Re: OT 10Mhz references


 

Hi David,
You are correct. It has proved to be extremely difficult to measure frame dragging and it is too small to have an effect on the GPS satellites.

The military is working on a much more precise positioning system which may someday replace GPS. I remember reading an article on the seemingly insurmountable theoretical obstacles to making that a reality. I wish I could find that article. It represented some of the most far out thinking (that had real world practical application) I ever read.

Dennis Tillman W7PF

-----Original Message-----
Sent: Monday, March 14, 2016 8:39 AM
Subject: Re: [TekScopes] Re: OT 10Mhz references

On Sun, Mar 13, 2016 at 11:18 PM, Dennis Tillman <dennis@ridesoft.com> wrote:
I once read a fascinating article on what is done to keep the Cesium
Clocks on the GPS satellites accurate. If I remember correctly there
are five different relativistic effects that have to be compensated
for. Frame dragging is one of the most interesting.
Frame dragging is much too weak to affect the GPS satellites. If you read about the saga of Gravity Probe B, you'll see how difficult it is to measure it at all.
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Posted by: David DiGiacomo <telists@davmar.org>
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