Question

What about the nature of GPS technology requires for the satellites to be aware of and make corrections for general relativity? What would happen if general relativity corrections were not made?

Answer 1

Satellites will be affected by the space-time curvature of earth. On the surface of earth, the space-time curvature effects are more compared with that of satellites which are far from the surface of earth. Clocks will tick more slowly near the surface of earth, which is a prediction of General theory of relativity, according to which clocks will slow down near massive objects.

According to calculations, a clock on the satellite will get ahead of the clocks on the surface of earth by 38 s, which corresponds to around 10 km. So the error per day is 10 km and after a few days GPS will be useless if we do not take into account of General theory of relativity.