The Large Hadron Collider: We’ve Definitely Found the Higgs Boson

higgs-boson1In July 2012, the CERN laboratory in Geneva, Switzerland made history when it discovered an elementary particle that behaved in a way that was consistent with the proposed Higgs boson – otherwise known as the “God Particle”. Now, some two years later, the people working the Large Hadron Collider have confirmed that what they observed was definitely the Higgs boson, the one predicted by the Standard Model of particle physics.

In the new study, published in Nature Physics, the CERN researchers indicated that the particle observed in 2012 researchers indeed decays into fermions – as predicted by the standard model of particle physics. It sits in the mass-energy region of 125 GeV, has no spin, and it can decay into a variety of lighter particles. This means that we can say with some certainty that the Higgs boson is the particle that gives other particles their mass – which is also predicted by the standard model.

CERN_higgsThis model, which is explained through quantum field theory  – itself an amalgam of quantum mechanics and Einstein’s special theory of relativity – claims that deep mathematical symmetries rule the interactions among all elementary particles. Until now, the decay modes discovered at CERN have been of a Higgs particle giving rise to two high-energy photons, or a Higgs going into two Z bosons or two W bosons.

But with the discovery of fermions, the researchers are now sure they have found the last holdout to the full and complete confirmation that the Standard Model is the correct one. As Marcus Klute of the CMS Collaboration said in a statement:

Our findings confirm the presence of the Standard Model Boson. Establishing a property of the Standard Model is big news itself.

CERN_LHCIt is certainly is big news for scientists, who can say with absolute certainty that our current conception for how particles interact and behave is not theoretical. But on the flip side, it also means we’re no closer to pushing beyond the Standard Model and into the realm of the unknown. One of the big shortfalls of the Standard Model is that it doesn’t account for gravity, dark energy and dark matter, and some other quirks that are essential to our understanding of the universe.

At present, one of the most popular theories for how these forces interact with the known aspects of our universe – i.e. electromagnetism, strong and nuclear forces – is supersymmetry.  This theory postulates that every Standard Model particle also has a superpartner that is incredibly heavy – thus accounting for the 23% of the universe that is apparently made up of dark matter. It is hoped that when the LHC turns back on in 2015 (pending upgrades) it will be able to discover these partners.

CERN_upgradeIf that doesn’t work, supersymmetry will probably have to wait for LHC’s planned successor. Known as the “Very Large Hadron Collider” (VHLC), this particle accelerator will measure some 96 km (60 mile) in length – four times as long as its predecessor. And with its proposed ability to smash protons together with a collision energy of 100 teraelectronvolts – 14 times the LHC’s current energy – it will hopefully have the power needed to answer the questions the discovery of the Higgs Boson has raised.

These will hopefully include whether or not supersymmetry holds up and how gravity interacts with the three other fundamental forces of the universe – a discovery which will finally resolve the seemingly irreconcilable theories of general relativity and quantum mechanics. At which point (and speaking entirely in metaphors) we will have gone from discovering the “God Particle” to potentially understanding the mind of God Himself.

I don’t think I’ve being melodramatic!

Source: extremetech.com, blogs.discovermagazine.com

News From Space: Cosmic Inflation and Dark Matter

big bang_blackholeHello again! In another attempt to cover events that built up while I was away, here are some stories that took place back in March and early April of this year, and which may prove to be some of the greatest scientific finds of the year. In fact, they may prove to be some of the greatest scientific finds in recent history, as they may help to answer the most fundamental questions of all – namely, what is the universe made of, and how did it come to exist?

First up, in a development that can only be described as cosmic in nature (pun intended), back in March, astrophysicists at the Harvard-Smithsonian Center announced the first-ever observation of gravitational waves. This discovery, which is the first direct evidence of the Big Bang, is comparable to significance to CERN’s confirmation of the Higgs boson in 2012. And there is already talk about a Nobel Prize for the Harvard crew because of their discovery.

big_bangThis theory, which states that the entire universe sprung into existence from a tiny spot in the universe some 13.8 billion years ago, has remained the scientific consensus for almost a century. But until now, scientists have had little beyond theory and observations to back it up. As the name would suggest, gravitational waves are basically ripples in spacetime that have been propagating outward from the center of the universe ever since the Big Bang took place.

