Yazdani Lab, Princeton University
Princeton University scientists used scanning-tunneling microscope to show the atomic structure of an one-atom-wide iron wire on a lead surface. The zoomed-in portion of the image depicts the quantum probability of the wire containing an elusive particle called the Majorana fermion. Importantly, the image pinpoints the particle to the end of the wire, which is where it had been predicted to be over years of theoretical calculations.
Image: A plot of Tevatron (Fermilab) data sho
Discovery, At Last?
July 3, 2012 --
It seems that the Higgs boson just keeps bringing out the crazy in people. As we get closer and closer to cornering the secretive particle, there's been no shortage of myths, rumors and just downright odd (yet physically sound) theories to add some entertaining sideshows to the proceedings. So, this week, physicists who are working tirelessly with CERN's Large Hadron Collider (LHC) near Geneva, Switzerland, have a big announcement. But will it be
announcement we've all been waiting for? In typical quantum physics style, a
discovery announcement will be unlikely -- but we are slowly, yet surely, closing in on the particle's hiding place. While we wait for that precious "5-sigma" result, here are some peculiar Higgs stories and odd boson facts that have entertained, mystified and confused us ever since the LHC revved up its superconducting magnets.
Credit: Delta Publishing
Not the "God Particle" Let's get this crime of physics out of the way first. The hunt for the Higgs boson has nothing to do with God. The Higgs is not a divine entity; it is a gauge boson -- i.e. it is a particle that mediates mass and therefore endows all matter with (you guessed it) mass. (And no, that's not mass as in "religious service mass;" it's mass, a "property of matter mass.") So why the heck do we see, with alarming regularity, the "God Particle" reference plastered across every tabloid newspaper? Ever since Nobel Prize-winning physicist Leon M. Lederman and science writer Dick Teresi gave the elusive particle the tongue-in-cheek moniker in their 1993 book "The God Particle: If the Universe Is the Answer, What Is the Question?" mainstream media grabbed hold of the nickname as if physicists were looking for The Almighty himself. Alas, the hunt for the Higgs has nothing to do with God, but it is a critical step forward in our understanding of what gives all matter in the Universe its mass. Of course, if the tabloid press mentions the "God Particle" as an ironic or sarcastic reference, that's fine. Physicists have a sense of humor too.
There's a Higgs Family?! In 2010, physicists at the DZero collaboration at Fermilab's Tevatron particle accelerator came up with an interesting proposition: What if there are actually five different types of Higgs bosons? Perhaps old Higgsy has a mom, dad and twin sisters! Known as the "two-Higgs doublet model," the mere hint that there may be more Higgs particles to hunt down will likely make any particle physicist sweat, but it would explain some of the strange science results coming from the DZero collaboration. According to Discovery News' Jennifer Ouellette, this has potential implications for the "God Particle" misinterpretation: "Along with many physicists, I hate the term 'god particle' to describe the Higgs," says Ouellette. "Fermilab's Leon Lederman coined the term over a decade ago, and it's been misleading innocent civilians ever since into thinking physicists are trying to prove or disprove the existence of god or something. But it did give the blog 80 Beats the best line yet about these new results: 'If the Higgs boson is the God Particle, then some particle physicists just turned polytheistic.'"
Credit: Test Tube Games
It Has An App Like everything else in the Universe, the Higgs particle has its own app. Naturally, LHC physicists are the villains of the game and you have to use other Standard Model particles to hide the Higgs from detection. You may not need a Ph.D. to play the game, but a vague understanding of quantum particles might help.
Image: The massive CMS detector in the LHC. C
God Hates It It seems that the longer a particle evades detection, the more stir-crazy some scientists become. This may not be an established law of physics, but it certainly seems to be the case for one distinguished physicist who, in 2009, published a lighthearted paper about why the Higgs is so difficult to find. The upshot: God hates the Higgs boson. What's with all the 'God' references? In a nutshell, as the Higgs boson can transmit a signal back in time when it is created by a particle accelerator, this signal will ultimately sabotage the accelerator before the thing has even been built. Nature, and therefore "God," doesn't want old Higgsy to see the light of day. Dennis Overbye of the New York Times summarized the situation quite nicely: "...the hypothesized Higgs boson, which physicists hope to produce with the collider, might be so abhorrent to nature that its creation would ripple backward through time and stop the collider before it could make one."
Image: A simulation of the production and dec
It's a Time-Traveling Assassin Reading like the plot of Jean-Claude Van Damme's 1994 movie "Timecop," the Higgs boson's time-traveling capabilities may be used for evil. Yes, it could go back in time to kill your grandfather. Or, at least, a signal utilizing the Higgs' time-traveling capabilities could be used to send a signal back in time to an assassin who is waiting for the signal to start a killing spree. Actually, that might really be the sequel to Timecop. This time-traveling Higgs theory was thought up by Vanderbilt University theoretical physicists Tom Weiler and Chui Man who admit their idea "is a long shot," but it "doesn't violate any laws of physics." Yay physics! Based on the theory that when a Higgs particle is generated a Higgs "singlet" particle is also generated at the same time, this singlet can utilize the "fifth dimension" of spacetime to zip through time and travel into the past. According to Weiler and Man's calculations, this could allow a Higgs singlet signal to be sent back in time, and could therefore be used for all kinds of freaky shenanigans.
