July 4, 2012
Physicists Find Elusive Particle Seen as Key to Universe
By DENNIS OVERBYE
ASPEN, Colo. — Signaling a likely end to one of the longest, most expensive searches in the history of science, physicists said Wednesday that they had discovered a new subatomic particle that looks for all the world like the Higgs boson, a key to understanding why there is diversity and life in the universe.
Like Omar Sharif materializing out of the shimmering desert as a man on a camel in “Lawrence of Arabia,” the elusive boson has been coming slowly into view since last winter, as the first signals of its existence grew until they practically jumped off the chart.
“I think we have it,” said Rolf-Dieter Heuer, the director general of CERN, the multinational research center headquartered in Geneva. The agency is home to the Large Hadron Collider, the immense particle accelerator that produced the new data by colliding protons. The findings were announced by two separate teams. Dr. Heuer called the discovery “a historic milestone.”
He and others said that it was too soon to know for sure, however, whether the new particle is the one predicted by the Standard Model, the theory that has ruled physics for the last half-century. The particle is predicted to imbue elementary particles with mass. It may be an impostor as yet unknown to physics, perhaps the first of many particles yet to be discovered.
That possibility is particularly exciting to physicists, as it could point the way to new, deeper ideas, beyond the Standard Model, about the nature of reality.
For now, some physicists are simply calling it a “Higgslike” particle.
“It’s something that may, in the end, be one of the biggest observations of any new phenomena in our field in the last 30 or 40 years,” said Joe Incandela, a physicist of the University of California, Santa Barbara, and a spokesman for one of the two groups reporting new data on Wednesday.
Here at the Aspen Center for Physics, a retreat for scientists, bleary-eyed physicists drank Champagne in the wee hours as word arrived via Webcast from CERN. It was a scene duplicated in Melbourne, Australia, where physicists had gathered for a major conference, as well as in Los Angeles, Chicago, Princeton, New York, London and beyond — everywhere that members of a curious species have dedicated their lives and fortunes to the search for their origins in a dark universe.
In Geneva, 1,000 people stood in line all night to get into an auditorium at CERN, where some attendees noted a rock-concert ambience. Peter Higgs, the University of Edinburgh theorist for whom the boson is named, entered the meeting to a sustained ovation.
Confirmation of the Higgs boson or something very much like it would constitute a rendezvous with destiny for a generation of physicists who have believed in the boson for half a century without ever seeing it. The finding affirms a grand view of a universe described by simple and elegant and symmetrical laws — but one in which everything interesting, like ourselves, results from flaws or breaks in that symmetry.
According to the Standard Model, the Higgs boson is the only manifestation of an invisible force field, a cosmic molasses that permeates space and imbues elementary particles with mass. Particles wading through the field gain heft the way a bill going through Congress attracts riders and amendments, becoming ever more ponderous.
Without the Higgs field, as it is known, or something like it, all elementary forms of matter would zoom around at the speed of light, flowing through our hands like moonlight. There would be neither atoms nor life.
Physicists said that they would probably be studying the new particle for years. Any deviations from the simplest version predicted by current theory — and there are hints of some already — could begin to answer questions left hanging by the Standard Model. For example, what is the dark matter that provides the gravitational scaffolding of galaxies?
And why is the universe made of matter instead of antimatter?
“If the boson really is not acting standard, then that will imply that there is more to the story — more particles, maybe more forces around the corner,” Neal Weiner, a theorist at New York University, wrote in an e-mail. “What that would be is anyone’s guess at the moment.”
Wednesday’s announcement was also an impressive opening act for the Large Hadron Collider, the world’s biggest physics machine, which cost $10 billion to build and began operating only two years ago. It is still running at only half-power.
Physicists had been icing the Champagne ever since last December. Two teams of about 3,000 physicists each — one named Atlas, led by Fabiola Gianotti, and the other CMS, led by Dr. Incandela — operate giant detectors in the collider, sorting the debris from the primordial fireballs left after proton collisions.
