The Electroweak Interaction

In the 1970s, Steven Weinberg (1980) and Abdus Salam (1980) independently unified electromagnetic and weak interaction resulting in the electroweak interaction. Electromagnetic and weak interaction should therefore be regarded as one ensemble. For this important achievement Weinberg and Salam obtained the Nobel Prize of Physics in 1979. This unification is similar to the way in which James Clerk Maxwell 150 years ago unified electric and magnetic forces towards the electromagnetic interaction. To that time, Maxwell did not see and interpret the weak interaction as additional partner-force, since the weak interaction is active in the innermost interior of atoms only, a region that was studied more intensively at the beginning of the 20th century.

Today, the electroweak interaction has become part of standard theory. It is important to know that the weak interaction fits - despite of its asymmetry and despite of its weakness - into general electrodynamics. Electromagnetic Coulomb forces that are known among students for determining atomic and molecular relations are no more only influenced by the virtual exchange of photons, which are as y-quanta the gauge bosons of the electromagnetic interaction, but also by the vector bosons Z0 of the weak interaction. The uncharged (neutral) Z0 vector boson had indeed been measured experimentally. It is now entirely implemented in electroweak theory and gives rise to the weak neutral current.

It is evident that the electromagnetic component and the weak component, which we just have combined to the electroweak interaction, are an unequal pair. The weak part is largely hidden behind the electromagnetic interaction as a small correction being restricted to minute distances and possessing extremely small absolute values. But with respect to optically active and chiral molecules, the 'new' quality of the weak component has to be considered, especially its capability to differentiate between right- and left-forms.

6 As a consequence, atoms can be optically active and rotate the plane of polarization of linearly polarized light by a tiny angle that already had been measured experimentally.

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