Phillip James Edwin Peebles (born April 25, 1935) is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who is currently the Albert Einstein Professor in Science, Emeritus, at Princeton University. He is widely regarded as one of the world's leading theoretical cosmologists in the period since 1970, with major theoretical contributions to primordial nucleosynthesis, dark matter, the cosmic microwave background, and structure formation. Peebles was awarded half of the Nobel Prize in Physics in 2019 for his theoretical discoveries in physical cosmology. He shared the prize with Michel Mayor and Didier Queloz for their discovery of an exoplanet orbiting a sun-like star. While much of his work relates to the development of the universe from its first few seconds, he is more skeptical about what we can know about the very beginning, 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." Peebles has described himself as a convinced agnostic. Early life Peebles was born on April 25, 1935 in St. Vital in present-day Winnipeg, Manitoba, Canada, the son of 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. He then went on to pursue graduate studies at Princeton University, where he received his PhD in physics 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 the supervision of Robert Dicke. He remained at Princeton for his whole career. Peebles was a Member in the School of Natural Sciences at the Institute for Advanced Study during the academic year 1977–78; he made subsequent visits during 1990–91 and 1998–99. Academic career Most of Peebles' work since 1964 has been in the field of physical cosmology to determine the origins of the universe. In 1964, there was very little interest in this field and it was considered a "dead end" but Peebles remained committed to studying it. Peebles has made many important contributions to the Big Bang model. With Dicke and others (nearly two decades after George Gamow, Ralph A. Alpher and Robert C. Herman), Peebles predicted the cosmic microwave background radiation. Along with making major contributions to Big Bang nucleosynthesis, dark matter, and dark energy, he was the leading pioneer