Last winter, they both reported hints of the same particle. They were not able, however, to rule out the possibility that it was a statistical fluke. Since then, the collider has more than doubled the number of collisions it has recorded.
The results announced Wednesday capped two weeks of feverish speculation and Internet buzz as the physicists, who had been sworn to secrecy, did a breakneck analysis of about 800 trillion proton-proton collisions over the last two years.
Up until last weekend, physicists at the agency were saying that they themselves did not know what the outcome would be. Expectations soared when it was learned that the five surviving originators of the Higgs boson theory had been invited to the CERN news conference.
The December signal was no fluke, the scientists said Wednesday. The new particle has a mass of about 125.3 billion electron volts, as measured by the CMS group, and 126 billion according to Atlas. Both groups said that the likelihood that their signal was a result of a chance fluctuation was less than one chance in 3.5 million, “five sigma,” which is the gold standard in physics for a discovery.
On that basis, Dr. Heuer said that he had decided only on Tuesday afternoon to call the Higgs result a “discovery.”
He said, “I know the science, and as director general I can stick out my neck.”
Dr. Incandela’s and Dr. Gianotti’s presentations were repeatedly interrupted by applause as they showed slide after slide of data presented in graphs with bumps rising like mountains from the sea.
Dr. Gianotti noted that the mass of the putative Higgs, apparently one of the heaviest subatomic particles, made it easy to study its many behaviors. “Thanks, nature,” she said.
Gerald Guralnik, one of the founders of the Higgs theory, said he was glad to be at a physics meeting “where there is applause, like a football game.”
Asked to comment after the announcements, Dr. Higgs seemed overwhelmed. “For me, it’s really an incredible thing that’s happened in my lifetime,” he said.
Dr. Higgs was one of six physicists, working in three independent groups, who in 1964 invented what came to be known as the Higgs field. The others were Tom Kibble of Imperial College, London; Carl Hagen of the University of Rochester; Dr. Guralnik of Brown University; and François Englert and Robert Brout, both of Université Libre de Bruxelles.
One implication of their theory was that this cosmic molasses, normally invisible, would produce its own quantum particle if hit hard enough with the right amount of energy. The particle would be fragile and fall apart within a millionth of a second in a dozen possible ways, depending upon its own mass.
Unfortunately, the theory did not describe how much this particle should weigh, which is what made it so hard to find, eluding researchers at a succession of particle accelerators, including the Large Electron Positron Collider at CERN, which closed down in 2000, and the Tevatron at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Ill., which shut down last year.
Along the way the Higgs boson achieved a notoriety rare in abstract physics. To the eternal dismay of his colleagues, Leon Lederman, the former director of Fermilab, called it the “God particle,” in his book of the same name, written with Dick Teresi. (He later said that he had wanted to call it the “goddamn particle.”)
Finding the missing boson was one of the main goals of the Large Hadron Collider. Both Dr. Heuer and Dr. Gianotti said they had not expected the search to succeed so quickly.
So far, the physicists admit, they know little about their new boson. The CERN results are mostly based on measurements of two or three of the dozen different ways, or “channels,” by which a Higgs boson could be produced and then decay.
There are hints, but only hints so far, that some of the channels are overproducing the boson while others might be underproducing it, clues that maybe there is more at work here than the Standard Model would predict.
“This could be the first in a ring of discoveries,” said Guido Tonelli of CERN.
In an e-mail, Maria Spiropulu, a professor at the California Institute of Technology who works with the CMS team of physicists, said: “I personally do not want it to be standard model anything — I don’t want it to be simple or symmetric or as predicted. I want us all to have been dealt a complex hand that will send me (and all of us) in a (good) loop for a long time.”
Nima Arkani-Hamed, a physicist at the Institute for Advanced Study in Princeton, said: “It’s a triumphant day for fundamental physics. Now some fun begins.”
