The Large Hadron Collider (LHC) is the biggest and most complicated machine ever built. To complete it took 100,000-person-years of work – the same amount of time it took to build the Great Pyramid of Giza. Inside sub-atomic particles are fired at 99.999999 per cent of the speed of light through tunnels colder than outer space and collide in an explosion 100,000 times hotter than the centre of the sun. But the real wonder is not so much in the making as in the questions it asks. Just a few thousand years ago we were rubbing sticks together to make fire. Now we are building machines that can look back in time to the origins of the universe itself.