We've all heard of 'six degrees of separation', the idea that everyone in the world can be connected in just a few steps. But what if those steps don't just relate to people but also to viruses, neurons, proteins and even to fashion trends? What if this 'six degrees of separation' allowed us an insight into something at the core of Nature? We used to think the way in which web pages, power grids and people tied together was more or less random. But recently two young physicists independently discovered that fundamental laws govern networks. It's a discovery that may prove as important as Newton's observations of gravity or Darwin's theory of evolution.