Niklas Elmehed

The Nobel prize in physics has been awarded to James Peebles, Michel Mayor and Didier Queloz for their contributions to our understanding of the evolution of the universe and Earth’s place in the cosmos.

One half of the award went to James Peebles at Princeton University for theoretical discoveries in physical cosmology, and the other half was jointly awarded to Michel Mayor at the University of Geneva and Didier Queloz at the universities of Geneva and Cambridge for their discovery of an exoplanet orbiting a solar-type star.

Peebles’ research over two decades has formed the basis for our understanding of the universe’s history after the big bang. He made theoretical predictions about the shape of the universe and the matter and energy that it contains. These were later validated by measurements of background radiation.


Peebles’ work has helped us understand how the release of light from the big bang played a decisive role in how matter could later clump to form galaxies and galaxy clusters.

His work has also shed light on dark matter and dark energy, which make up 95 per cent of the universe. We only know about five percent of the universe’s content – the matter that makes up the earth, planets and stars – and the rest remains a mystery of modern physics.

“Although we have made great advances in understanding the nature of evolution of our universe, there are still many open questions,” said Peebles via phone link at the Nobel press conference.

In October 1995, Mayor and Queloz were the first to discover a planet orbiting a solar-type star outside our solar system: the exoplanet 51 Pegasi b.

It marked the first time a planet was found to orbit a star similar to our Sun. The Jupiter-sized exoplanet couldn’t be seen directly: Mayor and Queloz made the discovery by looking at wobbles in the motions of stars.

When a planet orbits a star, the gravitational influence makes the star wobble back and forth, which can be picked up as a Doppler shift in the star’s spectrum. The effect is similar to how the sound of an ambulance siren changes in pitch when it approaches then moves away.

“We had thought that other solar systems would be similar to our own. We were wrong,” said Ulf Danielsson, a theoretical physicist at Uppsala University in Sweden and a member of the Nobel committee for physics.

It spurred an astronomy revolution: since then, more than 4000 exoplanets have been discovered in the Milky Way, including Earth-like planets with the potential to host life.

“Through the study of these exoplanets, we will learn more about the physics of how planets form and evolve, and get a new perspective on our planetary home,” said Danielsson.

“This year’s Nobel Laureates in physics have painted a picture of a universe far stranger and more wonderful than we ever could have imagined,” said Danielsson. “Our view of our place in the universe will never be the same again.”

How to be an exoplanet detective: Jo Barstow at New Scientist Live