Mangat The Theory of Everything Milan Mangat Mr. Simnett SPH4UA 15 December 2019 Mangat 1 Introduction The search for a unifying theory of everything has been the subject of much controversy and excitement amongst physicists since the early 1920’s. The idea of whether the nature of the universe could be explained using a single set of laws, the theory of everything (TOE), has been questioned but not yet proven. As scientists try to come up with what it is, they must prove and disprove ideas to develop more accurate conclusions. Recently, scientists believe that the TOE can be explained using a detailed examination of the unification of the four fundamental forces and through the use of the superstring theory. Gravity Let Us Down Scientists believe that they have found the elementary particles that make up everything in the universe. They are split into two categories, matter particles and force-carrying particles, where matter particles release force-carrying particles. Since these particles emit waves of frequencies larger than visible light, they cannot be detected directly, but have been proven to exist because when a matter particle releases or gains a force carrying particle its velocity changes. According to the effects of the force-carrying particles scientists have determined the four fundamental forces in the universe. The first is the electromagnetic force, this force is produced when the force-carrying particle, the photon, is released to produce visible light. Moreover, the weak nuclear force is responsible for radioactivity which is created by two force-carrying particles called bosons, more specifically the W bosons (W+ and W-) and Z boson. The electroweak theory is the unification of the weak nuclear and electromagnetic forces (figure 1 (a)). Furthermore, the strong nuclear force creates the structure of the atom by holding protons and neutrons together. It is also responsible for holding the contents of individual protons and neutrons together. This force is created through the emission of the force-carrying particles called gluons. The electromagnetic, weak nuclear and strong nuclear forces become one force at the grand unification energy level (figure 1 (b)). However, the gravitational force has not yet been able to be unified with the rest. a b c Figure 1 (a) at higher energy levels the electromagnetic and weak nuclear forces become the unified electroweak force. (b) At consecutively higher energy levels the strong nuclear force gets weaker until, the electroweak force and strong nuclear force meet to become the Grand Unified Theory (GUT). (c) The Theory of Everything (TOE) is where gravity unifies with GUT and all four forces as well as their force-carrying particle become identical. Mangat 2 The gravitational force is by far the weakest of the four forces, its affects are only noticeable because it can act over long distances and because it is always attractive. All of the other fundamental forces release force-carrying particles which leads scientists to believe that the graviton is the forcecarrying particle for gravity. Unlike the other three forces, a graviton is purely theoretical and because of gravity’s bases on the general theory of relativity its fundamentals differ greatly from those of the other forces proving them hard to combine. Since TOE cannot be achieved without gravity (figure 1 (c), above) and the energy level required by the TOE cannot be produced in particle accelerators, it can never be tested for. In order to prove that the TOE is a possibility, scientists must research and theorize what the graviton is and although a single graviton has not yet been detected, gravitational waves have. On February 11, 2016, using the LIGO (Laser Interferometer GravitationalWave Observatory) scientists detected a gravitational wave created by a collision between two black holes that happened nearly 1.3 billion years ago (figure 3). Both LIGOs, located in Livingston, Louisiana and Hanford, Washington detected the ripple only 7 milliseconds apart and the waves matched the ones that were calculated by supercomputers using the theory of relativity which helped confirm their discovery. The gravitational waves proved gravitons exist (figure 2) but despite this evidence the TOE still cannot be proved because even in gravitational waves, the individual gravitons cannot be detected. Due to this, scientists are left with no option but to create an experiment that has enough energy to detect a single graviton or find a new way to prove its existence and is essentially what they wish to do using the superstring theory. Figure 3, shows how electromagnetic waves are produced of individual photons. This knowledge led scientists to believe that gravitational waves are produced by individual gravitons. Figure 2, gravitational waves squeeze and stretch space therefore as a gravitational wave passes the LIGOs laser beams, the time the beams take to reach the mirrors should change because the wavelengths of the laser beams will change. Mangat 3 Hanging on By A Thread Superstring theory is one method to explain the Theory of Everything where the fundamental components of the universe are made up of strings, not points. It is also said that different