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To: Lonesome in Massachussets
Gravitational shifting can be towards the blue, as when a photon approaches a black hole.

Is that in any way detectable?

Or the re-tuning of the atomic clocks on GPS satellites.

I know that GPS technology takes into account Relativity theory, both Special and General. Special deals with the high rate of speed of the satellites and the effects that has on time (between the sat and ground), while General deals with the effects of time due to Earth's gravitational field, which of course is stronger at the surface than high above it at the sat's altitude.

Interestingly, as the speed aspect causes the sat's clock to tick more slowly (from the ground's perspective), the increased gravity at the surface causes the ground-based clock to tick more slowly. The surprising (to me anyway) net result is that the gravitational effects win out slightly over the speed effects, and so the earth-bound clock ticks out time more slowly than the sat's, and therefore adjustments need to be made to insure better precision of the system.

50 posted on 07/02/2017 5:16:16 AM PDT by ETL (Obama-Hillary, the REAL Russia-US scandal (UraniumOne Deal, Missile Defense, Nukes) See my home page)
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To: ETL

The received frequency of GPS satellite signals is higher than the transmitted frequency, the definition of blue shift. The bigger problem is that the same oscillators are used to create the transmitted waveforms as are used to time transmissions. The start of frames are multiples of 1.5 seconds. One could use a time scale that beat seconds at the rate of the orbiting GPS constellation and let it march ahead of terrestrial clocks, so long as the constellation was mutually synchronized. The drawback to this approach would be that “GPS time” would have no simple relationship to terrestrial time scales. A side benefit of GPS is that it affords a very simple and highly accurate method of time synchronization worldwide. GPS clocks are steered to closely track UTC for this purpose.


52 posted on 07/02/2017 5:31:37 AM PDT by Lonesome in Massachussets (Psephomancers for Hillary!)
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