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Particle Puzzle: The Mysterious Undertakings of the Large Hadron Collider
There is one question which all of us has asked but has yet to have the same answer: “What is the world made of and what holds it all together?” To finally find an answer to this question, scientists from all around the world are investing their energy in the possibilities of one, gigantic machine: The Large Hadron Collider (LHC). Located 100 meters underground the countries of France and Switzerland, this machine will hopefully help scientists understand and discover even smaller particles than before, which will lead to the understanding of the nature of the universe.
Thus far, physicists have formed a very detailed and probable explanation for how the universe was formed. However, the details of the exact moment of the universe’s formation are yet to be known. The Big Bang theory has lead physicists to believe that the universe materialized from an explosion in a vacuum that occurred 13.7 billion years ago. The four known forces of the universe, which are the electromagnetic force, gravitational force, strong nuclear force and weak nuclear force, are believed to have been fused into a single force due to the conditions of an unbelievably high temperature and density. The combination of these forces is known as the unified force. The unified force remained until 10−43 seconds after the Big Bang, when gravity separated from the other three forces because of the cooling of the universe.
“It is believed that the remaining three forces remained unified until about 1×10-33 seconds after the Big Bang when the strong nuclear force separated from the electroweak force when the temperature of the primeval Universe had fallen to 1×1027 degrees Kelvin, with the electroweak force splitting into the electromagnetic and weak nuclear forces when the temperature had fallen to 1×1015 degrees Kelvin at about 1×10-12 seconds…If the electromagnetic force…did not decouple from its unity with the weak nuclear force until well after the other forces, how could it “keep matter alive” (Wayne McDonald)?
A good question, but we first must understand its importance.
The universe is believed to be composed of space, matter and time. The matter of the universe is believed to be composed of atoms, and dark matter. Einstein’s formula, E = mc2, proves the matter in the universe to be interchangeable with energy. In 1969 Jerome Friedman, Henry Kendall and Richard Taylor developed the Standard Model Theory which describes the universe in terms of matter and force.
“The Standard Model describes approximately 200 particles and their interactions using 17 fundamental particles: 6 quarks, 6 leptons, 4 force-carrying particles, and the Higgs boson… [However,] the theory does not include the effects of gravitational interactions. These effects are tiny under high-energy Physics situations, and can be neglected in describing the experiments” (Ben Best).
This modelhas satisfied physicists’ longing to understand the building blocks of particles and how those particles interact with each other. This theory was built using other discoveries previously made. In 1964 the idea of quarks was proposed by Murray Gell Mann and George Zweig. This idea of quarks is now officially considered another fundamental particle along with leptons. From these fundamental particles, physicists can understand protons and neutrons because they are a combination of quarks. A lepton, on the other hand is a fundamental particle on its own. Leptons and quarks are fundamental particles because a quark is never found alone, and a lepton never forms separate elements.
Higgs boson is a hypothetical force-particle which is believed to cause an interaction which leads to particles having mass. However, this model does not prove the particles exists and does not accurately convey the interactions of particles, for gravity is excluded in this model.
“Even though physicists knew the masses of all the quarks except for top quark for many years, they were simply unable to accurately predict the top quark's mass without experimental evidence because the Standard Model lacks any explanation for a possible pattern for particle masses….We will need to extend the Standard Model with something totally new in order to thoroughly explain mass, gravity and other phenomena” (Particle Data Group at the Lawrence Berkeley National Laboratory).
The discovery of the Higgs Boson is the most basic goal of the LHC. However, the idealistic purpose of this enormous machine is to discover new particles and concepts to go beyond the Standard Model, by incorporating gravity.
The Big Bang theory is the most widely accepted theory of the formation of the Earth. However, there are a few questions that remain unanswered. The LHC will explain the unanswered questions of the Big Bang theory by simulating a process called annihilation. Earlier, we established the question of, how could the universe keep matter alive. This question goes hand in hand with the question: why is there so much more matter than antimatter?
“If matter and antimatter were perfectly symmetrical, the cooling of the universe would have resulted in particle/antiparticle annihilation that would have left the universe filled only with photons. But for every billion mutual annihilations a particle of matter remained -- comprising the existing matter of the universe. About 99% of the photons in the universe are the result of Big Bang annihilations” (Ben Best).
This sounds more complicated than it is. For every matter particle, there is an antimatter particle with an opposite charge. A proton, for example, is electrically positive whereas an antiproton is electrically negative. When an antimatter particle and a matter particle meet, they destroy each other and vaporize, leaving behind the energy that they were made of. Physicists call this process annihilation. While this process is well understood, physicists do not understand how there is so much more matter in the universe than antimatter if their only difference is an opposite charge. At 10-12 seconds after the Big Bang with the electroweak force split, it is also believed that the universe was filled with a hot plasma that included leptons and antiparticles. At 10−6 seconds hadrons began to form.
