Home » Posts tagged 'Large Hadron Collider'
Tag Archives: Large Hadron Collider
By: Lawrence Krauss
“On July 4, the physics community responded with jubilation to an announcement that had been anticipated for 50 years: the discovery of the Higgs Boson. Just as half of the country was ecstatic in 2008 when Barack Obama was first elected—supposedly heralding the end of “business as usual” in Washington—the Higgs breakthrough appeared to herald a new era in particle physics, one that could bring us closer to a possible unified theory describing all of the fundamental forces of nature.
Unfortunately, in both cases, reality has intervened. Obama discovered that being elected and governing a divided and partisan country are two different things. In physics, too, we are uncomfortably close to what many of us would consider the nightmare scenario. The initial buzz of the Higgs discovery has faded, and now we face a monstrous hangover: What happens next?
Briefly, the Higgs is an elementary particle predicted 50 years ago during the development of the standard model of particle physics. The standard model beautifully describes three of the four fundamental forces in nature and is one of the most remarkable theoretical constructions in the history of science. Specifically, the Higgs was predicted in order to provide a natural mechanism to explain what now appears to be an amazing cosmic accident: the fact that some particles have mass and others don’t. (For a thorough explanation, listen to my conversation with Blogging Heads’ Robert Wright.)
Before the Large Hadron Collider at CERN in Switzerland was turned on, there were five possibilities for what might be revealed: 1) No Higgs and nothing else, 2) a Higgs with unexpected properties and nothing else, 3) lots of other stuff but no Higgs, 4) a Higgs and lots of other stuff, and 5) a single Higgs with the properties predicted in the standard model.
Many might imagine that physicists were rooting for door No. 5 because we like to be vindicated. In fact, nothing could be further from the truth. The discovery of the Higgs validates the prediction of the standard model, and with that much of the theoretical underpinning of modern fundamental physics and cosmology. But now we are completely baffled about the origins of the standard model itself. I, for one, was rooting for no Higgs at all, because that would have meant our fundamental ideas were on the wrong track. Nothing can be more exciting than finding that we have to start from scratch and discover a whole new reality hidden.
While the Higgs discovery was announced in July, the announcement was based on preliminary data. In Kyoto in November, the LHC teams reported on six more months’ worth of data, giving us more clues as to what we really have on our hands. If the LHC reveals the a standard model Higgs and nothing else—that is what we have seen in the data reported in Kyoto—we will confront some major problems. That would mean we have no empirical clues as to what theoretical ideas we should next explore in hopes of answering long-standing questions, including perhaps what caused the Big Bang itself. We won’t know where to focus next. Will the next great discovery be just around the corner, to be made at a successor machine in Geneva or elsewhere? Or do we have to build an implausibly large accelerator perhaps the size of the solar system?
It was hard enough to convince the governments of the world to spend money pushing the edges of knowledge even when we had a pretty good idea what we were looking for, as was the case with the Higgs. In the current world, with shrinking budgets for everything (except maybe weapons and debt repayments), it is hard to imagine any government willing to fund the next generation of research when the outcome may be only that we need to work harder still and pay yet more money to uncover the secrets of the universe.
Indeed, because of the unfortunate way in which we fund big science projects in this country, it is almost impossible to preserve funding for long-term, large-scale projects that are relatively esoteric. For example, the Superconducting Supercollider, which was being built in Texas in the 1980s and early ’90s and which would have been a much grander and more powerful machine than the LHC, was killed, even though it had been approved by three consecutive presidents in their budgets.
One is virtually guaranteed to have some kind of economic recession every decade or two, and if a grand science endeavor takes that long to complete, it is easy pickings for a Congress intent on cutting budgets without offending constituencies with influential lobbyists. Scientists, you may be surprised to learn, are not power players in Washington. We don’t vote as a block, and in economic hard times, it is pretty challenging to convince people to fund projects that don’t promise direct technological spinoffs but rather might answer fundamental questions about the universe. Over much of the last decade in this country, the funding of particle physics, for example, has not even kept up with inflation. This, in spite of the fact that perhaps one-half of the current U.S. GDP might be due to investments in curiosity-driven fundamental research a generation or two ago.
