Perhaps cutting the links between such places, then, would be an easier way to break the internet? There are uncountable miles of cables wrapped around the globe, and many of the biggest are just lying there unprotected – albeit often underwater. Indeed, cables do sometimes get severed just by accident, for instance during earthquakes or when ships’ anchors slice through them on the seabed. It’s believed that significant internet disruptions in 2008 that affected countries including Egypt were caused by these sort of cable breaks.

Distributed resilience

But the effects of these failures in the physical infrastructure of the net aren’t as far-reaching as you might think, because they come up against the original designed resilience of the system. It’s people like Paul Baran, a Polish-born American engineer, who we can thank for this. Baran is one of a few people who, way back in the early 1960s, believed a communications network could be designed with significant physical survivability, to withstand even a nuclear attack.

He wrote many fascinating papers about it, but at first no-one took him seriously. It might have stayed like that except for Donald Davies, a Welsh computer scientist, who came up with the same fundamental idea as Baran, completely independently and at almost exactly the same time. Their idea was called “packet-switching” and it describes a communications protocol that breaks messages down into small blocks, or packets. These are fired across a network via the fastest route available – whatever that route is – until they all arrive at their destination, where they are then reassembled. Take out one link in the network, even an important one, and messages can still arrive where they are expected by taking one of the many alternative routes.