Shri Khalpada explains the physics of GPS. “GPS is fundamentally a translation tool: it converts time into distance. A satellite sends a signal, your phone catches it, and the delay between those two events tells the phone exactly how far away the satellite is. Everything else is about making that measurement precise enough to be useful: accounting for bad clocks, satellite geometry, and eventually, Einstein’s theories.”

Previously: Bartosz Ciechanowski Explains GPS.