A collective of NIST, University of Colorado, Instituto Nazionale di Ricerca Metrologica and Politecnico di Torino announces (warning: PDF linked) the creation of an atomic clock with an instability of 10^-18. Such a level of instability is equivalent to specifying the Earth’s diameter with a precision to less than the width of an atom.
Better still, consider the gravitational redshift, a consequence of general relativity dictating that clocks ‘tick’ slower in stronger gravitational elds. With a maximum instability of 10^-18, one can discern a difference shown by two such clocks separated by only 1 cm in elevation above the Earths surface.
Now, it is likely that an operator of half-a-world-away-remote-controlled-drones won't actually need such a precision, but it becomes important in designing experiments to test unification theories employing non-metric couplings without asking for a cosmological setup (may one dream of gravitational waves detection without causing — or expecting — supernova explosions or birth of blackholes type of events?)"
Link to Original Source