Atom smashing in the world's greatest machine

April 24, 1998

It houses a scientific instrument longer than London's Circle Line, and employs some of the brightest physicists on the planet. Ayala Ochert reports from Cern - where the mission is to discover the ultimate nature of the universe

Switzerland may be an unlikely setting for the demolition of the clockwork universe but, nestled between the Alps and the Jura mountains is Cern, the European Laboratory for Particle Physics, where experiments explore the bizarre and far-from predictable behaviour of matter.

Hundreds of metres below ground, tiny particles of matter are driven round huge circular tunnels until they smash together, recreating in a blinding flash the conditions of the early universe. The idea for this extraordinary laboratory was explicitly political. After the end of the second world war, it was hoped that a European centre could be established where scientists who had previously fought each other could work together towards a non-military goal. In 1952, Unesco chose nuclear research as that goal. Nowadays, concerned to distance itself from anything "nuclear", Cern prefers to be known by its acronym rather than its original full title of Conseil Europeen pour la Recherche Nucleaire.

Cern was the first international organisation that Germany joined after the war, and the first to take in countries from the former Soviet Union. Although it retains its European identity, it has become increasingly international; non-Europeans comprise 30 per cent of its "users", all working towards an understanding of the nature of the material world.

Physicists had hoped for a straight-forward description of matter in terms of one or two elementary particles, but, over the years, accelerators - the machines that drive matter through the tunnels - churned out more and more particles, thwarting hopes of a simple explanation. Larger and more elaborate machines were designed to cope with this "particle explosion", each working at higher energies, emulating the environment soon after the Big Bang.

The biggest accelerator, the Large Electron-Positron collider (LEP), built in 1989, uses up 40 megawatts of electricity - the output of a small power station - and is housed in a tunnel longer than the London Underground's Circle Line. It will be wound down in 2000 to make way for the Large Hadron Collider (LHC). All hopes are now pinned on the LHC, which will be housed in the same km tunnel but will run at much higher energies, to provide evidence of yet more particles and to test current theories of matter and its interactions, particularly the so-called "standard model" of the universe.

Economising on magnets

The mood among scientists at Cern is currently upbeat thanks to the promise that the LHC accelerator will be up and running at full strength by 2005.

Yet when Cern asked its member governments to stump up the cash to build the world's most powerful accelerator, the response was negative. As director-general Chris Llewellyn Smith recalls being told: "The most you're going to get is a budget that is going down 1 per cent each year in purchasing power. Can you do it or not? And if the answer's no - no LHC." His intentionally ridiculous solution was to build the LHC leaving out every third magnet. The machine would then run at two-thirds capacity until there was money to install the rest of the magnets.

Until then, all the funding for Cern's infrastructure had come from its European members alone, non-members contributing only to the experiments themselves and by sending over their own scientists. But Llewellyn Smith dared ask for more: "I got on a plane and went to Washington, Tokyo, Moscow, Delhi, Tel Aviv and Ottawa and said, what about it? You're getting a free ride anyway on the world's greatest machine." The argument worked and Cern recently secured enough money to build the machine in one go.

The United States was the last to agree, but its involvement is the most significant. In recent decades, there has been a "friendly war" between US and European high-energy physics, which the Americans planned to "win" by building the gargantuan Superconducting Supercollider (SSC). But in 1993, Congress cancelled the project. Budgeted at $2 billion, it was heading for $15 billion by the time it was dropped. Many of the scientists working on the SSC have now transferred to Geneva.

Back at Cern, they are acutely aware of the need to stick to budgets. "In Europe, if we go even 20 per cent over cost, that's going to be the end of the project," says Llewellyn Smith. He believes that the Americans could have kept costs down, as Cern has done, by building the accelerator at an existing site, rather than trying to start from scratch in the middle of nowhere in Texas, as they tried to do.

But he also believes that they made other crucial mistakes. "They hyped it, and they let their political supporters hype it to a degree that was intellectually dishonest. Statements such as the SSC's going to cure cancer. They stood back and let people say that," he says.

When campaigning for these expensive high-energy accelerators, says Llewellyn Smith, the primary justification must always be the value of the research itself, that "we should go on pushing back the frontiers of knowledge". Although there have been spin-offs from the work done at Cern - medical imaging scanners derive from the laboratory's particle detectors and the invention of the world wide web, - their value is impossible to quantify.

Cern's ability to stimulate industry, by providing an extremely demanding technical environment, however, can be measured. "On average, for every pound that Cern places on an order with high-tech industry, that company generates three pounds in business later." High-tech industries seem to enjoy Cern's company so much, that many have parked a few miles away. They know that Cern will test their latest technology to its limits. In fact, computers do not exist that are fast enough to analyse data at the rate of the 3000 bits per second that the LHC will produce.

