After Higgs, Supercharged LHC to Probe Physics Frontier
With the power of an early universe in its control, what will the LHC find next?
Don Lincoln is a senior scientist at the U.S. Department of Energy's Fermilab, America's largest Large Hadron Collider research institution. He also writes about science for the public, including his recent "The Large Hadron Collider: The Extraordinary Story of the Higgs Boson and Other Things That Will Blow Your Mind" (Johns Hopkins University Press, 2014). You can follow him on Facebook. Lincoln contributed this article to Live Science's Expert Voices: Op-Ed & Insights.
Somewhere under the French-Swiss border, two protons have a date with destiny. Trapped inside the Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator, they follow a circular path in opposite directions with velocities very near the speed of light.
As they approach each other, their fate is clear: A collision is inevitable. One could imagine that an impact between two protons might look like a collision between subatomic billiard balls. But the rules of the microrealm are quite different from what familiar intuition developed in the corner pub would suggest. [Wow! Watch a Drone Fly Through the World's Largest Atom Smasher]
Colliding with Success After a hiatus of more than two years, the LHC is up and running again. After a broad program of refurbishments, retrofits and upgrades, the accelerator is essentially an entirely new facility. Operating at nearly double the energy and triple the number of collisions per second, the LHC will create collisions within the centers of four huge experiments, each ready to make the discovery of the century.
Since Einstein's 1905 papers on relativity, physicists have known of the equivalence between energy and mass. As described by Einstein's famous equation (E=mc2), energy can be converted into matter and vice versa. And that's one of the big things that happens inside a particle accelerator. The huge kinetic (i.e., moving) energy of the two incoming beam particles is converted into the mass of particles that didn't exist before the collision.
It is in this manner that two protons, each having a low mass (about 1 billion electron volts for the techno-crowd), can collide and make the Higgs boson, which is a particle with a mass about 125 times heavier than that of a proton. The motion energy of the protons is literally transformed into a very heavy particle.
When the LHC began operations in 2010, it had a clear mission. Two large experiments, each comprised of around 3,000 scientists, were focused predominantly on finding the Higgs boson. Predicted in 1964, the Higgs boson is connected to the Higgs field, which is thought to give the mass to fundamental (i.e., pointlike) subatomic particles. Finding the Higgs boson meant that the idea of the Higgs field was validated.
Prior to its discovery, the Higgs boson was the last missing component of the wildly successful Standard Model of particle physics. When combined with Einstein's theory of general relativity, the Standard Model can describe the behavior all of the matter ever observed - from the matter in you and me, to majestic galaxies careening through the cosmos.
While the discovery of the Higgs boson in 2012 was indeed an enormous success for the scientific community, the triumph came with a disappointment. Explaining this is simple: Essentially, the Higgs boson was like a final piece that completed the Standard Model puzzle. However, as any puzzle enthusiast will tell you, it is the tabs and blanks of pieces that allow one to build a puzzle. The hanging tab gives you a hint as to what the next piece will be. But a completed puzzle is silent on what to do next.
The Mysteries That Remain It's not like we don't have mysteries in the world of physics. From our observation of galaxies, we know that they rotate faster than can be explained by the known laws of gravity and the matter we can detect. To explain that mystery, we invented an unobserved form of matter called dark matter. The fundamental nature of dark matter is certainly a big mystery.
Another mystery stems from that famous Einstein equation, E=mc2. It actually says that when energy is converted into matter, an equal amount of antimatter will be made. During the Big Bang, the universe was full of energy, and this energy transformed into equal amounts of matter and antimatter. Yet when scientists look at the universe, they see only matter. So where did the antimatter go? While physicists have had a few hints from previous experiments, we don't really know the answer. This is another mystery.
There are other mysteries, too, like wondering if there are smaller building blocks of the universe than those with which we are now familiar. Following the history of investigations into that question, we have learned of molecules and then atoms. Research in the early 1900s revealed protons, neutrons and electrons, and the 1960s brought to light the quarks and leptons that are currently considered the smallest particles of nature. However, it is natural to ask if there might be even smaller building blocks. While scientists don't know the answer, there must be some sort of deeper and more fundamental physics that can explain the patterns seen in the quarks and leptons. The answer to that question is yet another mystery.
