What Is a Grand Unified Theory?

Grand unified theories (GUTs), or GUT for short, is also called the theory of all things. Because there are only four kinds of interaction forces between microscopic particles, universal gravity, electromagnetic force, strong interaction force, and weak interaction force. In theory, all phenomena in the universe can be explained by these four forces. By further studying the connection and unification between the four forces, the search for a theory or model that can uniformly explain the four interaction forces is called the grand unification theory.

As early as the 1920s, the famous physicist Einstein was committed to finding a unified theory to explain all interactions. It can also be said to explain all physical phenomena, because he believed that the concept of "unity" in natural sciences might be Is a basic rule. It can even be said that in Einstein's philosophy, the concept of "unification" is deeply ingrained, and he is convinced that "the nature should satisfy the principle of simplicity".

Shortly after the theory of relativity was introduced in the 1930s, Einstein set out to study the "great unified theory", trying to explain the universe simply through the unified thinking of "weak action, magnetic field, and strong action", and further explained the four kinds of interactions found at the time. Unify into a theoretical framework to find the root cause of these four interactions. This work lasted until his death in 1955, and almost exhausted his energy for the rest of his life, and the unified thinking was inconsistent with the mainstream thought of the physics community at the time, so that some historians of science asserted that this was a major mistake by Einstein. .

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What really becomes the problem is our very rebellious view here: the so-called grand unification theory first reflects only the ideological intentions and subjective desires of people regarding physics; as for what or what the content of a true grand unification theory is, Maybe no one knows. Moreover, we also believe that this is the most basic ideological understanding of the theory of the Grand Unification; without this most basic ideological understanding, the basic understanding of all the Great Unification Theory will be divorced from reality. Therefore, the exploration of the unified field theory introduced by the people may just be following people's feelings, and the true nature of things is far from being understood. For example, an extremely serious problem may be unified field theory or grand unified theory, not necessarily strong interactions, weak interactions,

The famous physicist Shen Zhiyuan proposed that space-time is discontinuous? The term popularized in physics in the 20th century is "quantization." Physical quantities such as energy, momentum, and angular momentum are all quantized. Quantum field theory is not enough for one quantization, and then a second quantization. For decades, physicists Put forward various versions of "theory of all things" (unified field theory): string theory, circle theory, spin theory, twistor theory, space-time non-reciprocity theory, etc. Most of them are based on space-time quantization. It is believed that both time and space have The smallest unit-Planck time (10-43 seconds) and Planck length (10-35 meters). The problem is that they believe that time and space smaller than Planck's time and Planck's length do not exist at all, thus denying that the unit of time and space has connotation. The famous circle theory researcher Smolin is monographing "What is Time and Space" The book emphasizes the discreteness of time and space and denies its continuity, and considers continuous space to be only an "illusion". In his opinion, this is the only way to the unified field theory. This view is representative in the field of unified field theory. It denies that continuity deviates from the main idea of quantum theory. Quantization introduces discrete quantum, but does not deny continuity. Take electromagnetic field as an example, its energy is discrete in units of photons, but the electromagnetic field and electromagnetic wave in space are continuous. Furthermore, it is the Fourier analysis of continuous electromagnetic fields that yields a discrete energy spectrum in a closed space and a continuous energy spectrum in an open space.

The Grand Unified Theory treats quark and lepton as different states of a particle. In mathematical terms, the Grand Unified Theory fills quark and lepton in the same linear representation, and connects them through the action of the SU (5) gauge. Strong Interactions, weak interactions, and electromagnetic interactions are unified into a SU (5) gauge interaction at very high energies (the rest energy level of a billion billion protons, and the rest energy of a proton is about 1 billion electron volts). The energy decreases, and through the first break of the Higgs field, the SU (3) symmetry describing strong interactions and the SU (2) × U (1) symmetry describing weak electrical interactions are separated. The energy continued to decline. At the magnitude of the 100-fold proton rest energy, a second break in the Higgs field occurred, and the electromagnetic and weak effects were separated again, forming the three kinds of interactions observed in the experiment. In the unified theory, quark Lepton and lepton can transform each other through the SU (5) gauge field. In principle, the proton is no longer stable, and it may decay into mesons and leptons. Although the theory predicts that the lifetime of proton decay is very long, the average lifetime is about 1031 years. But proton instability causes instability of the nucleus, and materials constructed by atomic molecules will be unstable. Since the early 1980s, people have closely watched the development of experiments, but the experiments did not observe the phenomenon of proton decay predicted by the Grand Unified Theory. Of course, such experiments are more difficult to do, and have strong background interference (such as cosmic ray interference). Some people are constantly improving equipment and methods, and trying to find examples of proton decay. It is widely accepted that the average proton life is greater than 1032 years, so the experiment does not support the SU (5) unified model.

The strong, weak, and electric interactions have not been truly unified, and the standard model is just a phenomenological theory, which contains more than a dozen tunable parameters and is too arbitrary. Physicists hope that a truly unified solution should A single group is used to describe the symmetry of the three interactions, and only one coupling constant appears in the theory to describe the strength of the interaction. More specifically, the three interactions have different strengths, which is only in the case of low energy Behavior is the result of breaking symmetry. On a higher energy scale, the three interactions unify into a force with only one strength of action. It is like Maxwell's equation unifies electricity and magnetism into one Electromagnetic interaction.

The Standard Model is the result of the hard work of several generations of physicists. The standard model is used to explain the most basic constituent particles in the universe and the interaction forces between them. Physicists believe that there are six kinds of quarks and three leptons in matter particles; there are four kinds of interaction forces between matter particles: electromagnetic force, gravitation , Strong interaction and weak interaction. Gravity is not included in the standard model. The standard model seems to be perfect, but the standard model cannot explain the basic facts: whether it is nuclear fission or fusion, a large number of neutrons, neutrinos, and gamma photons are produced (many neutrino studies are in nuclear reactors Nearby). That is to say, there are neutrons, neutrinos, and gamma photons in the material. We know that neutrinos are a kind of mysterious cosmic particles, which have incredible and strong penetrating ability, and can freely pass through walls, mountains Or even the Earth and other planets. Physicists estimate that neutrinos can freely penetrate iron plates that are billions of times thicker than the distance between the earth and the sun. If there is a barrier made of lead that is several light years thick, , Neutrinos can also pass through calmly. That is to say, neutrinos interact with almost different substances. Neutrinos exist in matter, but once they leave the substance, they almost no longer interact with matter. Why is this? Now that neutrinos exist in matter, we have to ask: why can neutrinos exist in matter? In other words, what kind of particles and what forces are trapped in matter by neutrinos? The standard model cannot be explained because the standard model does not contain the force that traps neutrinos. As for the gamma photons, the same problem still exists. Gamma photons exist in matter and interact with almost any substance. Feel great gravity, but gravity is not included in the standard model. Even if gravity is included in the standard model, it is not useful for gamma photons, because the stationary mass of known matter particles simply cannot provide an extremely large gravitational force enough to trap gamma photons. Since gamma photons exist in matter, Then we have to ask: why can gamma photons exist in matter? In other words, what kind of particles and what forces are trapped in matter by gamma photons? The standard model cannot be interpreted because the force that traps gamma photons is not included in the standard model ^[3] .