Editing Unified field theory (section)

=== Forces ===

All four of the known fundamental forces are mediated by fields. In the [[Standard Model]] of particle physics, three of these result from the exchange of [[gauge boson]]s. These are:
*[[Strong interaction]]: the interaction responsible for holding [[quark]]s together to form [[hadron]]s, and holding [[neutron]]s and also [[proton]]s together to form [[atomic nucleus|atomic nuclei]]. The exchange particle that mediates this force is the [[gluon]].
*[[Electromagnetic interaction]]: the familiar interaction that acts on electrically charged particles. The [[photon]] is the exchange particle for this force.
*[[Weak interaction]]: a short-range interaction responsible for some forms of  [[radioactivity]], that acts on [[electron]]s, [[neutrino]]s, and quarks. It is mediated by the [[W and Z bosons]].

[[General relativity]] likewise describes gravitation as the result of the metric tensor field, which describes the shape of [[spacetime]]:
*[[Gravitational interaction]]: a long-range attractive interaction that acts on ''all'' particles. In hypothetical quantum versions of GR, the postulated exchange particle has been named the [[graviton]].