It is too early to settle on a tale of doom and gloom, just as it is not yet time to give up on the hope of Obama changing the status quo in Washington. The LHC will run for several more years, and there is still a good chance that it will uncover new clues that can guide us. But fortune favors the prepared mind, and that sometimes means preparing for the worst.
This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. Future Tense explores the ways emerging technologies affect society, policy, and culture. To read more, visit the Future Tense blog and the Future Tense home page. You can also follow us on Twitter.
By: Lawrence Krauss
“Who would have believed it? Every now and then theoretical speculation anticipates experimental observation in physics. It doesn’t happen often, in spite of the romantic notion of theorists sitting in their rooms alone at night thinking great thoughts. Nature usually surprises us. But today, two separate experiments at the Large Hadron Collider of the European Center for Nuclear Research (CERN) in Geneva reported convincing evidence for the long sought-after “Higgs” particle, first proposed to exist almost 50 years ago and at the heart of the “standard model” of elementary particle physics—the theoretical formalism that describes three of the four known forces in nature, and which to date agrees with every experimental observation done to date.
The LHC is the most complex (and largest) machine that humans have ever built, requiring thousands of physicists from dozens of countries, working full time for a decade to build and operate. And even with 26 kilometers of tunnel, accelerating two streams of protons in opposite directions at more than 99.9999 percent the speed of light and smashing them together in spectacular collisions billions of times each second, producing hundreds of particles in each collision; two detectors the size of office buildings to measure the particles; and a bank of more than 3,000 computers analyzing the events in real time in order to search for something interesting, the Higgs particle itself never directly appears.
I say candidates, because so far each of the two major LHC experimental collaborations has claimed to discover a new particle with properties consistent with the other, and consistent with the general predictions of the standard model, which suggests that the Higgs particle should be produced at a rate comparable to the rate observed and should decay into the specific combinations of known elementary particles that are observed. They are being very conservative. One can in fact quantify the likelihood that the observations are mistaken and that the events are actually background noise mimicking a real signal. Each experiment quotes a likelihood of very close to “5 sigma,” meaning the likelihood that the events were produced by chance is less than one in 3.5 million. Yet in spite of this, the only claim that has been made so far is that the new particle is real and “Higgs-like.” The existing data set is still too small to statistically determine with precise accuracy that the data is consistent with the standard model.
This cautious approach is actually a good thing, because it leaves open the possibility that the particle being observed is not exactly the simple Higgs particle of the standard model. Instead, it may point the way toward understanding whatever new physics underlies the standard model—and perhaps explain outstanding mysteries from the question of why the universe is made of matter and not antimatter, to whether our universe is unique.
The idea of the Higgs particle was proposed nearly 50 years ago. (Incidentally, it has never been called the “God particle” by the physics community. That moniker has been picked up by the media, and I hope it goes away.) It was discussed almost as a curiosity, to get around some inconsistencies between predictions and theory at the time in particle physics, that if an otherwise invisible background field exists permeating empty space throughout the universe, then elementary particles can interact with this field. Even if they initially have no mass, they will encounter resistance to their motion through their interactions with this field, and they will slow down. They will then act like they have mass. It is like trying to push your car off the road if it has run out of gas. You and a friend can roll it along as long as it is on the road, but once it goes off and the wheels encounter mud, you and a whole gang of friends who may have been sitting in the back seat cannot get it moving. The car acts heavier.
Within a few years, it had been recognized that this phenomenon could not only explain why elementary particles like the particles that make up our bodies have the masses they do, but it could also illuminate why two of the four known forces in nature, electromagnetism and the so-called “weak” force (responsible for the processes that power the sun), which on the surface appear very different at the scales we measure, are actually at a fundamental scale merely different manifestations of a single force, now called the “electro-weak” force.
