Unification, in simple words, is the method of unifying and simplifying two or more entities. It has been in human nature for thousands of years to simplify things even a little bit, to put them into a single framework so they do not have to look up for them separately. In the field of Science and Physics, unifying is the act of combining two or more separate areas of Physics that were earlier considered different. For decades, scientists have been attempting to unify and merge the four forces of nature. Some scientists have tried to unify the two or even three and have not achieved it yet. So, what really are the forces of nature?
The Four Fundamental Forces of Nature:
Since the birth of the universe, the whole of the universal model is comprised of the basic four forces namely, the Electromagnetic force, the Strong Nuclear Force, the Weak Nuclear Force, and the Gravitational force.
See also: Is Gravity a Force?
The Electromagnetic Force:
The electromagnetic force is further comprised of two fundamental forces, electricity and magnetism. James Clark Maxwell, in the 19th century, provided a unified theory of electricity and magnetism which earlier were considered as separate forces. This was the first unification of the forces.
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| Electromagnetism Image Credit: New Scientist |
The Strong Nuclear Force:
At the sub-atomic level, between the protons and neutrons in the nucleus, this force is found. It binds the protons and neutrons together, preventing them to scatter away.
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| Strong Interaction Between Protons and Neutrons |
The Weak Nuclear Force:
It is also found between the nucleus but is the opposite of the strong force, it lets the sub-atomic particles scatter away, hence causing radioactivity and nuclear fission.
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| Weak Force |
The Gravitational Force:
This is the only force of the four fundamental forces to not be at a quantum level but at a macro level.
This is found between large bodies, like planets, moons, Sun, and stars. the more massive a celestial body is, the higher it has gravitational force. All things whether living or non-living has gravitational force. Even a sub-atomic particle has some fraction of a gravitational force but is very small that it is negligible.
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| Gravitational Force |
The Unified Theories:
So far as we already know that electricity and magnetism have been united into a single unified force as the electromagnetic force. In 1968, Abdul Salam, Sheldon Glashow, and Steven Weinberg developed a unified model of the weak force and electromagnetic force called the Electroweak Theory for which they also received a Nobel Prize. Since then, many physicists are trying to unify the strong interaction with the electroweak force to develop a theory called the Grand Unification Theory, uniting the three forces, i.e. the Electromagnetic Force, the Strong Nuclear Force, and the Weak Nuclear Force. So, where is the Gravitational Force in this game?
Theory of Everything:
Many physicists are working to unify gravity with the three other forces to develop the theory of everything. A single, field equation that would explain everything from the macro level to the quantum level.
Einstein's Theory of General Relativity explains the celestial bodies and gravity as space and time, and Quantum Mechanics explains everything at a very small scale level (atomic and sub-atomic). The unification of these two would be an essential part of the theory of everything.
Attempts and Successes for the Unified Theories:
Not only the above theories can be considered unified theories, but unification is a long-term concept of merging two or more ideas into a single framework. Many scientists and physicists have developed unified theories without even realizing that what they are doing is in fact the unification of theories (or forces).
Newton's Law of Universal Gravitation:
Sir Isaac Newton, in 1687, published a law in his book Philosophiae Naturalis Principia Mathematica, Universal Law of Gravitation that explains the force between two bodies. This law actually is the unification with Kepler's Laws of Planetary Motion which couldn't explain why objects fall down and why planets have elliptical orbits. Newton's Law provided the explanation of all these problems that helped us develop the trajectories of rockets and satellites.
Maxwell's Electromagnetic Theory:
As explained above, James Clark Maxwell succeeded in unifying electricity and magnetism.
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| Electromagnetic Theory Image Credit: The Open University |
Einstein's Attempt for Unified Theory:
Albert Einstein, before his death, attempted to unify the general theory of relativity and quantum mechanics that would simplify the two great pillars of Physics into a single one, but he did not succeed at it.
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| Albert Einstein |
Salam-Glashow-Weinberg Electroweak Theory:
Abdul Salam, Sheldon Glashow, and Steven Weinberg developed a successful model of the electromagnetic and weak interaction known as the Electroweak theory. It was truly a remarkable work that unites two of the fundamental forces of nature.
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| Glashow, Salam, and Weinberg. |
Thermodynamics:
It is the study of heat and heat changes. This explains the relationship between heat and dynamics, therefore a unification between both.
And there are many more of these kinds of theories...
Attempts for The Theory of Everything:
Yes, many physicists have been attempting to develop the theory of everything and even to this day, some of the famous theories have been established and are being worked at in full swing.
String Theory:
This theory is composed of the idea that all matter is not comprised of particles but instead of strings that are vibrating at certain frequencies. Though this theory has yet to be proved experimentally many researchers around the world are working on it.
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| Explanation of String Theory Image Credit: Futurism |
Loop Quantum Theory:
It is the rival of the String Theory that attempts to unify general relativity and quantum gravity.
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| Loop Quantum Gravity Illustration by Hearl Ritsch Image Credit: Fine Art America |
Difference Between String Theory and Loop Quantum Theory:
The main difference between the two is that the String theory unifies the four fundamental forces of nature while the Loop Quantum Theory does not do that, it simply unifies the relativity with quantum gravity although both have the same approach and the same goal, i.e. to develop a single equation that would explain it all!
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