[time-nuts] Gravity, solid Earth tides

[Tom Van Baak]

Hi Hal,

Yes, both CERN, and especially LIGO, need to take the gravitational 
effects of the moon and sun into account.

Also, some of the very best pendulum clocks ever made were good enough 
that their timekeeping was affected by lunar/solar tides. One is the 
English Shortt-Synchronome and another is the Russian Fedchenko.

The way you "detect tides" is if your pendulum clock is so incredibly 
good at timekeeping that the only remaining error source(s) are random 
earthquakes or periodic variations correlated to the relative positions 
of the earth, moon, and sun. Sometimes you can see this in the phase 
(time) or frequency (rate) time series. Another way is to observe 
effects with stacking, FFT, PSD, or ADEV analysis.

It's a particular interest of mine. A couple of links for you:

http://leapsecond.com/pend/shortt/
http://leapsecond.com/pend/pdf/1985-Apr-NAWCC-Boucheron-Shortt.pdf
http://leapsecond.com/pend/pdf/1986-Mar-AH-Boucheron-Shortt.pdf
http://leapsecond.com/hsn2006/
http://leapsecond.com/pend/synchronome/quake.htm

/tvb


On 5/15/2020 9:22 PM, Hal Murray wrote:
> Are any clocks good enough to detect solid Earth tides?
>
> I remember a story about a CERN experiment that wasn't working until they
> corrected for the phase of the moon.  It was extremely sensitive to the
> diameter of the ring which changed slightly with the tides.
>
>