Click Below to
Select a Force:
Mediating Boson: Relative Strength: Effective Range
of the Force:
Strong Nuclear Gluon 1 10-17 cm.  This is about the same
size as a proton. 
Electromagnetic Photon 1/137th Essentially, this force operates over an infinite distance.
Weak Nuclear W± & Z 10-13 10-20 cm.  This is about 1/1000th the size of a proton. 
Higgs Higgs Unkown Unkown
Until the 1970s, protons and neutrons were considered fundamental particles, and a strong (attractive) force was postulated as the way to overcome the natural tendency for protons to repel each other.  Then protons and neutrons were identified as composite particles each comprising three quarks. Physicists realized that the attracting force holding nucleons together in the atomic nucleus was a byproduct of the strong force within the nucleons that held together the quarks.   

It is the theory of Quantum Chromodynamics, developed in the 1970s, that explains the strong nuclear force holding quarks and gluons together to form hadrons; that is, protons, neutrons and all the other composite particles like mesons.  Gluons mediate the strong force between the quarks and anti-quarks within all the hadrons.  I discuss this in more detail in the section on Quantum Physics.  It is the strong nuclear force that is liberated during nuclear reactions that take place in, for example, the Sun, nuclear power plants, and nuclear bombs.

The residual strong force, or nuclear force, between neutrons and protons within the nucleus of an atom is a much weaker, secondary effect of the force between quarks, and it does diminish in strength with distance, though not in an easily definable way.  Although not strictly correct, the nuclear force can be understood as virtual light mesons, typically Pions and Rho Mesons, mediating the residual force between protons and neutrons in the nucleus. 

The strong force between quarks is sometimes called the Color Force to distinguish it from the residual strong force, or nuclear force, between protons and neutrons, but they are essentially the same force manifested in slightly different ways. 

Strong Nuclear Force - The Gluons



Standard Model

Forces & Bosons -