Key points are not available for this paper at this time.
The time it takes the Earth to make a full turn fluctuates by a few milliseconds per day because tides, atmospheric changes, and perhaps movements in the Earth9s core are constantly shifting the planet9s mass. Now the world9s largest ring laser gyroscope, a glass block more than a meter across threaded by counterrotating laser beams, will keep track of Earth9s vagaries from a cave in New Zealand.
Alexander Hellemans (Fri,) studied this question.