The 6bn gun aimed at the secrets of the atom

At last the Large Hadron Collider, the atom smasher that straddles the Swiss-French border, has been switched on. There is a suspicion it has been over-hyped but it has been a long time coming, almost 100 years, in fact.

It was Ernest, later Lord, Rutherford, whose team at Manchester in 1909 fired microscopic bullets at a thin gold film and noticed that one in 8,000 bounced back. What was so astonishing was that then the prevailing image of the atom was of a cloud of tiny "electrons".

Seeing the microscopic bullets coming back from the gold atoms was like firing real bullets into a cloud of gnats and seeing them ricochet back. The picture physicists had of the atom was clearly badly wrong.

Rutherford deduced - correctly - that there must be something hard and small at the centre of an atom, something that could stop a bullet in its tracks and turn it around.

He had discovered the atomic nucleus, around which the electrons flitted like planets around the sun.

The shock was how small it was compared with the atom. Matter - which means you and me - is overwhelmingly made of empty space. Squeeze all the space out of all the atoms that make up the human race and the remainder would fit in the volume of a single sugar cube.

Rutherford had started something. The race was on to fire ever-faster bullets into matter to expose its inner structure. In 1932, Cambridge's Sir John Cockcroft and Ernest Walton used artificially accelerated protons to "split" the atom, winning the Nobel prize for their pains.

That race has culminated in the LHC, the true heir of Rutherford's gold foil experiment in ingenuity as well as aims. Rutherford's microscopic bullets were spat out at 25,000 kilometres per second from a sample of radioactive radium; his tabletop experiments were often cobbled together from sealing wax and string.

At a cost of ¤6 billion, the LHC is decidedly higher-tech than that. But while the Americans tried to build an atom smasher using tried-and-tested technology and had to abandon it because of cost overruns, the frugal Europeans adapted an already existing collider tunnel and banked on new technology that was then still over the horizon.

And it comes from a lab that gave us the World Wide Web, one in the eye for those who think basic science has no practical spin-offs. Much will be said about the LHC's goals, such as uncovering the origin of mass. But the lesson from the last century's experiments is that whenever we probe deeper into matter, nature rewards us by surprising the hell out of us. And there is no reason at all to believe it will be different this time.

Marcus Chown's latest book is Quantum Theory Cannot Hurt You: A Guide to the Universe (Faber and Faber, £8.99).