The nature of matter and mass: One of the Greatest Mysteries of Modern Science
40 years ago, an unknown physicist in Edinburgh, Scotland, came up with a theory of how the universe holds together - sparking a multibillion dollar race to find the key particle. Is the most sought after prize in modern physics about to be won at last?
Amid 800 acres of landscaped grounds a mile from Princeton, New Jersey, stands the Institute for Advanced Study, one of the world’s most prestigious centers of scientific thought. Within this intellectual microcosm, many of the most accomplished physicists in history, from Oppenheimer to Einstein, have wrestled with the deepest puzzles of the universe. To be invited to talk at Einstein’s former lab remains among the highest honors a scientist can receive. And it was with this terrifying thought in mind that in March 1966 Peter Higgs, a 36-year-old physicist from Edinburgh University, loaded up his car and headed up the freeway.
Tucked into Higgs’s luggage was the reason he had been invited. The notes for his highly contentious lecture overturned some of the most deeply-held beliefs of the resident experts. They proposed something remarkable, that an invisible field, which stretches throughout the entire universe, holds the key to one of the greatest mysteries of modern science - the nature of matter and mass.
Higgs was pondering the talk and how it would go down among the biggest brains in physics, when it all suddenly became too much for him. Out of the window, he glimpsed a roadsign to Princeton. It was enough to trigger a fit of panic. Shaking, Higgs pulled into a rest area and sat there panting, waiting to regain his composure.
More than 40 years later, Higgs is still largely unknown beyond his field, but that is about to change. The multibillion dollar race to discover if his theory is right is finally nearing its climax. Either way, the answer will propel 21st-century physics into a new and uncertain era. Higgs, who turned 78 in May, is clearly a Nobel prizewinner in waiting. “I have to ask my GP (general pracitioner) to keep me alive,” he says, when we met in his Edinburgh apartment.
Higgs rarely gives interviews; it’s not so much that he refuses as lets the requests gather dust until it’s too late. The phone goes unanswered, pleas through friends come to nothing, emails evaporate in the ether. Good old letters are his preferred means of communication. Luckily, Higgs has found a few hours to spare before rushing off to join his wife for another round of Monteverdi madrigals at the festival that first attracted him to the city in 1949. He tells the story of his unwitting discovery of something in the emptiness that surrounds us. “It has consequences,” says Higgs, pausing to fold his arms so that each hand can rub the opposite’s elbow. “If it wasn’t there, we wouldn’t be here.”
Higgs was born in Newcastle in 1929, but the family moved around with his father’s job, as a sound engineer with the BBC. He missed a lot of early schooling. Bouts of serious asthma drifted into pneumonia (”not funny when there aren’t any drugs”) and he was kept home and taught by his parents. As a young boy, Higgs was raised by his mother in Bristol while his father relocated to Bedford. “She was very motivated to push me,” he says. “My father, I think he was just rather scared of children.”
At Cotham Grammar School in Bristol, Higgs would stand at the back of morning assembly, reading the names of the school’s most honored alumni. Appearing more times than any other was the Nobel prize-winning physicist and founding father of quantum mechanics, Paul Dirac, who, like Stephen Hawking, took the seat at Cambridge that was once occupied by Sir Isaac Newton. It was Dirac’s work that enthralled Higgs and put him on the path to study theoretical physics. “It’s about understanding! Understanding the world!” Higgs says, his voice full of excitement.
When illness wasn’t disrupting Higgs’ education, the war was. Bristol had already been thumped by German bombers, the old center almost completely flattened, but the outskirts where he lived and went to school took hits, too, from bombs shed by planes almost as an afterthought as they turned home from raids on the oil storage depots and ports at Avonmouth. “One of the first things I did on arriving at school was to break my left arm falling into a bomb crater,” Higgs says. Later, the family was forced to leave home when a cluster of unexploded bombs was discovered across the road.
The family was not reunited until the end of the war, when Peter, aged 17, joined City of London School, specializing in mathematics. Among the gifted, he was the odd one out. He alone had no desire to go to Oxford or Cambridge, the thought enough to make him shudder. “They all wondered why I wasn’t going to do the same,” he says. “I think some of the family attitude to Oxford and Cambridge had rubbed off on me, which was that those places were all very well for the children of the idle rich to go and waste their time and that of their tutors, but if you were serious about university, you went somewhere else.”
In Higgs’ case, somewhere else was King’s College, London, and it was there that it became clear he was hopeless at experiments. “There were accidents,” he says, refusing to elaborate.
In his early 30s, Higgs moved to Edinburgh University, where he became interested in what must be one of the most curious puzzles in physics: why the objects around us weigh anything.
