How GPS Actually Works (Atomic Clocks, Einstein & Your Phone)

Your phone finds you to within a few meters by listening to atomic clocks flying 20,200 km overhead, and it never sends a thing back. In this video we break down how GPS really works: from Sputnik and the Navy's Transit system to trilateration, the "fourth satellite" trick, atomic clocks, Einstein's relativity corrections (+38 microseconds a day!), the errors that make your blue dot wander and the clever fixes, how your phone gets a fix in seconds, other satellite systems like Galileo, GLONASS and BeiDou, and the hidden role GPS time plays in cell networks, power grids and banking. CHAPTERS 0:00 Cold Open 0:33 A Quick History 1:40 The Three Segments 2:24 What the Satellites Say 3:04 Time Into Distance 3:47 The Fourth Satellite 4:30 Clocks in Space 5:02 Einstein in Orbit 5:54 Errors and Fixes 7:15 Your Phone's Fast Fix 7:54 Not Just GPS 8:27 Beyond Maps 9:02 Recap Sources: gps.gov (space, control and accuracy pages), NASA, NIST, FAA (WAAS), ESA Navipedia, Johns Hopkins APL, Reagan Presidential Library, Ohio State University, N. Ashby (Living Reviews in Relativity, 2003), RTI International / NIST (2019 GPS economic benefits study), EUSPA. Full source list available on request. Voice: Kokoro-82M (Apache-2.0) Visuals and music generated for this video. Subscribe for more How Things Work, and tell us in the comments what we should explain next! #GPS #HowThingsWork #Science