[ntp:questions] National time standard differences

John Ackermann N8UR jra at febo.com
Fri Feb 12 18:47:05 UTC 2010

unruh wrote:
> On 2010-02-12, John Ackermann N8UR <jra at febo.com> wrote:
>> Another great experiment -- done by an amateur 
>> time-nut, Tom Van Baak -- took three 5071As on a camping trip up a 
>> mountain in Washington state and verified Einstein's prediction of a 
>> change in clock rate with elevation.  Take a look at 
>> http://www.leapsecond.com/great2005/index.htm and be amazed.
> That's about 2Km, which is a time difference of 2 parts in 10^-13. Ie,
> if he was up there a day, the time difference would be 10ns. I wonder if
> they are really that accurate. 
> The ultimate was the Vessot experiment in which a H maser clock was shot
> up to 10000Km and the special relativisitic and general relativistic
> time shifts were measured.
> Bender claims that the GPS engineers did not believe that GR was real,
> and had a software switch which they could use to eliminate the General
> Rel corrections in the GPS.

I think Tom spent closer to two days on the mountain, and he was using 
5071As with the high stability cesium tube option (and the three he took 
up were selected as best performers from his collection).  The 5071As 
have stability down to parts in 10e14.  I'm not certain, but I think 
that his stationary reference was an H-Maser.  His measurement 
resolution was in the picoseconds.


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