ASPEN, Colo. — Last week, physicists around the world were glued to computers at very odd hours (I was at a 1 a.m. physics “party” here with a large projection screen and dozens of colleagues) to watch live as scientists at the Large Hadron Collider, outside Geneva, announced that they had apparently found one of the most important missing pieces of the jigsaw puzzle that is nature.
The “Higgs particle,” proposed almost 50 years ago to allow for consistency between theoretical predictions and experimental observations in elementary particle physics, appears to have been discovered — even as the detailed nature of the discovery allows room for even more exotic revelations that may be just around the corner.
It is natural for those not deeply involved in the half-century quest for the Higgs to ask why they should care about this seemingly esoteric discovery. There are three reasons.
First, it caps one of the most remarkable intellectual adventures in human history — one that anyone interested in the progress of knowledge should at least be aware of.
Second, it makes even more remarkable the precarious accident that allowed our existence to form from nothing — further proof that the universe of our senses is just the tip of a vast, largely hidden cosmic iceberg.
And finally, the effort to uncover this tiny particle represents the very best of what the process of science can offer to modern civilization.
If one is a theoretical physicist working on some idea late at night or at a blackboard with colleagues over coffee one afternoon, it is almost terrifying to imagine that something that you cook up in your mind might actually be real. It’s like staring at a large jar and being asked to guess the number of jelly beans inside; if you guess right, it seems too good to be true.
The prediction of the Higgs particle accompanied a remarkable revolution that completely changed our understanding of particle physics in the latter part of the 20th century.
Just 50 years ago, in spite of the great advances of physics in the previous half century, we understood only one of the four fundamental forces of nature — electromagnetism — as a fully consistent quantum theory. In just one subsequent decade, however, not only had three of the four known forces succumbed to our investigations, but a new elegant unity of nature had been uncovered.
It was found that all of the known forces could be described using a single mathematical framework — and that two of the forces, electromagnetism and the weak force (which governs the nuclear reactions that power the sun), were actually different manifestations of a single underlying theory.
How could two such different forces be related? After all, the photon, the particle that conveys electromagnetism, has no mass, while the particles that convey the weak force are very massive — almost 100 times as heavy as the particles that make up atomic nuclei, a fact that explains why the weak force is weak.
What the British physicist Peter Higgs and several others showed is that if there exists an otherwise invisible background field permeating all of space, then the particles that convey some force like electromagnetism can interact with this field and effectively encounter resistance to their motion and slow down, like a swimmer moving through molasses.
As a result, these particles can behave as if they are heavy, as if they have a mass. The physicist Steven Weinberg later applied this idea to a model of the weak and electromagnetic forces previously proposed by Sheldon L. Glashow, and everything fit together.
This idea can be extended to the rest of particles in nature, including the protons and neutrons and electrons that make up the atoms in our bodies. If some particle interacts more strongly with this background field, it ends up acting heavier. If it interacts more weakly, if acts lighter. If it doesn’t interact at all, like the photon, it remains massless.
If anything sounds too good to be true, this is it. The miracle of mass — indeed of our very existence, because if not for the Higgs, there would be no stars, no planets and no people — is possible because of some otherwise hidden background field whose only purpose seems to be to allow the world to look the way it does.
Dr. Glashow, who along with Dr. Weinberg won a Nobel Prize in Physics, later once referred to this “Higgs field” as the “toilet” of modern physics because that’s where all the ugly details that allow the marvelous beauty of the physical world are hidden.
But relying on invisible miracles is the stuff of religion, not science. To ascertain whether this remarkable accident was real, physicists relied on another facet of the quantum world.
Associated with every background field is a particle, and if you pick a point in space and hit it hard enough, you may whack out real particles. The trick is hitting it hard enough over a small enough volume.
And that’s the rub. After 50 years of trying, including a failed attempt in this country to build an accelerator to test these ideas, no sign of the Higgs had appeared. In fact, I was betting against it, since a career in theoretical physics has taught me that nature usually has a far richer imagination than we do.
