# Unified field theory in layman's terms

I watched some videos on the unified field theory, specifically interviews with Michio Kaku and John Hagelin, and want to learn a bit more about it. I looked up the theory of everything, string theory and unified field theory but most of it goes over my head.

In one of the interviews with John Hagelin he describes the unified field as being the deepest level of the universe. He refers to it as intelligence or a field that has the potential for matter. So, what does this consists of if it isn't the smallest form of matter?

Also, is there a definite view in the scientific community that the unified field exists and what it is?

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– grasshopper Feb 9 at 16:47

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If you like this question, you may also enjoy reading this or this Phys.SE post. – Qmechanic♦ Feb 9 at 20:00

## 1 Answer

First we need to understand what the word "field" means in the context of physics. A field essentially is an object that assigns a value for each point in space and time. So if you have a set of properties that you are interested in, then the field would tell you what their exact values are for all of time and space. Basically, it is a function where you input your position in space and time, and out pops all the physical information you could possibly want to know about that position.

A unified field theory would then encompass some sort set of principles, axioms and equations that would tell you what the field is for all space and time and tell you how it behaves under changes in its parameters. In principle it would provide some predictive capability given some initial input.

The popular discussion of unified field theory centers around the desire to find a theory that can describe how the universe behaves under the action of the four known forces: Strong, Electromagnetic, Weak and Gravity. Historically, the archetypical unification model is Maxwell's success in unifying the electric and magnetic forces into the electromagnetic force.

One of the successes of the last 40 years was the success of unifying the electromagnetic and weak forces as part of electroweak theory. The discovery of the Higgs Boson has effectively proven that the electromagnetic and weak forces are in fact the same force, so in reality, there are only three forces that need to be unified: Strong, Electroweak and Gravity.

Grand Unified Theories, or GUTs, are an attempt to unify the Electroweak and Strong forces. Although the Standard Model effectively predicts behavior of those combined forces at low energies, it still falls short of true unification. It is expected that unification of the Strong and Electroweak forces will occur at energies higher than what we can probe currently, however it is possible that when LHC reaches full power we will see evidence some indication of how these forces might unify.

Quantum Gravity is generally used synonymously with Unified Field Theory, although this is not entirely accurate. Loop Quantum Gravity is a proposed theory of Quantum Gravity that does not include known particle physics, and can therefore not be considered a Unified Field Theory.

String Theory is a the most favored model for a Unified Field Theory. Through various dualities, most importantly the AdS/CFT duality, and through an understanding of asymptotic limits, String Theory can effectively morph itself to encompass most if not all of the current theories governing the four forces. The chief difficulty associated with the current theory is that the fundamental vacuum solution, or kernel, of the theory is unknown and there are $10^{500}$ possible solutions that would satisfy the constraints of the theory. This effectively means that we have a means of understanding how a field would be governed by String Theory, but no means to decide what that fundamental field actually is.

I would say that the view is that we have evidence that their is a fundamental field theory, and a path, but we simply do not have the resources to find out if we are right or wrong. It is unfortunately entirely possible that we will never know.

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Thanks for the answer, I hope physicist will confirm one of theories soon, it will be interesting to see what impact it will have on the world. – grasshopper Feb 11 at 10:31
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