[time-nuts] Cesium vs H Maser clocks

[Jim Palfreyman]

2008/11/29 Mike S <mikes at flatsurface.com>

> At 01:30 AM 11/29/2008, Tom Van Baak wrote...
> >Note also that clocks at NIST run about 1.8e-13 fast due to the high
> >elevation of Boulder, CO (general relativity), which is yet another
> >factor that has to be corrected for compared to the official sea-level
> >definition of the second.
>
> Do they really adjust to sea level on earth? That isn't part of the
> definition. Within that convention, as the mean sea level rises (~20 cm
> in the last 100 years), does the length of the second change
> (relatively)?
>
> A clock will run faster the lower the strength of the gravitational field.
Even though the mean sea level might rise 20cm in 100 years, it doesn't mean
the gravitational field is changing in any meaningful way in that time.
Daily tidal variations would be far greater.

One would assume the definition of the second is in reference to the
gravitational field at the surface of the mean geoid and has nothing to do
with sea level.

Jim