Join three trailblazing scientists on a quest to uncover the nature of our Universe and discover whether our understanding is in crisis.

Please join us for this exciting public talk at the Ray Dolby Centre.

Speakers:

Prof. George Efstathiou (Kavli Institute for Cosmology, Cambridge)

Prof. Wendy Freedman (Kavli Institute for Cosmological Physics)

Prof. Risa Wechsler (Kavli Institute for Particle Astrophysics and Cosmology)

Summary:

Two mysterious ingredients – dark matter and dark energy – make up 95% of the Universe, yet we still do not understand what they actually are. Join three leading cosmologists as they discuss the quest to uncover their true nature. From the largest scales imaginable, mapping the cosmic microwave background and the three-dimensional distribution and shapes of galaxies across the sky, down to the smallest, studying dwarf galaxies and the delicate streams of stars torn from them by gravity, researchers are gathering clues from every corner of the cosmos. Along the way, intriguing cracks have appeared in our standard model of the universe – including the puzzling mismatch between different ways of measuring how fast the Universe is expanding today. A new generation of cutting-edge surveys is coming online to sharpen these measurements. Could they resolve the puzzle, or reveal that our understanding of the Universe is really in crisis?

Speaker Bios:

George Efstathiou is Emeritus Professor of Astrophysics (1909) at the Institute of Astronomy, University of Cambridge. He received his BA in Physics from the University of Oxford and PhD in Astronomy from Durham University. He has held postdoctoral fellowships at the University of California, Berkeley, USA and the University of Cambridge. He was Savilian Professor of Astrophysics at Oxford, where he served as Head of Astrophysics until 1994. He returned to Cambridge in 1997 as Professor of Astrophysics, where he also served as Director of the Institute of Astronomy and the first Director of the Kavli Institute for Cosmology. Among many recognitions he received the 2011 Gruber Cosmology Prize, the 2022 Gold Medal of the Royal Astronomical Society and the 2025 Shaw Prize in Astronomy. He is a Fellow of the Royal Society of London and the Royal Astronomical Society, UK. He is a Fellow of King’s College, Cambridge.

Wendy Freedman joined the University of Chicago in 2014 as the Sullivan University Professor of Astronomy and Astrophysics, one of nine named University Professors. Previously, she held the Crawford H. Greenewalt Directorship of the Carnegie Observatories in Pasadena, California. She was the founding chair of the Board of Directors (2003-2015) for the Giant Magellan Telescope, a 25-meter optical telescope scheduled for construction in Chile in 2032. Freedman is an elected member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society. She is an elected Fellow of the American Physical Society, and a Legacy Fellow of the American Astronomical Society. She was elected Fellow of the Royal Society in 2023. Her awards include the Dannie Heineman Prize for Astrophysics by the American Institute of Physics and American Astronomical Society, and she was one of three co-recipients of the 2009 Gruber Cosmology Prize. In 2025, she was a recipient of the National Medal of Science.

Risa Wechsler is the Humanities and Sciences Professor at Stanford University and Director of both the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) and the Center for Decoding the Universe (C4DU). She earned her SB in Physics from the Massachusetts Institute of Technology and her PhD in Physics from the University of California, Santa Cruz, followed by postdoctoral fellowships at the University of Michigan and the University of Chicago. She joined the faculty at Stanford in 2006, and holds appointments in the Stanford Department of Physics and in the Department of Particle Physics & Astrophysics at SLAC National Accelerator Laboratory. She has played leadership roles in major international survey collaborations, including the Dark Energy Survey, the Dark Energy Spectroscopic Instrument, and the Vera Rubin Observatory’s Legacy Survey of Space and Time. She is also active in research and strategy at the interface of AI and science, and since 2026 is Associate Director of Research in the Physical and Natural Sciences at the Stanford Institute for Human-Centered AI and Data Science. Wechsler is an elected member of the National Academy of Sciences and the American Academy of Arts and Sciences and a Fellow of the American Physical Society and the American Association for the Advancement of Science. She has served on advisory committees for the National Academy of Sciences, the Department of Energy, the National Science Foundation, NASA, and several foundations, and on the boards of the Aspen Center for Physics and the LSST Discovery Alliance. She is committed to public engagement with science

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