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Fundamental Interaction

Last updated date: 24th May 2024
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Fundamental Particles and Interactions

Fundamental interactions, also referred to as fundamental forces in physics, are interactions that do not seem to be reducible towards more basic interactions. Fundamental interactions, also referred to as fundamental forces in physics, are interactions that do not seem to be reducible towards more basic interactions.

The gravitational and electromagnetic interactions, that produce important long-range forces whose consequences could be observed instantly in daily life, and the strong and weak interactions, that produce forces at insignificant, subatomic ranges and regulate nuclear interactions. These are the four basic interactions that are known to exist. Some scientists believe a fifth force exists, but these theories are still hypothetical.

Every known fundamental interaction could be mathematically described as a field. The curvature of spacetime, as explained by Einstein's general theory of relativity, is responsible for the gravitational force.

The strong interaction is borne by a particle named the gluon in the Standard Model, and it is essential for quarks connecting to form hadrons like protons and neutrons. It produces the nuclear force, which binds these last particles to form atomic nuclei as a side effect. The weak interaction is borne by particles known as W and Z bosons, and this also behaves on atom nuclei, causing radioactive decay. The photon's electromagnetic force produces electric and magnetic fields, that are necessary for the attraction amongst orbital electrons and atomic nuclei that hold atoms around each other, and also chemical bonding and electromagnetic waves, comprising visible light, and are the foundation for electrical technology.

Four Fundamental Interactions

Below given are the four fundamental interactions:-


At the atomic level, wherein electromagnetic interactions rule, gravity is by far the poorest of the four interactions. However, the notion that gravity's weakness could be conveniently proven by suspending a pin with a basic magnet was fundamentally flawed. Because of its proximity, the magnet is capable of holding the pin against the gravitational pull of the surface of the entire earth. There is a short distance amongst magnet and pin where a breaking point is achieved, and this distance is very short compared to Earth's massive mass.

For two reasons, gravity is perhaps the most important of the four fundamental forces for astronomical objects travelling great distances. First, unlike strong and weak interactions and more similar to electromagnetism, gravitation does have an unlimited range of effectiveness. Second, gravity tends to show attraction and never repulsion; celestial bodies, on the other hand, tend to have a near-neutral net electric charge, in which the repulsion to one charge and the attraction from the opposite charge majorly leads to the cancellation of each other's effect.

Even though electromagnetism is much more powerful than gravity, electrostatic attraction is irrelevant for massive celestial bodies including stars, planets, and galaxies since they have the same number of protons and electrons and therefore have a net electric charge of zero. Nothing can "cancel" gravity because it is only attractive, while electric forces can be both attractive and repulsive. All objects with mass, on the other hand, are subjected to the gravitational force that only draws. As a result, only gravitation affects the universe's large-scale structure.

Electroweak Interaction

At low energies, electromagnetism and weak interaction fundamental forces seem to become very distinct. Two different hypotheses can be used to model them. They would combine into a single electroweak force beyond unification energy, which is on the order of 100 GeV.

The electroweak theory is crucial for modern cosmology, especially in terms of understanding how and why the universe evolved. It is because the electromagnetic and weak interaction forces of nature were still unified as a single electroweak force sometime after the Big Bang when the temperature had been above nearly 10-15K.

Sheldon Glashow, Abdus Salam, and Steven Weinberg have been granted the Nobel Prize in Physics in the year 1979 for their contributions to the merging of the weak and electromagnetic interactions between elementary particles.


The force which operates amongst electrically charged particles is known as electromagnetism. The electrostatic force operating within charged particles at rest, as well as the combined effect of magnetic and electric forces applying within the charged particles moving relative to one another, are all examples of this process.

Electromagnetism, like gravity, does have an unlimited number but is considerably greater, and thus describes a variety of macroscopic effects encountered in daily life, such as friction, lightning, rainbows, and all human-made devices that use electric current, including lasers, television, and computers.

Weak Nuclear Force Definition

Certain nuclear phenomena, including beta decay, are caused by weak interaction or weak nuclear force. As per the Weak nuclear force definition, this discovery was observed to be the very first step toward the unified theory which is referred to as the Standard Model. Electromagnetism and the weak nuclear interaction have become and are understood to be two components of a unified electroweak interaction.

1. Example of Weak Nuclear Force:

An example of weak force can be beta decay. A neutron is substituted by an electron, a proton, and a neutrino throughout beta decay.

2. Range of Weak Nuclear Force:

The range of weak nuclear force lies up to 10-17metre. The weak interaction's efficiency is limited to a range of 10-17metre or about 1% of the circumference of a standard atomic nucleus. The weak interaction strength in radioactive decays is 100,000 times less than that of the electromagnetic force intensity.

3. The Relative Strength of Weak Nuclear Force:

The relative strength of weak nuclear force is observed to be 10-5.

Strong Interaction Force

The strong interaction force, also known as the strong nuclear force, is by far the most complex interaction due to how it differs and changes with distance. The strong force is nearly undetectable at distances higher than 10 femtometers. Furthermore, it only exists within the atomic nucleus.

Just after the nucleus was identified in 1908, it was evident that the current force, presently referred also as nuclear force (strong interaction forces of nature), was required to surpass the positively charged protons' electrostatic repulsion, a representation of electromagnetism. The nucleus would not exist if this were not the case.

The discovery of the pion in 1947 marked the beginning of the modern era of particle physics. From the 1940s to the 1960s, hundreds of hadrons were discovered, and a highly complex hypothesis of hadrons as strongly interacting particles had been established.

FAQs on Fundamental Interaction

1. Give the Order of Strength of Four Fundamental Interactions?

Ans. The order of strength of four fundamental interactions is (i)strong nuclear force (the strongest), (ii) the electromagnetic force, (iii) the weak nuclear force, and (iv) gravity (the weakest).

2. What is the Altitude at Which Zero Gravity Occurs?

Ans. Gravity gradually decreases near the Earth's surface (sea level), so that linear extrapolation will result in zero gravity at an elevation of about one half of the radius of the earth.

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