What is Strong Nuclear Force

strong nuclear force
A figure representing how this nuclear force work

Strong Nuclear Force is one of the fundamental interactions along with Gravity, electromagnetism, weak nuclear force. The strong nuclear force holds the most ordinary matter together because it confines quarks into hadron particles such as neutron and proton. The strong force binds neutrons and protons together to create atomic nuclei. Most of the mass of a common proton or neutron is the result of the strong nuclear field energy.


physicists were uncertain as to how the atomic nucleus was bound together before the 1970s. Although they were familiar that the nucleus was composed of Protons and Neutrons and that protons possessed positive electric charge. While neutrons were electrically neutral. By the understanding of physics at that time. Positive charges would repel one another and the positively charged protons should cause the nucleus to fly apart. but this was never observed and a new physics was needed to explain this phenomenon.

A stronger attractive force was put forward to explain the atomic nucleus bound in spite of protons’ mutual electromagnetic repulsion. This force was called the strong force. Later it was believed to be a fundamental force that acted on the protons and neutrons that make up the nucleus.

Later on, it was discovered that protons and neutrons are not fundamental forces. rather than they are made up of constituent particles called quarks. The strong attraction between nucleons was the side-effect of a force that bound the quarks together. Theroy of quantuim chromodynamics suggests that quarks carry what is called a color charge. It does’nt have a relation with visible colors and its spectrum which we see. Quarks with unlike color charge attract one another as a result of strong interaction and the particle that medidates this was called the gluon.

How strong nuclear force behave

strong force
Behavior of nuclear force

The reason strong word is used here is because strong interaction is the strongest of the four fundamental forces. The force carrier particle of the strong interaction is the gluon. Gluon is a massless boson particle. The gluon carries a color charge. Quarks and gluons are the only fundamental particles that carry a non-vanishing color charge. Due to which they participate in strong interactions with only each other.

The strong force acts between quarks. Unlike all other fundamental forces, the strong force does not diminish in strength with increasing distance between the quarks. No matter how much farther the distance between the quarks. As the separation between the quarks grows, the energy added to the pair creates new pairs of matching quarks between the original two. Making it impossible to create separate quarks. The very energy added to the system required to pull two quarks apart would create a pair of new quarks that will pair up with the original ones. In quantum chromodynamics (QCD) this phenomenon is called color confinement. As a result, it can only be observed in hadrons and not in free quarks. The failure of all experiments that have searched for free quarks is taken as evidence.

The elementary gluon and quark particles involved in a high-energy collision are not directly observable. The interaction creates jets of newly created hadrons that are observable. Those hadrons are created as a manifestation of mass-energy equivalence.

Residual strong force

Types of Quarks, Leptons, and Gauge Bosons.

Irrespective of the description of distance independence. In the post-Big Bang universe, it is not the case that every quark in the universe attracts every other quark. Color confinement implies that the strong force acts without distance-diminishment only between pairs of quarks. In compact collections of bound quarks, the net color-charge of the quarks essentially cancels out. This results in a limit of the action of the color forces.

Though nuclear force is weaker than strong interaction itself. it is still highly energetic as its transitions produce gamma rays. The mass of nucleus significantly different from the summed masses of the individual nucleons. Differences between mass defects power nuclear fusion and nuclear fission.


The Grand Unified Theories (GUT) aims to describe the strong interaction and the electroweak interaction as a result of a single force. It is similar to how electromagnetic and weak interactions were unified by the model of electroweak interaction presented by Glashow-Weinberg-Salam. The strong interaction has a property called asymptotic freedom. Wherein the strength of the strong force diminishes at higher energies or temperatures.

If GUT is correct despite of having some flaws and have unsolved problems which exist in the world of physics than the electroweak epoch of the universe, the electroweak force separated from the strong force. Accordingly, a GUE (Grand Unification Epoch) is hypothesized to have existed prior to this.



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