asciilifeform: mircea_popescu: notice that folks who actually need the cesium fountain for practical work do not bother with the metaphysics. but simply end up defining precise timebase as 'the thing that, if any noisier, now you can't geolocate but to +/-1km...'
asciilifeform: as far as anyone has been able to determine to date, the atom does not temporally misbehave, and so it can be used as clock to the limits of the measurement precision.