Bosons are the fundamental particles responsible for mediating the interactions (forces) between the fermions. They include the photon, gluon, and weak bosons, as well as the Higgs boson. Some physicists have speculated the existence of the graviton; however, it is unknown if such a particle exists.

Electromagnetic Force

The electromagnetic force is one of the four fundamental forces. It governs the interactions between charged particles (like charges repel, opposites attract) and is mediated by the photon. All of the quarks, plus the electron, muon, and tauon, all interact with the electromagnetic force. The weak bosons are also charged, and therefore themselves also interact with the electromagnetic force.


Fermions are the fundamental particles that make up all of the matter in the universe. Fermions are themselves divided into two categories: quarks and leptons.

Fundamental Forces

In classical mechanics, forces are thought of as a push or a pull on an object. But in modern physics, forces are thought of more generally as interactions between particles. Although we experience many different forces in our everyday lives, these can all ultimately be explained by just four fundamental interactions between the particles making up everything around us: the weak force, the strong force, electromagnetism, and gravity. The first three are incorporated into the Standard Model of particle physics, while gravity is explained by Einstein’s theory of General Relativity.


The gluon is a boson that mediates the strong interaction. Gluons are hypothesized to interact with each other to form transient composite structures called glueballs.


The graviton is a theorized boson intended to include the gravitational force in the Standard Model. No graviton has ever been experimentally observed and its theoretical underpinnings remain uncertain.


Gravity is classically considered a force between massive objects governed by the equation F = Gm1m2/r^2 first discovered by Isaac Newton. However, General Relativity reframes gravity as a property of spacetime. Gravity is one of the four fundamental forces.

Higgs Boson

The Higgs boson is a boson in the Standard Model that is responsible for giving the fundamental particles their characteristic masses.


Leptons are the collection of fermions that don’t interact with the Strong force. There are six leptons: electron, muon, tauon, electron neutrino, muon neutrino, and tauon neutrino.


The photon is a boson in the Standard Model responsible for mediating the electromagnetic force. Photons can have different energy levels ranging from low-energy x-rays to high-energy gamma rays. A particular range of photons within the visible light spectrum can be seen by humans as the colors of the rainbow.