See Inside November 2010

Dr. Unification: Steven Weinberg on Getting the Forces of Nature Together

For years the cosmos and the atom have been at odds with one another. If any physicist can reconcile them, it's Steven Weinberg

Photograph by Jeff Wilson

Steven Weinberg came up with a good idea one day while driving his red Camaro. The paper he wrote, “A Model of Leptons,” was just two and a half pages long—including references and acknowledgments. When it came out in 1967, it was largely ignored. But it became one of the most quoted physics papers ever and helped to earn Weinberg the 1979 Nobel Prize, shared with Abdus Salam and Sheldon Glashow.

In those two and a half pages, Weinberg showed that two of the four forces of nature, electromagnetism and the weak nuclear force, which outwardly seem completely different, could be different aspects of a single unified set of “electroweak” forces. This theory predicted the existence of a new neutral particle among those that carry out the action of the weak force, known as the weak bosons. And he showed how the innate symmetry of the electroweak forces becomes hidden or, as physicists say, “spontaneously broken,” so that we perceive electromagnetism and the weak force as dissimilar. This symmetry-breaking process endows particles such as quarks with mass.

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