4 ms·

General Relativity is a mathematical model. Model needs mapping between physical world and model.

• ben_w 3y ago
  My phone's GPS only works because that mapping keeps being better than anything else we've tested on that scale. The atomic clocks (as I mentioned in another comment) demonstrating gravitational time dilation within a building is another fun example.
  • oneshtein 3y ago
    Your phone works because engineers did it. I see strong annual signal in GPS: https://link.springer.com/article/10.1007/s10291-017-0686-6 https://link.springer.com/article/10.1007/s10291-017-0686-6 . Why it there?
    • ben_w 3y ago
      > Your phone works because engineers did it. The engineers implemented results from GR. > Why it there? Not that it matters, but the answer is in the introduction.