Editing Scientific theory (section)

===Unification===
[[File:HAtomOrbitals.png|thumb|200px|In [[quantum mechanics]], the [[electron]]s of an atom occupy [[Atomic orbital|orbitals]] around the [[Atomic nucleus|nucleus]]. This image shows the orbitals of a [[hydrogen]] atom (''s'', ''p'', ''d'') at three different energy levels (1, 2, 3). Brighter areas correspond to higher probability density.]]

In some cases, two or more theories may be replaced by a single theory that explains the previous theories as approximations or special cases, analogous to the way a theory is a unifying explanation for many confirmed hypotheses; this is referred to as ''unification'' of theories.<ref name=Weinberg>Weinberg S (1993). ''Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature.''</ref> For example, [[electricity]] and [[magnetism]] are now known to be two aspects of the same phenomenon, referred to as [[electromagnetism]].<ref>Maxwell, J. C., & Thompson, J. J. (1892). [https://archive.org/details/atreatiseonelec02thomgoog A treatise on electricity and magnetism]. Clarendon Press series. Oxford: Clarendon.</ref>

When the predictions of different theories appear to contradict each other, this is also resolved by either further evidence or unification. For example, physical theories in the 19th century implied that the [[Sun]] could not have been burning long enough to allow certain geological changes as well as the [[evolution]] of life. This was resolved by the discovery of [[nuclear fusion]], the main energy source of the Sun.<ref>{{cite web|url=https://www.nobelprize.org/nobel_prizes/physics/articles/fusion/#1|title=How the Sun Shines|website=www.nobelprize.org}}</ref> Contradictions can also be explained as the result of theories approximating more fundamental (non-contradictory) phenomena. For example, [[atomic theory]] is an approximation of [[quantum mechanics]]. Current theories describe three separate [[Fundamental interaction|fundamental phenomena]] of which all other theories are approximations;<ref>The [[strong force]], the [[electroweak force]], and [[gravity]]. The electroweak force is the unification of [[electromagnetism]] and the [[weak force]]. All observed causal interactions are understood to take place through one or more of these three mechanisms, although most systems are far too complicated to account for these except through the successive approximations offered by other theories.</ref> The potential unification of these is sometimes called the [[Theory of Everything]].<ref name=Weinberg/>