Until last week.
Every second at the Large Hadron Collider, enough data is generated to fill more than 1,000 one-terabyte hard drives — more than the information in all the world’s libraries. The logistics of filtering and analyzing the data to find the Higgs particle peeking out under a mountain of noise, not to mention running the most complex machine humans have ever built, is itself a triumph of technology and computational wizardry of unprecedented magnitude.
The physicist Victor F. Weisskopf — the colorful first director of CERN, the European Center for Nuclear Research, which operates the collider — once described large particle accelerators as the gothic cathedrals of our time. Like those beautiful remnants of antiquity, accelerators require the cutting edge of technology, they take decades or more to build, and they require the concerted efforts of thousands of craftsmen and women. At CERN, each of the mammoth detectors used to study collisions requires the work of thousands of physicists, from scores of countries, speaking several dozen languages.
Most significantly perhaps, cathedrals and colliders are both works of incomparable grandeur that celebrate the beauty of being alive.
The apparent discovery of the Higgs may not result in a better toaster or a faster car. But it provides a remarkable celebration of the human mind’s capacity to uncover nature’s secrets, and of the technology we have built to control them. Hidden in what seems like empty space — indeed, like nothing, which is getting more interesting all the time — are the very elements that allow for our existence.
By demonstrating that, last week’s discovery will change our view of ourselves and our place in the universe. Surely that is the hallmark of great music, great literature, great art ...and great science.
Lawrence M. Krauss, the director of the Origins Project at Arizona State University, is the author, most recently, of “A Universe From Nothing.”
ISLAMABAD—The pioneering work of Abdus Salam, Pakistan’s only Nobel laureate, helped lead to the apparent discovery of the subatomic “God particle” last week. But the late physicist is no hero at home, where his name has been stricken from school textbooks.
Related: What is the Higgs-boson and why the hunt for the god particle matters
Praise within Pakistan for Salam, who also guided the early stages of the country’s nuclear program, faded decades ago as Muslim fundamentalists gained power. He belonged to the Ahmadi sect, which has been persecuted by the government and targeted by Taliban militants who view its members as heretics.
Their plight — along with that of Pakistan’s other religious minorities, such as Shiite Muslims, Christians and Hindus — has deepened in recent years as hardline interpretations of Islam have gained ground and militants have stepped up attacks against groups they oppose. Most Pakistanis are Sunni Muslims.
Salam, a child prodigy born in 1926 in what was to become Pakistan after the partition of British-controlled India, won more than a dozen international prizes and honours. In 1979, he was co-winner of the Nobel Prize for his work on the so-called Standard Model of particle physics, which theorizes how fundamental forces govern the overall dynamics of the universe. He died in 1996.
Salam and Steven Weinberg, with whom he shared the Nobel Prize, independently predicted the existence of a subatomic particle now called the Higgs boson, named after a British physicist who theorized that it endowed other particles with mass, said Pervez Hoodbhoy, a Pakistani physicist who once worked with Salam. It is also known as the “God particle” because its existence is vitally important toward understanding the early evolution of the universe.
Physicists in Switzerland stoked worldwide excitement Wednesday when they announced they have all but proven the particle’s existence. This was done using the world’s largest atom smasher at the European Organization for Nuclear Research, or CERN, near Geneva.
“This would be a great vindication of Salam’s work and the Standard Model as a whole,” said Khurshid Hasanain, chairman of the physics department at Quaid-i-Azam University in Islamabad.
In the 1960s and early 1970s, Salam wielded significant influence in Pakistan as the chief scientific adviser to the president, helping to set up the country’s space agency and institute for nuclear science and technology. Salam also assisted in the early stages of Pakistan’s effort to build a nuclear bomb, which it eventually tested in 1998.
Salam’s life, along with the fate of the three million other Ahmadis in Pakistan, drastically changed in 1974 when parliament amended the constitution to declare that members of the sect were not considered Muslims under Pakistani law.
