Nobel Prize in Physics 2019

They have been 2500 years of progress that have resulted in a clear image of how the cosmos appeared, what is in it and what properties it has, in addition to verifying that the Earth is not the only planet and that there is an extraordinary diversity of worlds beyond. James Peebles (Canada, 1935) has been awarded for his theoretical studies in cosmological physics. Professor emeritus of Princeton University, where he earned his doctorate in 1962, carrying out his entire career as a researcher, has made essential contributions in fields that cover from the formation of large-scale cosmological structures, microwave background radiation (the footprint which left the Big Bang, the beginning of the universe), the primary nucleosynthesis of chemical elements or the discovery of the existence of dark matter. His studies have been essential for cosmology to move from a speculative discipline to a fully established one, as recognized by the committee that awarded him the Shaw Prize in 2004. That is, to become a predictive science that allows to verify the different theories proposed to explain the observed data. Therefore, it has played an essential role in establishing the standard cosmological theory and in the contemporary image of the universe.

In 1995, Michel Mayor and his then student Didier Queloz presented at an international conference in Florence the discovery of the first planet that orbited around a solar-type star, 51 Peg, located about 50 light-years from Earth. This communication broke down one of the last barriers of anthropocentrism. Since then, more than 4000 exoplanets have been identified and, most significantly, an extraordinary diversity has been described both in their intrinsic properties (masses, radii, surface temperatures, densities, atmospheres in some cases) and the architectures of planetary systems ( properties of the star or stars around which they orbit, distances to them, number of planets). It can be said without any doubt that it has therefore entered the golden age of exoplanetary studies. The exoplanet of the 51 Peg stars is not the first such object whose existence has been announced. Prior to their discovery in 1995, several candidates for exoplanets had been identified, some of them controversial, that would be rejected in subsequent investigations or confirmed only after the announcement of Mayor and Queloz, or that orbited around neutron stars, super dense remains that they remain after the death of stars more massive than the Sun. However, the discovery of the two Swiss astrophysicists, who suffered some initial skepticism and great scrutiny by the community, was based on a technological development that allowed us to obtain the precise measurements of radial velocity, an indirect technique that is based on the periodic effect that the planet causes the star to orbit both around the common center of gravity. This is done through the use of spectrographs, instruments that break down light into its fundamental, very precise and stable elements.

The 51 Peg planet was identified on the 1.93 m Haute-Provence Observatoire telescope and the ELODIE spectrograph, installed a year earlier and developed with André Baranne, who together with Mayor had previously designed a precursor. Later Mayor and Queloz have developed or participated in other instruments of greater precision, such as HARPS, installed at the La Silla Observatory, the terrestrial spectrograph that more planets have discovered. In addition, Didier Queloz is the main scientific head of the European Cheops satellite, with a planned launch in December 2019, which will use the planetary transits technique to characterize previously identified planets with racial velocity. Michel Mayor (Switzerland, 1942) is Professor Emeritus of the University of Geneva, where he received a PhD in 1971. Didier Queloz (Switzerland, 1966), studied at the same university, where he obtained his PhD in 1995 under the direction of Higher. He is currently a professor at the University of Cambridge. On the occasion of the Nobel Prize, Michel Mayor has declared: “It is a fantasy to think that we can go there [the exoplanets]” and advocated the remote study through telescopes on land and in orbit. Both have jointly received the 2011 BBVA Frontiers of Knowledge awards and the 2017 Physics Wolf. Mayor’s work has also been recognized with the Royal Society gold medal in 2015, among other awards. Now the Nobel puts a well-deserved brooch to brilliant careers.

AUTOR  | David Barrado Navascués, Director científico Unidad María de Maeztu Centro de Astrobiología (CSIC-INTA)

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