Phillip James Edwin Peebles CC OM FRS (born April 25, 1935) is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who was Albert Einstein Professor in Science, emeritus, at Princeton University.

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.

With Dicke and others (nearly two decades after George Gamow, Ralph A. Alpher and Robert C. Herman), Peebles predicted the cosmic microwave background radiation.

[13] 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.

[14] 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.