Large Hadron Collider – will it cause the end of the world?

After 14 years of effort and an expenditure of £4.4 billion pounds, a milestone will be passed in commissioning the Large Hadron Collider, the biggest and most complex experiment ever devised to lay bare the secrets of nature. 

The monster atom smasher is located in a 17 mile circumference underground tunnel near Geneva, at the European Organisation for Nuclear Research, known by its French acronym, CERN.

The project will generate spin off benefits for leading edge technology, a boost for physics education, and marks a seismic shift in the epicentre of world research in particle physics away from America, where the rival Superconducting Supercollider was scrapped in 1993, to Europe where Britain alone has contributed £500 million to the project.

There have been well publicised legal challenges to halt the project, often accompanied by the headline "Will the World End on Wednesday?"

But the planet’s best known scientist, Prof Stephen Hawking of Cambridge University, dismissed concerns that the LHC will seed a black hole to swallow the Earth: "The world will not come to an end." 

Nature routinely produces higher energies than the LHC in cosmic-ray collisions and, though focused in a tiny spot, each collision between particles only releases an amount of energy comparable to two colliding mosquitoes.

"The LHC is feeble compared with what goes on in the universe," says Prof Hawking. "If a disaster was going to happen, it would have happened already."

Tomorrow will see the first particles circulating in the tunnel, as the giant machine limbers up to smash particles for the first time, in around 30 days.

When operational, two beams of subatomic particles called ‘hadrons’ – either protons or lead ions – will travel in opposite directions inside the circular accelerator, gaining energy with every lap.

Physicists will use them to recreate the simpler conditions that existed just after the Big Bang, by colliding the two beams head-on.

The LHC will produce beams seven times more energetic than any previous machine, and around 30 times more intense when it reaches its design performance, probably by 2010.

In this way, researchers will probe more deeply than ever into the mysteries of the universe.

Among the possible unknowns that the LHC will investigate are the origins of mass, which would be signalled by the discovery of the so called Higgs particle, after the Newcastle born physicist who put forward the idea, along with two researchers in Brussels. Some call it the "God particle," a tongue in cheek reference to how it should unlock many mysteries.

Prof Hawking has placed a bet of $100 that the LHC won’t find the Higgs, though he added there were plenty of other crucial findings that might be made by the machine, not least the creation of mini black holes.

If these were to evaporate in a way he predicted in a theory that blends quantum mechanics and general relativity, "I don’t think there is any doubt, I would get a Nobel Prize."

"However I think the probability that the LHC has enough energy to produce little black holes is less than 1 per cent – so I’m not holding my breath."

The LHC may also find extra dimensions of space, evidence for dark matter – a mysterious source of gravity – and an insight into the puzzling preponderance of matter over antimatter, which should have been created in equal amounts in the Big Bang.

Most of all, scientists hope it will fill in important missing pieces in our understanding of how the cosmos words. For decades, the "Standard Model" has served physicists well as a means of understanding the fundamental laws of Nature. But it does not tell the whole story.