Electroweak interaction

Article By:

Baltay, Charles Department of Physics, Yale University, New Haven, Connecticut.

Last reviewed:March 2019

DOI:https://doi.org/10.1036/1097-8542.227375

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• Electroweak interaction, published January 2014:Download PDF Get Adobe Acrobat Reader

A fundamental force representing unification of the electromagnetic and weak nuclear interactions. Until the early 1970s, the four fundamental forces — strong nuclear, electromagnetic, weak nuclear, and gravity — could only be described as distinct entities. The work of U.S. particle physicist Sheldon Lee Glashow, U.S. theoretical physicist Steven Weinberg, and Pakistani theoretical physicist Abdus Salam showed that the electromagnetic and the weak nuclear forces can be unified and understood as a single interaction, called the electroweak interaction. This unification was a major step in understanding nature, similar to the achievement of Scottish physicist James Clerk Maxwell and others a century earlier in unifying the electric forces and magnetic forces into the electromagnetic interactions. A goal of theoretical physics is to achieve a further simplification in understanding nature by describing the presently known basic interactions in a unified way. Attempts to unify the strong force with the electroweak interaction are usually referred to as grand unified theories (GUTs). Various frameworks that seek to further unify with the fourth fundamental interaction, gravity, are known as M-theory, superstring theory, or a "theory of everything." Physicists broadly theorize that initially, all forces were united in the extreme energy and temperature at the beginning of the universe in the big bang. The forces then separated out as the temperature decreased (Fig. 1). See also: Electromagnetism; Fundamental interactions; Grand unification theories; Gravitation; M-theory; Maxwell's equations; Strong nuclear interactions; Superstring theory; Weak nuclear interactions

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