It's the end of the world as we know it, but a bunch of scientists far underground feel fine


At last it’s D-Day for physics wonder machine the Large Hadron Collider, but those involved say it will not mean another Big Bang, writes DICK AHLSTROMScience Editor

GOOD NEWS – if you are reading this after 8.17am, then the end of the world has not arrived.

Some predicted it would once the world’s biggest atom smasher got up to speed and began creating the highest energies ever recorded on Earth.

At 8.17am precisely this morning, operators at the €4 billion Large Hadron Collider (LHC) at Cern on the French/Swiss border were scheduled to begin crashing hydrogen nuclei together.

Travelling around the underground 27km-long LHC ring at close to the speed of light, these collisions give off tremendous energies akin to those generated after the Big Bang that created the universe.

There were unwarranted concerns about the project.

Some feared that once the LHC started crashing particles together, the energy would trigger a mini black hole that would gobble up the Earth and consume us all in an instant.

But if 8.17am Irish time has come and gone, then we should be grand. We will have to wait for Nama or some other cataclysm to overtake us.

The collider’s operators, including the Irish scientist in charge, Belfast man Dr Steve Myers, were this morning not contemplating the other possibility – that the machine might break before collisions could occur.

This happened back in September 2008 when, within days of a successful first start-up, the LHC blew a gasket and had to be shut down. It took more than a year and €40 million to put things right.

As a result, the LHC team was very cautious once they started the machine up again last autumn. They brought energy levels up very slowly and developed a whole new protection system to prevent the kind of failures seen at the last shutdown.

The science behind the huge collider is staggering. Enormous electromagnets placed around the LHC ring control twin beams of hydrogen nuclei.

The nuclei travel in opposite directions and move at close to the speed of light, which gives them huge kinetic energy.

On command, these beams can be crossed to allow collisions to occur. It is no small thing to achieve this, however, as Dr Myers points out.

“Just lining the beams up is a challenge in itself. It is a bit like firing needles across the Atlantic and getting them to collide half way,” he said before this morning’s start-up.

Physicists collide particles because doing so informs them about the nature of matter and its inner structure.

The energy levels involved are so high that “big” things like single atoms break down into their constituent parts, allowing scientists to find the fundamental or smallest possible parts.

These fundamental particles only last for an instant before reforming into something else. Sensitive detectors, including one called the LHCb, which has Irish involvement, can measure the short-lived fundamental particles and classify them.

Energies involved in colliding particles are measured in electron volts, and in the case of the LHC we are talking about a million million electron volts, or tera electron volts – TeVs.

The previous record holder, the Fermilab complex in Illinois, USA, achieved beam energies of 0.93 TeV each, or combined collision energies of 1.96 TeV.

Just before Christmas, Cern sent twin beams of 1.18 Tev each around the ring, giving collision energies of 2.36 TeV, but this morning’s collisions are of a different order altogether. Beam energies of 3.5 TeV will give collisions of 7 TeV.

Such a record, if set this morning, will also be dwarfed in time.

The LHC is designed to achieve routine energies up to 14 TeV, and possibly double that if they use lead particles rather than hydrogen for the collisions.