The Return of the Large Hadron Collider
The Large Hadron Collider (LHC) was recently turned back on after a two year hiatus. During its initial run in 2012, the LHC made headlines with the first detection of the Higgs boson. Now, the newly upgraded particle accelerator has the potential to provide new knowledge through the study of antimatter, solve the mystery of dark matter, and even reveal the existence of extra dimensions.
Hi I’m Sabrina Stierwalt, and I’m Ask Science bringing you Quick and Dirty Tips to help you make sense of science.
Earlier this week, the Large Hadron Collider (LHC) in Geneva, Switzerland was turned on again after being offline for over two years. During its first three year run, the particle accelerator delivered big time with the likely detection of the Higgs boson, news so huge that it was the focus of two previous Math Dude episodes and one Ask Science episode. The Higgs boson was a missing piece to the Standard Model, the framework scientists use as the foundation of our understanding of pretty much all of physics.
The Standard Model predicts the existence of the Higgs, but prior to the LHC, the elusive particle had never been detected. Now, thanks to the collider’s roughly $3.6 billion first run, a three-year stint that generated around 90 petabytes of data, the pieces of evidence for the Standard Model are coming together. And, by the way, that’s an average of $1 for every 25 Megabytes of data—a steal!
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What Will the Updated LHC Tell Us?
The LHC was shut down in early 2013 for planned upgrades. During its down time, scientists and engineers worked to replace the magnets used to steer the particles on their collision course, as well as maintain the more than 10,000 electrical interconnections between those magnets. The cryogenics, needed to keep the magnets in their superconducting state, were updated, as was the coating along the inside of the beam. That coating keeps electrons from getting ripped off the sides of the pipe and thus interfering with the experiments.
Most importantly, the particle beams are now more focused (i.e narrower) and of much higher energy. The collisions created in the LHC can now reach 13 TeV (that’s 13 tera electronvolts), nearly twice the 8 TeV limit of its prior run. To put those numbers into perspective, since most of us don’t regularly throw around units of TeV, the prefix “tera” means that “13” is followed by twelve zeroes. A normal photon of visible light carries only 1 to 3 electronvolts (no following zeroes). The splitting of a uranium atom through nuclear fission produces 200 Mega electronvolts (that’s 200 with six following zeroes).
These higher energies will unlock the chance to detect particles and test physical theories not possible before the upgrade.
For example, even though the detection of the Higgs boson supplied a huge piece of the Standard Model puzzle, there are still gaps, or physics we know to be true that the Standard Model as it stands does not yet explain. The theory of supersymmetry is an extension proposed to fill some of those gaps in the Standard Model, like where mass originates from. Some particle physicists have suggested that all of the particles we know through the Standard Model actually have partners called “supersymmetric particles.” The high energy collisions of the LHC should produce these particles, if they exist. Such detections would be strong evidence that supersymmetry does, in fact, offer an explanation of our universe.
As discussed in a previous episode, dark matter makes up most of the matter in the universe, and yet we still aren’t sure what it is even made of. One theory suggests that these so far undetected supersymmetric particles may make up the missing matter. Thus, their detection with the LHC could hold answers to related areas of astrophysics.
Certain theories about the different forces that govern how particles interact with each other further predict the existence of particles that don’t use the electromagnetic force to feel each other’s presence. Since much of what we understand about our everyday surroundings involves electricity, magnetism, light, and thus the electromagnetic force, particles that don’t behave this way are considered “exotic.” These particles are only predictions at this point, since not interacting via the electromagnetic force makes them much harder to detect. However, they may interact with the Higgs boson. The beefed up LHC may be able to determine whether or not these particles exist, and thus which of our particle theories are more likely to be correct.
The higher energies will also allow more antimatter to be produced in the collisions. Physicists have found that every particle of matter has a matching antiparticle—its near identical with the only difference being its charge. When matter and antimatter, like an electron and a positron, collide, they annihilate, creating a burst of energy. What physicists can’t explain is why there is so much more matter in the universe than antimatter when our theories tell us they should have been produced in equal amounts during the Big Bang. Being able to study more of these antimatter particles may hold the answer.
Although anyone who has fallen down a set of stairs or parachuted out of a plane may not believe it, gravity is actually a pretty weak force compared to the other forces, like the so-called strong force that holds the atoms in our bodies together. Some physicists have suggested that the gravitational force that we experience may be weak because it is actually being spread out over extra dimensions.
The same particles we know and love in our dimensions may thus exist in heavier forms in these extra dimensions where gravity is stronger. These heavy particles are completely theoretical but could be revealed thanks to the high energies of the upgraded LHC. So putting that all together, the LHC has the ability to reveal the existence of other dimensions!
Is the LHC Safe?
So, with all this talk of exotic particles, antimatter, and extra dimensions, you may be asking, “Are the experiments at the LHC safe?” The answer is a resounding “yes,” despite these potential discoveries that seem to border on science fiction.
Even before the 27-kilometer ring of superconducting magnets was originally turned on, a lot of inaccurate reports claimed that physicists were risking the fate of the planet with their experiment. Rumors spread that the LHC had the ability to create a black hole. There are many physical reasons that make this scenario impossible, but the most convincing one is that we are still here.
The collisions created in the LHC have already been produced in nature over and over again. Their natural occurrence is precisely why the particle physicists at the LHC are interested in studying them. By observing them up close and in a relatively controlled environment, scientists can hopefully shed light on some of the unsolved mysteries of our universe that still remain just out of our reach.
For more information on how the LHC works, check out the facts and figures page provided by CERN, the European Council for Nuclear Research.
Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.comcreate new email.
LHC image courtesy of CERN. Extra dimensions image courtesy of Shutterstock.
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About the Author
Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.
