre of elevation produces a measurable shift.
05Why it was not testable before
The effect was predicted a century ago and only became measurable when clock stability crossed the required threshold.