[time-nuts] Pendulums & Atomic Clocks & Gravity

Jean-Louis Oneto Jean-Louis.Oneto at obs-azur.fr
Sat May 26 16:25:43 EDT 2007


Hi,
I think that on a satellite orbiting around the Earth, only the 
gravitational field of the Earth is zeroed, since it is equivalent to a 
freefall in the Earth gravitational field. The effects of all others 
perturbations are exactly the same (if you neglect the altitude of the 
satellite with respect to the Earth-Sun or Earth-Moon distances). Beside 
that, the Doppler effects (both classical and relativistic) are not 
negligible at all and are in fact corrected in GPS by offsets in the onboard 
clocks, steered to UTC(USNO).
Have a nice day,
Jean-Louis Oneto
OCA GEMINI - Avenue Copernic - 06130 Grasse - France
----- Original Message ----- 
From: "WB6BNQ" <wb6bnq at cox.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Saturday, May 26, 2007 8:02 PM
Subject: Re: [time-nuts] Pendulums & Atomic Clocks & Gravity


> Brooke Clarke wrote:
>
>> 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 â^' U1)/c2, where the Us are
>> gravitational potentials, only smaller by c squared.
>
> If all of the above affects the gravitational action on the surface of the 
> Earth,
> then how is the statement, below, true ?
>
>> 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.
>
> It would seem that the satellite, which is just an arms throw from the 
> surface,
> would have the same affects acting upon it, albeit perhaps in modified 
> ways.  I
> would think the satellite would have to be placed at the center of the SUN 
> to have
> all of the effects (within our solar system) reduced to the smallest 
> amount.
>
> Can anyone elaborate on this ?  Thanks,
>
> Bill......WB6BNQ
>
>
>
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