James Peebles will get half the prize, whilst Michel Mayor and Didier Queloz share a quarter

Three scientists have won the Nobel Prize in physics for the discovery of how the early universe evolved after the Big Bang and finding the first exoplanet orbiting a faraway star.

One half of the prize, a sweet 4.5 million Swedish kroner – about $492,800 or £368,400 – goes to James Peebles, 84, a Canadian-born retired cosmology professor from Princeton University. Peebles was instrumental in producing detailed analytical models describing the universe unfolding fractions of a second after it came to be, all the way until the present, and the future. Along the way, scientists uncovered new fundamental principles.

“James Peebles took on the cosmos, with its billions of galaxies and galaxy clusters,” said The Swedish Academy, an organization responsible for awarding Nobel laureates. “His theoretical framework, developed over two decades, is the foundation of our modern understanding of the universe’s history, from the Big Bang to the present day.”

His work revealed what the universe looked like when just 5 per cent of its contents was known, the other 95 per cent was made up of dark matter and energy. One of his seminal papers published in 1965 described how the first galaxies could only form when the universe had sufficiently cooled down enough for matter to clump together under gravity.

The energy leftover from the Big Bang is still observable today. As the universe expanded, the wavelengths have increased over time to become the cosmic microwave background.

“When I started working in this subject — I can tell you the date, 1964 — at the invitation of my mentor, Professor Robert Henry Dicke, I was very uneasy about going into this subject because the experimental observational basis was so modest. … I just kept going,” Peebles said over the phone during the Nobel news conference. “Which particular step did I take? I would be very hard-pressed to say. It’s a life’s work.”

The first exoplanet in 1995

The second half of the prize will be shared by two Swiss astrophysicists: Michel Mayor, 77, a researcher working at the Observatory of Geneva, and one of his doctoral students, Didier Queloz, 53, a professor at the University of Geneva and the University of Cambridge.

IN 1995 the pair found the first exoplanet, 51 Pegasi b, orbiting a main sequence star, 51 Pegasi, similar to our own Sun, about 50 light years away in the Milky Way. Mayor and Queloz will each receive a quarter of the prize money – 2.25 million Swedish kroner ($246,400 or £199,800).

Nearly 4,000 otherworldly planets have been confirmed so far. The most popular method used to scout out these bodies is the Doppler shift, which involves monitoring a star’s brightness levels over time.

If it is harbouring an exoplanet, it’s brightness should periodically dip as an orbiting body crosses in front of it. Other techniques like the radial velocity allow astronomers to estimate the exoplanet’s mass.

Mayor and his colleagues built a new type of spectrograph that made it possible for them to observe a large number of stars covering a patch of sky in wavelengths from 390 to 680 nanometers.

They hit the jackpot when they published their paper titled “A Jupiter-mass companion to a solar-type star” in Nature. They discovered that 51 Pegasi b was just eight million kilometers from its parent star, a distance closer than Mercury is to our Sun. They believed that it was a gas-giant planet that was brought closer to its star over time.

“Discovery opened our exploration of these brand-new worlds, and now 24 years later we are at the verge of finding out if we are alone in the universe,” Lisa Kaltenegger, an accomplished exoplanet hunter and director of Cornell University’s Carl Sagan Institute, commented.

“The next steps, inspired by the amazing discovery 24 years ago of the first exoplanet, is to collect enough light from these small planets in the habitable zone to figure out if there are signs of life in their atmosphere. We are already building the telescopes that can collect enough light to answer the fundamental question of whether we are alone in the universe – or not.” ®

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