Ahmadis believe their spiritual leader, Hadhrat Mirza Ghulam Ahmad, who died in 1908, was the Promised Messiah — a position rejected by the government in response to a mass movement led by Pakistan’s major Islamic parties. Most Muslims consider Muhammad the last prophet and those who subsequently declared themselves prophets as heretics.
All Pakistani passport applicants must sign a section saying the Ahmadi faith’s founder was an “impostor” and his followers are “non-Muslims.” Ahmadis are prevented by law in Pakistan from “posing as Muslims,” declaring their faith publicly, calling their places of worship mosques or performing the Muslim call to prayer. They can be punished with prison and even death.
Salam resigned from his government post in protest following the 1974 constitutional amendment and eventually moved to Europe to pursue his work. In Italy, he created a centre for theoretical physics to help physicists from the developing world.
Although Pakistan’s then-president, general Zia ul-Haq, presented Salam with Pakistan’s highest civilian honour after he won the Nobel Prize, the general response in the country was muted. The physicist was celebrated more enthusiastically by other countries, including India.
Despite his achievements, Salam’s name appears in few textbooks and is rarely mentioned by Pakistani leaders or the media. By contrast, fellow Pakistani physicist A.Q. Khan, who played a key role in developing the country’s nuclear bomb and later confessed to spreading nuclear technology to Iran, North Korea and Libya, is considered a national hero.
Officials at Quaid-i-Azam University had to cancel plans for Salam to lecture about his Nobel-winning theory when Islamist student activists threatened to break the physicist’s legs, said his colleague Hoodbhoy.
“The way he has been treated is such a tragedy,” said Hoodbhoy. “He went from someone who was revered in Pakistan, a national celebrity, to someone who could not set foot in Pakistan. If he came, he would be insulted and could be hurt or even killed.”
The president who honoured Salam would later go on to intensify persecution of Ahmadis, for whom life in Pakistan has grown even more precarious. Taliban militants attacked two mosques packed with Ahmadis in Lahore in 2010, killing at least 80 people.
“Many Ahmadis have received letters from fundamentalists since the 2010 attacks threatening to target them again, and the government isn’t doing anything,” said Qamar Suleiman, a spokesman for the Ahmadi community.
For Salam, not even death saved him from being targeted.
Hoodbhoy said his body was returned to Pakistan in 1996 after he died in Oxford, England, and was buried under a gravestone that read “First Muslim Nobel Laureate.” A local magistrate ordered that the word “Muslim” be erased.
Large Hadron Collider restarts after two-year shutown
The world's largest particle collider has restarted after a two-year upgrade. Scientists are hoping the upgrade will provide still more energy to research so-called "dark matter."
Scientists at the European Organization for Nuclear Research, or CERN, on Sunday shot the first particle beams through the restarted Large Hadron Collider (LHC), after the particle accelerator underwent two years of work to increase its collision capacity.
The LHC - also known as the "Big Bang" collider -, which consists of a 27-kilometer-long (16.8-mile-long) tunnel beneath the Swiss-French border, is being used by researchers to study the "dark universe" - the subatomic particles that make up some 96 percent of matter in the known universe, along with the forces that hold them together.
The collider hit the headlines in 2012 with the discovery of the Higgs Boson, a subatomic particle that confers mass, whose existence had been theorized since 1968 but not confirmed.
The discovery earned the Nobel prize for two of the scientists who had proposed the existence of the particle.
The LHC uses powerful magnets to bend beams of protons coming from opposite directions, thus creating collisions that are monitored by sensors.
The subatomic debris is scanned for unknown kinds of particles and also provides information on coherent forces.
Scientists say the collider has nearly twice its previous energy following the upgrade, which will enable it to produce even more powerful collisions.
The restart was delayed last Saturday following a short-circuit in one of the LHC's magnet circuits.
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