[time-nuts] Time Nuts at PTTI this past week

Tom Van Baak tvb at leapsecond.com
Sat Dec 9 15:08:12 EST 2006

```> but what source(s) did you use to arrive at the
> 1.5E-13 figure?

John,

Good question. Here's how: c = 299792458 m/s and
to a few percent g is 9.806 m/s^2. The GR redshift is
gh/c^2 so that's where the 1.091e-16 / meter number
comes from.

Now the back-of-envelope redshift prediction prior to
the trip was: home lab elevation (300 m), mountain
parking lot elevation (1640 m), gives a net elevation
gain 1340 m; 1340 m x 1.091e-16 / m = 1.46e-13.

told me the experiment was feasible -- because I had
a nearby mountain high enough, TIC's that could easily
measure 20 ns, and Cs that were stable to 1e-14 at
a day.

The time dilation prediction after the trip was made
by integrating actual GPS positions of the minivan
during the trip. Clearly we didn't go instantly from
home at 300 meters, to the mountain at 1640 meters,
or spend exactly 40 hours up there. Based on this
GPS data, the total number of meter-seconds was
calculated and the predicted time dilation was 22.3 ns.

/tvb

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