In the event that it fell to you to identify the most exciting place on the planet, the likelihood is small, I imagine, that you would pack a bag and travel at once to Switzerland. Still less, I dare say, would you turn your back on Geneva and head out past its western suburbs and into the pleasant but uneventful countryside beyond. There, in a broad valley shared with France, stands a collection of buildings that look like the leftovers from a 1960s Festival of Bad Design.

This is it. You have found it. This is CERN, the European Organisation for Nuclear Research. Over the next few days the people who run the place will cautiously restart the immensely large machine (almost 27 kilometres around) known as the Large Hadron Collider and begin swooshing particles around it in a way that will, when it is fully humming, recreate conditions as they were in the Universe one millionth of a millionth of a second after the beginning of the big bang.

Click here to see a graphic of the Large Hadron Collider (pdf)

Imagine the moment before that moment, when there was no space, no time, no matter, nothing. It is not easy to conceive such a nothingness, but that is what there was. Then, in a moment of unimaginable majesty and abruptness, there came into being the spacious, mysterious void in which we float, and all the matter therein and much else besides. Everything there is — light, matter, the laws of physics — traces back to that moment of creation. Now, for the first time in 13½ billion years, the circumstances of that event can be replicated, but with the crucial difference that this time some of the smartest people on Earth can draw up chairs and watch. It is this that may soon make CERN the most exciting place on Earth, or possibly anywhere.

CERN: what went wrong the first time?

The LHC shut down last year when one of 50,000 soldered joints failed. A CERN expert explains why it probably won't again

BACKGROUND

• Back to the beginning: a history of CERN

• LHC: a force to be reckoned with

• Where is God at the LHC?

• LHC: Black holes and bunkum

Particle physicists divine the secrets of the Universe in a startlingly straightforward way: by flinging particles together with violence and seeing what flies off. The process has been likened to firing two Swiss watches into each other and deducing how they work by examining their debris. “We like to think it is a little more sophisticated than that,” James Gillies, a CERN physicist who is now director of communications, tells me, smiling, as he shows me into a vast hall called the Magnet Assembly and Test Facility.

Just over a year ago, as you may recall, CERN experienced a big bang of its own when the newly unveiled LHC suffered an electrical arc in one of its 50,000 soldered joints. The result was something called “a thermal runaway event” in the area known as Sector 3-4. This isn’t something you want to have happen in your kitchen kettle, much less in the world’s biggest and most expensive machine.

Off to one side in the magnet hall is a length of LHC pipe containing one of the damaged magnets. Part of the cover has been removed to expose the interior and Gillies invites me to have a look. The damage appears to be surprisingly mild considering that this has shut the project down for a year and cost millions. There is no soot or scorching or anything like that. All that betrays the costly havoc within is a small array of delicate metal prongs that should lie flat and are instead curled backwards. They look as if they could be smoothed flat again with one’s fingers and that all would then be fine.

“It doesn’t look too bad,” Gillies judiciously agrees. A genial Englishman in his forties, Gillies has a kindly knack for making even the most ill-informed comments sound judicious. “But obviously we didn’t want anything like that to happen again. A big part of the past year has been spent going over the whole system extremely carefully.”

The first thing that strikes you when you see the Large Hadron Collider is how remarkably uncomplex it looks. It is essentially just a long, shiny pipe running through a large concrete tunnel. It looks like a pipe that would run under any city street, carrying water or sewage, but this is a deception. The interior of the pipe is a wondrous, sleek realm of cryogenics, superconducting materials and much else of a technologically ambitious nature. To accelerate particles satisfactorily, the medium through which they fly must be as airless as the surface of the Moon and as cold as deep space. Try to maintain that over 27 kilometres of tubing — actually 54, because there are two tubes, shooting particle beams around in opposing directions — and you will begin to appreciate what is meant by the words “cutting edge”.

“Every bit of the technology is brand new and extremely precise,” Gillies tells me. “It’s nothing like firing Swiss watches together.” The particles the LHC uses are protons or lead ions — together known as hadrons — and when fully accelerated they will be moving so fast that they will circle the 27-km-long track 11,245 times a second, at a speed 99.9999991 per cent the speed of light. That is so fast that if a light beam and a CERN beam were sent simultaneously to the star Alpha Centauri, 4.3 light years away, the CERN beam would arrive just two seconds after the light beam. Keeping the particles shooting around the racetracks without banging into the sides or shooting off into space is a fantastically delicate operation; getting them to collide on command is even more so.

“The amount of precision required is pretty breathtaking,” Gillies tells me. “I worked it out mathematically, out of cur-iosity, and I can tell you that getting two protons to collide is exactly equivalent to firing two knitting needles from opposite sides of the Atlantic Ocean and having them strike in the middle.”

“Wow,” I say, and he nods with satisfaction.

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