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by beojan
3225 days ago
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> If we hadn't known about GR when we built the GPS system, wouldn't we have realised there was an unexpected drift in the clocks and found a way to recalibrate them periodically? And hence have discovered GR in the process. Alternatively (and more likely) we would have decided the idea simply doesn't work. |
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No, we would just keep beating on it until it works. It's a myth that science always precedes engineering. It's a very regular drift, and worst case scenario, if they just couldn't work it out, they'd build several ground stations in known locations, derive corrections as those drift, and upload corrections into the system periodically. (Similar things are done today: https://en.wikipedia.org/wiki/Differential_GPS )
Even with the science that we have, there's still fudge factors and empirically-determined values we have to use anyhow, because the Earth is not homogeneous and we have to take its slightly-lumpy gravity field as a given, not something we can "scientifically" determine. (Of course we "use science" to determine the lumps, but the lumps themselves are simply a given.)