How Does GPS Know Exactly Where You Are?

Your phone finds you within about 16 feet, and it doesn't send a single signal to space. It only listens. Here's how GPS really works: satellites shouting the time, light-speed timing, a fourth satellite that fixes your phone's cheap clock, and a correction that only works because Einstein was right. Twice. In this video: what GPS satellites actually broadcast, why time equals distance, how 3 spheres pin down your position, why you really need 4 satellites, the 38 microseconds a day that relativity adds to satellite clocks, why your blue dot jumps around in cities, how a 1983 tragedy opened GPS to everyone, and why banks and power grids depend on GPS time. 0:00 Intro 0:36 Clocks in the sky 1:32 Time is distance 2:28 Three spheres 3:09 The fourth satellite 4:06 Einstein's correction 5:19 Why it's not perfect 6:12 From missiles to maps 7:07 The hidden clock 7:42 Listening to the sky Orbits are simplified for clarity (shown closer to Earth than in reality). #gps #science #einstein