Resident’s work continues to impact the international physics world

By Corrinne Lennox

Resident Writer

Oscar W. (Wally) Greenberg is a theoretical physicist and a published poet as well.  Greenberg, who has lived in Riderwood for more than two years, is a graduate of Rutgers and Princeton University, from which he received his Ph.D.  He was a Professor of Physics at the University of Maryland, College Park for 54 years until his retirement two years ago.

While a graduate student at Princeton, he had tea with Einstein in his home on Mercer Street.  He published a poem, “Mercer Street,” about that visit. That encounter was one of five Wally had with Einstein, including introducing him at his last talk.

In 1964, Wally was a member of the Institute for Advanced Study.  In that year, quarks were proposed as the smallest particles which form protons and neutrons.  Virtually no one believed in the existence of quarks because it contradicted a fundamental law of physics, known as the Exclusion Principle. Also, in 1964, Wally proposed a way to reconcile the existence of quarks with the Exclusion Principle by proposing a new three-valued charge, colloquially called “color.” At the same time he made a table of predictions of experiments that would confirm “color.”

Physicists were skeptical of “color,” because nobody had ever heard of a three-valued charge.  Wally showed his “color” theory paper to J. Robert Oppenheimer, the Director of the Institute for Advanced Study.  A week later Oppenheimer said, “Greenberg, it’s beautiful!”

“I was ecstatic,” Wally said.  Then Oppenheimer paused and continued, “but I don’t believe a word of it.” Nobel Prize winners, such as Steven Weinberg, also did not believe in “color” at the time.

It was only after 10 years, when the experiments that Wally proposed confirmed his theory of “color,” that it was universally accepted by the scientific community.“Color” is one of the two basic components of quantum chromodynamics (QCD), of the standard model of elementary particles.

In 2014, an international conference was held to celebrate 50 years of quarks and “color”.  It was attended by the world’s leading particle physicists.

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