Society relies on GPS — and the technology is vulnerable Meddlers range from nation-states to teenagers. If it went out, you'd notice. We need a backup. By Kate Murphy Text size Copy shortlink: Time was when nobody knew, or even cared, exactly what time it was. The movement of the sun, phases of the moon and changing seasons were sufficient indicators. But since the Industrial Revolution, we've become increasingly dependent on knowing the time, and with increasing accuracy. Not only does the time tell us when to sleep, wake, eat, work and play; it tells automated systems when to execute financial transactions, bounce data between cellular towers and throttle power on the electrical grid.