Could the internet go offline? Inside the fragile system holding the modern world together

The real doomsday event internet experts still worry about is a sudden, snowballing error in the decades-old protocols that underlie the whole internet. Photograph: Sergio Azenha/Alamy

It is the morning after the internet went offline and, as much as you would like to think you would be delighted, you are likely to be wondering what to do.

You could buy groceries with a chequebook, if you have one. Call into work with the landline – if yours is still connected. After that, you could drive to the shop, as long as you still know how to navigate without 5G.