Is The New LHC Run The End Of Particle Physics As We Know It?
The Large Hadron Collider (LHC) at the CERN facility (the European Organisation for Nuclear Research) near Geneva, is the largest and most powerful particle accelerator in the world. It has been used in a large number of experiments, which have proved that the Standard Model of particle physics encompasses essentially every particle that makes up the universe and the forces that act upon them. The most significant of these was the discovery of the Higgs boson, the last particle predicted by the Standard Model to be discovered.
After being offline for two years for upgrading, the LHC is now back up and running again for its second run of experimentation. This time it's even more powerful and the investigations are going beyond the Standard Model. Scientists are particularly excited and anxious about this run because it could prove theories that go far beyond the reach of the Standard Model or suggest that no more research is required as the Standard Model is all there is.
The New and Improved Large Hadron Collider
Consisting of 27 kilometres of superconducting magnets, the LHC contains two separate particle beam pipes kept in ultra-high vacuum. These beams travel at close to the speed of light and cause the particles to collide at a force equivalent to an apple hitting the moon hard enough to create a six-mile wide crater. Since its upgrade, the LHC has nearly doubled its collision energy to a record-breaking 13 teraelectronvolts. Scientists hope that this new level of energy will allow more radical discoveries.
Theories Beyond the Standard Model
One of the theories to be tested in this run is the 'Supersymmetry' theory, which suggests that 23% of the universe could be made up of dark matter, which is not included in the Standard Model. Some scientists believe that further study of the Higgs boson could prove the existence of dark matter, as it seems to be attracted to particles with mass such as dark matter. Studying the way the Higgs boson interacts with other particles could unlock that mystery. Another question that the Standard Model is not able to answer concerns anti-matter. A new set of experiments called LHCb (Large Hadron Collider beauty) are currently investigating the similarities between matter and anti-matter particles by studying the beauty quark.
Rolf Heuer, the Director-General of CERN stated that, “with this new energy level, the LHC will open new horizons for physics and for future discoveries”. However, if it fails to prove any theories beyond the Standard Model, it is highly likely that these theories will never be proven and will render further experimentation obsolete. However, CERN is not the only organisation trying to make important breakthroughs in particle physics and for those other experiments equipment, such as stepper motors that can operate in ultra-high vacuum conditions, is essential.
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Photo credit: CERN
What is the Standard Model?
The Standard Model in particle physics definitely does not suggest that the answer to life, the universe and everything is 42. However, it does give physicists a profound understanding of what life, the universe and everything is made up of. It describes the fundamental particles that essentially make up all matter and the forces that act upon them. CERN (the European Organisation for Nuclear Research) states that, “how these particles and three of the forces are related to each other is encapsulated in the Standard Model of particle physics.”
Even though the development of the Standard Model was a cumulative effort of scientists around the world for many years, the term itself was coined in the 1970s. They categorised the basic elementary particles, quarks and leptons into six groups, which were then paired and called 'generations' based on their weight and stability. The lightest and most stable particles were called the first generation and they make up all stable matter in the universe. The Standard Model has been used to not only identify different types of particles but also to predict their existence. Over the years its reliability at predicting the existence of particles has been proven time and time again as these particles have subsequently been discovered.
There are four Fundamental Forces that are exerted on these elementary particles and they are the strong force, the weak force, the electromagnetic force and the gravitational force. Interestingly, the Standard Model includes all of these forces except gravity. Being the best known force to the average person, it seems odd that this force is not included but it does not fit comfortably into the Standard Model and this is partly due to the fact that gravitational force is so weak when exerted on particles that its effect is negligible. Each of the other forces works by matter particles exchanging force-carrier particles called 'bosons'. Different forces have different bosons. The strong force has one called 'gluons', while the weak force is carried by the 'W and Z bosons'. Electromagnetic force is carried by 'photons' but, although it is thought that gravity should have a force-carrying particle called a 'graviton', it has never been discovered.
This is an example of how the Standard Model is “still incomplete” as CERN states. It cannot explain dark matter and CERN suggests that it is “part of a bigger picture that includes new physics hidden deep in the subatomic world or in the dark recesses of the universe”. Experiments are done continuously to test theories within and beyond the Standard Model such as the attempts to discover the Higgs boson particle in the Large Hadron Collider at CERN. However, many other such experiments are taking place all over the world using vacuum conditions to isolate particles.