Your online traces are helping fuel a revolution in the understanding of human behaviour – one that's revealing the mathematical laws of our lives

EVERY move you make, every twitter feed you update, somebody is watching you. You may not think twice about it, but if you use a social networking site, a cellphone or the internet regularly, you are leaving behind a clear digital trail that describes your behaviour, travel patterns, likes and dislikes, divulges who your friends are and reveals your mood and your opinions. In short, it tells the world an awful lot about you.

Now, as any researcher will tell you, good data is gold dust. Its absence leaves theories in the realm of speculation, and worse, poor data can lead you down blind alleys. Physics was the first science to be transformed by ...