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# Universal Forces

Although gravity is the well known force, the scientists have extended the list of fundamental forces existing in nature and called as universal forces. These are basic forces existing in universe which are namely strong force, weak force, gravitational force and electromagnetic force.The nuclear force is the strongest force and gravitational force is weakest. Lets see about them.

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## Universal Force Definition

There are four fundamental forces existing in the universe so called universal forces. They are the strong nuclear force, the weak nuclear force, the electromagnetic force and the gravitational force. The strong nuclear force is the strongest force acting while gravity is weakest. The strong force acts over a short range of distance while gravitational force acts over a large distance as a weak force.

 Name Relative strength Range Interacting particle Strong force 1 2 $\times$ 10-15 m Gluon Electromagnetic force 10-3 Infinity Photon Weak force 10-16 10-18 Boson Gravitational force 10-41 Infinity Graviton

Scientists are taking efforts to combine these forces into one. James Maxwell combined the electrical and magnetic forces as electromagnetic force. Scientists have even combined the electromagnetic force and the weak force into one as electro weak force but later they haven't been able to combine any of the other forces till now.

## Fundamental Forces

The fundamental forces are nothing but the fundamental interactions that happens in a physical systems that do not get reduced any more. These are basically of four types- Strong force, electromagnetic force, weak force and gravitational force.
• Strong nuclear force - It is the strongest of all fundamental forces. This is a short range force which acts between two nucleons against the force of repulsion. Yukawa modeled this strong force as exchange force acting between pions and other particles.It has strength of 1 having range 10-15 m having particles such as gluons and nucleons.
• Weak nuclear force - It is the fundamental force acting due to the exchange of bosons. It is also a short range force having range 10-18 m which is necessary to build a heavier nuclei.
• Electromagnetic force - It is one of the weak force compared to strong force acting due to electric and magnetic effects like attraction and repulsion. Both the magnetic and electric force gives out the exchange of photons. This force is of infinite range having strength 1/137 and acts over certain distance where there is field effect.
• Gravitational force - It is long range weak force acting everywhere in this universe. It is due to force of attraction between any two masses.This force increases with mass and decreases with distance.

## Electromagnetic Force

The Electromagnetic force is a force that exists everywhere in the universe and has infinite range where the field effect acts. It  attract and repel charges. It is the result of force between the two charges and magnetic force. This force acts as a exchange force between the photons. It acts over the infinite range and holds both the atoms and molecules together. It has range 1/137. The electromagnetic force is the force acting due to force between the two charges and magnetic force. This force acts as a exchange force between the photons. It acts over the infinite range and holds both the atoms and molecules together. The electromagnetic force generates three field types - electrostatic field, magneto static field and electromagnetic field.

## Nuclear Forces

Nuclear force is the force acting between the two or more nucleons. This is a short range force and acts between the distance of about 1 femtometer (fm). Here protons and neutrons bind together in a atomic nuclei. It is also known as strong force. This force using the elementary particles and quark concept and tells how proton and neutron get form in atomic nucleus.This energy that binds the nucleons together is known as Binding energy and when the nucleons splits in the fission reaction energy gets released and this huge amount of energy gets used in nuclear power plants and nuclear weapons.

The Mass defect formula is given by
$\Delta$ m = Z mH + (A-Z) mn - MWhere $\Delta$ m is mass defect, Z is atomic number, mH is mass of H atom, A is atomic mass number, mn is neutron mass, M is mass of atom.
The Nuclear force as a fundamental force is classified into strong force and weak force.

## Strong Nuclear Force

The strong Nuclear force is the strongest all fundamental forces. This force acts due to the exchange of $\pi$ mesons between the nucleons. Its like passing a ball between two people continuously. As long as this exchange of mesons are there, this force is there. This exchange force of mesons creates the mutual repulsion force and hence the nucleons stay bound together. This gives us even the reason the nucleus with neutron instead of proton. The reigning theory of particle physics gives the Standard Model that tells how the basics of building blocks of matter and their interaction. The theory got developed in 1970 using some experiments which gave out a well-tested physics theory as per the CERN.

## Weak Nuclear Force

The Weak force is even though stronger than gravity it is named so!. Infact it is one of the strongest force as the particles involved are big like W and Z bosons. These weigh very high as some 80 GeV and 91 GeV where proton weighs some 0.9 GeV. It is also a short range force as it is a nuclear force.Beta decay gives the example of the weak force. In this decay the interaction is in the subatomic level where neutron turns into proton releasing the electron. If the weak force were not to exist, matter would be much more stable.Without this force, the sun would have never existed.The weak force helps out in the fusion of protons and neutrons that forms deuterium. The excess energy due to fusion acts as a heat source from the sun.