Until recently, few even questioned where mass comes from. Newton coined the term in 1687 in his famous tome, Principia Mathematica, and for 200 years scientists were happy to think of mass as something that simply existed. Some objects had more mass than others - a brick versus a book, say - and that was that. But scientists now know the world is not so simple. While a brick weighs as much as the atoms inside it, according to the best theory physicists have - one that has passed decades of tests with flying colors - the basic building blocks inside atoms weigh nothing at all. As matter is broken down to ever smaller constituents, from molecules to atoms to quarks, mass appears to evaporate before our eyes. Physicists have never fully understood why.
While working on the conundrum, Higgs came up with an elegant mechanism to solve the problem. It showed that at the very beginning of the universe, the smallest building blocks of nature were truly weightless, but became heavy a fraction of a second later, when the fireball of the big bang cooled. His theory was a breakthrough in itself, but something more profound dropped out of his calculations.
Higgs’s theory showed that mass was produced by a new type of field that clings to particles wherever they are, dragging on them and making the heavy. Some particles find the field more sticky than others. Particles of light are oblivious to it. Others have to wade through it like an elephant in tar. So, in theory, particles can weigh nothing, but as soon as they are in the field, they get heavy.
Scientists now know that Higgs’s extraordinary field, or something very similar to it, played a key role in the formation of the universe. Without it, the cosmos would not have exploded into the rich, infinite galaxies we see today. The spinning disc of cosmic dust that collapsed 4.5 billion years ago to form our solar system would never have been. No planets would have formed, nor a sun to warm them. Life would not have stood a chance.
In late summer 1964, two years before he would give his Princeton lecture, Higgs rushed out a succinct letter, packed with mathematical formulae that backed his discovery and sent it to a leading physics journal run from Cern, the European nuclear research organization in Geneva. The paper was published almost immediately, but went largely unnoticed. Higgs planned a second paper, to emphasize his discovery, but for now that would have to wait.
Through CND meetings in Edinburgh - Higgs had been an activist while studying in London - he had met Jo, an American linguist and his future wife. The two had planned a weekend’s camping in the west Highlands, on the recommendation of a friend who’d read the place had the lowest rainfall in Scotland. As it happened, the trip was a disaster. “It turned out she’d misread it. It was the highest rainfall in all of Scotland,” Higgs says.
The scientist took the chance to retreat to Edinburgh and write his second paper, this time elaborating on the true implications of his work. In autumn 1964, he sent it to the same journal for publishing, but astonishingly the Cern editors rejected it. Evidently, it was considered “of no obvious relevance to physics”. He quickly sent it to America’s leading physics journal, where it appeared later that year.
Despite Cern’s misgivings, Higgs’s ideas now exploded into the world of theoretical physics and thousands wanted to be first to prove Higgs right. Detecting the field itself is thought to be impossible with modern technology, but Higgs also predicted a particle that is created in the field, and finding this would be the proof they sought. Officially, the particle is called the Higgs boson, but its elusive nature and fundamental role in the creation of the universe led a prominent scientist to rename it the God particle.
The name has stuck, but makes Higgs wince and raises the hackles of other theorists. “I wish he hadn’t done it,” he says. “I have to explain to people it was a joke. I’m an atheist, but I have an uneasy feeling that playing around with names like that could be unnecessarily offensive to people who are religious.”
Strictly, the particle should bear the names of three scientists. Unknown to Higgs at the time, two Belgian physicists at the Free University in Brussels were working on the same problem. Using completely different maths, they reached the same staggering conclusion - that a never-seen field must pervade the universe and confer mass on almost everything in it. Robert Brout and Fran?§ois Englert didn’t doubt their discovery, but checked and checked for mistakes before publishing. Their paper was published in August 1964, a few weeks before Higgs’ first paper, which was in press at the time.
It makes for an awkward situation, not least for Higgs, who agrees all three should share credit for the discovery. He recounts a tale when a colleague referred to the “Higgs mechanism” in a lecture in Germany more than two decades ago. In the front row, a look of displeasure flushed over one of the men in the audience. Realizing his mistake, the speaker said, “Of course, I know this was also discovered by others, but I refer to it by the person with the shortest name.” “My name has five letters, too,” piped Brout.
A few months ago, Brout and Englert, who are close as brothers and finish each other’s sentences, talked to me about the events long ago. After publishing their work, the two were having a beer on the balcony of a 17th-century cafe overlooking a Brussels park. “In the spring of 1964 we were both extremely excited,” said Brout. “For the first time in my life, I felt what it might be to be a great physicist.” Neither, he says, blames Higgs for their work being sidelined.
Whatever name it takes, many scientists believe that finding the particle will not only reveal the origin of mass, but will nudge open the door to a new realm of unknowns. We can see only 4% of the matter that makes up the universe. The Higgs particle may shed light on the rest - the dark matter in which galaxies form, and the dark energy that drives the expansion of the universe, for example. The particle may also shed light on string theory, an ambitious but powerful way of viewing the universe that sees every particle not as a point, but as a vibrating string of energy, where different frequencies create different particles.