Big science

Cern has little difficulty attracting talented young scientists, taking in more than 300 PhD students each year. Particle physics, like cosmology, is considered a glamorous area, and acts as a flagship science, attracting young people to study physics in the first place. But, in the US at least, the physics community has been criticised for encouraging its young physicists to train in particle physics when the opportunities for most of them to continue in the field are limited.

Cern claims to be more realistic. It promotes itself to young scientists as an opportunity to gain experience in an international environment, learning skills that they can take with them to industry. As a result, Cern physicists are highly sought after. Many will end up working with computers, but they have also become very attractive to fund managers for operating computer simulated economic forecasts. So if they are not looking for fundamental particles, they may end up looking after your pension.

Whatever the justification, particle physics has to maintain its high profile simply because it is the most expensive subject there is. Cern likes to consider itself a model for what big science can achieve. But bigger may not always be better, as Llewellyn Smith admits: "Because of the long timescale and the cost there is inflexibility. You cannot go to governments and say, nobody's ever looked at this before, I haven't got the slightest idea what it'll produce but it's new, can you please give me Pounds 1 million? You have to say, I think I'm going to discover 'this'. Of course, if you knew you were going to discover it, then you wouldn't have to do the experiment, so it's a paradox."

He also claims that measures have been taken to limit the problem, for example by encouraging competition between different detector teams and by building "general purpose" detectors. "We deliberately look at the craziest ideas people have had for improving the standard model of matter and make sure the detector can look at anything."

But with billions invested in improving the standard model, is there really any chance of generating a non-standard model?

The story so far

Modern physics has a modest enough aim - to explain the world in terms of the basic particles of matter and the forces that bring them together or drive them apart. That goal seemed closer when there were only a few fundamental particles to deal with - electrons, protons and neutrons. But there are now more kinds of particle than ever and, if some people are to be believed, there are many more yet to be detected.

Physicists divide the world into elementary particles and fundamental forces, of which there are four: gravity, electromagnetism, the weak nuclear forces and the strong ones. Gravity operates according to the principles of Einstein's theory of general relativity, and physicists' understanding of how matter interacts with the other three forces is embodied in the standard model of matter.

According to this model, there are three generations of matter particles, each containing four fundamentally irreducible particles - two quarks and two leptons. Just to confuse matters, physicists also like to think of fundamental forces as being carried by force particles or bosons. The particle that carries the electromagnetic force, for example, is the photon.

They also have a penchant for unifying theories. Why have four theories, they ask, one for each force, when you can have just one? In the 1960s, the "electroweak" interaction was born out of the unification of the electromagnetic and the weak nuclear force. This theory predicted the W and Z bosons and in 1983, Carlo Rubbia headed a 100-strong team of Cern physicists that detected these particles to the applause of the scientific community.

But just as Rubbia and others were trying to simplify their physical theories, other were predicting the existence of a new set of particles which were duly discovered. For every matter particle, there is a particle of "antimatter", identical in every feature but with an opposite electrical charge. So, corresponding to the electron, is the positron.

What is mass?

Dealing with the acknowledged shortcomings of the standard model will occupy Cern well into the next century. The most publicised of these problems, thanks to cosmologist Stephen Hawking, is that of unifying all four fundamental forces into a "theory of everything". When the LHC is switched on in 2005, it will measure the relative strengths of the four forces at energies higher than ever before produced, and, in so doing, will put constraints on any ambitious unified theories thought up in the meantime.

A separate problem is that of mass itself. "Newton told us that particles weigh because they have mass, but he didn't tell us what mass was," says Cern theoretician John Ellis. "Einstein told us that mass is the same thing as energy, but he still didn't tell us what mass was. The question that we now hope to be able to answer is, what is mass?" It sounds impossibly metaphysical, but theoreticians believe they have a plausible solution to the "problem of mass" in the form of the Higgs boson - a unique, as yet undiscovered, particle postulated by Peter Higgs of Edinburgh University. "You have to imagine that the universe is filled with an invisible field associated with this Higgs boson. You can think of it as being some sort of universal cosmic mud that the different particles are trying to wade through," says Ellis. "They may get more or less weighed down by the mud and so be able to move faster or slower through it." So while massless particles such as photons can move at light speed, particles with mass are slowed down by this "mud".

But while it accounts for the property of mass, the Higgs boson makes the standard model unwieldy. "Many of us think that, in addition to the Higgs particle, there must be a whole bunch of other particles. According to this theory (known as supersymmetry), all the known matter and force particles must be accompanied by very similar particles which have the same charges - the only difference is that they 'spin' by a different amount," says Ellis. Like mass and charge, "spin" is a defining property of elementary particles. "So corresponding to the quark, there should be a squark. Corresponding to the photon, there should be a photino."

Should the LHC detect the Higgs boson and some supersymmetric particles, says Ellis, then the problem of mass would be solved. Because they also believe that the lightest of these putative supersymmetric particles is stable, it may still remain as an ancient relic of the Big Bang. "In fact, many of us think that this (supersymmetric particle) is the prime candidate for the 'dark matter' so beloved of cosmologists." Dark matter is matter which physicists calculate must be around in the universe, yet they are unable to see it.

