Living Without Atomic Clocks

Re:Living Without Atomic Clocks by monochromatic on Wednesday February 17, 2016 @10:36PM (#11123530)

> For instance, if you look at a clock on a GPS satellite, moving fast relative to you, you can see it run slower than the one on your wrist.

Actually, the general relativity effects of weaker gravitational field dominate the special relativity effects of velocity[1]. So the GPS satellite clock actually runs faster, not slower.

[1] http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps....

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Re:Living Without Atomic Clocks by techdragon on Wednesday February 17, 2016 @11:57PM (#11123823)

There's a really neat thing about this, the relationship balances out at a certain orbital height, before it flips over so there's an orbit where your chronologically in synch with the ground.

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Re:Living Without Atomic Clocks by jhayward on Thursday February 18, 2016 @05:17PM (#11129774)

That's only true with respect to a given locus of points on the ground, not the full surface. I.E., the relative velocity of the SV isn't the same for all points that may be measuring.

In practice the GR effect is compensated by the satellite at manufacturing, the SR effect is treated in the receiver - for just that reason.

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Re:Living Without Atomic Clocks by monochromatic on Thursday February 18, 2016 @12:08AM (#11123840)

Hadn't thought about it that way, but you are right.

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