It's a Social Media Superstar It may come as no surprise that the Higgs boson has become something of a celebrity. Even though the vast majority of the public have no clue what the Higgs boson actually is, the hypothetical particle has become more popular than Lindsey Lohan and, for a time, was a trending topic alongside Lady Gaga and... Santa. True story. As we've already mentioned, the myth of the Higgs has often been a little more exaggerated than the truth, so in the spirit of "going viral," old Higgsy had its own meme on Twitter. Using the hashtag #HiggsRumors, hundreds of Higgs fans -- evidently exacerbated by the flurry of half-truths and rumored discoveries -- invented their own rumors about the elusive particle. It all began when @drskyskull tweeted: "I hear the Higgs boson once shot a man just to watch him die. #HiggsRumors" The rest, as they say, is social media history.
CERN is expected to make its announcement about the possible Higgs boson confirmation on July 3. For updates, keep an eye on Discovery News and the @Discovery_Space Twitter feed.
MORE ARTICLES BY IAN O'NEILL
If you thought the search for the Higgs boson — the elusive particle that endows matter with mass — was epic, spare a thought for the physicists who have been trying to find a way to discover another subatomic particle that has remained hidden since it was first theorized in the 1930s.
But now, through the use of a two-story-tall microscope, the very strange and (potentially) revolutionary particle has been tracked down.
Introducing the Majorana fermion: a particle that is also its own antiparticle, dark matter candidate and possible quantum computer enabler.
The Majorana fermion is named after the Italian physicist who formulated the theoretical framework that described this unique particle, Ettore Majorana. In 1937, Majorana predicted that a stable particle could exist in nature that was both matter and antimatter. In our everyday experience, there is matter (which is abundant in our known universe) and antimatter (which is very rare). Should matter and antimatter meet, they both annihilate, disappearing in a flash of energy.
One of the biggest conundrums in modern physics is how the universe became more matter than antimatter. Logic suggests that matter and antimatter are one in the same thing, like the opposite sides of the same coin, and should have been created at the same rate. In this case, the universe would have annihilated before it could have even gained a foothold. But some process after the Big Bang ensured that more matter than antimatter was produced, so matter won out to create the matter-filled universe we know and love today.
However, the Majorana is different; it is its own antiparticle. Whereas an electron is matter and the positron is the electron's antimatter particle, for example, the Majorana is both matter and antimatter -- at the same time. It is this matter/antimatter duality that has made this little beastie so hard to track down for the past eight decades.
But track it down physicists did and it took some stunning ingenuity and a whopping great microscope to accomplish the task.
Theory suggests that the Majorana should emerge at the edge of other materials. So the Princeton team constructed an atom-thick iron wire on a lead surface and zoomed in on the end of that wire with the mega-microscope at the ultralow-vibration laboratory at Princeton's Jadwin Hall.
“This is the most direct way of looking for the Majorana fermion as it is expected to emerge at the edge of certain materials," said lead physicist Ali Yazdani of Princeton University, N.J., in a press release. “If you want to find this particle within a material you have to use such a microscope, which allows you to see where it actually is."
Yazdani's research was published in the journal Science on Thursday (Oct. 2).
The search for the Majorana is very different from searches for other subatomic particles that have seen much mainstream press. The hunt for the Higgs boson (and particles like it) need the most powerful accelerators on the planet to generate the vast collisional energies required to simulate the conditions soon after the Big Bang. This is the only way to isolate a rapidly-decaying Higgs boson and then study its decay products that betray its existence.
In contrast, the Majorana can only be detected in a material by its effect on the atoms and forces surrounding it — so no powerful accelerators are required, but powerful scanning-tunneling microscopes are a must. Also, very fine controls on the target material is required so the Majorana can be isolated and imaged.
This stringent control required extreme cooling of the thin iron wire to ensure superconductivity. Superconductivity is attained when the thermal vibrations in a material are lowered to such an extent that electrons can pass through that material with zero resistance. By lowering the target to -272 degrees Celsius — just one degree above absolute zero, or 1 Kelvin — the perfect conditions for Majorana formation could be attained.
“It shows that this (Majorana) signal lives only at the edge," Yazdani said. “That is the key signature. If you don't have that, then this signal can exist for many other reasons."
Previous experiments have picked up possible Majorana signals in similar setups, but this is the first time that a definite signal — after all other sources of interference have been removed — of a Majorana fermion at the location it was predicted to be. This could only be achieved by keeping the experimental setup simple and not using exotic materials that could introduce noise, argues Yazdani.
“What's very exciting is that it is very simple: it is lead and iron," he said.
From Dark Matter to Quantum Computing
Now it has been discovered, there are some exciting implications for several areas of modern physics, engineering and astrophysics.
For example, the Majorana is extremely weakly interacting with normal matter, much like the ghostly neutrino. Physicists are not sure whether the neutrino has a separate antiparticle or whether, like the Majorana fermion, is its own antiparticle. Neutrinos are abundant in the universe and astronomers often point to neutrinos being a significant portion of dark matter that is thought to fill the cosmos. Perhaps neutrinos are also Majorana-like particles and Majorana fermions are also a dark matter candidate.
There is also a potentially revolutionary industrial application should physicists be able to encode matter with Majorana fermions. Currently, electrons are being used in the quantum computing effort, potentially creating computers that can solve previously incalculable systems in an instant. But electrons (also a fermion) are notoriously difficult to control, often collapsing calculations after interacting with other materials surrounding them.
The Majorana fermion, however, is extremely weakly interacting with matter due to its matter/antimatter duality and is surprisingly stable. It is for these reasons that scientists may be able to harness the Majorana, engineering it into materials, encoding it and potentially opening up new and novel quantum computing applications.
So although its discovery may not have the drama and action of smashing relativistic particles together in the vacuum chambers of the LHC's building-sized detectors, the more subtle Majorana discovery could develop a new understanding for dark matter and aid a revolution in computing.
That 80-year wait for its discovery was probably worth it after all.
Source: Phys.org/Princeton University