The Oldest Light in the Universe: The Search for Cosmic Origins | Jo Dunkley

In this conversation with the world-renowned cosmologist Jo Dunkley, we explore one of the deepest questions in science: the origin of the universe. We trace how our understanding of this story developed, beginning with Albert Einstein’s theory of general relativity, and then turn to Georges Lemaître, Edwin Hubble, and other key figures who helped establish the Big Bang model.

We discuss the discovery of the cosmic microwave background — the oldest light in the universe — and how it allows scientists to peer back more than 13 billion years. We also examine the mystery of dark matter — the invisible substance that makes up about 27% of the universe — and the search for primordial gravitational waves from the first fraction of a second after the Big Bang.

We reflect on how the scientific view of the universe changes our perspective. Jo explains how the atoms in your body, forged in stars, connect your story to the history of the universe.

Jo Dunkley is the Joseph Henry Professor of Physics and Astrophysical Sciences at Princeton University. She received her Ph.D. in astrophysics at the University of Oxford. Her research is in cosmology, where she studies the origins and evolution of the universe, and connects cosmological theory, data, and statistical methods. She is especially interested in the earliest moments of the universe’s history, and in understanding the composition of the cosmos including its invisible dark matter.

She has received several awards over her career, including the Tomassoni Chisesi physics prize, the New Horizons in Physics Prize, and the Gruber Prize for Cosmology. She was also appointed Officer of the Order of the British Empire (OBE), for her services to science in 2019, and was elected a Fellow of the Royal Society in 2024. Her first book, Our Universe: An Astronomer's Guide was published in 2019.