> Then a pendulum calculator at: > http://www.ajdesigner.com/phppendulum/simple_pendulum_equation_period.php > allows solving any of 8 pendulum related equations.
Note that this simplistic l/g formula does not characterize the period of precision pendulum clocks, as it ignores factors such as circular error, and a host of other static and dynamic corrections. But it should be good enough for your SWCC. > Tom has pointed out that the stability limit on pendulum clocks is in the area > of 1E-7 because of the complex effect of the Sun and Moon on the value of "g". > http://www.leapsecond.com/hsn2006/ch1.htm > Gravity also effects atomic clocks, see: http://www.leapsecond.com/great2005/ > and this puts a limit on what can be done with any atomic clock that's on > Earth. "g" will always have minor fluctuations (noise) due to all sorts of > things like the Sun, Moon, planets, asteroids, earthquakes, etc. It's still a > direct "g" effect called red shift like (U2 − U1)/c2, where the Us are > gravitational potentials, only smaller by c squared. Mostly Sun ( > > I expect that in not too many years the official master clocks will no longer > be on Earth, but instead in satellites. There "g" is precisely known to be > zero. Since GPS satellites are excellent for time transfer that's where they > will be. The ensemble will be the full constellation. > > In "Time Too Good to Be True" Kleppner > http://www.physicstoday.org/vol-59/iss-3/p10.html > says "...a primary standard in space would not overcome the problem of > comparing time or frequency at different locations on Earth." > > I don't understand why that would be the case with a standard in a GPS > satellite. Granted E-18 can not now be done using the current GPS system, but > when atomic clocks get into the E-16 or better area and are in satellites, I > think the quality of time transfer will keep up. > > Just an idea & Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.precisionclock.com > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts