Jim Peebles

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Lore & Background

Peebles was born on April 25, 1935, in St. Vital in present-day Winnipeg, Manitoba, Canada, to Ada Marion Green, a homemaker, and Andrew Charles Peebles, who worked for the Winnipeg Grain Exchange. He completed his Bachelor of Science at the University of Manitoba and earned his Ph.D. in physics from Princeton University in 1962, completing a doctoral dissertation titled 'Observational Tests and Theoretical Problems Relating to the Conjecture That the Strength of the Electromagnetic Interaction May Be Variable' under Robert Dicke. He remained at Princeton for his whole career, with visits to the Institute for Advanced Study in 1977–78, 1990–91, and 1998–99. Most of his work since 1964 has been in physical cosmology, a field then considered a 'dead end.' In 1965, with Dicke and two other Princeton physicists, he connected the cosmic microwave background radiation discovered by Arno Allan Penzias and Robert Woodrow Wilson to a plasma cooling event in the early universe, creating a sensation leading to wide acceptance of the Big Bang model. He used the radiation's temperature, 3K, to compute the first accurate estimate of primordial elemental abundance based on nuclear physics and cosmic expansion, a model called Big Bang nucleosynthesis. He was the leading pioneer in the theory of cosmic structure formation in the 1970s and contributed to dark matter and dark energy. In 1987, he proposed the primordial isocurvature baryon model. He is also known for the Ostriker–Peebles criterion, relating to the stability of galactic formation. Peebles has described himself as a convinced agnostic.

Reader's Guide

Peebles's significance lies in transforming cosmology from a highly speculative field into a precision science. His 1965 connection of the cosmic microwave background to the Big Bang model was a turning point, leading to widespread acceptance of the theory. He provided the first accurate estimate of primordial elemental abundances through Big Bang nucleosynthesis, and his work on dark matter and structure formation laid foundations for modern cosmology. The Shaw Prize citation states he 'laid the foundations for almost all modern investigations in cosmology, both theoretical and observational, transforming a highly speculative field into a precision science.' Peebles has expressed skepticism about theories of the universe's beginning, stating, 'It's very unfortunate that one thinks of the beginning whereas in fact, we have no good theory of such a thing as the beginning.' His honors include the asteroid 18242 Peebles named after him, election to the American Academy of Arts and Sciences in 1977, and election to the National Academy of Sciences in 1988. His publications include 'Physical Cosmology' (1971), 'Large-Scale Structure of the Universe' (1980), 'Principles of Physical Cosmology' (1993), 'Finding the Big Bang' (2009), 'Cosmology's Century' (2020), and 'The Whole Truth' (2022).

Did You Know?

• Peebles completed his doctoral dissertation under Robert Dicke on whether the strength of the electromagnetic interaction might be variable.
• In 1965, Peebles and three other Princeton physicists connected the cosmic microwave background radiation to a plasma cooling event, leading to wide acceptance of the Big Bang model.
• Peebles used the 3K temperature of the cosmic microwave background to compute the first accurate estimate of primordial elemental abundance.
• He has described himself as a convinced agnostic and stated, 'It's very unfortunate that one thinks of the beginning whereas in fact, we have no good theory of such a thing as the beginning.'
• Asteroid 18242 Peebles is named after him.