Originally predicted as part of Einstein’s General Theory of Relativity in 1916, these waves are believed to have existed since a trillionth of a trillionth of a trillionth of a second after the Big Bang took place, and have been propagating outward for roughly 14 billion years. The theory also predicts that, if we can detect some gravitational waves, it’s proof of the initial expansion during the Big Bang and the continued inflation that has been taking place ever since.

bicep2-640x425Between 2010 and 2012, the BICEP2 – a radio telescope situated at the Amundsen–Scott South Pole Station (pictured above) – the research team listened to the Cosmic Microwave Background (CMB). They were looking for hints of B-mode polarization, a twist in the CMB that could only have been caused by the ripples of gravitational waves. Following a lot of data analysis, the leaders announced that they found that B-mode polarization.

The work will now be scrutinized by the rest of the scientific community, of course, but the general consensus seems confident that it will stand up. In terms of scientific significance, the confirmation of gravitational waves would be the first direct evidence that the universe started out as nothing, erupted into existence 13.8 billion years ago, and has continued to expand ever since. This would confirm that cosmic inflation really exists and that the entire structure of the universe was decided in the beginning by the tiniest flux of gravitational waves.

planck-attnotated-580x372And that’s not only discovery of cosmic significance that was made in recent months. In this case, the news comes from NASA’s Fermi Gamma-ray Space Telescope, which has been analyzing high-energy gamma rays emanating from the galaxy’s center since 2008. After pouring over the results, an independent group of scientists claimed that they had found an unexplained source of emissions that they say is “consistent with some forms of dark matter.”

These scientists found that by removing all known sources of gamma rays, they were left with gamma-ray emissions that so far they cannot explain. And while they were cautious that more observations will be needed to characterize these emissions, this is the first time that potential evidence has been found that may confirm that this mysterious, invisible mass that accounts for roughly 26.8% of the universe actually exists.

darkmatter1To be fair, scientists aren’t even sure what dark matter is made of. In fact, it’s very existence is inferred from gravitational effects on visible matter and gravitational lensing of background radiation. Originally, it was hypothesized to account for the discrepancies that were observed between the calculations of the mass of galaxies, clusters and entire universe made through dynamical and general relativistic means, and  the mass of the visible “luminous” matter.

The most widely accepted explanation for these phenomena is that dark matter exists and that it is most probably composed of Weakly Interacting Massive Particles (WIMPs) that interact only through gravity and the weak force. If this is true, then dark matter could produce gamma rays in ranges that Fermi could detect. Also, the location of the radiation at the galaxy’s center is an interesting spot, since scientists believe that’s where dark matter would lurk since the insofar invisible substance would be the base of normal structures like galaxies.

fermi_gamma-raysThe galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas. It’s also where astronomers expect to find the galaxy’s highest density of dark matter, which only affects normal matter and radiation through its gravity. Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built.

Dan Hooper, an astrophysicist at Fermilab and lead author of the study, had this to say on the subject:

The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it. The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models.

Hooper and his colleagues suggest that if WIMPs were destroying each other, this would be “a remarkable fit” for a dark matter signal. They again caution, though, that there could be other explanations for the phenomenon. Writing in a paper submitted to the journal Physical Review D, the researchers say that these features are difficult to reconcile with other explanations proposed so far, although they note that plausible alternatives not requiring dark matter may yet materialize.

CERN_LHCAnd while a great deal more work is required before Dark Matter can be safely said to exist, much of that work can be done right here on Earth using CERN’s own equipment. Tracy Slatyer, a theoretical physicist at the Massachusetts Institute of Technology and co-author of the report, explains:

Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we’re already learning about its interactions from the lack of detection so far.This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time.

Still, they caution that it will take multiple sightings – in other astronomical objects, the LHC, or direct-detection experiments being conducted around the world – to validate their dark matter interpretation. Even so, this is the first time that scientists have had anything, even tentative, to base the existence of Dark Matter’s on. Much like until very recently with the Big Bang Theory, it has remained a process of elimination – getting rid of explanations that do not work rather than proving one that does.

