What is Fundamental force?
{{Merge|Standard Model|discuss=Talk:Fundamental force#Merge}} There are four '''fundamental forces''', sometimes called '''fundamental interactions'''. The [[force]]s are called ''fundamental'' because there is no simpler way for [[physicist]]s to understand what the forces do or how they do it (their [[wikt:action|action]]). They are called [[wikt:interaction|interaction]]s because the action of one object on another is matched by a [[reaction]] from the other. We feel the effects of [[gravity]] and [[electromagnetism]] all the time. * The [[gravitational force]] is described by [[Einstein|Einstein's]] [[general theory of relativity]] and is understood to be due to the ''curvature'' of [[spacetime]] by the [[mass]] of [[matter]]. * The [[electromagnetic force]] is due to [[electric charge]]. Charge causes electric force and movement of charge causes [[magnetism|magnetic force]]. The strong and weak interactions are forces at the smallest distances and explain [[nuclear physics|nuclear]] interactions. *The [[strong force]] binds [[protons]] and [[neutrons]] together and also keeps the [[atomic nucleus|nuclei]] of [[atoms]] together. *The [[weak force]] causes [[beta decay]]. A complete description of the forces requires advanced [[physics]]. The [[Standard Model]] explains three of these forces (electromagnetism, the weak force, and the strong force). Most [[physicist]]s think that these become a single force under very high [[temperature]]s. This idea is known as the [[grand unification theory]].<ref>Franklin, Allan; Fischbach, Ephraim 2016. ''The rise and fall of the fifth force: discovery, pursuit, and justification in modern physics''. 2nd ed, Springer. ISBN 978-3319284125</ref> ==From the future to the past== In the future, new forces may explain [[dark energy]] and [[dark matter]]. We may also get a [[Theory of everything]] that explains the four known fundamental forces. Even if we first ''unify'' the three forces of the Standard Model, we may continue to think of those forces as fundamental. Thi