Inside the Large Hadron Collider
It’s been years since its last major — and largely predictable — discovery. Will the Large Hadron Collider ever unlock the mysteries of the universe?
He looks a bit 1968 — beard, leather waistcoat, jeans — and his job title is downright hippie- psychedelic. Paul Collier is Head of Beams. I meet him in a tunnel 100m below Switzerland, or maybe France. Down here, it’s hard to tell. We are inside the biggest machine in the world, the Large Hadron Collider (LHC), a 27km ring beneath the villages and farmland on the Franco-Swiss border.
Luckily for me, this machine is not switched on. When it is, there is radiation and something odd happens to the surrounding air, none of which is good for your health. I’m here now not only because it’s safe to explore but also because the LHC is having one of its periodic upgrades. This one is perhaps the most important since the discovery of the Higgs boson particle in 2012.
When it is switched on, subatomic particles rush round tubes inside the tunnel 11,245 times a second; these are the beams of which Collier is the head. He tells me the particles reach a speed that is within “walking distance” of the speed of light. I press him on this. He recalculates. It turns out the figure is 10km/h short of the speed of light — “so probably jogging speed”. Still, not bad considering light travels at 300,000km per second.
At certain points on their journey these particles are tricked into committing suicide by crashing into particles going the other way round. The resulting splatters and spirals may, one day, tell us what everything is made of and how it came to be that way. Or not. Geneva-based Cern — the European Organisation for Nuclear Research — is the great hope of every physicist. It runs the LHC, which is not only the biggest but also the best instrument of its type in the world. If the truth is to be found, surely it will be here.
Seven years ago, it seemed to be happening. Cern announced it had discovered an elusive particle called the Higgs boson. Cernies almost pass out with glee at the memory of this. “I queued for 12 hours to get into the room where the announcement was made,” says Sarah Williams, a 30-year old physicist at Cambridge University.
It was a triumph, but a predictable one. The Higgs more or less had to exist because it is what gives mass to almost everything in the universe — cars, people, buildings, planets, whatever. But what has not yet emerged from the petabytes of data spewed out of the LHC — and this has made some claim the experiment to be a failure — is the holy grail of contemporary science: a new physics.
Here, in a paragraph, is the problem with the old physics. We have quantum theory for very small stuff, relativity for very big stuff, and the “Standard Model” — which classifies all the known elementary particles. All seem to be true, yet relativity and quantum theory contradict each other and the model doesn’t entirely work. “You can’t plug the Standard Model into the universe, as it would vanish,” explains Cern physicist Mark Williams. On top of that, scientists can only study four per cent of the universe. The rest is made up of dark matter and dark energy that we can’t see or, yet, detect.
In short, 500 years after Copernicus, 300 years after Newton and 100 years after Einstein, physics is back to square one. If there’s one thing more astounding than our breathtaking knowledge, it’s our stupendous ignorance. For the physicists at Cern, that’s thrilling. “We have the exciting prospect of the next generation of experiments,” Williams says, “both at the LHC and elsewhere, which will make us even more sensitive to new physics — discoveries beyond our current understanding.”
At first sight, Cern is probably the least impressive temple of truth ever built, an assembly of nondescript, generally shabby postwar architecture inside which long, beige corridors seem to lead nowhere. There’s a canteen that’s full of young people — mainly school groups — and intense huddles of physicists and engineers.
All the real grandeur of the mission is below ground. Here you are confronted with the central paradox of the place: in order to track, observe and manipulate the smallest things in the world, we have to build the biggest machine in the world.
The tunnel is so long that it flexes with the phases of the moon. This could be a problem for Collier’s beams. “The moon deforms the tunnel,” explains Glyn Kirby, the engineer in charge of magnets, “so the LHC, like the sea, is moving. We correct for this with thousands of small magnets that push the beam back into position.”
This kind of scale can inspire wonder, but also fear. When the LHC first went into action in 2008, some feared it would create a black hole that sucked in the entire world or caused a “vacuum metastability disaster”, which would eliminate the universe. Mercifully, none of this happened.
Magnets are the muscles of the collider. They bend the particle beams round the tunnel by exploiting a phenomenon known as superconductivity: in certain conditions, certain materials conduct electricity without any resistance at all. Kirby remarks that if we all had superconductors running into and around our homes, we could run the entire planet off a single power station.
The first problem with superconductivity is that it happens at very low temperatures, a few degrees above absolute zero: –273°C. They have to use superfluid helium to keep 36,000 tonnes of equipment at this temperature. The second problem is that it can go wrong. Any little nudge of current or magnetic field can cause resistance in the electrical flow, at which point things heat up very quickly. The entire magnetic system can burn up in minutes. To prevent this, the energy from the magnets is diverted into big metal boxes called dump resistors. From there, it is dispersed into the ground. Why not just sell the power back to the electrical grid, I ask Collier. He looks at me as though he has only just realised I am an idiot. Because, of course, it would fry the grid.
