Let's see, arguably the most accurate pendulum clock was the Shortt clock. It was good to 200 microseconds/day, or about 2 E-9, where you could see the effect of the moon and the sun, just.
Suppose I have one of those beauties in my basement, with the requisite apparatus to compare it to a Caesium clock disciplined by GPS. Suppose my wife drives her 3000 pound car out of the garage, about 20 feet away. What will be the affect of that local change in mass? Could I discipline a Shortt clock to GPS by using a PLL that slid a one ton mass along the basement floor near the free pendulum? Sliding the one ton mass is left as an exercise for the reader, as is installing it in the basement. Yours in search of more perfect knowledge outside my field, Bill Hawkins _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.