In the 1990s in the United States, a gigantic machine called the Superconducting Super Collider was being built (involving the largest tunnel ever dug—some 60 miles in circumference) to search for the Higgs—and the origin of mass. But Congress, in its infinite wisdom (Congress seems to have gotten no wiser since), decided that the country couldn’t afford the $5 billion to $10 billion that had already been approved by three different presidents. Back then, $5 billion was a lot of money! So, the LHC was constructed in Geneva by a group of European countries, and the rest is history, or will be.
The discovery announced today in Geneva represents a quantum leap (literally) in our understanding of nature at its fundamental scale, and the culmination of a half-century of dedicated work by tens of thousands of scientists using technology that has been invented for the task, and it should be celebrated on these accounts alone.
But I find it particularly exciting for two reasons—one scientific, the other more personal. First, the standard model, as remarkably successful as it has been, leaves open more questions than it answers. What causes the Higgs field to exist throughout space today? Are there other forces that dynamically determine its configuration? Why doesn’t the same phenomenon that causes the Higgs particle to exist at the mass it does cause gravity and the other forces in nature to behave similarly? Over the past 40 years or so, a host of theoretical speculations have been developed to answer these questions. But like those who are sensorially deprived, we may just be hallucinating. The cold water of experiment may now wash away many of our wrong ideas and, perhaps more importantly, could point us in the right direction. In the process I expect what we will discover about the universe may currently be beyond our wildest dreams.
More than this, however, the Higgs field implies that otherwise seemingly empty space is much richer and weirder than we could have imagined even a century ago, and in fact that we cannot understand our own existence without understanding “emptiness” better. Readers of mine will know that as a physicist, I have been particularly interested in “nothing” in all of its forms and its relation to something—namely us. The discovery of the Higgs says that “nothing” is getting ever more interesting.
By Robert Evans
GENEVA (Reuters) – Scientists chasing a particle they believe may have played a vital role in creation of the universe indicated Monday they were coming to accept it might not exist after all.
But they stressed that if the so-called Higgs boson turns out to have been a mirage, the way would be open for advances into territory dubbed “new physics” to try to answer one of the great mysteries of the cosmos.
The CERN research centre, whose giant Large Hadron Collider (LHC) has been the focus of the search, said it had reported to a conference in Mumbai that possible signs of the Higgs noted last month were now seen as less significant.
A number of scientists from the centre went on to make comments that raised the possibility that the mystery particle might not exist.
“Whatever the final verdict on Higgs, we are now living in very exciting times for all involved in the quest for new physics,” Guido Tonelli, from one of the two LHC detectors chasing the Higgs, said as the new observations were announced.
CERN’s statement said new results, which updated findings that caused excitement at another scientific gathering in Grenoble last month, “show that the elusive Higgs particle, if it exists, is running out of places to hide.”
The centre’s research director Sergio Bertolucci told the conference, at the Indian city’s Tata Institute of Fundamental Research, that if the Higgs did not exist “its absence will point the way to new physics.”
Under what is known as the Standard Model of physics, the boson, which was named after British physicist Peter Higgs, is posited as having been the agent that gave mass and energy to matter just after the Big Bang 13.7 billion years ago.
As a result, flying debris from that primeval explosion could come together as stars, planets and galaxies.
In the subterranean LHC, which began operating at the end of March 2010, CERN engineers and physicists have created billions of miniature versions of the Big Bang by smashing particles together at just a fraction under the speed of light.
The results of those collisions are monitored by hundreds of physicists not just at CERN but in linked laboratories around the world which sift through the vast volumes of information generated by the LHC.
Scientists at the U.S. Fermilab near Chicago have been in a parallel search in their Tevatron collider for nearly 30 years. Last month they said they hoped to establish if the Higgs exists by the end of September, when the Tevatron closes down.
For some scientists, the Higgs remains the simplest explanation of how matter got mass. It remains unclear what could replace it as an explanation. “We know something is missing, we simply don’t quite know what this new something might be,” wrote CERN blogger Pauline Gagnon.
“There are many models out there; we simply need to be nudged in the right direction,” added Gagnon, an experimental physicist.
(Editing by Andrew Heavens)