As if his physics credentials weren’t enough, Collier also worked on “the non-linear mechanical behaviour of cellular plastics”. This led to the development of air soles in running shoes. So cool. They’re all like that — somehow saintly in their strange asceticism. Another Cern physicist, Pippa Wells, rapidly and lucidly explains, justifies and celebrates the whole operation. She lives physics. “You’re very enthusiastic,” I say, then immediately regret it as she blushes furiously.
Glyn Kirby loves his magnets so much he can’t stop stroking them. Dave Barney, who is working on an upgrade to some of the sensors, crouches like a Swiss watchmaker over his new hexagonal design, explaining every detail. This upgrade — which should significantly increase the energy levels and the number of particle collisions — is the reason the machine is turned off.
“We are already running at twice the original design intensity,” says Wells. After the next big shutdown — scheduled for completion by 2026 — they will move to “high luminosity” mode, in which the LHC will produce up to seven times more particle collisions and provide 10 times more data over the following decade.
Will it be enough to yank the new physics out of the swirls and splats? Quite probably not. But the Cernies have a 70-year road map for an even bigger machine — the Future Circular Collider (FCC). This will be a 100km ring under Lake Geneva that’ll cost around $37 billion, four times as much as the LHC. They’re a little hazy about how they will raise this huge sum; Cern is funded by its 23 member states and there are dark mutterings about a cash squeeze at the moment.
If only they eased up on their saintly idealism, they could probably pay for half a dozen FCCs. In the past Cern has avoided patents, preferring to share its innovations in order to further scientific discovery. Since one of the things it invented was the worldwide web — the usable internet — this might be seen as a missed opportunity. In 1989, Tim Berners-Lee conceived the web while working in an office off one of those beige corridors. There’s a plaque on the corridor wall, but it doesn’t identify the exact office because anybody working in it would be swamped by visitors.
Cern, then, gave away trillions by not having a patent on the web. Nevertheless, an ethos of transparency and collaboration is baked into the place. “I think it’s fundamental that we are open to all,” Kirby says. “This way of working accelerates the world’s understanding and its ability to solve important problems such as global warming.”
When you ask what the LHC is for, Cernies all default to one of two answers. Either they say that seeking ultimate answers and voyaging into the unknown is just what humans do, and should do; or they say that many useful applications will flow from their work. They’re right about the latter — if you like the internet, then you should love Cern. Moreover, they’re about to be even more right.
In the canteen I talk to Manjit Dosanjh, the sole medical scientist on the staff at Cern — “I’m as rare as a Higgs boson!” she cries. She shows me a 3D, coloured X-ray of a human wrist. It was made using Medipix technology, developed by Cern and various collaborators. It works, it’s affordable and it delivers a radiation dose no greater than that of our present monochrome, 2D imagers.
Cernies know more about beams than anybody else on the planet, and beams are what drive much medical research — in imaging and in the treatment of cancer. If you were to suggest that the LHC might one day cure cancer, the arguments surrounding funding and politics would look quite different. But, of course, Cernies are really explorers, not fixers. They might be discovering new technologies, but what they’re really trying to do is scratch an itch they cannot yet reach, the itch to know how it all came to be. Why, for example, is there something rather than nothing? (There should be nothing, because in the early universe there were equal amounts of matter and antimatter; they should have cancelled each other out and we should not exist.) Where is dark matter and dark energy? Why don’t our present theories work? What lies beyond them that we cannot see?
These are, in a good way, childish questions; questions we grow out of because we realise we can never answer them. But, again in a good way, Cernies don’t grow up like the rest of us. Most gave me stories of a childish wonder that would not go away — Pippa Wells, for example, says she was struck, as a schoolgirl, by the need to see the smallest possible thing.
I descend again into the tunnel to see the Compact Muon Solenoid (CMS), a mighty particle detector that encircles a section of the collider. It’s a monstrous 14,000-tonne tube, 21m long and 15m across. Inside its vast cathedral-like vault, the machine has been split apart to reveal an interior of indecipherable complexity. The scale is disorientating, vertigo-inducing. You just shouldn’t be in a room with something that big. As an architectural experience, it is unique.
In the end, the answer to the “What is all this for?” question is poetry. Unlike poetry, it is madly expensive and involves thousands of people; but, like poetry, it is an attempt to say something that has never been said before and to describe a reality previously hidden from us. Perhaps the Cernies will never get there, perhaps the new physics is a myth. But I don’t care; I like poets.
The Times