Joel Primack, UCSC Physicist Who Advanced Cold Dark Matter Theory, Dies at 80

Joel R. Primack, a professor of physics and astrophysics at the University of California, Santa Cruz, who helped explain how tiny quantum fluctuations after the Big Bang grew into galaxies and larger cosmic structures, died on Nov. 13 in Palo Alto, Calif. He was 80. His wife, Nancy Ellen Abrams, said the cause was pancreatic cancer.

Dr. Primack was a key contributor to a 1984 paper in Nature, with George Blumenthal, Sandra Faber and Martin Rees, that provided a coherent account of how the universe evolved and identified essential properties of dark matter. The authors argued that dark matter had to be “cold,” made of larger particles that moved relatively slowly, so that slightly denser regions from cosmic inflation could grow into the clumps that seeded galaxies; scientists still do not know what dark matter is, the article noted.

He went on to use numerical simulations on supercomputers to make detailed predictions about the structure and growth of dark matter concentrations that could be compared with observations. Dr. Primack also played a role in science policy; inspired by his graduate adviser Sidney Drell, he and others organized workshops on political and social issues, and one eventual outcome was the American Association for the Advancement of Science fellowship for scientists to advise members of Congress.

Colleagues described him as a leader in rethinking scientists’ responsibilities to society. Born on July 14, 1945, in Santa Barbara, Calif., Dr.

Key Topics

Science, Joel Primack, Uc Santa Cruz, Cold Dark Matter, Cosmic Inflation, Nature Journal