Phillip James Edwin Peebles OM FRS (born April 25, 1935) is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who is currently the Albert Einstein Professor Emeritus of Science 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.
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 in the theory of cosmic structure formation in the 1970s. Long before it was considered a serious, quantitative branch of physics, Peebles was studying physical cosmology and has done much to establish its respectability. Peebles said, "It was not a single step, some critical discovery that suddenly made cosmology relevant but the field gradually emerged through a number of experimental observations. Clearly one of the most important during my career was the detection of the cosmic microwave background (CMB) radiation that immediately attracted attention both experimentalists interested in measuring the properties of this radiation and theorists, who joined in analyzing the implications". His 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 a long record of innovating the basic ideas, which would be extensively studied later by other scientists. For instance, in 1987, he proposed the primordial isocurvature baryon model for the development of the early universe.Similarly, Peebles contributed to establishing the dark matter problem in the early 1970s. Peebles is also known for the Ostriker–Peebles criterion, relating to the stability of galactic formation.
Peebles' body of work was recognized with him being named a 2019 Nobel Laureate in Physics, "for theoretical discoveries in physical cosmology"; Peebles shared half the prize with Michel Mayor and Didier Queloz who had been the first to discover an exoplanet around a main sequence star.