vibrations of these strings produce all of the elementary particles that we know, such as photons and bosons (figure 4). General relativity was the first to explain the idea of gravity caused by the warping of space and time in four dimensions so it was believed by some scientists that another dimension would be required if they wanted to describe another force. When this idea was tested by Theodor Kaluza for the electromagnetic force, with the addition of a fifth dimension, Kaluza ended up with the original equation for magnetism that was originally determined by Clerk Figure 4, this shows the elementary Maxwell but through the use of equations based on five dimensions. This particles of the diamond as stings, the shape of the string indicates it is vibrating seemingly supports the idea that the superstring theory would require multiple dimensions in order to work. According to scientists such as Kaluza, these extra dimensions are proposed to be so small in size that they are practically invisible thus unnoticeable. Many scientists believe that the 11 dimensions of the superstring theory each explain a fundamental aspect of the world. It is thought that numbers like the mass of an electron, the strength of the electromagnetic force and etc., are believed to be based on the forms of the dimensions. This ideology is based on the fact that those values are constants therefore a change in them would altered the universe we know just like how a change in the dimensions we live in would have the same affect. These extra dimensions take the form of Calabi-Yau’s (figure 5). Figure 5, the extra dimensions Essentially, strings are affected by the shapes of the dimensions because the way fold in on themselves to form a they vibrate is altered by the geometry of the extra dimensions. If the shape of Calabi-Yau shape, where the grid is the dimension of space time. the extra dimensions can be discovered physicists believe they would be able to On the smallest possible scale calculate the exact vibrations that strings would have in each dimension. The this is how the universe would vibrations should correlate with the fundamental values (e.g. mass of the appear according to superstring electron or strength of the electromagnetic field) that are known, and if they do theory then the superstring theory as well as the TOE can be proved. Using the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland scientists hope to test for these other dimensions specifically to unify gravity with the other fundamental forces. As stated in the section above, the search for the graviton would require such large amounts of energy that it is practically impossible. However, physicists believe that it can be done with the addition of another dimension because it would cause the intensity of gravity to decrease rapidly (figure 6a-d, below). This interaction cannot be observed so scientists have planned to measure the energy and momentum in our dimension before and after the collisions to see if it changes. Due to the law of conservation of momentum and energy, if either of these change from before the collision to after there would be Mangat 4 reason to believe it has entered another dimension. If this test can be done and proved scientists would be one step closer to the complete theory of everything. a b c d Figure 6, 6a and 6b show how the LHC sends particles travelling in opposite direction, near the speed of light and into head on collisions. After the two particles collide, 6c and 6d show how a graviton is released into a fifth dimension. Conclusion All in all, physicists have gained more knowledge about the theory of everything and what it could be through thorough research on the four fundamental forces and the importance of uniting gravity with the electromagnetic, weak nuclear and strong nuclear forces. Since it is nearly impossible to do so with experiments alone, the superstring theory is being used to help explain the existence of the graviton. If it can be proved through experiment it would unlock the key to the grand unified theory. Ultimately, physics greatest breakthroughs start off as questions of what something could be, where tests, experiments and theories are developed to support or reject ideas and conclusions are made. For all we know, the proven existence of extra dimensions and the graviton can open the door to understanding concepts like dark matter or dark energy or even something far more unimaginable than that. Mangat 5 Work Cited Hawking, Stephen. A Brief History of Time. Bantam Books, 2017. “Extra Dimensions, Gravitons, and Tiny Black Holes.” CERN, home.cern/science/physics/extradimensions-gravitons-and-tiny-black-holes. OpenStaxCollege. College Physics, 23 Jan. 2012, opentextbc.ca/physicstestbook2/chapter/guts-theunification-of-forces/. “Unified Forces.” CERN, home.cern/science/physics/unified-forces. “What Is a Gravitational Wave?” NASA, NASA, 26 Nov. 2019, spaceplace.nasa.gov/gravitationalwaves/en/. Wood, Charlie. “String Theory: A Brief Overview.” Space.com, Space, 11 July 2019, www.space.com/17594-string-theory.html. Mann, Adam. “What Is the Theory of Everything?” Space.com, Space, 29 Aug. 2019, www.space.com/theory-of-everything-definition.html.
