# Understanding nature through its fundamental forces

October 28, 2017

In is 1979 and the Nobel Prize for Physics is awarded to Professor Dr. Abdus Salam, the first Muslim Nobel Prize laureate in Science.

Dr. Abdus Salam proved the electroweak unification theory of electromagnetism and weak nuclear forces, though separate in today’s world, were united at the time of the Big Bang at 246 GeV and over. The breakthrough is considered the biggest stepping stone in the Grand Unified Theory (GUT).

Particle physics is major branch of physics that has produced the evidence of different types of quarks making it closely related to all of the fundamental forces of nature excluding gravity. Above: A depiction of a Higgs boson being produced and decayed as a result of the collision of two protons in the Large Hadron Collider at CERN.

So what exactly are the four fundamental forces of nature? They are namely gravity, strong nuclear, weak nuclear and electromagnetism. Gravity is the first and weakest force. It has an infinite range though its effects diminish as the distance in away from the source of gravity increases. Gravitational force is attractive between any two  masses. Since mass and energy are related by the mass-energy equivalence equation, E=mc^2, all forms of energy also attract, albeit by a factor of 9x10^(-16) compared to the same unit of mass. These forms of energy include light and electromagnetic waves. Gravity is most aptly described by Einstein’s theory of General Relativity as a curvature in the very fabric of space. Newton’s first law of universal gravitation describes gravity as the force between two bodies that cause them to attract, with the force proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Gravity is almost 10^29 times weaker than the weak nuclear force and 10^39 times weaker than the strong nuclear force, as result it has almost no bearing at a subatomic level. However due to its infinite range it is dominant at the macroscopic level, being the basis for orbits of planetary bodies, tides, evolution of the Solar System and the birth of stars and galaxies. Gravity is the odd force between the four, having no particle by which it acts. The particle, theoretically called a ‘graviton’, has never been found and studies are much focused on this direction

The next force, called the weak nuclear force, is the second weakest of the four. It takes place at a very small, nearly subatomic distances, at less than 1/4th of the diameter of a proton. The weak nuclear force is responsible for the decay of the radioactive substances and hence has a significant bearing upon nuclear physics. Each particle is made up of some of six types of quark. The weak nuclear force gives a particle the ability to transform its quarks, for example the down quark in a neutron transforms into an up quark for beta decay to form a proton. The weak nuclear force governs fusion and fission.

The electromagnetic force is the second strongest force. It governs the laws of electricity and magnetism. It is a large ranged force and has a great bearing on atoms. The electromagnetic force binds the electrons into orbits around the nucleus and plays a role in forming the electrostatic forces of repulsion and attraction. There are numerous mathematical equations relating magnetism and electricity, establishing both force as one as done first by Hans Christian Oersted. Roughly speaking, everything above the subatomic level excluding gravity is governed by this force. This force also encompasses momentum, movement and all chemical reactions.

The strong nuclear force is the last and strongest force. The strong nuclear force is at the scale of 10-15 m and 137 times stronger than electromagnetism. The strong force binds quarks together to form the nucleus. The simplest example of the strong force’s strength is the fact that is holds together numerous protons which repel each other through electromagnetic forces. The range of strong nuclear force is very small. At a sub-particle level, the strong nuclear force holds together quarks and gluons which make up subatomic particles. The range of the strong nuclear force is even smaller than the size of atoms hence it only has a role at the subatomic scale. The force is attractive from 1 femtometer to 2.5 femtometer, changing to repulsive under 0.7 femtometer.

According to scientists, under the GUT, the gravitational force is separated first, from a single super-force that governed the Universe at a time of 10-15 seconds after the Big Bang. It was closely followed by the strong nuclear, electromagnetic and weak nuclear forces separating later. At high energy levels, theoretically, these forces could be united again however this has never been proven as this can only be done in an environment at a temperature of nearly 10^32 K or 10^19 GCV which cannot be produced artificially.

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