Albert Einstein famously said that quantum mechanics should allow two objects to affect each other’s behaviour instantly across vast distances, something he dubbed “spooky action at a distance” 1.

Pose a question to a Magic 8 Ball, and it’ll answer yes, no or something annoyingly indecisive. We think of it as a kid’s toy, but theoretical computer scientists employ a similar tool. They often ...

The original version of this story appeared in Quanta Magazine. They say a bird in the hand is worth two in the bush, but for computer scientists, two birds in a hole are better still. That’s because ...