The Curious Higgs boson Mass Physicists don't know the answer to any of those fundamental questions, and, to be honest, it is possible that the LHC won't teach us about any of those secrets of nature. But there is one question for which LHC data is a surer bet.
It stems from mysteries that arise in calculations of the Higgs boson's mass. When scientists try to calculate this value directly from the theory, the result is much higher than the LHC data suggest.
Because of the laws of quantum mechanics, the Higgs boson can fluctuate into other types of particles (e.g., the top quark, the W and Z bosons, and even pairs of Higgs bosons). This behavior leads to predictions of the mass of the Higgs boson that are closer to the Planck mass which is a hundred quadrillion times heavier than the mass that scientists have measured. (The Planck mass is the highest mass our current theories could possibly apply and marks a frontier beyond which we are certain that we will have to rethink everything.)
Obviously, this is a problem, and physicists have spent several decades imagining possible explanations, even before the Higgs boson's discovery. (After all, it was clear even early on that this problem would exist if the Higgs boson had a mass that could be discovered.)
Supersymmetry The most popular theoretical explanation is a principle called supersymmetry. This idea essentially postulates that the force-carrying bosons (particles with a subatomic spin that is integer multiple of ?, which is the natural unit for spin in the quantum world). For example, photons of spin 1 × ? and the matter-carrying fermions (particles with half integer subatomic spin, e.g. electrons of spin 1/2 x ?) should appear in the theory in a symmetric way. That means if you swap all the fermion and boson symbols, the equation will remain unchanged. Essentially this puts forces and matter on equal footing, making them conceptually interchangeable.
And in theories with supersymmetry, a new set of particles emerge, cousins of the familiar particles of the Standard Model. Supersymmetry says that the familiar quarks and leptons must come with new, related particles physicists now call squarks and sleptons. Similarly, supersymmetric analogs of the photon and gluon, called photinos and gluinos, must exist.
Mind you, no direct evidence for the existence of these supersymmetric particles has ever been found. However, if they do exist, scientists can use these particles' quantum mechanical properties to cancel the contribution of the familiar particles in calculations of the mass of the Higgs boson. With supersymmetry accounting for the other particles, the calculations result in a predicted mass of the Higgs boson that is small, in accordance with measurements.
Some scientists' enthusiasm for supersymmetry has been dampened by the fact that supersymmetric particles haven't been observed. Thus, researchers are exploring other possibilities, for example, the ideas that there might exist additional dimensions of space or that the Higgs boson might contain smaller particles within it. These ideas and others are alternative approaches for taming the unruly predictions of the mass of the Higgs boson.
To quote the famous philosopher Yogi Berra, it's hard to make predictions, especially about the future. Thus it is difficult to know exactly what discoveries will be made at the LHC. However, it seems probable that the mystery of the mass of the Higgs boson is the most promising thread at which scientists can tug. Hopefully, the right tug will let us unravel the existing Standard Model and allow us to knit an even better theory. Only time will tell if we will be successful.
More from Livescience.com:
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Why a Physics Revolution Might Be on Its Way The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science. Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
The Large Hadron Collider is the world's most powerful particle accelerator. In June 2015, the LHC was restarted at nearly twice the energy at which it operated during its first run, which ended in 2013.
Did you own a toy race-car track as a child? Ever crash your model trains into one another just to see what happened? If you did, then congratulations, you already know some of the basic principles behind the Large Hadron Collider (LHC). Built by the European Organization for Nuclear Research (CERN), the 27-kilometer tunnel buried in the Swiss countryside exists to smash particle beams into each other at velocities approaching the speed of light. The idea is to use the resulting data to better understand the structure and origins of the universe. We're talking heavy questions and even heavier answers. Perhaps it's understandable that some critics, conspiracy theorists, crackpots and (alleged) time travelers might fear something more substantial than the Higgs boson particle. In this article, we'll run through some of the more popular misconceptions about the LHC and how little you have to fear about it causing the end of the world as we know it.
