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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
The photon is the basic unit of electromagnetism, the quantum of the electromagnetic field and the basic "unit" of all forms of electromagnetic radiation.  Having zero rest mass, and traveling always at the speed of light, a photon does not experience "time passing".  Thus, however long its journey, even billions of light years, from the photon's perspective, it is instantaneous. 

Today, the photon is considered a Boson in the standard model, mediating the electromagnetic force.  Being governed by quantum mechanics, photons exhibit properties of both waves and particles; known as wave-particle duality.  Albert Einstein first hypothesized the quantum nature of light which was proven by subsequent experiments.  This lead, amongst many advances in physics, to quantum field theory, and the probabilistic interpretation of quantum mechanics.

Like many people, I found the concept of wave-particle duality somewhat disconcerting.  I think the best way to look at it is to say that a photon, for example, is neither a wave nor a particle but something completely different.  It just happens to behave like a particle sometimes, and like a wave at other times, but it is never actually either. 

In 1932, Louis de Broglie suggested that the photon was a composite particle comprising a neutrino and an antineutrino as, at that time, neutrinos were thought to have no mass.  There was a resurgence in interest for this theory in the 1960s.  Recently, however, it has been shown experimentally that all three neutrino flavors do have a very small mass, finally puting this idea to rest. 

Electromagnetic Force - The Photon



Standard Model

Forces & Bosons -