Unified Field Theory

We have learned of various field theories in our previous sessions. Field theory helps to understand the behaviour of particles when they are placed at different points in the field. Field theories such as electric and magnetic field theories can be used for studying the electric and magnetic fields of a unit positive charge. Using the field theory, even electromagnetic waves can be analyzed. In this session, let us know about an essential theory known as unified field theory.

Unified Field Theory

Combination of Standard Model and Gravity

The strong force, the weak force, the gravitational force, and the electromagnetic force are known as fundamental forces. These forces are mediated by fields, which in the Standard Model of particle physics, result from the exchange of gauge bosons. Specifically, the four fundamental interactions to be unified are:

Strong interaction: the interaction responsible for holding quarks together to form hadrons, and holding neutrons and also protons together to form atomic nuclei. The exchange particle that mediates this force is the gluon.

Electromagnetic interaction: the familiar interaction that acts on electrically charged particles. The photon is the exchange particle for this force.

Weak interaction: a short-range interaction responsible for some forms of radioactivity that acts on electrons, neutrinos, and quarks. It is mediated by the W and Z bosons.

Gravitational interaction: a long-range attractive interaction that acts on all particles. The postulated exchange particle has been named the graviton.

Modern unified field theory attempts to bring these four forces and matter together into a single framework.

The concept of unified field theory is covered under particle Physics. It aims at describing all fundamental forces as well as the relationship between elementary particles in a single theoretical framework. Unified field theory is also referred to as Theory of Everything (ToE). It focuses on explaining nature as well as the behaviour of matter and energy that exists. This theory made an attempt to explain that fundamental forces like gravity and electromagnetism would emerge as different aspects of a single fundamental field.

As we know force can be described on fields that facilitate interactions between separate objects. Forces are not directly transmitted between objects that are interacting but they are described and interrupted by intermediary entities called fields.

The aim of developing a unified field theory has led to the progress of theoretical Physics. Let us now see how unified field theory was developed.

Evolution of Unified Field Theory

In the 19th century, famous Physicist James Clerk Maxwell developed the first field theory in his theory of electromagnetism. Later in the 20th century, the theory of general relativity was developed by Albert Einstein. Along with other scientists, Einstein attempted to develop a unified field theory where gravity and electromagnetism would emerge as different aspects of a single fundamental field.

Quantum field theory combines the theories of special relativity, classical field theory, and quantum mechanics. This theory treats particles (quanta) as excited states of their underlying quantum fields, which are more fundamental than the particles. The theory of relativity explains the nature and behaviour of all phenomena on the macroscopic level (things that are visible to the naked eye); a quantum theory explains the nature and behaviour of all phenomena on the microscopic (atomic and subatomic) level. The four fundamental forces of nature are electromagnetic interaction, strong interaction, weak interaction, and gravitational interaction.

In the course of the 1960s and 70s, physicists found that matter is made of fundamental particles called quarks and leptons. The quarks are bound within larger particles like protons and neutrons. Quarks are bound by the short-range strong force that engulfs electromagnetism at subnuclear distances.

During the 1970s quantum field theory dedicated to the strong force known as quantum chromodynamics (QCD) was developed. In quantum chromodynamics, interaction of quarks takes place through the exchange of particles known as gluons. Physicists further proceeded to find if strong force can be unified with the electroweak force in a grand unified theory (GUT). A grand unified theory still did not include gravity and is not a successful field theory.

Equation of Unified Field Theory

the changing magnetic flux/attractive transition and the electric field is given by:

In the integral form, the above equation can be written as:

Where,

The equation for magnetic flux is:

Unified field theory was aimed at unifying the laws of cosmos given as;

Tensors are the formulas used in Einstein’s Unified Field equation.

Hope you have understood the history of unified field theory in detail. Stay tuned with BYJU’S to know more.