"So if we were able to find supersymmetry, we might also solve one of the biggest problems in astrophysics and cosmology as a 'spin-off' of our particle physics experiments," predicts Ellis.

Cern woman

Helenka Przysiezniak does not fit the stereotype of a physicist. To begin with, she is a woman, which puts her in a minority of less than one in eight. An amiable character, she quickly puts people at their ease.

But many of the physicists at Cern do fit the bill, says Przysiezniak. They lack basic social skills and some do not take care of themselves. So she is not as surprised as she might be to hear the story of a theoretical physicist at Cern who managed to get scurvy from eating nothing but junk food from the cafeteria. But there is one characteristic that she says that all physicists have - herself included - and that is "arrogance".

Przysiezniak's friends may be horrified by the transformation she goes through whenever she discusses physics with a colleague, but she justifies the change. "It sounds like you're having a big argument, but actually you're just discussing things. You want to prove that something is right if you believe in it. That's just how it works when you're discussing the 'truth'," she claims. "You can't survive (as a physicist) if you don't have a bit of ego."

These impromptu debates are central to culture at Cern - they happen in corridors, in the cafeteria, in one another's offices - and they took Przysiezniak some getting used to. Having done her master's degree in Canada as a theoretician in astrophysics, she was used to working alone, and was at first reluctant to leave the safety of her computer. But that was not the only culture shock that she experienced on getting to Cern:

"When you arrive, you're one of only a handful of women and everyone just stares at you or makes comments, so you don't dare go out of your office. If you sit alone at the cafeteria, you're bound to have comments thrown at you."

Despite this unwanted attention, Przysiezniak "fell in love with the physics" and decided to do her PhD at Cern. "It's a very elegant theoretical model mathematically, and that pleased me. And the experiments - when I got there somebody said, here, take care of this beam of particles, shoot it into that detector and take data - it was a lot of fun."

Przysiezniak suggests that a psychological analysis of the personalities that physics attracts would reveal that they are very focused, one-track minded, obsessive even. They tend to be just as passionate about their other interests - many are accomplished musicians and concerts are held at Cern almost daily. The mountains and lakes around Geneva offer the chance for skiing, mountaineering and sailing. In the summer, social life moves into a higher gear as the place is inundated with students who have come for the "Cern experience".

What they might not be warned about is the strange effect that physics can have on the mind. "When you've been working for ten days non-stop, you do walk out of your office with nothing to say. You feel you're on another planet and you're not particularly sensitive towards other people," she says.

Although she is unable to explain why there are not more women like her who are interested in physics, she does believe that physics could benefit from becoming more "feminine", and she offers some hope: "Women are less arrogant than men, but you don't have to be completely arrogant to do physics."

The Web

Research at Cern has led to many technological spin-offs, but none bigger than the world wide web. Nor could its arrival have come at a better time for Cern. In 1994, when the world was just beginning to wake up to the web's potential, Cern went to its members to ask for billions to fund its LHC project. The project was approved.

Although the Internet itself had been used by academics and computer enthusiasts for years, Cern physicists were frustrated by its limitations, and asked their computer department to devise a solution. The result was a joint proposal in 1990 by Tim Berners-Lee and Robert Cailliau to set up the world wide web. The web would allow documents to be linked seamlessly across the network for the first time.

It has since been claimed that had the world wide web not been developed at Cern, it would have developed elsewhere, but Cailliau believes that the environment at Cern was crucial. "What we needed was a non-proprietary network system. We could not have it linked to a specific company, to a specific software vendor or to a specific telecoms company, and it had to work on any machine," he says. Networked computer systems like the Minitel developed by France Telecom failed to take off, says Cailliau, because they were tied to a particular company. No company would ever have developed a system with the web's universal nature.

But once the project began to gather momentum, he and Berners-Lee were afraid that someone would develop the web as a purely commercial product, so they set up the International World-Wide Web Consortium (W3C), bringing all interested parties together to cooperate on web development. They succeeded in bringing representatives from software arch-rivals Microsoft and Netscape around a table to agree on how the web should work.

The rapid spread of the web's popularity was a great surprise to its inventors. But they soon became frustrated at the way the web was taken out of their hands and used in ways they had never intended.

Apart from the problem of undesirable content, (such as pornography) Cailliau felt that people mistook the web for "modern paper" rather than something "much more useful".

Please login or register to read this article

Register to continue

Get a month's unlimited access to THE content online. Just register and complete your career summary.

Registration is free and only takes a moment. Once registered you can read a total of 3 articles each month, plus:

  • Sign up for the editor's highlights
  • Receive World University Rankings news first
  • Get job alerts, shortlist jobs and save job searches
  • Participate in reader discussions and post comments
Register

Have your say

Log in or register to post comments