Slovenia's Uroš Seljak wins Gruber Prize in Cosmology

New Haven, 7 May - Uroš Seljak, a Slovenian physicist, cosmologist and astronomy professor at the University of California, Berkeley is among the recipients of this year's Gruber Prize in Cosmology, awarded by Yale University. It comes for his significant contribution in developing methods of key importance for studying the creation of the universe.

Seljak has been awarded a gold medal and will share the US$500,000 prize with his colleagues Marc Kamionowski of Johns Hopkins University from Baltimore and Matias Zaldarriga of the Institute for Advanced Study in Princeton.

The accolades will be conferred on the winners at the 24th International Conference on Particle Physics and Cosmology (COSMO'21), which will take place on 2-6 August at the University of Illinois and online.

The work of the trio focused on the cosmic microwave background (CMB), which is residual electromagnetic radiation from the early universe, when atoms were created, and radiation from the primordial plasma.

Atoms have remained in the form of matter, while radiation remained in the form of a faint background noise that encompasses the entire universe in all directions and presents an image of the universe when it was approximately 379,000 years old.

The award winners have developed a mathematical method for studying the early universe, back to the first fraction of second of its existence. The findings were first published in the Physical Review Letters journal in 1997 are still studied today.

By observing polarisation, the cosmologists were able to determine the age of the universe at 13.8 billion years and that it is 5% ordinary (baryonic) matter, 26% dark matter and 69% dark energy.

Their work has inspired new generations of research programmes whose objective is to discover the last remaining part of the cosmological model, i.e. inflation or the theoretical inception of the universe or the Big Bang.

The Gruber Prize in Cosmology had been received in the past by other scientists from this field, and now it goes to the scientists who had set the foundation. The prize also recognises their lifetime achievements in cosmology.

Even before the 1997 article, Seljak and Zaldarriaga developed a computer code, called CMBFAST, that facilitated the studying of certain aspects of CMB by thousand times. The code is available to scientists free of charge.

Born in 1966 in Nova Gorica, Seljak graduated from the University of Ljubljana and also earned a master's degree there in 1991, and then a PhD at the Massachusetts Institute of Technology (MIT) in 1995.

After post-doctoral studies at the Harvard-Smithsonian Center for Astrophysics, he worked at Princeton University, Zürich University and International Centre for Theoretical Physics in Trieste. He has been teaching at Berkeley since 2008.