Can we unlock the secrets of the Big Bang?

Physicists might be about to get answers to some of their biggest questions, writes Tanya Thompson

IT IS billed as the world's biggest scientific experiment and brings with it the promise of unravelling the deepest mysteries of the cosmos. Scientists will tomorrow "switch on" the most powerful particle accelerator ever built as they prepare for an epic journey to catch a glimpse of what happened at the dawn of time.

Experts are attempting to recreate the forces that occurred in the immediate aftermath of the Big Bang. But as critics point out, the gamble is not without risk and no-one really knows what will happen when scientists flick the switch.

Some have even predicted the end of the world, and those behind the project have received death threats and frantic phone calls from members of the public who fear the machine could cause earthquakes, tsunamis and cosmological phenomena that will destroy the planet.

The 5 billion Large Hadron Collider (LHC) will smash protons – one of the building blocks of matter – into each other at energies up to seven times greater than any achieved before. In the flashes from the collisions, scientists expect to reproduce conditions that existed during the first billionth of a second after the Big Bang.

Built by the European Organisation for Nuclear Research (Cern), the collider lies beneath the French-Swiss border, near the institution's headquarters in Geneva.

No-one knows precisely what will come tumbling from the disintegrating protons, but scientists say they could find answers to some of the biggest questions in physics, such as why the universe looks the way it does, and how to explain mass, gravity and mysterious "dark matter".

They could also find the first evidence of extra-spatial dimensions, and even create mini-black holes that blink in and out of existence in a fraction of a second.

The LHC is housed in a 17-mile tunnel buried under 100 metres of rock between Lake Geneva and the Jura mountains. Beams of protons will be accelerated in opposite directions through the ring-shaped tunnel, which is supercooled to minus 271C, just 1.9 degrees above absolute zero , the lowest temperature allowed by nature.

Reaching speeds of 99.9999991 per cent of the speed of light, each beam of the tiny particles will pack as much energy as a Eurostar train travelling at 100mph. The particles will then be brought together in four huge "detectors" placed along the ring, with each detector, like a giant microscope, designed to probe deeper into the heart of matter than has ever been possible before.

Particle physicist Dr Brian Cox, from the University of Manchester, who will be working on Atlas – one of the two largest detectors – said: "The Large Hadron Collider is the biggest scientific project since the Apollo astronauts went to the Moon, and that's no exaggeration. It is the most complex machine ever built, and it's going to take us to a place we've never been before."

Dr Cox, who in the 1990s played keyboards in the chart-topping band D:Ream, will be in the Cern control room for the "switch on".

It all sounds great in theory, but critics will be asking whether it is really worth the risk, given there is even the smallest possibility that it could signal the end of the world. A number of respected scientists believe that the experiment could create a shower of unstable black holes that could "eat" the planet from within, and they have launched last-ditch efforts to halt it in the courts.

Professor Otto Rossler, a German chemist from a group of scientists mounting a last-minute court challenge, is especially worried about the creation of black holes. He fears the experiment may create a devastating quasar – a mass of energy fuelled by black holes – inside the Earth.

Prof Rossler is predicting earthquakes and tsunamis in a "biblical armageddon" and a dramatic change in weather patterns that could wipe out life on Earth. He said attempts were still being made in the European Court of Human Rights to halt the experiment on the grounds that it violated the right to life.

So, if we're not all wiped out tomorrow, what's in it for us? Could the machine really solve the mysteries of the cosmos, or are we just getting caught up in the hype? At 5 billion, this experiment does not come cheap and the public will surely want to know how this venture will materially improve our quality of life.

Those leading the project insist the benefits for mankind could be huge. Major spin-offs have already emerged from earlier particle accelerator experiments at Cern. Scanners and modern radiotherapy machines are two examples of key medical applications, and proton accelerators – like the LHC but on a much smaller scale – are now being tested for their ability to kill tumours.

Among the many things scientists are hoping to find, the "Holy Grail" would be the Higgs boson, named after the former University of Edinburgh physicist Peter Higgs. It is an elusive particle that scientists believe gives everything in the universe its mass, and hence its weight.

Richard Kenway, a professor of mathematical physics at Edinburgh University, has 20 of his colleagues working on LHC and he is quick to dispel the apocalyptic vision trotted out by some of his peers.

"It's tabloid nonsense to say it's the end of the world. The usual concern is that a collision of protons might create a small black hole that would swallow up the earth. That's nonsense," he said.

"These collisions at Cern are happening all the time when cosmic rays hit the atmosphere. Throughout the history of the Earth these collisions have happened and clearly we're still here to tell the tale."

He added: "Five billion pounds is not a huge amount of money, given the potential benefits. Many countries are pooling the cost, and when you compare it to the cost of a single military aircraft – or the Olympics – it's worthwhile.

"There are huge technical spin-offs and it inspires young people to follow careers in science. We're going for gold in the cosmic Olympics."