altimeeter
An altimeeter is a hypothetical instrument designed to measure time intervals with extreme precision by integrating multiple time-keeping references and direct time-transfer techniques. The term is not part of standard metrology and is mainly used in speculative discussions or fictional settings to denote an ideal time-measuring device.
Conceptually, an altimeeter would combine a primary frequency standard (such as an optical atomic clock), a
Operation would entail continuous synchronization to a reference frame, active error cancellation for environmental effects, and
In modern metrology, real devices achieving comparable performance include optical lattice clocks and advanced atomic clocks,
See also: atomic clock, timekeeping, chronometer, time transfer, metrology.