After a two-year shutdown, the $6.6bn Large Hadron Collider will have another go at unravelling the mysteries of the cosmos early next month. It confirmed the Standard Model of everything, but now scientists want to debunk it.
Prof Tara Shears has unfinished business with the universe, and she’s not alone.
All over the world, thousands of particle physicists have blocked out the first two weeks of March in their diaries for the biggest event since the discovery of the Higgs boson particle – the restart of the gigantic Large Hadron Collider (LHC) in Switzerland.
Twenty-seven kilometres in circumference and buried more than 50 metres underground between the Jura mountains in France and Lake Geneva in Switzerland, the vast particle accelerator took a decade to build at a cost of US$6.6 billion (Dh24.24bn) when it was finished in 2008.
Now, after a two-year shutdown and refit, the largest and most expensive experiment ever created is being gently warmed up for its second tilt at uncovering the secrets of the universe.
“The LHC gives us a microscope with which to examine the very smallest parts of the universe,” says Prof Shears, who leads the LHC team at the University of Liverpool, England.
“We think that everything in the universe – from ourselves, to the planets and stars – is made of the same basic building blocks.”
To understand how the universe behaves “we need to identify these building blocks and understand what holds them together and, essentially, makes the universe look the way it does”.
But she is hard pressed to explain why we need to know what makes the universe tick, or how that knowledge, should we ever definitively discover it, could benefit humanity.
It is true that the project and its need to connect scientists around the world is often credited with having given us the World Wide Web, while the science it has spawned has helped to improve particle accelerator-based medical scanning technology.
But she says that probably the greatest achievement of a project conceived after the Second World War and the dawn of the atom bomb era, has been to allow scientists of different nations “to collaborate together on questions of fundamental scientific importance, but without being constrained by research towards any sort of military gain”.
The LHC is operated by Cern, the European Organisation for Nuclear Research. Each year, come good times or belt-tightening recession, Cern is funded by more than 20 European countries to the tune of well over $1bn (the annual electricity bill alone exceeds $23 million).
This makes its Quixotic pursuit of universal truth not only the purest, but also the most expensive example of seeking knowledge for knowledge’s sake.
Cern, says Prof Shears, “reflects something very good about human nature, that was a reaction to something that happened which reflected the very worst parts of human nature”.
And the very existence of the vastly complex LHC provides physical proof of the ability of human beings to work together.
Whatever the lofty cause, back under the ground the LHC is gearing up to do its thing.
It works by firing two beams of particles, such as protons, in opposite directions at close to the speed of light (1,080 million kph), which means they circle the 27-kilometre tunnel 11,245 times a second.
When these beams are made to collide, which they do at up to 40 million times a second, for “a tiny instant in time” the LHC creates the incredibly high temperatures necessary to break down matter into its constituent parts.
Watching and waiting for those fleeting moments is an array of experiments, says Prof Shears, designed to “take snapshots of those fundamental building blocks of matter as they fly outward from the collisions”.
It’s a process that generates an insane amount of data. By the time the LHC was shut down in 2013 for its first scheduled overhaul, thousands of computers around the world were grinding their way through 100 petabytes of raw data, or the equivalent of 700 years of high-definition movies.
It was this process that in 2012 led to confirmation that a particle about which physicists had theorised for 50 years actually existed.
The Higgs boson is the cornerstone of the Standard Model of particle physics, the so-called “theory of almost everything” that explains, well, the existence of pretty much everything.
In the Standard Model, it is the previously elusive Higgs boson that gives mass to all other particles, which means it is the key to the very existence of all matter, including us.
But now, having more or less proved the Standard Model to a degree of certainty that most mortals would consider a slam dunk, the LHC scientists are licking their lips at the prospect of debunking it.
“The Standard Model is brilliant,” says Prof Shears. “Its predictions agree with everything we’ve seen. However, we know it’s incomplete at best, and that it’s not the whole story.”
There are, she says, “many phenomena that we cannot understand with it – what dark matter is, how to describe gravity, why there is so little antimatter in the universe – really big questions”.
That means the much-vaunted Standard Model is almost certainly flawed, Prof Shears says, which seems a shame given that finding the Higgs boson cost an estimated $13bn.
“So what we’re really looking for now in the LHC is that point at which our theory starts to break, because this is going to give us the direction that we need to go to really understand what’s going on in the universe.”
All this depends on the LHC actually working properly and, as a calamitous failure in 2008 demonstrated, the success of this high-tech collaboration of thousands of the greatest minds from 20 countries can fall foul of something as simple as the low-tech incompetence of an electrician with poor soldering technique.
The first run of the LHC ended with a bang and a whimpering of disappointed scientists.
The first beam was successfully steered around the accelerator on September 10, 2008. But the whoops of joy in the Cern control room had barely died down when, just nine days later, the failure of a component worth a few cents brought the collider to its knees.
“It was shortly after we turned up the current and turned on the magnets,” Prof Shears recalls with a sigh.
The LHC uses hundreds of giant supercooled magnets to keep the particles on track. Without the force they exert, the particles would simply keep going in a straight line.
Just one of the many thousands of tiny wired connections between two of the magnets failed, creating a hot spot. This heated up the supercooled helium around it, which then vaporised, escaping explosively.
In all, 53 magnets had to be removed for repair or cleaning, putting the LHC out of commission after barely a week of use.
“Mending the machine and cleaning it out took almost a year,” says Prof Shears. “We wanted to be absolutely sure that it wouldn’t happen again, so we introduced many more safety features.”
After its unscheduled 12-month shutdown, the LHC ran trouble-free for the next three years, creating “hundreds of trillions of proton-proton collisions” to be monitored and analysed.
In July 2012, seven months before it was due to be closed for the scheduled maintenance that is now coming to an end, the particle “consistent with the Higgs boson” was detected.
The machine was switched off in February 2013 for what Cern called “LS1”, its first long scheduled shutdown.
More discoveries would come now only if the LHC could be run at higher energies and, in addition to routine maintenance, all of the connections between the magnets had to be rebuilt so the machine could run at its target power.
Scientists are expecting to fire one beam around the LHC next month, followed shortly afterwards by the other, travelling in the opposite direction, to test that the machine is working properly.
It will be at least two months before those beams are allowed to collide.
“It’s not a case of just switching it on and going,” says Prof Shears.
“We have to test it out step by step, and we’re hoping for what we call physics, which is two beams in the machine giving us collisions over a certain rate, to occur by May.”
Then, she says, the first order of business will be “to really nail the Higgs. This is an opportunity to see whether we have actually got something really associated with the Standard Model, or whether it’s not quite”.
“And it is that ‘not quite-ness’ that is going to give us our first direction in extending our understanding of the universe.”
Soldering allowing, of course.