Virtual Event: P. J. E. Peebles at the Royal InstitutionThe Whole Truth

Scientists have questioned how reality could agree with physical theories that keep changing. Today, concepts like dark matter and dark energy further complicate and enrich the search for objective reality.

Join P. J. E. Peebles as he explores big questions about the nature of science, and how we are discovering the nature of reality in successive approximations through increasingly rigorous scrutiny.

In this talk, Peebles will draw on a lifetime of experience as a leading physicist and using cosmology as an example for this personal reflection. Discover if the concept of objective reality is meaningful.


Phillip James Edwin Peebles 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.


A century ago, thoughtful people questioned how reality could agree with physical theories that keep changing, from a mechanical model of the ether to electric and magnetic fields, and from homogeneous matter to electrons and atoms. Today, concepts like dark matter and dark energy further complicate and enrich the search for objective reality. The Whole Truth is a personal reflection on this ongoing quest by one of the world’s most esteemed cosmologists.

What lies at the heart of physical science? What are the foundational ideas that inform and guide the enterprise? Is the concept of objective reality meaningful? If so, do our established physical theories usefully approximate it? P. J. E. Peebles takes on these and other big questions about the nature of science, drawing on a lifetime of experience as a leading physicist and using cosmology as an example. He traces the history of thought about the nature of physical science since Einstein, and succinctly lays out the fundamental working assumptions. Through a careful examination of the general theory of relativity, Einstein’s cosmological principle, and the theory of an expanding universe, Peebles shows the evidence that we are discovering the nature of reality in successive approximations through increasingly rigorous scrutiny.

A landmark work, The Whole Truth is essential reading for anyone interested in the practice of science.