5. CERN Is Making an Antimatter Bomb
The Dan Brown detective novel (and movie adaptation) "Angels and Demons" centers on a plot to steal an antimatter bomb from CERN and blow up the Vatican with it. While the blockbuster delivered its share of action and intrigue, it fell short on facts. Two of the film's biggest mistakes revolved around antimatter's potential use as both an energy source and a weapon. Yes, when an antimatter particle comes in contact with normal matter, the two particles destroy each other and release energy. But CERN is quick to point out that the energy payoff simply isn't there. In fact, the transaction is so inefficient that scientists only get a tenth of a billionth of their invested energy back when an antimatter particle meets its matter counterpart. As for developing an antimatter bomb, the same principles apply. CERN points out that, at current production rates, it would take billions of years for the organization to produce enough antimatter to generate an explosion equal to an atomic blast.
4. Fun-sized Black Holes
Some concepts don't become tamer when you tack a "micro-" or a "mini-" prefix in front of them. For example, a mini-stroke is still an excellent reason to visit the hospital, and you'd certainly be ill advised to question the power of a minigun. So when CERN scientists mention that they might create microscopic black holes in the midst of their particle smashing, it's easy to understand some of the ensuing panic. Based on Einstein's theory of relativity, a few speculative theories lend a sheen of possibility to micro-black hole creation. The good news is that these theories also predict the micro-black holes would disintegrate immediately. If these black hole welterweights did hang around a little longer, it would take billions of years to consume the mass of a tiny grain of sand. That means no reducing the European countryside to a singularity and certainly no destroying the planet "Star Trek" style.
3. Attack of the Strangelets
Read enough space publications and your perception of the universe changes pretty fast. Once you get beyond the absurd vastness of the cosmos, you encounter such mind-rending notions as black holes, antimatter and dark matter. After you've swallowed the notion of a gigantic star collapsing into something smaller than a pinhead, it's easy to get bowled over by the idea of universe-destroying strangelets. Strange matter is presumed to be 10 million times denser than lead and was birthed during the Big Bang from the hearts of dense stars. The fear, which originated with the start-up of the Relativistic Heavy Ion Collider (RHIC) in 2000, is that the LHC will inadvertently produce strangelets -- tiny particles of strange matter -- and that these particles will swiftly convert surrounding normal matter into even more strange matter. It only takes a thousand-millionth of a second for the chain reaction to convert the entire planet. Strangelets, however, are purely speculative, and haven't surfaced in over eight years of RHIC operation. CERN says that the RHIC was far more likely to produce the theoretical matter than the LHC, so there's really no chance of it consuming the planet.
2. Time Travelers Hate It
In "Bill & Ted's Excellent Adventure," the titular slacker duo wields time travel with the logic of a 12-year-old. When Bill and Ted need a cell key to bust a few historical figures out of a modern California jail, they simply make a mental note for their future selves to travel back in time and plant the key where they can find it. While the 1989 buddy comedy is pretty much the antithesis of hard science fiction, its view of time-travel logic is shockingly similar to a 2009 theory regarding the LHC. Danish string theory pioneer Holger Bech Nielsen and Japanese physicist Masao Ninomiya, in a series of posted physics articles, laid out their theory that the Higgs boson particle is so abhorrent to nature that its future creation will send a ripple back through time to keep it from being made. Naturally, this theory summons images of T-800s, Jean-Claude Van Damme and Hermione Granger all galloping back through time to prevent future disasters, but not everyone is busy cracking jokes and reminiscing about time-travel movies. The two scientists aren't even talking about shadowy strangers from the future, but merely "something" looping back through the fourth dimension. Imagine a poorly designed bomb that, upon creation, destroys half the bomb factory. Now expand that example out from the confines of linear time.
1. Gateway to Hell
Black holes, antimatter explosions and even strangelets all originate from scientific fact and theory (albeit with a bit of imagination thrown in). Forget all that for the moment and consider the "Satan's Stargate" theory, proposed by Chris Constantine, better known on the Internet as YouTube user gorilla199. Constantine charges that the LHC exists "to disrupt a hole in the Van Allen belt that surrounds the Earth" and "to allow the return of the Annunaki from the planet Nibiru in order that they can come here, corrupt the rest of the Earth and do battle with God at Armageddon." There's also some stuff in there about freemasonry, cosmic rays and the Old Testament offspring of humans and fallen angels. According to BBC News, Constantine received a suspended sentence for DVD pirating after his defense attorney charged that Constantine suffered from a serious psychiatric condition. The Antichrist could not be reached for comment.