SM: Fundamental Forces

The standard model of particle physics contains 3 of the 4 fundamental forces in the universe: Electromagnetism, the weak force and the strong force.

The 4th fundamental force is called gravity (which I am guessing you are all familiar with). Gravity is the weakest of these forces, and its effect only comes into play at very large energies – much larger than the ‘standard model of particle physics’ is there to predict.

The other forces in the standard model are mediated by a types of particles called ‘Gauge bosons’…


The electromagnetic force is mediated by a gauge boson called the photon. Photons are all around, forming what is commonly termed as light. Although it is photons that we use to see they also allow electrically charged objects to attract or repel. For example when you touch a table a stream of photons moves from your hand to the table (or vice versa) causing a repulsive force.

The weak force is mediated by, not one, but three different types of Gauge boson. The weak force is responsible for certain types of decays. In particular without the weak force we would not have stars, since the mechanics they undergo to produce light and energy requires decays mediated by the weak force.

The strong force is mediated by a gauge boson called a gluon. As the name suggests this glues together matter. As you sit there reading this blog post, (nearly) everything around you is made up of atoms. At the centre of these atoms is a nucleus which is held (or should I say ‘glued’) together by the strong force.

If you don’t like reading …



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