Congratulations to Professor Ryan Cooke from our Department of Physics who is the joint recipient of the 2025 Gruber Foundation Cosmology Prize.
Ryan has been awarded the prize together with his collaborator and former PhD supervisor Professor Max Pettini (University of Cambridge).
The prize recognises their groundbreaking work to perfect a method to measure the composition of the Universe moments after the Big Bang.
Ryan and Max have studied the creation of the light elements by nuclear reactions in the first few minutes of the Universe’s expansion.
Their work has focused on measuring the amounts of deuterium and hydrogen in clouds of galactic fog that are seen by chance in silhouette against bright background quasars (supermassive black holes). This galactic fog, unrelated to the quasars themselves, have remained unchanged since the Big Bang.
The deuterium/hydrogen ratio correlates with the density of regular matter, or baryons, helping physicists to understand the make-up of the early Universe.
Ryan and Max’s research focused only on ‘near-pristine’ clouds of gas - meaning galaxies relatively free of stars (whose birth process can destroy deuterium). These chemically unevolved galaxies would, the duo believed, retain a fingerprint of the early Universe.
Together, their work has achieved precise measurements of the deuterium/hydrogen ratio – where other studies had previously struggled.
The results showed that baryons constitute around five percent of the mass-energy density of the Universe today. Their result corresponds perfectly to other measurements of the composition of the Universe based on the afterglow light of the Big Bang – a picture of the Universe 378,000 years after its birth – confirming the accuracy of their work.
Speaking about the award Ryan said he was ‘stunned’ and still absorbing the honour of the Gruber Foundation Cosmology Prize.
He hopes to invest some of the prize money in initiatives to help inspire and develop future generations of scientists.
Ryan is committed to engaging children in science from an early age. Alongside his world-leading research, he has authored several science-focused children’s books. He is also part of the Stargoal project, a series of interactive children’s activities about science and football.
The Gruber Foundation Cosmology Prize honours leading cosmologists, astronomers and physicists who are advancing our understanding of the Universe.
It is co-sponsored by the International Astronomical Union and awarded annually to recognise those at the forefront of continued pioneering work in space science.
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