this post was submitted on 15 Jun 2024
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The clocks involved in gps are accurate enough that they have to take relatively into account for gps to be accurate. That's far more accurate than you need to measure the speed of light.
And to calculate the offset needed to get them all synced up involves calculating time dilation, which involves knowing/assuming the speed of light. These synchronizations work just as well if the two way speed of light is different than the one way speed of light.
To know the speed of light you assume the speed of light is c, but you're trying to calculate c so all those clocks aren't verified synced.
Just read through the wiki or Harvard's books if you'd like, this is an unsolved "problem" in physics for a reason or do you think no one cares about how fast c is?
See also This or, more accessibly "Synchronization conventions"
I read all those and every test has reduced the amount that the speed of light could be anisotropic. From "it could be twice as fast in this direction to the other" to "it could be a small fraction of the relativistic effect of moving a clock through space." Every improvement in measurement trends towards isotropic.