11 September 2008
What is LHC?
The Large Hadron Collider atom smasher, or the LHC, a 17-mile circular tunnel situated 100 metres underground near Geneva, is the biggest experiment ever.
Located at CERN, the European Centre for Nuclear Research, it is the most powerful in a series of particle accelerators that, over the last 70 years, have allowed us to penetrate deeper into the heart of matter.
It will recreate conditions not seen since the big bang of creation to probe the secrets of the cosmos.
Well, in the words of Stephen Sondheim, I'm still here. And so are you, I hope. Despite all the newspaper headlines about black holes, practically no one expected any cataclysmic consequences to arise from the switching on of the Large Hadron Collider at CERN.
The apocalyptically-minded among you can continue to worry a bit, however; it will be several months before the particles begin to collide at a couple of Tevs under c (which is to say 99.9999991 per cent of the speed of light). Perhaps we'll all be engulfed then.
Scientists controlling computer screens at CERN
But the point of the experiments being conducted beneath Geneva are that nothing in the standard model of physics suggests any such danger, Instead, they may provide us with confirmation of the existence of subatomic particles (such as the celebrated boson named for Professor Peter Higgs) which have so far eluded detection, but which would fill the gaps in the arithmetic of theorectical physicists.
At the most simplistic level possible, one of the reasons for attempting to recreate the circumstances of the plasma, or primordial soup, which sprang into being fractions of seconds after the Big Bang, is that the universe ought not to exist.
Were any of several factors (energy, momentum, quantity of matter, proportions of heavy elements) even slightly different, there would be nothing here now. Every visitor to CERN – I was lucky enough to go down into the tunnels last year – is overwhelmed by the sheer scale of this enterprise: millions of man hours, 17 miles of tunnel, 10,000 researchers and £4.4 billion.
The machines are the size of tower blocks, but built to within tolerances smaller than a human hair. The people who work there are very keen to point out the practical applications, no doubt in response to those who suggest that this is a lot of money to spend, and that science spending might be better devoted to curing cancer, or devising an alternative to fossil fuels.
Actually, CERN has done pretty well on the practicality front: MRI scanners for medical use owe almost everything to the work undertaken there, and it gave the world (entirely free) the World Wide Web.
But the lack of an immediate quotidian purpose is, in fact, one of CERN's chief triumphs. It is a vindication of the human desire to understand more about the world we live in, simply for the sake of pure knowledge.
All the same, for those of us who have trouble getting our minds round the finer points of this fearsomely difficult physics, I was comforted when Dr James Gillies, CERN's head of communications, admitted to me that almost everyone who works there occasionally thinks of the particles they are studying in terms of billiard balls clacking into one another, and conceded that one of the things they might find out is that human beings are – in evolutionary terms – not all that well designed for understanding the finer points of the universe's structure.
CERN is routinely compared, as a work of engineering, with the great cathedrals. It has also been cited as the principal wonder of the modern world. It is both. Look at the trouble humans will go to to understand just a little more about the world we live in, and be grateful that we do.
