How does the time‑dilation effect used in GPS influence your daily navigation, and what would happen if engineers ignored relativity?
Most people use GPS without realizing it relies on corrections from both special and general relativity. Satellite clocks run faster by about 38 microseconds per day due to weaker gravity, and slower by about 7 microseconds per day due to their speed—a net gain of 38 − 7 = 31 microseconds. Ignoring this would cause positioning errors of roughly 10 kilometers per day, rendering the system useless for navigation. Recognizing this invisible relativity underscores how abstract physics shapes concrete technology.
Use a GPS app on your phone to record your location at a known landmark, then compute the expected error if relativistic corrections were turned off (approximately 10 km/day). Share the result on social media to illustrate the real-world impact of Einstein's theories.