Grand Unification Theory Explained


In particle physics, the Grand Unified Theory (GUT) is a model where there is one single force of energy that encompasses the three gauge interactions of the Standard Model are merged together at high energy levels. This interaction, which is unified, would be characterized by one larger gauge symmetry. Instead of several force carriers, there would be one coupling constant if GUT is realized.

The motivation for this theory is based on how electrons and protons seem to interact with each other. The electric charges of each cancel each other out with such extreme precision is the foundation of the macroscopic world as we understand it today. We have descriptions for weak and strong interactions within the Standard Model, but there isn’t an explanation for the higher-level interactions that may occur.

The creation of the GUT would be a possible explanation that would provide symmetry, creating predictive values for all elementary particle charges as they disengage into their individualized interactions.

Numerous Grand Unification Theories Exist

Because the macroscopic world offers numerous opportunities for particle unification, there have been a number of GUT theories proposed. None of them are considered to be universally accepted.

There is even a theory involving GUT that includes all fundamental forces being merged together at higher energy levels. It is often referred to as the “Theory of Everything” and even includes gravitation.

The problem with creating a GUT is that the different forces involved each tends to behave in a different way. Take electromagnetism as an example. It is long-ranged, with the weak force being short-ranged, and the strong force tends to be weak when it is placed in a high-energy environment. To unify these forces, it becomes necessary how they can all be components of a single item, but still be able to manifest in such varied ways when operating in real-world conditions.

In reality, we don’t know if all three can be unified. To make matters more complicated, to approach a Theory of Everything, we must also have a GUT be able to exist in the first place. Otherwise, there isn’t the possibility of having general relativity and quantum mechanics be combined in a logical manner.

Dark Energy and the Grand Unification Theory

To thicken the plot for a GUT, there may be other forms of matter and energy in the universe that we know very little about. This includes dark energy and dark matter. Atoms, which are the focus of most Grand Unification Theories, could make up less than 5% of the total universe. This means even if we can unlock the potential of a GUT, we’ll still lack an understanding of nearly 95% of what happens to be in the universe.

That is why the focus on a GUT has been set aside by many physicists. Before we can unify, we must be able to understand.

Limitations of the Grand Unification Theory

Although there are unsolved problems in particle physics that suggest a Grand Unification Theory is a likely explanation, there is no hard evidence to support such a theory as of yet. Neutrino oscillations indicate that even our Standard Model is currently incomplete. As of today, there are few experimental tests that could confirm GUT, though fermion masses and proton decay do offer some potential.

There is also a problem with protons in the GUT. Early predictions show that quarks could potentially change into a lighter particle, including protons. Many unification theories predicted that this would cause protons to be unstable over a period of time that was much longer than the lifetime of the universe. During the first experiments to detect proton decay, it was discovered that a proton lifetime was actually much longer than any GUT was able to predict.

This brought the unification theories to the idea of super-symmetry. This would give more particles that are involved in the decay effects, extending the lifetime of a proton beyond what previous experiments had been able to detect. No super-symmetry particles have yet to be discovered, however, so even with this potential solution, there are still problems.

Even though a Grand Unification Theory is not a point of emphasis as it was in the 1970s and 1980s, it is still an impulse that is being hunted. Numerous experiments have been proposed to potentially discover proton decay with greater precision than ever before. By finding out more information in this area of science, we could potentially know more about how the forces of nature have united to provide us with the universe we have today.