Search form

Nobel Prize in Physics Celebrates Cosmology & Exoplanets

Tuesday, October 8, 2019 - 16:21

This post is adapted from a Royal Swedish Academy of Sciences press release

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2019 to James Peebles (Princeton University), Michel Mayor (University of Geneva, Switzerland), and Didier Queloz (University of Geneva, Switzerland, and University of Cambridge, United Kingdom), "for contributions to our understanding of the evolution of the universe and Earth's place in the cosmos," with one half to Peebles "for theoretical discoveries in physical cosmology" and the other half jointly to Mayor and Queloz "for the discovery of an exoplanet orbiting a solar-type star."

Jim Peebles, Michel Mayor, Didier Queloz
Jim Peebles (Princeton), Michel Mayor (Geneva) & Didier Queloz (Geneva/Cambridge)

Jim Peebles's insights into physical cosmology have enriched the entire field of research and laid a foundation for the transformation of cosmology over the last fifty years, from speculation to science. His theoretical framework, developed since the mid-1960s, is the basis of our contemporary ideas about the universe.

The Big Bang model describes the universe from its very first moments, almost 14 billion years ago, when it was extremely hot and dense. Since then, the universe has been expanding, becoming larger and colder. Barely 400,000 years after the Big Bang, the universe became transparent and light rays were able to travel through space. Even today, this ancient radiation is all around us and, coded into it, many of the universe's secrets are hiding. Using his theoretical tools and calculations, Peebles was able to interpret these traces from the infancy of the universe and discover new physical processes.

The results showed us a universe in which just 5% of its content is known, the matter that constitutes stars, planets, trees — and us. The rest, 95%, is unknown dark matter and dark energy. This is a mystery and a challenge to modern physics.

In October 1995, Michel Mayor and Didier Queloz announced the first discovery of a planet orbiting a normal star other than the Sun. At the Haute-Provence Observatory in southern France, using custom-made instruments, they were able to see planet 51 Pegasi b, a gaseous ball comparable with the solar system's biggest gas giant, Jupiter, orbiting a Sun-like star. Three years earlier, three planets outside our own solar system, called exoplanets, had been discovered around a pulsar — the collapsed remnant of a star that exploded in a supernova blast — but because of the extreme nature of the central star, these planets were pronounced uninteresting to scientists searching for life beyond Earth.

The discovery of 51 Pegasi b started a revolution in astronomy, and more than 4,000 exoplanets have since been found in the Milky Way. Strange new worlds are still being discovered, with an incredible wealth of sizes, forms, and orbits. They challenge our preconceived ideas about planetary systems and are forcing scientists to revise their theories of the physical processes behind the origins of planets. With numerous projects planned to start searching for exoplanets, we may eventually find an answer to the eternal question of whether other life is out there.

This year's Nobel laureates have transformed our ideas about the cosmos. While Peebles's theoretical discoveries contributed to our understanding of how the universe evolved after the Big Bang, Mayor and Queloz explored our cosmic neighborhoods on the hunt for unknown planets. Their discoveries have forever changed our conceptions of the world.

Prize amount: 9 million Swedish krona (about $909,000), with one half to Peebles and the other half jointly to Mayor and Queloz.

In 1993 Jim Peebles was the AAS Henry Norris Russell Lecturer, and in 2015 the AAS Council (now Board of Trustees) elected Michel Mayor as an Honorary Member of the Society.

The AAS and its journal-publishing partner, IOP Publishing, have compiled the following list of key articles in the AAS journals by the 2019 Nobel Prize in Physics laureates:

James Peebles

Fluid Dark Matter
P. J. E. Peebles, 2000 ApJ 534 L127

Interacting Dark Matter and Dark Energy
Glennys R. Farrar and P. J. E. Peebles, 2004 ApJ 604 1

The Cosmic Energy Inventory
Masataka Fukugita and P. J. E. Peebles, 2004 ApJ 616 643  

Massive Coronae of Galaxies
Masataka Fukugita and P. J. E. Peebles, 2006 ApJ 639 590  

A Primeval Magellanic Stream and Others
P. J. E. Peebles and R. Brent Tully, 2013 ApJ 778 137

Michel Mayor and Didier Queloz

Eccentricity Versus Mass for Low-Mass Secondaries and Planets
Tsevi Mazeh, Michel Mayor, and David W. Latham, 1997 ApJ 478 367  

Detection of Planetary Transits Across a Sun-like Star
David Charbonneau et al., 2000 ApJ 529 L45

The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458
Tsevi Mazeh et al., 2000 ApJ 532 L55  

New Low-Mass Eclipsing Binary Systems in Praesepe Discovered by K2
Edward Gillen et al., 2017 ApJ 849 11

The Kepler-10 Planetary System Revisited by HARPS-N: A Hot Rocky World and a Solid Neptune-Mass Planet
Xavier Dumusque et al., 2014 ApJ 789 154

The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b
David Charbonneau et al., 2008 ApJ 686 1341  

The Mass of Kepler-93b and the Composition of Terrestrial Planets
Courtney D. Dressing et al., 2015 ApJ 800 135  

Characterizing K2 Planet Discoveries: A Super-Earth Transiting the Bright K Dwarf HIP 116454
Andrew Vanderburg et al., 2015 ApJ 800 59

Congratulations to Jim Peebles, Michel Mayor, and Didier Queloz on their Nobel Prize!


The Royal Swedish Academy of Sciences, founded in 1739, is an independent organisation whose overall objective is to promote the sciences and strengthen their influence in society. The Academy takes special responsibility for the natural sciences and mathematics, but endeavours to promote the exchange of ideas between various disciplines.

Richard Tresch Fienberg
AAS Press Officer
AAS Controlled Subject Tags: