The Royal Academy of Sciences of Sweden has awarded the Nobel Prize in Physics 2019 to Michel Mayor, Didier Queloz and James Peebles. The first two were responsible for the discovery of the first planets outside the solar system. The third is one of the parents of cosmological theories that explain how the universe arose and what has been its evolution. In its announcement from Stockholm, the Swedish academy justifies its award for the contributions of the winners to human knowledge about the evolution of the cosmos and the place that Earth occupies in it.
Until less than 30 years ago, the existence of planets outside the solar system was only a theoretical approach, something that was very likely, but no one had been able to verify with direct observations. In 1992 Aleksander Wolszczan and Dale Frail announced the discovery of the first extrasolar planets in history. They orbited a neutron star, something that somehow devalued the discovery. Three years later, the Swiss Michel Mayor and Didier Queloz discovered the first extrasolar planet around a “normal” star and it was they who received recognition from the Swedish academy. Today more than 4,000 planets have been discovered outside the solar system, some of their atmospheres have begun to be studied and signs of biological activity will soon be sought. If Mayor and Queloz reminded us that our planet is just one more among the billions that roam the universe, the Canadian James Peebles developed theories decades ago to explain how it all started. In 1964, Robert Wilson and Arno Penzias, two Bell Labs company engineers, discovered while building a telecommunications antenna a background noise that they were not able to eliminate and whose origin they did not know.
That annoying signal was finally identified as the cosmic microwave background, a fossil radiation that was like a kind of echo of the Big Bang. The discovery, which also deserved the Nobel Prize in Physics, gave the reason to the scientists who had defended the idea that the universe began at a small point extremely hot and dense from which it expanded. More than half a century later, Peebles, one of the scientists who had predicted the existence of that background radiation, has also received the Nobel.
Even more than most scientific findings, the impact of the theories and discoveries of Peebles, Mayor and Queloz has an evident existential aspect. In 1600, astronomer Giordano Bruno was burned at the stake for defending, precisely, that the sun was one more star and that around the stars that were seen in the sky orbiting planets inhabited by intelligent beings. The second part has not yet been proven, but we already know that there are countless planets and that it is not so far-fetched to think that anyone welcomes beings who think. Peebles’ work approaches the mystery par excellence, the origin of everything. Despite the confirmation of many of his ideas, he himself doubts that one day that mystery ceases to be.