Archive for Thursday, November 14, 1991


November 14, 1991


A Nobel Prize-winning physicist ventured into the world of subatomic particles and beyond during a speech Wednesday night at Kansas University.

During a program titled "Are We Really Make of Quarks?," Jerome Friedman, Massachusetts Institute of Technology physics professor, outlined how scientists came to believe that protons and possibly other parts of atoms are made of smaller particles called quarks.

"In 1969 it was considered extremely bizzare that there was something inside the proton," said Friedman, who won the 1990 Nobel Prize in physics for his work in the study of subatomic particles.

But at that time, scientists had been conducting experiments trying to prove the existence of particles inside protons. He said about 60 subatomic ``elementary'' particles had been discovered.

"THE (ELEMENTARY) particles were divided into families . . . and quarks were believed to be the building blocks of the families," he said.

Using a two-mile long linear particle accelerator at Stanford University, scientists in 1969 found the first direct evidence of quarks, Friedman said. The discovery was made after scientists aimed a beam of electrons at protons and studied how the beam scattered after making contact.

If an electron beam hits something that is not dense, "say something like Jell-O," he said, the direction of the beam would change little.

But the Stanford accelerator revealed that when electrons would strike protons, the beam would rebound off the protons.

"It's kind of like bouncing something off a rock . . . it won't pass through, it will bounce away at a greater angle."

Friedman said scientists discovered three quarks are found in each proton. Six quarks now are believed to exist, he said.

HOWEVER, he said quarks are so small that scientists have not been able to accurately measure their size.

"Just think of it as if an atom was the size of the Earth," Friedman said. "A quark would be about the size of a half of an inch."

He said the force that holds quarks together "assumes the form, if you will, of what we see as matter.''

Friedman said scientists are unsure whether quarks are made up of smaller particles.

He said that the superconducting supercollider, a 54-mile circular particle accelerator that is being built near Dallas, will help scientists answer such questions, as well as other questions about the nature of matter.

Friedman's lecture was sponsored by the KU Physics and Astronomy Department.

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