So for those hoping that 2014 will be the year that the existence of Dark Matter is finally proven – similar to how 2012 was the year the Higgs Boson was discovered or 2013 was the year the Amplituhedron was found – there are plenty of reasons to hope. And in the meantime, check out this video of a gamma-ray map of the galactic center, courtesy of NASA’s Goddard Space Center.


Sources:
extremetech.com, IO9.com, nasa.gov, cfa.harvard.edu, news.nationalgeographic.com

Work Begins on Successor to Large Hadron Collider

CERN_upgradeIn 2012, scientists working for the CERN laboratory in Switzerland announced the discovery of the Higgs Boson. After confirming this momentous discovery, CERN scientists indicated in April of 2013 that the Large Hadron Collider was being taken offline in order to upgrade its instruments for the next great project in its ongoing goal of studying the universe. And this past February, work began in earnest on planning for the LHC’s successor.

This massive new marvel of scientific instrumentation, which has been dubbed the “Very Large Hadron Collider”, will measure some 96 km (60 mile) in length – four times as long as its predecessor – and smash protons together with a collision energy of 100 teraelectronvolts (which is 14 times the LHC’s current energy). All of this will be dedicated to answering the questions that the first-time detection of the Higgs Boson raised.

Peter Higgs (who proposed the Higgs boson), hanging out at LHC’s CMS detector
Peter Higgs (who proposed the Higgs boson), hanging out at LHC’s CMS detector

While this discovery was a watershed moment, its existence poses more questions than it answers; and those answers probably can’t be answered by the LHC. Thus, to keep high-energy physics moving forward, the international team of scientists at CERN knew they needed something more accurate and powerful. And while the LHC is slated to remain in operation until 2035, it is the VLHC that will addressing the question of how the Higgs get’s its mass.

Basically, while the discovery of the Higgs Boson did prove that the Standard Model of particle physics is correct, it raised some interesting possibilities. For one, it suggests that particles do indeed gain their mass by interacting with a pervasive, ubiquitous Higgs field. Another possibility is that the Higgs boson gains its heaviness through supersymmetry — a theory that proposes that there’s a second, “superpartner” particle coupled to each and every Higgs boson.

CERN_LHCScientists have not yet observed any of these superpartners, and to discover them, a stronger collider will be necessary. It is hoped that, when the LHC powers up to 14 TeV by the end of 2014, its scientists will discover some signs of supersymmetry. This will, in turn, inform the creation of the LHC’s successor, which still remains a work in progress. And at this point, there are two groups presenting options for what the future of the VLHC will be.

One group consists of Michael Peskin and a research group from the SLAC accelerator in California, who presented an early VLHC concept to the US government back in November. This past February, CERN itself convened the Future Circular Collider study at the University of Geneva. In both cases, the plan calls for a 80-100km (50-62mi) circular accelerator with a collision energy of around 100 TeV.

large_hadron_colliderAs the name “Very Large Hadron Collider” implies, the plans are essentially talking about the same basic build and functionality as the LHC — just with longer tunnels and stronger magnets. The expected cost for either collider is around $10 billion. No telling which candidate will be built, but CERN has said that if it builds the successor, excavation will probably begin in the 2020s, so that it’s completed before the LHC is retired in 2035.

In the shorter term, the International Linear Collider, a 31-kilometer-long (19.2 mile) particle accelerator, is already set for construction and is expected to be completed in or around 2026. The purpose of this device will be to conduct further tests involving the Higgs Boson, as well as to smash electrons together instead of protons in order to investigate the existence of dark energy and multiple dimensions.

center_universe2The future of high-energy physics is bright indeed, and with all this research into the deeper mysteries of the universe, we can expect it to become a much more interesting place, rather than less of one. After all, investigating theories does not dispel the mystery of it all, it only lets you know where and how they fell short. And in most cases, it only confirms that this thing we know of as reality is beyond what we previously imagined.

Sources: extremetech.com, indico.cern.ch