Friday, 28 December 2012

The Four Forcemen

The second half of the 20th century and the first decade of the 21st century saw huge changes in Physics. With the foundations of Quantum Theory and Relativity generating success after success of predictions and producing huge amounts of experimental results and technologies it seemed possible that these great theories could be understood at the most fundamental level.

This generated the modern Standard Model of Particle Physics and the Standard Model of Cosmology (or Lambda-CDM). These 2 models currently represent our largest insight into our universe.

 The Standard Model of Particle Physics describes 3 of the four fundamental forces of nature:

(1) The Strong Nuclear Force that holds protons and neutrons together in the atomic nucleus and describes the fundamental interactions of the quarks and gluons that hold the protons and neutrons themselves together.
(2) The Electromagnetic Force that describes the fundamental interactions between the quanta of electromagnetic waves, photons, with charged particles such as electrons which describes how atoms and molecules are held together and undergo chemical reactions.
(3) The Weak Nuclear Force that describes radioactive decay, neutrinos, and under unification with the Electromagnetic force describes the Electroweak Interaction which describes symmetry breaking in the Standard  Model and incorporates the Higgs Mechanism.

Gravity is not described by The Standard Model because there is no known interaction in quantum mechanics that incorporates gravity such that it can be theoretically predicted and experimentally tested. Physicists know what a quantum theory of gravity should look like, as it must incorporate some gravity force-carrier particle often called "the graviton" however the best descriptions of Gravity at the moment are with Newton's Theory of Gravity and Einstein's General Theory of Relativity which is expanded in the Standard Cosmological Model.

The Four Forces are:

And as Explained by Dr. Michio Kaku:




Many Physicists who have contributed to this model were unaware of the complete unification of their work into such large models- In a way there is no such thing as "Particle Physics" or "Astrophysics" as these are just massive collections of other field of physics. In this sense, these 2 subjects are the almanacs of the physical science and make them excellent educational subjects as you get a huge dose of knowledge about many branches of physics from either one of them.

Some of the greatest thinkers of our time have certainly realised the information potential of the fields of Particle Physics and Cosmology and the general interest this creates in people across all walks of life across the world have made them the most famous educators of physics.


In drawing an analogy to the four fundamental forces, there are 4 physicists who have made the largest contributions to the fundamental forces of nature while also becoming educators of science par excellence:

(1) Murray Gell-Mann - Developed Quantum Chromodynamics and Gell-Mann Matrices
(2) Richard Feynman - Developed Quantum Electrodynamics with Julian Schwinger and Shin-Itiro Tomonaga
(3) Stephen Weinberg - Developed Electroweak Theory with Abdus Salam
(4) Stephen Hawking - Developed No Boundary Universe Model with James Hartle and Black Hole Thermodynamics that incorporates aspects of Quantum Theory observable with Hawking Radiation


Anyone studying fundamental physics today realises that they are standing on the shoulder's of these giants.