CERN congratulates James Peebles, Michel Mayor and Didier Queloz on the award of the Nobel Prize in physics “for contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos”. Peebles receives the prize “for theoretical discoveries in physical cosmology” and Mayor and Queloz are recognised “for the discovery of an exoplanet orbiting a solar-type star”.

Cosmology studies the universe’s origin, structure and ultimate fate. Peebles’ theoretical framework of cosmology, developed since the mid-1960s, is the foundation of our knowledge of the cosmos today. Thanks to his seminal theoretical work, physicists now have a model that can describe the universe from its earliest moments to the present day, and into the distant future.

Meanwhile, Mayor and Queloz have explored our cosmic neighbourhood and announced in 1995 the first discovery of an exoplanet – a planet outside our Solar System – orbiting a solar-type star in the Milky Way. The discovery of this exoplanet, dubbed 51 Pegasi b, was a milestone in astronomy and has since led to the discovery of more than 4000 exoplanets in our galaxy.

Particle physics, like cosmology and astronomy, seeks to understand what the universe is made of and how it works. But instead of telescopes on the ground and in space, CERN uses particle accelerators to probe the building blocks of the universe. Although cosmological observations indicate that the universe is mostly made of dark energy and dark matter, in addition to a small amount of ordinary matter, physicists have yet to find out the particular nature of these two dark constituents.

Experiments at CERN are trying to hunt down new, unknown particles that could make up dark matter and shed light on the observed evolution of the universe. For example, the CMS and NA64 experiments have recently reported new results on searches for dark photons, and the ATLAS experiment on a search for light supersymmetric particles. At the same time, theoretical physicists at CERN help guide these experiments and prompt new ones with their research into high-energy physics, cosmology and related fields.

“The properties of dark matter, the need for Einstein’s cosmological constant, and the existence of dark energy still pose considerable empirical problems,” explained Peebles in a CERN interview in 2016. “I think that the new generation of experiments will drive us to a deeper understanding and a reconsideration of our previous ideas about these topics and I am looking forward to that.”