Unified field theory

Unified field theory: In physics, unified field theory is a field theory that tries to unify – introducing common principles – two previously considered different field theories. This would imply that it would be possible to describe the fundamental interactions between the elementary particles in terms of just one field.


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  • 1 Theoretical introduction
  • 2 History
  • 3 Maxwell’s Unified Field Theory
  • 4 Glashow-Weinberg-Salam Unified Field Theory
  • 5 Theories of Great Unification
    • 1 Main article: Theory of great unification
  • 6 Theories of Everything
    • 1 Main article: Theory of everything
  • 7 Reductionism
  • 8 Sources

Theoric introduction

In physics, the forces between objects can be described by the effects of “fields”. Current theories consider that for subatomic distances, these fields are replaced by quantum fields interacting according to the laws of quantum mechanics. Alternatively, using the wave-particle duality of quantum mechanics, the fields can be described in terms of the exchange of particles that transfer momentum and energy between objects. In this way, objects interact when they emit and absorb the exchanged particles. The fundamental basis of unified field theory is that the four fundamental forces (below) like matter are simply different manifestations of a single fundamental field. Unified field theory tries to reconcile the four fundamental forces (or fields) of nature (from strongest to weakest): Strong nuclear force: force responsible for the union of quarks to form neutrons and protons, and the union of these to form the atomic nucleus. The exchange particles that measured this force are gluons. Weak nuclear force: responsible for radioactivity, it is a short-range repulsive interaction that acts on electrons, neutrinos, and quarks. The W and Z bosons are the ones that mediate this force. Electromagnetic force: it is the force, for us familiar, that acts on electrically charged particles. The photon is the exchange particle for this force. Gravitational force: equally experienced, It is an attractive long-range force that acts on all particles with mass. It is postulated that there is an exchange particle that has been called a graviton, although it has not yet been verified. This is, among others, one of the key points to reveal in the LHC project.


The term unified field theory was introduced by Einstein when he attempted to treat gravity and electromagnetism in a unified way using a unified field theory. Maxwell had previously accomplished in 1864 what we would call the first unified theory, by formulating a field theory that integrated electricity and magnetism. Einstein’s search for a unified field theory for the electromagnetic field and the gravitational field, generalizing his general theory of relativity, was unsuccessful. Another interesting attempt to unify these two theories was the Kaluza-Klein theory, some of whose ideas inspired some aspects of string theory.modern, an ambitious attempt to formulate a theory of everything. Since the first attempts by Einstein and Kaluza, other types of interactions different from gravity and electromagnetism, such as weak interaction and strong interaction have been the subject of various attempts at unification, thus towards the end of the 1960s the electroweak model was formulated that in fact it is a unified field theory of electromagnetism and weak interaction. Attempts to unify the theory of strong interaction with the electroweak model and with gravity has since remained one of the still pending challenges for physicists, a theory that would explain the nature and behavior of all matter. The following list includes the unified field theories according to a historical chronology: electricity + magnetism = electromagnetism (performed by James Clerk Maxwell in the 1860s). electromagnetism + weak interaction = electroweak interaction (performed by Glashow,Salam and Weinberg in the 1960s). electroweak interaction + strong interaction = great unified theory (still to be verified) great unified theory + general relativity = unified field theory or “theory of everything” (still to be developed)

Maxwell’s Unified Field Theory

Historically, the first unified field theory was developed by James Clerk Maxwell. In 1831, Michael Faradayobserved that the variation in time of the magnetic fields could induce electric currents. Until then, electricity and magnetism were considered as unrelated phenomena. In 1864 Maxwell published his famous electromagnetic field theory. This was the first example of a theory that could unify earlier theories (electricity and magnetism) leading to electromagnetism. However, today it is known that the classical electrodynamics developed by Maxwell fails at quantum levels. In the 1940s a complete quantum theory was reached to describe the electromagnetic force, known as quantum electrodynamics (QED). This theory represents the interactions of charged particles using photons, the particles that transmit the interaction. This theory is based on the space-time symmetry of a field called gauge symmetry (actually phase symmetry). The theory was so successful that the principle of continuous gauge symmetry for all forces was quickly adopted.

Glashow-Weinberg-Salam Unified Field Theory

In 1967, Americans Sheldon Glashow and Steven Weinberg and Pakistani Abdus Salam independently proposed a unifying theory of electromagnetism and the weak nuclear force. They showed that the gauge field of the weak interaction was identical in structure to that of the electromagnetic field. This theory received experimental support for the discovery in 1983 of such W and Z bosons at CERN by Carlo Rubbia’s team. For their discoveries, Glashow, Weinberg, and Salam shared the 1979 Nobel Prize in Physics. Carlo Rubbia and Simon van der Meer received the same award in 1984.

Great Unification Theories

Main article: Theory of great unification

The next step toward unifying the fundamental forces of nature was to include strong interaction with electroweak forces in a theory called the Great Unified Theory. A quantum theory of strong interaction was developed in the 1970s under the name of quantum chromodynamics. The strong interaction works between quarks by exchanging particles called gluons. There are eight types of gluons, each carrying one charge of color and one charge of anti-color. Based on this theory, Sheldon Glashow and Howard Georgi proposed the first great unified theory in 1974, which applied to energies above 1000 GeV. Since then there have been new proposals, although none are currently universally accepted. The biggest problem with these theories is the huge scale of energies required by experimental tests, which are beyond the reach of today’s accelerators. However, there are some predictions that have been made for low energy processes that do not require accelerators. One of these predictions is that the proton is unstable and can decay. At the moment, it is unknown if the proton decays, although experiments have determined a lower limit for its half-life of years. Therefore, for the moment it is uncertain whether this theory is an adequate description of matter. One of these predictions is that the proton is unstable and can decay. At the moment, it is unknown if the proton decays, although experiments have determined a lower limit for its half-life of years. Therefore, for the moment it is uncertain whether this theory is an adequate description of matter. One of these predictions is that the proton is unstable and can decay. At the moment, it is unknown if the proton decays, although experiments have determined a lower limit for its half-life of years. Therefore, for the moment it is uncertain whether this theory is an adequate description of matter.

Theories of Everything

Main article: Theory of everything

Gravity is yet to be included in the theory of everything. Theoretical physicists have so far been unable to formulate a consistent theory that combines general relativity and quantum mechanics. The two theories have been shown to be incompatible and the quantization of gravity continues to be a serious problem in the field of physics. In recent years, the search for a unified field theory has focused on string theory and the M theory that aims to unify them.


There is some debate about the ultimate value of seeking a unified field theory. Thus some have argued that if such a “final” theory were found, this is the ultimate origin of matter, it would not solve all the other scientific problems about the universe. This is the point of view in which the ultimate understanding of particles does not give a complete understanding of the behavior of atoms and molecules or of any higher-level structure. Some physicists, such as PW Anderson, argue that large structures possess collective behaviors that are not described in terms of the behavior of their constituents [citation needed], and therefore there is no reason to consider such behaviors at the lowest level as more. fundamental.


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