Interactions happen everywhere and in every split-second. Some can be seen and their outcomes can affect us severely, and some are “invisible” and don’t affect us whatsoever.
The universe you
live in right now, the planet that is revolving around a star and which you are
a resident of, and all the processes that happen in this planet are said to be
a result of four fundamental laws of nature: Gravitation, Electromagnetism, Strong
Interactions, and Weak Interactions.
What Is It to Be a Law?
Generally, a law is a description of a phenomenon. It doesn't explain what happens behind that phenomenon or, why it exists in the first place - this is what a scientific theory does and can be often confused between with scientific law.
Peter Coppinger, an associate professor of biology and biomedical engineering at the Rose-Hulman Institute of Technology, said, "In science, laws are a starting place. From there, scientists can then ask the questions, 'Why and how?'"
In addition, there
are four reasons philosophers examine what it is to be a law of nature:
First, laws at least appear to have an essential role in any scientific phenomenon. Second, laws are crucial to some philosophical matters.
Third, Goodman
suggested that there is a link between law-hood and conformability by an
inductive inference. Fourth, philosophers like a great puzzle.[1]
The Four Fundamental Laws of Nature
With that said, we now proceed to know what are the 4 fundamental laws or categories of nature explained by Stephen Hawking in his book A Brief History of Time:
The first category is the gravitational force. It is universal, which means every particle feels, or is affected by, it, and the gauge of the effect is dependent on the particle’s mass or energy. Gravity is the weakest of all the other forces by a long way; it can act over large distances and is always attractive.
This basically means that the weak gravitational forces between the particles of two enormous bodies separated by a large distance, such as the Earth and Sun, can all add up to produce a significant force.
With a quantum mechanics viewpoint, you can picture the force between the particles of two bodies in a gravitational field as being carried by a particle of spin two called graviton.[2]
The gravitational force between the Earth and the Sun is ascribed by the exchange of these gravitons between the particles that make up these two bodies. Although virtual, they have a significant effect - the Earth orbiting around the Sun.
Real gravitons make up what classical physicists call gravitational waves, which are too weak and very difficult to detect that they have not yet been observed.
The second category is electromagnetic forces. They are much stronger than gravitational forces: In fact, the electromagnetic force between two electrons is about a million million million million million million million (1 with forty-two zeros after it) times bigger than the gravitational force.
However, there are two kinds of electric charge, positive and negative. Two similarly charged particles repel and, in contrast, differently charged ones attract.
A large body, such as Earth or Sun, nearly contains the same amount of positive and negative charges, which cancel out and a very little net electromagnetic force is produced. However, on a small scale, a microscopic scale to be more precise, electromagnetic forces dominate.
The electromagnetic attraction between the nucleus of an atom and an electron forces the electron to orbit around the nucleus: the same as gravitational attraction forcing the Earth to orbit the Sun.
He electromagnetic attraction is pictured as an exchange of large numbers of virtual mass less particles of spin 1 called photons.
Although photons are virtual particles, when an electron jumps from a level to another closer to the nucleus while orbiting the nucleus, it releases real photons, which you can observe as visible light. Equally, when a photon strikes an atom the energy is absorbed by an electron which causes it to jump to a higher level away from the nucleus.
The third category is called the weak nuclear force, which is responsible for deadly stuff like radioactivity and which acts on all matter particles of spin-½, but not on particles of spin 0, 1, or 2, such as photons and gravitons.
The weak nuclear force was not well understood until 1976 when Abdus Salam at Imperial and Steven Weinberg at Harvard both proposed theories that unified this interaction with the electromagnetic force, the same as Maxwell unifying electricity and magnetism about a hundred years earlier.
They suggested that in addition to the photon, there were other spin particles, known as massive vector bosons, that carried the weak force, each had a mass of about 100 GeV (GeV stands for giga electron-volt or one thousand million electron volts). The Weinberg-Salam theory exhibits a property known as spontaneous symmetry breaking.
This means that all these particles appear to be the same at low energies only in different states; however, at high energies, all these particles behave the same (read the book for more information).
The fourth category is the strong nuclear force, which holds the quarks together in a proton or neutron, and holds the protons and neutrons together in the nucleus of an atom.
It is believed that this force is carried by another spin particle called gluon, which interacts only with itself and quarks. This force has an intriguing and curious property called confinement.
It means that in order for quarks to get bonded to each other, for example, their combination must result in no colour. So, one cannot have a quark on its own (red, blue, or green). But, three quarks with different colors can be bonded together (red+ green+ blue=white). Such a triplet makes up a neutron or a proton.
Another combination that would work is bonding a quark and an anti-quark (red+ antired=white, etc). Such combinations make up what are called mesons, which are unstable because a quark and an anti-quark can annihilate each other, resulting in electrons and other particles.
Similarly,
confinement restricts having one gluon on its own because gluons are not
colorless. Instead, one has to have a combination of gluons with colors adding
up to white. Such a combination forms an unstable particle called a glueball.
Written by - Eyad
Aoun
Edited by – Adrija
Saha
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