“Most hadrons and antihadrons were eliminated by annihilation, leaving a small residue of hadrons by one second post-Big Bang. Between one and three seconds after Big Bang the universe was dominated by leptons/antileptons until annihilation of these particles left only a small residue of leptons. The universe was dominated by photons created by all of the matter/antimatter annihilations, and the predominance of matter over antimatter had been established. Between 3 and 20 minutes after the Big Bang protons and neutrons began to combine to form atomic nuclei. A plasma of electrons & nuclei ("ionized hydrogen & helium") existed for 300,000 years until the temperature dropped to 5,000ºC when hydrogen & helium atoms formed” (Ben Best).
This leads physicists to come up with a better description to explain why some particles exist. Now, the idea of the Higgs field which in theory interacts with other particles to give them mass relies on the discovery of the Higgs boson. The LHC will allow physicist to discover this particle by accelerating particles and then colliding them into each other by using the largest particle accelerator ever made.
Colliding particles together will allow physicists to create massive unstable particles and then study their properties. This creation of massive unstable particles comes from the collision of two different particles. Particle accelerators were invented to explore objects with a size less than 10-12 cm.Now there are two types of accelerates: linacs and synchrotrons. A linac accelerator is a linear arrangement where a particle simply starts at one end and then goes to the other. This type of accelerate makes use of a fixed tangent collision, where a charged particle (an electron or proton, for example) is accelerated by an electric field and then collides with a solid, liquid or gas target. Then a detector determines the components of the resulting particle such as the charge, momentum and mass.
This type of accelerator, a linac, was the invention based off of a machine called the Van de Graff Generator. This was a device conceived by Robert Van de Graaff (hence the name of the Generator). This device was built to build up a high voltage using simple principles of electrostatics.
“A belt of insulating material carries electricity from a point source to a large insulated spherical conductor. Another belt likewise delivers electricity of the opposite charge to another sphere. The spheres build up a potential until the electric field breaks down the air and a huge spark "arcs" across. By 1931 Van de Graaff could charge a sphere to 750 kilovolts, giving 1.5 megavolts differences between two oppositely charged spheres… By increasing the radius of the spheres, Van de Graaff could reach higher voltages without arcing. The maximum voltage in theory, in megavolts, roughly equalled the radius of the sphere in feet. He was soon planning a pair of spheres 15 feet across.”(American Institue of Physics).
However, managing high voltages isn’t easy and certainly isn’t all that safe. From Gaaff’s machine, physicsts came up with the idea to accelerate particles by using a lower voltage repeatedly. The man who first came up with this theory was named Gustav Ising, he lived in Sweden. However, he didn’t get very far. Then a man named Wideroe came about and he had designed an accelerator with a potential of 25,000volts alternated from positive to negative at radio frequencies. To reach higher energies, a physicist would only have to add more cylinders, each longer than the last to accommodate the increasing speed of the particles. Widero’s linear accelerator later lead to the synchrotron.
While linear accelerators are much cheaper and easier to build than synchrotrons, synchrotrons can provide more opportunity for a collision and use very high energy particles. A synchrotron accelerator is circular and needs an enormous radius to get particles to a high enough energy level. The LHC uses this arrangement and has satisfied the need for an enormous radius, considering the LHC has a radius of two and a half miles! In fact, it has a circumference of 16 miles! The circular accelerator uses a method called “colliding beams” to collide particles. This is where two beams of high energy particles are made to cross each other at a chosen point, or multiple points. Both of the beams have a sufficient amount of kinetic energy and this is what causes the collision to produce a very high mass particle. If the accelerator behaves as designed, the accelerator will create collisions six hundred millions times each second. Since the particles have a lot of momentum, they have short wavelengths. All particles behave like waves; we know this from Einstein relating energy with mass, smaller wavelengths allow for physicists to more successfully explore inside the atom.
“It is realized that the mass-energy relation (E = mc2) provides a new way to get information about particles. If particles could be made very energetic and then used to collide with other particles, some of their energy could be converted into the creation of previously unknown particles. When particles are produced in a collision, they are not particles that were somehow inside the colliding ones. They are really produced by converting the collision energy into mass, the mass of other particles…Which particles will be produced is partly determined by their mass - the lighter they are, the easier it is to produced them”(Review of the Universe).
In short, the LHC works by taking a particle from a variety of methods, such as heating a metal and then obtaining an electron, then accelerating that obtained particle using electromagnetic fields which attract or repel another particle, and then forcing those particles to collide by having the obtained particle move with the electromagnetic wave. While the electromagnetic wave provides the constant force needed on the particle to make it continue in a circle, magnets are used to direct the particle beams toward particles to help make the particles follow a curved path. The magnets alter the particle’s path just enough to keep it in the accelerator’s path.
The thousands of physicists working at the LHC hope to find a wide variety of things such as the origins of mass, dark matter, and even evidence of extra time dimensions of space-time. Nobody knows what will really happen, or if anything will be achieved at all. In fact, it may even be referred to as “a test to faith.” There has been a lot of controversy whether or not it is our place as humans to attempt to answer these questions, maybe the answers are “supposed” to be out of reach. But despite the political and social controversy, there is no doubt this machine could have the answers.
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