Editing Fundamental interaction (section)

=== Electroweak interaction ===
{{Main|Electroweak interaction}}
[[Electromagnetism]] and weak interaction appear to be very different at everyday low energies. They can be modeled using two different theories. However, above unification energy, on the order of 100 [[GeV]], they would merge into a single electroweak force.

The electroweak theory is very important for modern [[cosmology]], particularly on how the [[universe]] evolved. This is because shortly after the Big Bang, when the temperature was still above approximately 10<sup>15</sup>&nbsp;[[Kelvin|K]], the electromagnetic force and the weak force were still merged as a combined electroweak force.

For contributions to the unification of the weak and electromagnetic interaction between [[particle physics|elementary particles]], Abdus Salam, Sheldon Glashow and Steven Weinberg were awarded the [[Nobel Prize in Physics]] in 1979.<ref>{{Citation |first=Sander |last=Bais |year=2005 |title=The Equations. Icons of knowledge |isbn=978-0-674-01967-6 |url-access=registration |url=https://archive.org/details/veryspecialrelat0000bais }} p.84</ref><ref>{{cite web|url=http://nobelprize.org/nobel_prizes/physics/laureates/1979/|title=The Nobel Prize in Physics 1979|publisher=The Nobel Foundation|access-date=2008-12-16}}</ref>

==== Electromagnetism ====
{{Main|Electromagnetism}}
Electromagnetism is the force that acts between [[electric charge|electrically charged]] particles. This phenomenon includes the [[electrostatic force]] acting between charged particles at rest, and the combined effect of electric and [[Magnetism|magnetic]] forces acting between charged particles moving relative to each other.

Electromagnetism has an infinite range, as gravity does, but is vastly stronger. It is the force that binds electrons to atoms, and it [[chemical bond|holds molecules together]]. It is responsible for everyday phenomena like [[light]], [[magnet]]s, [[electricity]], and [[friction]]. Electromagnetism fundamentally determines all macroscopic, and many atomic-level, properties of the [[chemical element]]s.

In a four kilogram (~1 gallon) jug of water, there is
<div class="center"><math> 4000 \ \mbox{g}\,\rm{H}_2 \rm{O} \cdot \frac{1 \ \mbox{mol}\,\rm{H}_2 \rm{O}}{18 \ \mbox{g}\,H_2 O} \cdot \frac{10 \ \mbox{mol}\,e^{-}}{1 \ \mbox{mol}\,H_2 O} \cdot \frac{96,000 \ \mbox{C}\,}{1 \ \mbox{mol}\,e^{-}} = 2.1 \times 10^{8} C \ \, \ </math></div>
of total electron charge. Thus, if we place two such jugs a meter apart, the electrons in one of the jugs repel those in the other jug with a force of
<div class="center"><math> {1 \over 4\pi\varepsilon_0}\frac{(2.1 \times 10^{8} \mathrm{C})^2}{(1 m)^2} = 4.1 \times 10^{26} \mathrm{N}.</math></div>

This force is many times larger than the weight of the planet Earth. The [[atomic nucleus|atomic nuclei]] in one jug also repel those in the other with the same force. However, these repulsive forces are canceled by the attraction of the electrons in jug A with the nuclei in jug B and the attraction of the nuclei in jug A with the electrons in jug B, resulting in no net force. Electromagnetic forces are tremendously stronger than gravity, but tend to cancel out so that for astronomical-scale bodies, gravity dominates.

Electrical and magnetic phenomena have been observed since ancient times, but it was only in the 19th century [[James Clerk Maxwell]] discovered that electricity and magnetism are two aspects of the same fundamental interaction. By 1864, [[Maxwell's equations]] had rigorously quantified this unified interaction. Maxwell's theory, restated using [[vector calculus]], is the classical theory of electromagnetism, suitable for most technological purposes.

The constant [[speed of light]] in vacuum (customarily denoted with a lowercase letter ''{{mvar|c}}'') can be derived from Maxwell's equations, which are consistent with the theory of special relativity. [[Albert Einstein]]'s 1905 theory of [[special relativity]], however, which follows from the observation that the [[speed of light]] is constant no matter how fast the observer is moving, showed that the theoretical result implied by Maxwell's equations has profound implications far beyond electromagnetism on the very nature of time and space.

In another work that departed from classical electro-magnetism, Einstein also explained the [[photoelectric effect]] by utilizing Max Planck's discovery that light was transmitted in 'quanta' of specific energy content based on the frequency, which we now call [[photon]]s. Starting around 1927, [[Paul Dirac]] combined [[quantum mechanics]] with the relativistic theory of [[electromagnetism]]. Further work in the 1940s, by [[Richard Feynman]], [[Freeman Dyson]], [[Julian Schwinger]], and [[Sin-Itiro Tomonaga]], completed this theory, which is now called [[quantum electrodynamics]], the revised theory of electromagnetism. Quantum electrodynamics and quantum mechanics provide a theoretical basis for electromagnetic behavior such as [[quantum tunneling]], in which a certain percentage of electrically charged particles move in ways that would be impossible under the classical electromagnetic theory, that is necessary for everyday electronic devices such as [[transistors]] to function.

==== Weak interaction ====
{{Main|Weak interaction}}
The ''weak interaction'' or ''weak nuclear force'' is responsible for some nuclear phenomena such as [[beta decay]]. Electromagnetism and the weak force are now understood to be two aspects of a unified [[electroweak interaction]] — this discovery was the first step toward the unified theory known as the [[Standard Model]]. In the theory of the electroweak interaction, the carriers of the weak force are the massive [[gauge boson]]s called the [[W and Z bosons]]. The weak interaction is the only known interaction that does not conserve [[parity (physics)|parity]]; it is left–right asymmetric. The weak interaction even [[CP-violation|violates CP symmetry]] but does [[CPT symmetry|conserve CPT]].