What would happen if GPS stopped working?

For a start, we'd all have to engage our brains and pay attention to the world around

us when getting from A to B. Perhaps this would be no bad thing. We'd be less likely to

drive into rivers or overcliffs to misplace trust in our navigation devices.

Pick your own favourite story about the kind of idiocy only GPS can enable. Mine is the Swedish

couple who misspelled the Italian island of Capri and turned up hundreds of kilometres

away in Carpie, asking where the sea was.

These are the exceptions. Devices that use GPS usually stop us getting lost. If it failed,

the roads would be clogged with drivers slowing to peer at signs or stopping to consult maps.

If your commute involves a train, there'll be no information boards to tell you when to

expect the next arrival. Phone for a taxi, and you'll find a harassed operator trying

to keep track of her fleet by calling the drivers. Open the Uber app and… well… you get

the picture.

With no GPS, emergency services start struggling. Operators can't locate callers from their phone

signal or identify the nearest ambulance or police car. There are snarlups at ports.

Container cranes need GPS to unload ships. Factories stand idle when their inputs don't

arrive just in time. Farming, construction, fishing, surveying. These are other industries

mentioned by a UK government report that pegs the cost of GPS going down at about a billion

dollars a day for the first five days. If it lasts for much longer, we might start worrying

about the resilience of a whole load of other systems that might not have occurred to you

if you're thinking of GPS as a location service. It is that, but it's also a time service.

The global positioning system consists of 24 satellites that all carry clocks synchronised

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